There are quite a few CB applications. They are a sufficiently reliable and accessible means of communication, allowing the shop to communicate with the warehouse, the warehouse for road transport, etc. CB radio communication can be used in the small fleet - boats and yachts. In addition, the communication distance to the water increases sufficiently. CB radio communications have gained widespread use as mobile communications . In-car radio stations allow you to keep in constant contact with each other, get operational road information, help with route selection, in case of accidents or technical problems.
The use of portable CB radio stations is quite problematic as the wavelength in the CB range is 11 m and the full-quadrant wavelength antenna is 2. 7 m. Portable CB devices will have short antennas 10-20 times, which in turn reduces the range of communication.
In addition, the import portable CB radios were quite heavy (around 500g), had low creator and amplitude silencer efficiency, resulting in low bandwidth and cost effectiveness of such radio stations.
As a result, virtually all radio stations of this type were taken off production. At the same time, due to the propagation of radio waves in the 27Mhz range, portable CB radio stations have significant advantages over the "unlicensed" high frequency radio stations LPD 433Mhz, PMR 446Mhz, when used in dense forest and uneven terrain. The CB radio station is capable of communicating with the fire service, police, ambulance, emergency services through dedicated dispatcher services that will assist and call for assistance by telephone. Channel 9C is reserved for this purpose and is constantly on call by emergency services, look at this site .
Frequencies to be used
Worldwide, most CB channels can be used at frequencies starting at 26965kHz and coming into a 10KHz network. the Frequency Assist Network and new channels have emerged. They also have a 10kHz step, but they are offset to 5kHz. The first one got 51 (26960 KHz) titles the next - 52 (26970 KHz) and so on
Later, ranges were introduced that expand the number of channels up to 200 and in some countries up to 400. Some modern stations (up to a shifted network) support up to 800 channels. In Russia, personal radio communications were given channels that are considered worldwide to be supportive, ie with a 5KHz offset. However, not all radio stations support the extended range.
There are three types of modulation in CB: AM (Amplitude Modulation) and FM (Frequency Modulation) and SBB (Single Band Modulation). The maximum communication distance between AM and FM is practically the same. Most users of the Russian CB range use FM, which provides higher quality scanning. At the limit of communication, AM frequency intelligibility can be better than FM.
Using FM avoids most of the interference caused by amplitude. AM is used (traditionally) by long distance drivers. The SBB can be used to reach maximum distance (distance options are much greater than AM and FM power). The main obstacle to the distribution of SBB radio stations is the need for manual correction in order to achieve better understanding. Not all stations in the vicinity support SSB.
The dispatcher service may be located on its own frequency (rescue service or similar) in each region, but the C9FM channel (27065 kHz) received most of the distribution. Some radio stations have a fast switching function to this channel. Unfortunately, lately there has been a tendency to abandon the help channel, most of the on-call facilities used to work in this channel are closed. The most resilient are now the big city emergency services, ie the "Moscow help desk" in Moscow (27. 185 / 19C FM EUR) and the "Neva" in St. Petersburg. Petersburg (27.635MHz). It is also known that some road surveillance services on the Moscow - St. Petersburg route continues to monitor Channel 9, despite the fact that the information boards "Rescue service operated at 9CFM frequency " were changed to "
Apart from the dispatcher services, the CB frequency also has echo replicators or "parrots". An echo repeater is a stationary CB radio station with a repeater console connected, which repeats the previously received signal through the antenna. Thanks to its high antenna height, the repeater receives the signal even from low power portable or car stations in urban conditions, but you can hear the repeater signal within a 10 km radius.
Echo - Repeater lets you connect with mobile users tens of kilometers away. Echoing - an advantage of the repeater over the base dispatcher station - is that there is no need for staff to be on duty at the base.
Echo - Repeaters exist in many CIS countries and are usually installed by local car amateur associations. For example, Novosibirsk has an echo repeater "Nadezhda" at 27,635 MHz (19D FM channel).