Why did Facebook vanish?
According to Facebook's own explanation of the events, the problems started during a routine bit of maintenance on the company's internal backbone. This backbone is a series of fiber optic cables and data centers built and operated by Facebook to handle both internal communications and the external requests. Any time you log onto your Facebook account, browse Instagram, or send a message on WhatsApp, you're making such an external request.
Like any company maintaining a portion of the Internet's infrastructure, Facebook uses software tools to check on the status of its backbone. These tools are relatively simple: One might measure data throughput on a fiber line, for example, or temporarily take down one fiber line to test the redundancy of other lines. "These tools are not big, convoluted systems," says Yiannis Psaras, a researcher at Protocol Labs.
Apparently during some maintenance on Monday, a particular tool, instead of taking one line down for maintenance, sent out a command to take down every line. According to Psaras, it was as though the tool essentially cut every one of Facebook's fiber lines in half.
The problem compounded from there: Each of Facebook's own servers, unable to communicate with anything else, assumed it was the source of the fault, and therefore each one took itself offline.
Facebook uses larger data centers to hold all the content on its websites and apps, and smaller servers that handle Domain Name System (DNS) queries. DNS is often referred to as the Internet's phonebook—it's the system that converts plaintext URLs (such as spectrum.ieee.org) to IP addresses—the strings of numbers used to locate and retrieve a website's data.
When Facebook's DNS servers removed themselves from both Facebook's internal backbone, as well as the public-facing Internet, no one could reach anything Facebook-related for the same reason you can't call someone if you don't have their phone number. The DNS queries made by people trying to log onto their accounts all failed because there was no valid IP address to query.
Each of Facebook's own servers, unable to communicate with anything else, assumed it was the source of the fault, and therefore each one took itself offline.
As the hours passed, this slowed down the rest of the Internet too. Shiv Panwar, a researcher at NYU Wireless, explains that DNS is hierarchical—if a DNS query runs into a problem, it will check a wider range of servers to see if it can locate the information it needs. It's the equivalent of switching from a local phonebook to a regional one. In other words, people's attempts to log onto Facebook and Instagram affected requests for the rest of the Internet as their queries searched anywhere and everywhere for the information they were after.
Does Facebook's explanation make sense?
Yes, although the fact that a tool was the initial culprit surprised both Psaras and Panwar. Recall that the original problem was a tool sending out a command that managed to sever all of the routes between Facebook's data centers. "Why would the tool have this functionality, even as backup?" says Psaras.
Psaras explains that because software tools are designed to be simple, testing just one aspect of a network, it's a bit odd that the tool was able to cause a global screw up. It is possible, however, that Facebook does have and use a tool that could take down its internal backbone because of a bug.
Panwar suggests that the tool may have been designed to take down a particular route to test how the rest of the backbone picked up the slack. In other words, a tool designed to test the network's redundancy. It's easy to imagine a tool designed to take down a route, check the rest of the network, and bring the route back up before moving on to another potentially bugging out and taking down every route instead.
Could Facebook vanish again?
The answer is never "never," but it's unlikely. I've mentioned redundancy a few times—Facebook's backbone, like the rest of the Internet, has redundant routes to get from one location to another. Redundancy gives the Internet resiliency. It's not enough for one route to go down—every route has to fail to totally disrupt traffic.
The Internet is designed to survive "single-point failures." These are problems like a chip going bad, a link going down, a backhoe ripping a fiber line underneath a construction site, or someone pulling a plug in a data center. In fact, that's just the sort of thing Facebook's tool would have been testing for, if it was in fact supposed to be taking down one route to check the traffic load on the others.
Multi-point failures, on the other hand, are much rarer, because they're harder to pull off, either accidentally or intentionally. Of course, the fact that it did happen to Facebook is enough evidence that it's possible, if not probable.
You can rest assured, however, now that you're done reading this, you can log into Facebook or Instagram and know that they'll (almost definitely) load.
From Your Site Articles
Related Articles Around the Web
Top 10 Best Cb Base Station Radios
1. Uniden PROXL Channel CB Radio. Pro-Series, Compact Design. Public Address (PA) Function. Instant Emergency Channel 9, External Speaker Jack, Large Easy to Read Display. Black
- This compact sturdy radio is straightforward to make use of and can match into nearly any car with its compact dimension.
- The professionalxl is good for cb customers in search of an reasonably priced radio with cb and public handle performance, on the spot channel 9 emergency button, channel up/down buttons, and s/rf meter.
- Unidenâ€™s skilled sequence professionalxl is a compact and reasonably priced full 40 channel cb radio that includes cb and public handle capabilities with an easy-to-read giant backlit liquid crystal display show.
- Monitor your transmit energy and test the relative energy of incoming transmissions with the built-in sign/rf energy indicator, and use the general public handle perform to be heard exterior your car with an non-compulsory exterior pa speaker.
- Constructed-in exterior speaker jack permits connecting to an non-compulsory exterior speaker. included within the field: cb radio, four pin electret microphone, mounting hardware, mounting bracket, persons guide, two-year guarantee.
2. Cobra HH50WXST Hand Held CB Radio Emergency Radio, Travel Essentials, Earphone Jack, 4 Watt, Noise Reduction NOAA Alerts
- Noaa climate channels be the primary to know of incoming hazards or altering climate with on the spot entry to noaa climate channels 24 hours a day.
- Twin watch choose two channels to continuously monitor concurrently. preserve an ear open for incoming transmissions on a number of channels so youll hear alerts round you.
- Sound tracker the sound tracker system helps by slicing 90% of the noise, you will hear crystal clear communication with out the distractions of static and interference.
- Channel scan discover the channel with the very best sign robotically, with 40 channels to selected from. you will not must manually seek for a powerful sign once more.
- Prolonged vary four watt energy output permits most energy and prolonged vary of communication.
3. Uniden BEARCAT Channel SSB CB Radio with Sideband NOAA WeatherBand,7- Color Digital Display PA/CB Switch and Noise Cancelling Mic, Wireless Mic Compatible
- Massive easy-to-read show channel: illuminated management panel with 7 shade personalised show choices for simple use in all lighting situations. additionally options easy-to-read laser etched keys
- New noise cancelling microphone: noise canceling mic reduces background noise for crystal clear communication
- Keep linked: the bearcat ssb cb radio means that you can keep linked whereas out on the highway and is nice for folks with a protracted drive forward of them
- 40 channel: full spectrum cb operation immediately switches to emergency channel 9. options noaa climate channels with the push of a button
- Wi-fi microphone compatabile: the built-in swr offers good antenna matching. working with the uniden bcw cb wi-fi microphone the bearcat has develop into extra adaptable
4. Cobra 29LX Professional CB Radio Emergency Radio, Travel Essentials, NOAA Weather Channels and Emergency Alert System, Selectable 4-Color LCD, Auto-Scan and Radio Check, Black
- Noaa climate channels be the primary to know of incoming hazards or altering climate with on the spot entry to noaa climate channels 24 hours a day.
- Clock alarm â€“ show the present time on display and preserve your self alert by setting an alarm for anytime through the day to be sure tore all the time on time.
- Emergency radio cb radios present dependable communication which isnt depending on satellites and mobile networks that may be the distinction between getting skilled assist in an emergency and being left by yourself if you want help.
- Climate alert scan robotically tune into the strongest climate channel and alert tone accessible to catch each essential climate discover. with the 29lx you will not miss essential info whereas scanning by means of channels.
- Radio test frequency show robotically run diagnostics for voltage and rf output, with antenna matching to make sure that the sign is as robust as potential and dealing correctly. working cb and climate frequencies additionally displayed on display.
5. Uniden BCN MHz Channel Base/Mobile Scanner, Close Call RF Capture, Pre-programmed Search â€œActionâ€ Bands to Hear Police, Ambulance, Fire, Amateur Radio, Public Utilities, Weather, and More, Black
- The bcn options â€œclose name rf seize know-how,â€ which immediately tunes to alerts from close by transmitters. this pre-programmed search makes it simpler to search out lively frequencies and helps you keep on high of native happenings and emergencies in your space. ch/sec scan velocity (max)
- The bcn comes full with a backlit show, making it simpler to learn in low gentle situations, together with ac adapter, a dc energy cable and an automotive energy outlet plug, providing you with extra choices for supplying energy at residence or in your automobile. frequency vary for plane band is am mode eight step (khz) at , (decrease and higher)
- The uniden bearcat bcn cellular/base scanner is among the most function packed, user-friendly, entry degree scanners accessible at the moment. it may well decide up analog receptions together with 6 service banks for monitoring police, fireplace, emergency medical companies, marine, air, climate, and cb frequencies.
- It can save you as much as frequencies which might be scanned together with the preset frequencies. so everytime you encounter a newly activated native frequency for any service class, you possibly can add it to the financial institution for that class. this offers you fast entry to the frequencies you wish to hear.
- If youâ€™re searching for an reasonably priced option to leap into the world of scanners, the bcn will be the proper selection for you. (please notice: mannequin bcn shouldnt be appropriate for trunking or digital radio system monitoring. in case you reside in an space the place trunking or digital radio methods are used, its essential improve to a uniden digital mannequin (â€œdâ€ stands for digital), reminiscent of fashions
6. LATNEX RC-S Simplex Repeater Controller DMR Crossband Repeater and Radio Voice Recorder Connects to Virtually Any UHF, VHF Handheld, Base, Two Way, Amateur Ham or Mobile Radio
- âœ”ï¸multifunctional voice recorder whole recording time is sec with a most of three incoming messages. messages are despatched robotically each 15, 30 or 45 minutes. dtmf distant management for all capabilities
- âœ”ï¸appropriate works with hottest gmrs radio, cb, frs, pmr, novice radios, cellular radio. equipped okay plug appropriate cable connects with kenwood, baojie, linton, baofeng, puxing, wouxun, quansheng
- âœ”ï¸simplex repeater value efficient system for recording incoming transmissions and transmitting them on the identical frequency. extends the radio vary by re transmitting the message. might be used at residence or campground, or anywhere the place radio vary must be prolonged
- âœ”ï¸straightforward setup and transportable the only setup that may be carried out with a single handheld radio and is operated by batteries
- âœ”ï¸free prolonged guarantee 2 years guarantee ensures it will shortly develop into your favourite no-risk buy
7. Cobra 25LTD Professional CB Radio Emergency Radio, Travel Essentials, Instant Channel 9, 4 Watt Output, Full 40 Channels, 9 Foot Cord, 4 Pin Connector
- Instantaneous channel 9 speedy entry to emergency channel 9 to make sure youre driving safely from the very starting.
- four pin microphone connector permits you the handy choice of set up in your sprint for a smooth look or beneath your sprint for an area saving choice.
- Emergency radio cb radios present dependable communication which isnt depending on satellites and mobile networks that may be the distinction between getting skilled assist in an emergency and being left by yourself if you want help.
- 9 foot microphone twine simply attain all through cab with sufficient twine to comfortably talk. the coiled twine will stretch to the place you want it with out proscribing your calls.
- 40 channel entry navigate the whole vary of 40 channels for full protection of cb stations.
8. Patriot PAT12, watt, 12, Base Station CB Radio Antenna
- Consists of u-clamps to connect to an non-compulsory mast pipe.
- Simply tuneable , rated watt p.e.p no radials required.
- 12 foot tall fiberglass hello efficiency cb and 10 meter base roof vertical antenna.
- Accepts any non-compulsory coax cable with pl connector.
- Merchandise is made within the u.s.a !
9. Midland Micro Mobile GMRS Radio with Mount Base Mile Range, 15 Watts, Model MXT
- Prolonged vary the mxt contains a mile communication vary in open areas with little or no obstruction and the micromobileâ€™s full watts of energy and removable exterior magnetic mount cellular antenna provides functionality for prolonged vary past that of the typical gmrs radios.
- Noaa climate scan + alert noaa climate scan will robotically scan by means of 10 accessible climate (wx) band channels and locks onto the strongest climate channel to provide you with a warning of extreme climate updates. noaa climate alert will sound an alarm indicating that theres a danger of extreme climate in your space.
- 2-way radio the 15 watt micromobile walkie talkie is provided with 15 excessive/low energy gmrs channels and eight repeater channels for elevated communication vary.
- ctcss/dcs privateness codes the micromobile has privateness codes that offers you a lot channel choices so undesirable transmissions are usually not heard.
- Included within the field mxt micromobile gmrs 2-way radio, flip-frame removable mount, mounting hardware, removable antenna with magnetic mount, microphone, microphone holder, 12v energy twine with automobile adapter, fast begin information, and ownerâ€™s guide.
Tech specialist. Social media guru. Evil problem solver. Total writer. Web enthusiast. Internet nerd. Passionate gamer. Twitter buff.
- Hedge fund entry level
- Purina red bag
- 1999 mitsubishi eclipse black
- Sequoia front end swap
- Cambridge ma strip club
History/index of Cobra base station CB radio models
The other day I was thinking about all of the iconic Cobra base stations ever made. I have looked to see if anyone ever made a website dedicated to cataloging/indexing Cobra radios. It may be out there, but I'm not finding it. I kind of want to take this on as a project, and maybe some of you here can help me.
I know as far as the SSB models, you have, in order:
I know there was a Cobra , but many Cobra purists do not recognize this radio as genuine. I've never seen one in person, but I'm told it is very similar to that Cherokee channel AM/SSB base station I own.
As far as AM-only models, I only know of the following
-B&K Cobra Cam 88 (23 channel, tube radio)
-Cobra Cam 89 (23 channel, classic/iconic Cobra base station design)
-Cobra 87 GTL (I have never seen one in person, but Rooster on YouTube loves them)
-Cobra 89 XLR
-Cobra 89 GTL
-Cobra 90 LTD (desktop-style, not the iconic Cobra base look, 5-pin SSB mic)
I remember seeing a small, solid-state 23 channel model that is not the iconic base station look, that looks like it pre-dated the Cam It looked very cheap, had a volume, squelch and a channel dial. I have no idea what model that is.
Anyone here have anything to contribute?
|Cobra CB Radios||Cobra CB Radios|
|Cobra CB Radios||Cobra CB Radios|
|Cobra CB Radios||Cobra CB Radios|
|** Cobra CB Radios on Sale**|
|Cobra HH50 WXST Discontinued |
List Price: $
40 channel Cobra CB radio, compact CB radio, the entire radio fits in the palm of your hand, 10 weather channels, Dual watch - allows simultaneous monitoring of any 2 pre-selected channels. Channel scan - allows full 40 channel scan, LCD display panel indicated channel selected. Instant channel 9/19, sound tracker system to reduce unwanted noise.
|Cobra 75WXST More Info *In Stock NOW*|
List Price: $ Our Price $ Buy Now & Save
The Cobra CB radio model 75 WX ST has all 40 citizen band radio channels.
10 national weather channels (7 NOAA and 3 International) provide full coverage to keep you informed of weather conditions anywhere you go.
|Cobra 19DX IV More Info *In Stock NOW*|
List Price: $ Our Price $ Buy Now & Save
40 Channel Cobra CB radio, compact design, CB/PA function, RF Gain, instant channel 9/19, full function LCD display, easily installed into most cars and trucks.
|Cobra 18WXST II More Info *In Stock NOW*|
List Price:$ Our Price $ Buy Now & Save
40 Cobra CB radio, channels with channel scan, 10 NOAA weather channels, SoundTracker® noise reduction system, dual watch allows the monitoring of 2 channels simultaneously, front-firing speaker, last channel retention, signal strength & power meter
|Cobra 25 models to Choose from|
|Cobra 29 models to Choose from|
|Offering low prices & outstanding support before, during, & after the sale by seasoned radio techs. 30+ years experience. |
Our seasoned radio techs offer high quality radio repair, performance enhancements, antenna system troubleshooting and custom installation.
Need help or maybe just a recommendation? Our friendly & experienced staff is here to help.
We specialize in radio brands like Connex, Cobra, Galaxy, General, Magnum, Ranger, Stryker, Uniden and J&M motorcycle CB radio systems. Results Guaranteed!
Notice: For Citizen Band Radios
10 - Meter Radio License Disclosure:
Base cb radio cobra
Citizens band radio
Land mobile radio system
Citizens band radio (also known as CB radio), used in many countries, is a land mobile radio system, a system allowing short-distance person-to-person bidirectional voice communication between individuals, using two way radios operating on 40channels near 27MHz (11m) in the high frequency (a.k.a. shortwave) band. Citizens band is distinct from other personal radio service allocations such as FRS, GMRS, MURS, UHF CB and the Amateur Radio Service ("ham" radio). In many countries, CB operation does not require a license, and (unlike amateur radio) it may be used for business or personal communications. Like many other land mobile radio services, multiple radios in a local area share a single frequency channel, but only one can transmit at a time. The radio is normally in receive mode to receive transmissions of other radios on the channel; when users want to talk they press a "push to talk" button on their radio, which turns on their transmitter. Users on a channel must take turns talking. Transmitter power is limited to 4watts in the US and the EU. CB radios have a range of about 3 miles (km) to 20 miles (32km) depending on terrain, for line of sight communication; however, various radio propagation conditions may intermittently allow communication over much greater distances.
Multiple countries have created similar radio services, with varying technical standards and requirements for licensing. While they may be known by other names, such as the General Radio Service in Canada, they often use similar frequencies (26–28MHz) and have similar uses, and similar technical standards. Although licenses may be required, eligibility is generally simple. Some countries also have personal radio services in the UHF band, such as the European PMR and the Australian UHF CB.
Main article: CB radio in the United States
The citizens band radio service originated in the United States as one of several personal radio services regulated by the Federal Communications Commission (FCC). These services began in to permit citizens a radio band for personal communication (e.g., radio-controlled model airplanes and family and business communications). In , the original CB radios were designed for operation on the –MHz UHF band. There were two classes of CB radio: "A" and "B". ClassB radios had simpler technical requirements, and were limited to a smaller frequency range. Al Gross established the Citizens Radio Corporation during the late s to manufacture classB handhelds for the general public.:13 Originally designed for use by the public sector, the Citizens Radio Corporation went on to sell over , units, primarily to farmers and the US Coast Guard.
Ultra-high frequency (UHF) radios, at the time, were neither practical nor affordable for the average consumer. On September 11th :14 CB service classD was created on 27MHz, and this band became what is popularly known today as "Citizens Band". Only 23channels were available at the time; the first 22 were taken from the former amateur radio service 11meter band, and channel23 was shared with radio-controlled devices. Some hobbyists continue to use the designation "11meters" to refer to the Citizens Band and adjoining frequencies. Part95 of the Code of Federal Regulations regulates the classD CB service, on the 27MHz band, since the s and continuing today. Most of the –MHz band was reassigned for business and public-safety use; CB ClassA is the forerunner of the General Mobile Radio Service (GMRS). CB ClassB is a more distant ancestor of the Family Radio Service. The Multi-Use Radio Service is another two-way radio service in the VHF high band. An unsuccessful petition was filed in to create a CB ClassE service at MHz, (part of the amateur radio 1¼m band at the time) which was opposed by amateur radio organizations and others. There are several other classes of personal radio services for specialized purposes (such as remote control devices).
During the s, the service was popular among small businesses (e.g., electricians, plumbers, carpenters), truck drivers and radio hobbyists. By the late s, advances in solid-state electronics allowed the weight, size, and cost of the radios to fall, giving the public access to a communications medium previously only available to specialists. CB clubs were formed; a CB slang language evolved alongside codes, similar to those used in emergency services.
After the oil crisis, the U.S. government imposed a nationwide 55 mph speed limit, and fuel shortages and rationing were widespread. Drivers (especially commercial truckers) used CB radios to locate service stations with better supplies of fuel, to notify other drivers of speed traps, and to organize blockades and convoys in a strike protesting the new speed limit and other trucking regulations. The radios were crucial for independent truckers; many were paid by the mile, and the 55mph speed limit lowered their productivity.
The popularity spread further into the general population in the US in the middle of the s. Originally, CB (named Citizens Radio by the Federal Communications Commission as of ) required the use of a callsign in addition to a purchased license ($20 in the early s, reduced to $4 on March 1, ); however, when the CB craze was at its peak many people ignored the requirement and invented their own nicknames (known as "handles"). Lax enforcement of the rules on authorized use of CB radio led to widespread further disregard of the regulations (notably in antenna height, distance communications, licensing, call signs, and transmitter power). Individual licensing came to an end on April 28, 
The popularity of the use of CB radios in s made its way into films, television, and music by the late s. Films such as Smokey and the Bandit (), Breaker! Breaker! (), Citizens Band (a.k.a. Handle with Care) (), and Convoy (), made heavy reference to the phenomenon, as did television series such as Movin' On (debuted in ) and The Dukes of Hazzard (debuted ) helped cement CB radio's status as a nationwide craze in the United States over the mid- to lates. The phenomenon also inspired several popular and country music songs in and
- C.W. McCall's novelty song "Convoy" (), which climbed to #1 in the Billboard Hot in January, to #2 in the UK Charts during the spring of , and inspiring the film of the same name. In the UK, BBC Radio OneDJsDave Lee Travis and Paul Burnett covered the song with an altered UK song text, released as "Convoy GB" under the moniker Laurie Lingo & the Dipsticks, chart-peaking at #4 in the spring of
- "The White Knight", a novelty country music song made famous by Jay Huguely, who — recording as Cledus Maggard & The Citizen's Band — enjoyed a brief run of national popularity with the song when it became popular in 
- "Colorado Call" by Shad O'Shea & the 18Wheelers was another early hit song based on the CB-ing truckers myth, reaching the national US charts.
- "'Round the World with the Rubber Duck" is a sequel to "Convoy", recorded by C.W. McCall. It was released in late spring , and peaked at #1 in the BillboardBubbling Under Hot charts.
- "One Piece At A Time" by Johnny Cash (), peaked in the UK charts at #12 in early summer.
- "Teddy Bear" by Red Sovine () charted in the UK at #6 in late summer.
Betty Ford, the former First Lady of the United States, used the CB handle "First Mama".
Voice actor Mel Blanc was also an active CB operator, often using "Bugs" or "Daffy" as his handle and talking on the air in the Los Angeles area in one of his many voice characters. He appeared in an interview (with clips having fun talking to children on his home CB radio station) in the NBC Knowledge television episode about CB radio in Similar to Internet chat rooms a quarter-century later, CB allowed people to get to know one another in a quasi-anonymous manner.
Originally, the U.S. had 23CB channels; the 40channel band plan was implemented in Two more channels between 22 & 23, commonly referred to as 22A & 22B, were available. Several people had 22A, but few had 22B. In the early s Radio Shack sold a "base station" CB radio that contained a crystal for each of the 23channels, two extra slots existed, and one could order the 22A & 22B crystals for an easy plug-in. Channel9 was officially reserved for emergency use by the FCC in :12 Channel10 was originally often used for highway travel communications east of the Mississippi River, and channel19 west of the Mississippi; channel19 then became the preferred highway channel in most areas, as it did not have adjacent-channel interference problems with channel9. Many CBers called channel19 "the trucker's channel". The FCC originally restricted channel11 for use as the calling channel.
The original FCC output power limitation for CB radios was "5watts DC input to the final amplifier stage", which was a reference to the earlier radios equipped with tubes. With solid state radios becoming more common in the s, the FCC revised this specification at the same time the authorized channels were increased to The current specification is simply "4watts output (AM) or 12watts output (SSB)" as measured at the antenna connector on the back of the radio. The old specification was often used in false advertising by some manufacturers who would claim their CB radios had "5watts" long after the specification had changed to 4watts output. The older 23channel radios built under the old specifications typically had an output of around to watts output when measured at the antenna connector. The FCC simply rounded up the old "5watts DC input to the final amplifier stage" specification to the new "4watts output as measured at the antenna connector on the back of the radio", resulting in a far simpler and easier specification.
Initially, the FCC intended for CB to be the "poor man's business-band radio", and CB regulations were structured similarly to those regulating the business band radio service. Until ,:14 only channels9–14 and 23[a] could be used for "interstation" calls (to other licensees). Channels1–8 and 15–22 were reserved for "intrastation" communications (among units with the same license).[b] After the inter-station/intra-station rule was dropped, channel11 was reserved as a calling frequency (for the purpose of establishing communications); however, this was withdrawn in : During this early period, many CB radios had "inter-station" channels colored on their dials, while the other channels were clear or normally colored.[c] It was common for a town to adopt an inter-station channel as its "home" channel. This helped prevent overcrowding on channel11, enabling a CBer to monitor a town's home channel to contact another CBer from that town instead of a making a general call on channel
Boating and the U.S. Coast Guard
Since the price of CB was dropping and VHF Marine Band was still expensive, many boaters installed CB radios. Business caught on to this market, and introduced marine CBs containing a weather band (WX). Whether the Coast Guard should monitor CB radio caused much controversy, but they did, using Motorola base stations at their search and rescue stations. The Coast Guard stopped this practice in the late s and recommends VHF Marine Band radios for boaters.
CB has lost much of its original appeal due to development of mobile phones, the internet and the Family Radio Service. Changing radio propagation for long-distance communications due to the 11year sunspot cycle is a factor at these frequencies. In addition, CB may have become a victim of its own popularity; with millions of users on a finite number of frequencies during the mid-to-late s and early s, channels often were noisy and communication difficult, which reduced interest among hobbyists. Business users (such as tow-truck operators, plumbers, and electricians) moved to the VHF and UHF business band frequencies. The business band requires an FCC license, and usually results in an assignment to a single frequency. The advantages of fewer users sharing a frequency, greater authorized output power, clarity of FM transmission, lack of interference by distant stations due to skip propagation, and consistent communications made the VHF (Very High Frequency) radio an attractive alternative to the overcrowded CB channels.
The FCC restricts channel9 to emergency communications and roadside assistance. Most highway travelers monitor channel Truck drivers still use CB, which is an effective means of obtaining information about road construction, accidents and police speed traps.
Before CB was authorized in Australia, hand-held 27MHz "walkie-talkies" were available, which used several frequencies between the present CB channels, such as MHz. By the mids, hobbyists were experimenting with handheld radios and unauthorized 23channel American CB radios. At that time in Australia, licensed ham operators and Emergency Services still used the 11 meter band which was not yet available for CB use. Multiple CB clubs had formed by this time, which assigned call signs to members, exchanged QSL cards, and lobbied for the legalisation of CB. In late , having legalised Australian CB and allowed the import / sale of American and Japanese 23channel sets, the Federal Government drafted new interim regulations for Australian 18channel transceivers. The new RB regulations came into effect on January 1, and the last official registration date for 23channel sets was January 31, After this date, use of unregistered 23channel CB sets was deemed illegal and unlicensed sets were no longer eligible to be licensed. The 18channel band plan used 16channels of the 23channel CB radios plus 2extra channels at and MHz, to make up the 18channels. The original channels1, 2, 3, 4, 10, 21 and 23 were deleted from the 18channel band plan. So channel 1 on an 18 channel was actually channel5 on a 23channel radio. These roughly corresponded to the present channels5–22, except for the two unique frequencies that are known as 11A (Channel7 on an 18channel Australian CB) and 19A (Channel16 on an 18channel Australian CB) or remote control frequencies but are no longer part of the Australian 27MHz CB band since 40Channels were introduced. On January 1, , the American 40channel band plan was adopted.
From the outset, the government attempted to regulate CB radio with license fees and call signs, but eventually they abandoned this approach. Enthusiasts rushed for licences when the doors opened at post offices around Australia in mid and by the end of the first quarter of an estimated ,licences were issued (Australia's Population in was million). The regulations called for one licence per CB radio. The price for a licence in was AU$25per year (In mid the Australian Dollar exchange rate was AU$ to US$), a not insubstantial amount for the average Australian wage-earner. Australian CB radio uses AM, USB, and LSB modes (no FM) on 27MHz, allowed output power being 4Watts AM and 12Watts SSB. When UHF CB was first legalised the 27MHz CB Band was intended to be closed to Australian CBers in and only the MHz UHF band was to continue, however this did not eventuate. The first MHz CB radio in was designed and made in Australia by Philips TMC and was a 40channel CB called the FM
|Channel Number||Frequency (MHz)||Purpose|
|11||AM Call Channel|
|16||LSB Call Local|
|35||LSB Call DX|
The first CB club in Australia was the Charlie Brown Touring Car Club (CBTCC), which formed in Morwell, Victoria in and consisted mainly of four-wheel drive enthusiasts. The club used the prefix "GL" (for Gippsland), since "CB" could not be used. After July 1, , the club changed its name to Citizens Band Two Way Communication Club (CBTCC). Other early clubs were "LV" (Latrobe Valley) and "WB" (named after Wayne Britain). Members of these clubs are still active, and have also become amateur radio operators. Other Australian cities which became CB radio "hotspots" were Seymour, Benalla, Holbrook and Gundagai, all located on the busy Hume Highway between Melbourne and Sydney. Other regional cities such as Bendigo, Mildura, Mount Gambier and Port Augusta, developed lively, colourful CB radio communities.
With the introduction of UHF CB radios in , many operators used both UHF and HF radios and formed groups to own and operate local FM repeaters. Members of the CBTCC formed what became known as Australian Citizens Radio Movement (ACRM) in the early s; this organization became the voice for legalization of CB radio throughout Australia. After peaking in the s and early s, the use of 27MHz CB in Australia has fallen dramatically due to the introduction of MHz UHF CB (with FM and repeaters) and the proliferation of cheap, compact handheld UHF transceivers. Technology such as mobile telephones and the internet have provided people with other choices for communications. The Australian government has changed the allocation of channels available for UHF CB Radio from 40 to 80, and doubled the number of repeater channels from 8 to 
27MHz marine radio
See also: Marine VHF radio
Source: Several channels are allocated for maritime use in Australia. Australia also permits the use of marine VHF radio. 27MHz radios have the advantage of not requiring a certificate of proficiency to use, however they may not be monitored by rescue organisations or larger vessels. VHF radios are recommended by state agencies, such as Marine Safety Victoria and Marine Rescue NSW.
|Channel Number||Frequency (MHz)||Purpose|
|88||Distress, urgency, safety and calling (primary)|
|86||Distress, urgency, safety and calling (secondary)|
|68||Commercial operations (ship-shore/ship-ship)|
|90||Non-commercial operations (ship-shore)|
|91||Non-commercial operations (ship-shore)|
|94||Specific events only (ship-shore/ship-ship)|
|96||Non-commercial operations (ship-ship)|
|98||Safety/rescue operations (ship-shore/ship-ship)|
|72||Commercial fishing operations (ship-shore/ship-ship)|
|82||Commercial fishing operations (ship-shore/ship-ship)|
In Canada, the General Radio Service uses the identical frequencies and modes as the United States citizens band, and no special provisions are required for either Canadians or Americans using CB gear while traveling across the border. The General Radio Service was authorized in Initially, CB channels1–3 remained allocated to amateur radio and channel23 was used by paging services. American CB licensees were initially required to apply for a temporary license to operate in Canada. In April, the service was expanded to the same 40channels as the American service.
In Indonesia, CB radios were first introduced about when some transceivers were imported illegally from Australia, Japan and the United States. The dates are hard to confirm accurately, but early use was known around large cities such as Jakarta, Bandung, Yogyakarta, Surabaya and Medan. The Indonesian government legalized CB on 6October with a decision by the Minister of Communications, the "Ministerial Decree on the Licensing for the Operation of Inter-Citizens Radio Communication". Because many people were already using 40channel radios prior to legalization, the American band plan (with AM and SSB) was adopted; a VHF band was added in , along with allowing use of the Australian UHF CB channel plan at MHz On 10November , the Indonesian Directorate General of Posts and Telecommunications issued another decree establishing RAPI (Radio Antar Penduduk Indonesia) as the official citizens band radio organization in Indonesia.
In Malaysia, citizens band radios became legal when the "Notification of Issuance Of Class Assignments" by Communication and Multimedia Malaysia was published on 1April Under this class assignment, a CB radio is classified as a "Personal Radio Service device". The frequency band is HF, MHz to MHz (40 channels), power output is 4watts for AM and FM and 12watts PEP for SSB. Channel9 is reserved for emergencies, and channel11 is a calling channel. On UHF MHz, citizens band PRS radio devices are allowed 5 watts power output on FM on 39assigned channels spaced at kHz intervals from –MHz. Channel9 is reserved for emergencies, and channel11 for calling. A short-range simplex radio communications service for recreational use is from –MHz FM mode with 38channels and a power output of mW. A CB radio or Personal Radio Service Device under Class Assignment does not need an individual license to operate in Malaysia if it adheres to the rules of the Warta Kerajaan Malaysia
On 1April the MCMC (Malaysian Communications and Multimedia Commission) released a new regulation and later on  This includes a new UHF PMR MHz allocation: an eight-channel analog Personal Mobile Radio MHz (Analog PMR) with frequencies from –MHz (kHz spacing) FM with watt power output, and 16channels for Digital Personal Mobile Radio MHz (Digital PMR ). Frequencies for Digital PMR are from –MHz with kHz channel spacing in 4FSK mode and a power output of watt. An unofficial citizens band radio club in Malaysia is the "Malaysia Boleh Citizen Radio Group", known as "Mike Bravo" (Malaysia Boleh).
Main article: CB radio in the United Kingdom
In the UK, small but growing numbers of people were illegally using American CB radios during the late s and early s. The prominence of CB radio grew in Britain partly due to the popularity of novelty songs like C.W. McCall’s "Convoy" and Laurie Lingo & The Dipsticks’ "Convoy GB" in (both of which were Top5 hits). By , CB radio was becoming a popular pastime in Britain; as late as the summer of the British government was still saying that CB would never be legalized on 27MHz, proposing a UHF service around MHz called "Open Channel" instead. However, in November (after high-profile public demonstrations) 40frequencies unique to the UK, known as the 27/81 Bandplan using FM were allocated at 27MHz plus 20channels on MHz (–MHz with 50kHz spacing). CB's inventor, Al Gross, made the ceremonial first legal British CB call from Trafalgar Square in London.
The maximum power allowable on the MPT 27/81 system was 4watts (in common with the American system), although initially radios were equipped to reduce output power by 10dB (to watts) if the antenna was mounted more than 7meters (23') above ground level. The power-reduction switch is also useful in reducing TV interference. MPT also restricted antennas to a maximum length of meters (5'), with base loading being the only type permitted for 27MHz operation. Over the next several years antenna regulations were relaxed, with antenna length increasing to meters (5'5") and centre- or top-loading of the main radiating element permitted. On 1September the UK added the usual 40frequencies (–MHz) used worldwide, for a total of 80channels at 27MHz; antenna regulations were further relaxed, and the MHz band was withdrawn in
CB radio in the UK was deregulated in December by the regulatory body Ofcom, and CB radio in the UK is now license-free. The old MPT 27/81 band will continue to be available for the foreseeable future. On 27June , changes were made by Ofcom to allow the use of AM & SSB modes on CB in the UK legally for the first time. The rules regarding non-approved radios and power levels above 4Watts on AM/FM and 12Watts on SSB still apply, despite deregulation. Persons using illegal equipment or accessories still risk prosecution, fines or confiscation of equipment, although this is rarely enforced. AM and SSB on the freeband and amplifier use are common among enthusiasts. Packet radio is legal in the UK, although not widely used. Internet gateway stations are also beginning to appear; although illegal on 27MHz, these units are connected to other CB stations around the world.
Although the use of CB radios in the UK is limited they are still popular, especially with the farming community, truckers, off-roaders and mini-cab services. The widely used channel for the Young Farmers' Club is channel The normal calling and truckers' channel is channel 19, although many truck organisations and groups use other channels to avoid abuse.
CB radio is not a worldwide, standardized radio service. Each country decides if it wants to authorize such a radio service from its domestic frequency authorizations, and what its standards will be; however, similar radio services exist in many countries. Frequencies, power levels and modes (such as frequency modulation (FM), amplitude modulation (AM), and single-sideband modulation (SSB), often vary from country to country; use of foreign equipment may be illegal. However, many countries have adopted the American channels and their associated frequencies, which is generally in AM mode except some higher channels which are sometimes in SSB mode. In Sept the FCC approved the use of FM on CB radio. 
The standard channel numbering is harmonized through the FCC (America) and the CEPT (Europe).[d]
See also channel assignments for CB use in the United States.
- * Channels3, 7, 11, 15, and 19 have adjacent "hidden" channels (see below); channels23, 24, and 25 are numbered out-of-order for their frequency allocations in the United States.
When looking at the FCC/CEPT channel list there are some channels with a spacing of 20kHz instead of the regular 10kHz step. These intermediate frequencies are reserved for the Radio Control Radio Service (RCRS).[e] The RCRS service is commonly used for remote control of model aircraft and boats. It is an unofficial practice to name these channels by their next lower standard channel number along with a suffix"A". Specifically channel 11A is used to power Eurobalises.
Single-sideband (SSB) operation involves the selection of either the Lower Side Band (LSB) or the Upper Side Band (USB) mode for transmit and receive. SSB radios also have the standard AM mode for communicating with standard CB radio models. With the original 23CB channels SSB stations commonly used channel16, to avoid interference to those using AM (SSB stations are authorized to use 12watts, as opposed to 4watts for AM stations) and to more easily locate other SSB stations. With the FCC authorization of 40channels, SSB operation shifted to channels36– Channel36 (or 38 for LSB) became the unofficial SSB "calling channels" for stations seeking contacts, with the subsequent conversation moving to channels37– CBers with AM-only radios are asked to not use channels36 through In return, SSB stations stay off the remaining 35channels so they could be used by AM stations. This agreement provides interference-free operation for all operators by separating the far more powerful SSB stations from the AM stations. This solution also resolves the confusion created by the false advertising that SSB radios have channels compared to only 40 for AM radios.
While a SSB radio has three possible "modes" (AM, LSB, USB) it can operate in, operation is still limited to the same 40channels. Some manufacturers tried to sell more radios by claiming that with three different modes possible for each channel, it was the equivalent to channels. Reality is far different: Attempting an SSB conversation while an AM conversation is in progress results in jammed communications for everyone. In general, each channel can only support one AM conversation and no others; if no AM conversation is in progress, two SSB conversations can share one channel without interference if one is in LSB and the other in USB mode. For a particular conversation, everyone must be tuned to the same channel and same mode in order to talk with each other. Starting in Sept the FCC has approved FM for CB in the US with channel 1 being used as a FM call channel.
Main article: Personal radio service
The European Conference of Postal and Telecommunications Administrations (CEPT) adopted the North American channel assignments, except channel23, frequency MHz; channel24, frequency MHz; and channel25, frequency MHz. However, legal CB equipment sold in Europe does follow the North American channel designation. Some member countries permit additional modes and frequencies; for example, Germany has 40additional channels at 26MHz for a total of The United Kingdom has an additional 40channels between and MHz, also making 80channels in total. Before CEPT, most member countries used a subset of the 40U.S. channels.
In Russia and Poland the channels are shifted 5kHz down; for example, channel30 is MHz. Many operators add a switch to change between the "zeroes" (the Russian/Polish channel assignment) and the "fives" (the international/European assignment). Most contemporary radios for that markets can do "fives" as well as "zeroes" out of the box. Since roughly –, Russia and Poland have adopted use of the standard US channel offset as well as the older channel plan, for two overlapping "grids" of channels.
Russia uses an alphanumeric designation for their CB channel plans, because several "grids" or "bands" of 40channels each are used, along with both AM and FM mode. Russian CB allocations follow the CB band –MHz (designated as bandC), as well as –MHz (designated as bandB) and –MHz (designated as bandD). Some radios refer to the "mid band" (standard CB band) as "bandD" which shifts the letters up one (making –MHz "bandC" and –MHz "bandE".
For the convenience of users of the grid were marked by letters. Classic is considered the marking when the main range is designated letter"C". The most common description of the channel is considered to be similar to the following: (C9FM or C9EFM or C9EF or 9EF).
- the first letter («C») is indicated by a grid that contains a set of 40channels. If the first letter is not specified, it is considered that it is («C»). For example, (C9EF, 9EF)
- hereinafter ("9") – the channel number. Sometimes less than 10channels are designated 2digits. For example, (C9EF, C09EF)
- behind it – an optional designation («E») for "European" or mandatory («R») for "Russian" size frequency nets. For example, (C9EF, C9F, C9RF)
- end – the used modulation («FM») or («F»), («AM») or («A»). e.g. (C9EFM, C9EF, C9EAM, C9EA)
An example of correct designations: C9EF, C9EA, C9RF, C9RA
The 25–30MHz band (including the CB allocations and frequencies above and below the –MHz band) is heavily used for taxi cab and other mobile two-way communications systems in Russia, Ukraine and other former USSR country states.
New Zealand and Japan have unique allocations compared to any other country. New Zealand authorizes use of their New Zealand specific 40channel –MHz frequency plan in addition to the "standard" 40channel –MHz frequency plan for a total of 80HF CB channels. New Zealand has adopted the Australian UHF CB System as well.
Japan's CB allocation consists of 8voice and 2radio control channels with a maximum power output of mW. AM mode is the only mode permitted and antennas must be non-removable and less than cm (78inches) long. In Japan, the 26–28MHz range is allocated to fishery radio services and these frequencies are heavily used for marine communications. Japan's "double side band fishery radio" or "DSB Fishery Radio Service" covers MHzMHz, MHz, and MHz. However, frequencies such as MHz AM are widely pirated in Japan with very high power transmitters. This causes interference to the authorized low-power 1Watt DSB (1Watt AM) fishery radio service. Instead of 26–27MHz, Japan has authorized several UHF FM CB-type personal radio services in the MHz, –MHz and –MHz bands.
- MHz – Japanese CB Channel 1
- MHz – Japanese CB Channel 2
- MHz – Japanese CB Channel 3
- MHz – Japanese CB Channel 4
- MHz – Japanese CB Channel 5
- MHz – Japanese CB Channel 6
- MHz – Japanese CB Channel 7
- MHz – Japanese CB Channel 8 – Calling Channel
- MHz – Japanese Remote Control R/C Frequency
- MHz – Japanese Remote Control R/C Frequency
- MHz – Japanese Remote Control R/C Frequency
Indonesia has the usual 40channels at 27MHz, plus a unique channel allocation from –MHz.
In Brazil, CB channels were upgraded from 23 to 60 channels starting in and again in to 80 channels[pt] (from MHz to MHz).
CB Radio Channels (ANATEL)
South Africa, like New Zealand and the UK, permits the use of two HF CB bands. South Africa has a 23channel AM / SSB 29MHz CB allocation (called "29 Megs" or "29 MHz CB") from –MHz in kHz steps. South Africa also permits use of standard CB channels19–27 (–MHz) with AM / SSB permitted. Many radios sold in South Africa feature both the 27MHz and 29MHz bands. A license from ICASA is required to purchase or use a CB radio in South Africa.
Hungary allows use of the "low channels" for a total of 80channels (MHz to MHz).
Germany authorizes a similar allocation, with 40channels from –MHz and another 40channels from –MHz in regular 10kHz steps.
The Czech Republic authorizes 80 channels as well (same as the German 80channel plan). As in Germany, digital modes are allowed on certain frequencies.[f]Internet gateways and radio repeaters are allowed on channels 18[MHz] and 23[MHz]. Paging is permitted on channel1 (MHz) and channel80 (MHz) is the recommended call channel for Czech CB radio operators.
Using radios outside their intended market can be dangerous, as well as illegal, as frequencies used by Citizen's Band radios from other countries may operate on frequencies close to, or used by, emergency services (for example, the Indonesian service around MHz operates on frequencies allocated to a public safety network shared with police, fire and EMS services in Ontario, Canada).
In the Philippines, up to present time, the use of 27MHz CB is still banned since the Marcos regime banned it in s. A few operators still illegally utilize the 40CB channels. There are active CB groups that are now asking Senator Bongbong Marcos, the son of the late president Ferdinand Marcos, to lift the ban and make the use of CB radios legal again.
CB was the only practical two‑way radio system for the individual consumer, and served several subsets of users such as truck drivers, radio hobbyists, and those in need of short‑range radio communications, such as electricians, plumbers, and carpenters, who needed to communicate between job site and main office. While some users have moved on to other radio services, CB is still a popular hobby in many countries. The 27MHz frequencies used by CB, which require a relatively long aerial and tend to propagate poorly indoors, discourage the use of handheld radios. Many users of handheld radios (families, hunters and hikers) have moved on to 49MHz and the UHF Family Radio Service; those needing a simple radio for professional use (e.g., tradesmen) have moved on to "dot-color" Business Band radios and the VHF Multi-Use Radio Service.
CB is still popular among long-haul truck drivers to communicate directions, traffic problems and other relevant matters. The unofficial "travelers channel" in most of the world is channel19; in Australia it is channel8 (MHz) and UHF channel40 (MHz). In Russia it is channel15 (in addition to traditional emergency channel9 and truckers' channel19) and in Greece it is channel13, all AM. These frequencies may have evolved because tuned circuits (particularly antennas) work best in the middle of the band; the frequency for channel19 (not channel20) is the center of the 40channel US band and other things being equal, signals will be transmitted and heard the farthest. Since less standardization exists in Europe, CB there is more associated with hobbyists than with truckers.
Legal (short‑range) use of CB radio is sometimes impeded by users of illegal high‑power transmitters, which can be heard hundreds of miles away. The other problem with short‑range CB use is propagation; during long‑range "skip" conditions local signals are inaudible due to reception of multiple distant signals.
In the United States, the number of users and law enforcement financing by the Federal Communications Commission mean that only the worst offenders are sanctioned, which makes legitimate operation on the citizens band unreliable. Most offenders are not caught for interfering with other CB users; often, their self‑modified equipment generates harmonics and spurs which cause interference to services outside the citizens band and to consumer equipment.
The maximum legal CB power output level in the U.S. is 4watts for AM (un-modulated carrier; modulation can be four times the carrier power, or 16watts PEP) and 12watts for SSB, as measured at the transmitter antenna connection. However, external linear amplifiers are often used illegally.
During the s the FCC banned the sale of linear amplifiers capable of operation from 24–35MHz to discourage their use on the CB band, although the use of high‑power amplifiers continued. Late in , the FCC amended the regulation to exclude only 26–28MHz to facilitate amateur 10meter operation. Lax enforcement enables manufacturers of illegal linear amplifiers to openly advertise their products; many CB dealers include these amplifiers in their catalogs. Due to their rampant, unchecked use of linear amplifiers, American CB Radio operators are often referred to as "Alligators", by operators in other countries (suggesting American operators are "All Mouth and No Ears"). Attempts by law-abiding CB users to increase regulatory oversight have been ineffective.
At the beginning of the CB radio service, transmitters and receivers used vacuum tubes; solid-state transmitters were not widely available until , after the introduction of RF power-transistors.Walkie-talkie hand-held units became affordable with the use of transistors. Early receivers did not cover all the channels of the service; channels were controlled by plug-in quartz crystals, with one of several operating frequencies selected by a panel control in more expensive units. Superheterodyne receivers (using one or two conversion stages) were the norm in good-quality equipment, although low-cost toy-type units used super-regenerative receivers. With the earliest sets two quartz crystals were needed for transmitting and receiving on each channel, which was costly. By the mids "mixer" circuits made frequency-synthesized radios possible, which reduced cost and allowed full coverage of all 23channels with a smaller number of crystals (typically14). The next improvement came during the mids; crystal synthesis was replaced by PLL technology using ICs, enabling 40channel sets with only one crystal (MHz). Almost all were AM-only, although there were a few single sideband sets.
Most CB radios sold in the United States have the following features:
- Automatic noise limiter or noise blanker: Reduces background noise (such as spark ignition)
- CB / WX switch: Selects weather-radio receiver
- Automatic level control (ALC): Limits the transmitter modulation level to reduce distortion
- PA: Some transceivers can drive an external speaker and act as a low-power public address system, or "bullhorn".
- RF gain: Adjusts the RF amplifier gain of the receiver; used to reduce received background noise, and to reduce "clipping" due to over-amplification of already-strong signals (for example, when the receiver is near the transmitter)
- NOR / 9 / Quickly tunes preset channels for calling or emergency use
- SWR: Meter used to monitor reflected power caused by mismatched antennas and antenna cables
- Volume control
Microphone choices include:
27MHz is a relatively long wavelength for mobile communications, and the choice of antenna has a considerable impact on the performance of a CB radio. A common mobile antenna is a quarter-wave vertical whip. This is roughly 9feet (m) tall; it is mounted low on the vehicle body, and often has a spring-and-ball mount to enhance its flexibility when scraping or striking overhead objects. Where a nine-foot whip is undesirable, shorter antennas include loading coils to make the antenna impedance the same as a physically longer antenna. The loading coil may be on the bottom, middle, or top of the antenna, while some antennas are wound in a continuously-loaded helix.
Many truckers use two co-phased antennas, mounted on their outside mirrors. Such an array is intended to enhance performance to the front and back, while reducing it to the sides (a desirable pattern for long-haul truckers). To achieve this effect, the antennas must be separated by about eight feet, only practical on large trucks. Two antennas may be installed for symmetrical appearance, with only one connected.
Another mobile antenna is the continuously-loaded half-wave version. They do not require a ground plane to present a nearohm load to the radio, and are often used on fiberglass vehicles such as snowmobiles or boats. They are also useful in base stations where circumstances preclude the use of a ground-plane antenna. Handheld CBs may use either a telescoping center-loaded whip or a continuously-loaded "rubber ducky" antenna.
Base CB antennas may be vertical for omnidirectional coverage, or directional "beam" antennas may be used to direct communications to a particular region. Ground-plane kits exist as mounting bases for mobile whips, and have several wire terminals or hardwired ground radials attached. These kits are designed to have a mobile whip screwed on top (a full-length, quarter-wave steel whip is preferred) and mounted on a mast. The ground radials replace the vehicle body (which is the counterpoise for a mobile whip in a typical vehicle installation).
Main article: Skywave
All frequencies in the HF spectrum (3–30MHz) can be refracted by charged ions in the ionosphere. Refracting signals off the ionosphere is called skywave propagation, and the operator is said to be "shooting skip". CB operators have communicated across thousands of miles and sometimes around the world. Even low-power 27MHz signals can sometimes propagate over long distances.
The ability of the ionosphere to bounce signals back to earth is caused by solar radiation, and the amount of ionization possible is related to the year sunspot cycle. In times of high sunspot activity, the band can remain open to much of the world for long periods of time. During low sunspot activity it may be impossible to use skywave at all, except during periods of Sporadic-E propagation (from late spring through mid-summer). Skip contributes to noise on CB frequencies. In the United States, it is no longer illegal to engage in (or attempt to engage in) CB communications with any station more than km (mi) from an operator's location. This restriction used to exist to keep CB as a local (line-of-sight) radio service; however, in the United States the restriction has been dropped. The legality of shooting skip is not an issue in most other countries. A recent FCC decision now allows the shooting of skip in the United States.
Freebanding and export radios
Operation on frequencies above or below the citizens band (on the "uppers" or "lowers") is called "freebanding" or "outbanding".[g] While frequencies just below the CB segment (or between the CB segment and the amateur radio meter band) seem quiet and under-utilized, they are allocated to other radio services (including government agencies) and unauthorized operation on them is illegal. Furthermore, illegal transmitters and amplifiers may not meet good engineering practice for harmonic distortion or "splatter", which may disrupt other communications and make the unapproved equipment obvious to regulators. Freebanding is done with modified CB or amateur equipment, foreign CB radios which may offer different channels, or with radios intended for export. Legal operation in one country may be illegal in another; for example, in the UK until June only 80FM channels were legal.
Unlike amateur radios with continuous frequency tuning, CBs manufactured for export are channelized. Frequency selection resembles that of modified American CBs more than any foreign frequency plan. They typically have a knob and display that reads up to channel40, but include an extra band selector that shifts all 40channels above or below the band and a "+10kHz" button to reach the model control "A"channels. These radios may have 6 or even 12bands, establishing a set of quasi-CB channels on many unauthorized frequencies. The bands are typically lettered A through F, with the normal citizens band as D.
For example, a freebander with an export radio who wants to use MHz would choose channel19 (MHz) and then shift the radio up one band (+kHz). It requires arithmetic on the part of the operator to determine the actual frequency, although more expensive radios include a frequency counter or a frequency display — two different components, providing an identical result. Illegal operations may unintentionally end up on frequencies very much in use. For instance, channel19 shifted two bands up is MHz, which is in a Morse code / data-only part of the 10meter ham band. Voice transmissions in a Morse code-only segment are easily detectable by authorities. Amateur Radio Service operators record, locate, and report to the FCC frequency trespassing and intrusions of their frequency allocations by pirate transmissions or illegal operators for enforcement action.
Many freeband operators use amateur radios modified to transmit out of band, which is illegal in some countries. Older amateur radios may require component changes; for instance, the s Yaesu FT was modified for CB by replacing a set of crystals used to tune portions of the 10meter band, although some variants of the FT were sold with the US FCC channels standard and were capable of transmitting above and below the legal 40channels by another 10or more channels.: On some newer radios, the modification may be as simple as disconnecting a jumper wire or a diode. Many types of amateur transceivers may be found on CB and freeband, ranging from full-coverage HF transceivers to simpler 10meter mobile radios. In the United States, the FCC bans the importation and marketing of radios it deems easily modifiable for CB; it is illegal to transmit on CB frequencies with a ham radio except in emergencies where no other method of communication is available.
A gray market trade in imported CB gear exists in many countries. In some instances, the sale or ownership of foreign-specification CB gear is not illegal but its use is. With the FCC's minimal enforcement of its CB rules, enthusiasts in the US use "export radios" or European frequency modulation (FM) CB gear to escape the crowded AM channels. American AM gear has also been exported to Europe.
"Export radios" are sold in the United States as 10meter Amateur Radio transceivers. Marketing, import and sale of such radios is illegal if they are distributed as anything other than Amateur Radio transceivers. It is also illegal to use these radios outside of the Amateur Radio bands by anyone in the US, since they are not type-certified for other radio services and usually exceed authorized power limits. The use of these radios within the Amateur Radio Service by a licensed Amateur Radio operator within his / her license privileges is legal, as long as all FCC regulations for Amateur Radio are followed.
A callbook is a directory of radio station call signs. Originally a bound book that resembled a telephone directory, it contains the name and addresses of radio stations in a given jurisdiction (country). Modern Electrics published the first callbook in the United States in Today, the primary purpose of a callbook is to allow radio operators to send a confirmation post card, called a QSL card to an operator with whom they have communicated via radio. Callbooks have evolved to include online databases that are accessible via the Internet to instantly obtain the address of another amateur radio operator and their QSL managers. The most well known and used on-line QSL database for the 11meter / freebander community is QRZCOM, designed after its "big brother" QRZ.com for amateur radio.
During the s and s heyday of CB radio, many citizens band-themed magazines appeared on newsstands. Two magazines that dominated the time period were S9 CB Radio and CB Radio Magazine. S9’s successor was Popular Communications, which had the same editor under a different publisher beginning in It covered hobby radio as well as CB. The same publisher produced a magazine called RADIO! for RadioShack stores in the mids. In Australia, CB Action Magazine was produced monthly from mid and continuing publication through until the early s. CB Action spawned several other popular publications, including a communications and scanning magazine and Amateur Radio Action magazine, produced over several decades and running to some 18volumes.
In the early s, National Communications Magazine added CB radio coverage to its coverage of scanner radios and to this day remains the only magazine in North America covering CB radio.
- ^Channels10–14 and 23, after channel9 was reserved for emergency use.
- ^The terms "interstation" and "intrastation" appear in the FCC's Part95 rules from that time period.
- ^except channel9, which was usually colored red.
- ^Channels 23[MHz], 24[MHz], and 25[MHz] are not on the same radio frequencies in the CEPT standard.
- ^RCRS was formerly known as the Class C Citizens Radio Service until the changes.
- ^Channels24[MHz], 25[MHz], 52[MHz], 53[MHz], 76[MHz, and channel77[MHz]
- ^The term "outbanding" was introduced by Kneitel in the August issue of S9Magazine.:16
- ^Telecommunications, Government of Canada, Innovation, Science and Economic Development Canada, Office of the Deputy Minister, Spectrum, Information Technologies and (27 August ). "RIC — General Radio Service (GRS)". strategis.ic.gc.ca. Archived from the original on 12 January Retrieved 8 May
- ^"27Megacycle History". Archived from the original on 28 November Retrieved 10 February
- ^ abcdKneitel, Tom (). Tomcat's Big CB Handbook. Commack, NY: CRB Research Books. ISBN.
- ^"Citizen Band (CB) Radio". No Wires Radio. Retrieved
- ^"Overview". FCC Part Archived from the original on 21 October Retrieved 21 October
- ^Hurd, Peter M. (May–June ). "Amateur Radio and MARS News". Signal. p.
- ^ ab""I can't drive 55": The economics of the CB radio phenomenon". Independent Review. Vol.15 no.3. The Independent Institute.
- ^"The Southeast Missourian". news.google.com. Retrieved 8 May via Google News Archive Search.
- ^Holsendolph, Ernest (April 28, ). "Fading CB craze signals end to licensing". The New York Times. SectionA, page
- ^James Wesley Huguely=Cledus Maggard Retrieved 9 February
- ^Tweed, Michael (31 December ). "Back in view, a First Lady with her own legacy". The New York Times. Archived from the original on
- ^ abcChilton Automotive Editorial Department (). Chilton's CB Handbook. Radnor, PA: Chilton Book Company. ISBN.
- ^"Radio Information for Boaters". United States Coast Guard. Archived from the original on 14 June
- ^"Citizens Band Radio Service (CBRS)". fcc.gov. 4 August Archived from the original on 4 December Retrieved 8 May
- ^"CB Radio History". ACRM. Archived from the original on 17 September
- ^"Radiocommunications (27MHz Handphone Stations) Class Licence ". www.legislation.gov.au. Commonwealth of Australia. Retrieved 1 January
- ^"Movement". ACRM. Archived from the original on 17 September
- ^""Aussie" 18Channel Radio Guide". ACBRO. Archived from the original on 13 January
- ^"CB Radio History". www.acrm.org.au. Australian Citizens Radio Monitors (South Australia) Incorporated. Retrieved 1 January
- ^* GL (VK3PJB) ex-Secretary GL Club, Australia[full citation needed]
- ^"[no title cited]". Archived from the original on 8 May
- ^"Radiocommunications (Maritime Ship Station — 27MHz and VHF) Class Licence ". www.legislation.gov.au. Commonwealth of Australia. Retrieved 31 December
- ^"Marine radio qualifications". www.acma.gov.au. Australian Communications and Media Authority. 17 September Retrieved 1 January
- ^ ab"Marine radio". transportsafety.vic.gov.au. Transport Safety Victoria. Retrieved 1 January
- ^"Marine Radios". www.marinerescuensw.com.au. Marine Rescue NSW. Retrieved 1 January
- ^Spinello, Matt P. (July–August ). "Touring Canada with your CB rig". Elementary Electronics. Vol.10 no.2. New York, NY: Davis Publications. pp.55–
- ^"Licensing of General Radio Service Equipment"(PDF). TRC Government of Canada Department of Communications. 1 January Archived from the original(PDF) on 6 July Retrieved 3 January
- ^"CB Radio". Indonesian DX Club. Archived from the original on 2 February
- ^"Personal Radio Service Device"(PDF). Notification of Issuance Of Class Assignment. Communication and Multimedia Act. P.U.(B) Jil.48, No.22(e). Act Archived(PDF) from the original on 30 November Retrieved 1 November
- ^Communications and Multimedia Act Class Assignments No.1 of (PDF). Notification of Issuance of Class Assignments. Archived from the original(PDF) on 19 January Retrieved 19 January
- ^"Class Assignment No.1 of "(PDF). Archived(PDF) from the original on 19 January Retrieved 19 January
- ^"Senarai Keahlian". my27mhz.blogspot.com. Archived from the original on 14 September Retrieved 8 May
- ^Rohrer, Finlo (14 August ). "Over and out?". BBC News Magazine. Archived from the original on 4 September Retrieved 22 October
- ^"Citizens Band (CB) Scanner Frequencies and Radio Frequency Reference". radioreference.com. Archived from the original on 14 September Retrieved 8 October
- ^ ab"Arrêté du 31 mars relatif aux caractéristiques techniques et aux conditions d'exploitation des postes C.B."legifrance.gouv.fr. Archived from the original on 1 July Retrieved 8 May
- ^"(CB Rule7) On what channels may I operate?". frwebgate.access.gpo.gov. Archived from the original on 14 February Retrieved 8 May
- ^"Repeater Locations & Information". News. www.uhfcb.com.au. UHF CB Australia - New Zealand PRS. Archived from the original on 12 March Retrieved 8 May
- ^"An Indonesian government decision regarding CB, with frequency charts"(PDF). Archived from the original(PDF) on 20 January
- ^Adams, Alice (28 November ). "The first CB radio". Trucking: Tractor-Trailer Driver Handbook/Workbook. p. ISBN.
- ^""Omnibus" Amateur Radio Report and Order". cbradiosource.com. Archived from the original on 13 August Retrieved 8 May
- ^"Raytheon". Archived from the original on 24 April Retrieved 21 August gives the history of one US manufacturer's line of CB equipment
- ^"Learn the basics of CB radio". New Company Driver. Archived from the original on 1 October
- ^FCC regulations Part95 SubpartD.
- ^"RIC — General Radio Service (GRS)". Office of the Deputy Minister, Spectrum, Information Technologies, and Telecommunications. www.ic.gc.ca. Government of Canada. Innovation, Science and Economic Development Canada. Archived from the original on 15 June Retrieved 8 May
- ^"FCC Enforcement". www.arrl.org. Archived from the original on 10 September Retrieved 8 May
- ^"QTH.COM: FCC information regarding Illegal CB Radios". swap.qth.com. Archived from the original on 9 November Retrieved 8 May
- ^"Archived copy"(PDF). Archived(PDF) from the original on 6 July Retrieved 19 June CS1 maint: archived copy as title (link)
- ^"QRZ11". www.qrzcom. Archived from the original on 23 February Retrieved 8 May
- ^"CQ OPT"(PDF). Archived(PDF) from the original on Retrieved
- ^"Archived copy". Archived from the original on Retrieved CS1 maint: archived copy as title (link)
- ^"Archived copy". Archived from the original on 2 April Retrieved 10 March CS1 maint: archived copy as title (link)
- ^"Sugar Delta Home". www.sugar-delta.it. Italy. Archived from the original on 27 September Retrieved 8 May
With the exception of the odd radio that we have found to be unreliable, we stock every CB radio that is legal in the UK.
Because of the small difference in manufacturing costs, no manufacturer now makes 40 channel radios for the UK, all are now either 80 channel or "multistandard".
All the radios have 2 bands of 40 channels each - one band is the original UK 40 (made legal in ), the second band is the EU 40 (also known as Mid Band or CEPT). All 80 channel radios are compatible with the older 40 channel UK radios (eg those marked 27/81).
The latest trend is for new radios to be "multi-standard". This means that they are designed for use in almost all EU countries. You select what country you are using the radio in, and the radio will then automatically work only on the channels (and modes) that are legal in that country (eg 80 channel FM in the UK).
All radios are given a pre-sale service before despatch, to ensure that you get the maximum performance you can have. You would be surprised how far off tune many new radios are! This is why many customers find our radios work better than one bought elsewhere!
To make selection easier, we have now put the different makes of CB's on their own pages.
Click on one of the makes from the list above to see all their models.
You will also be interested:
- Ranked boost pokemon quest
- Film cell display frame
- Darth maul saga legends
- Guitar center martin custom
- Name colors minecraft
- Walmart bikes price
- 3 way monitor splitter
- Thread on tub spout
- Impractical jokers tennis episode
- Avalon park vancouver wa
- Accidents in southern maryland
- Mexican ufc fighters list
- Sales executive salary structure
Know, but I was attracted to this girl inexorably. The dancer, as if wishing to finish me off completely, dropped her leg and sat down on my hips, putting her hands on my shoulders. She began to move back and forth, pressing her groin tightly against my excited organ, which was trying to force its way through the sheet to her bosom.
- What are you doing, girl, - I suddenly said in a shrunken voice, - and it's not far from sin. - A clear ass.