Communications is a key element in our everyday lives, if you do not believe me try going a whole day with no cell phone, internet, TV or any other means of communications (COMMS). So it stands to reason that having COMMS when SHTF is essential to gaining intelligence (COMINT), the safety and security of your family, keeping informed and keeping at least one step ahead of anybody with bad intentions. Like any skill it is essential to practice, that means practicing before SHTF so that you have the necessary skills.
This article will expound on some terms you would have heard while taking your Technician class. We will also discuss the various radio services that could be available to use for CPT comms and their rules. Following the rules in normal times is strongly encouraged so that you do not draw attention to yourself from the authorities. Application of the rules when SHTF, well…….
Communications intelligence (COMINT), communications security (COMSEC), and signals intelligence (SIGINT) will be discussed in a future article.
SOME BASIC TERMS
Firstly let’s understand a little about frequencies, their uses and their availability to the average person. The use of frequencies in the U.S. is governed by the Federal Communications Commission (FCC). Some frequencies require a license and some are licensed by rule, meaning that the rules provide the allowable use without an individual license, such as Citizens Band (CB), Family Radio Service (FRS) and the marine band. Other services, such as Amateur Radio (HAM) and General Mobile Radio Service (GMRS) require an individual to have a license. Each licensed service has specific rules for use and radios designed for use within a specific service have to be type accepted for use in that service.
A channel is a “common” name for a frequency, or pair of frequencies, pre-assigned, such as CB channel 19, which is a single frequency. A channel can also be a pair of frequencies, such as when using a repeater, where one frequency is used for transmitting and another used for receiving. Where a single frequency is used, it is called ‘simplex’, or sometimes called ‘direct’. When a pair of frequencies are used this is called ‘duplex’.
Analog is a type of transmission of the voice signal, this is the most common type of signal and radio. The signal can be AM (amplitude modulation), FM (frequency modulation) or single side band (SSB) as used in HF (high frequency) transmissions.
Digital radio signals take the spoken audio and convert it to a packet of digital transmission. The signal transmitted from the radio contains ‘code’ or information about the signal and can include an ID of the radio. Digital signals are less prone to interference from co-located radio equipment. Digital signals have the disadvantage that if the signal is weak and ‘packets’ of the signal are lost most of the transmission can become unreadable.
There are a number of different formats for digital signals. P25 is an industry standard and common in newer public safety radio systems, most of these systems utilize a trunking radio system. A trunked radio system is controlled by a computer and radio channels are ‘virtual.’ The system assigns a pair of frequencies for those on the ‘virtual’ channel to talk on when one radio in that group presses the ‘push to talk.’
There are some Amateur Radio repeaters that use P25 digital signals. All newer scanners on the market can listen to P25 signals.
Digital Mobile Radio (DMR), also called MotoTRBO is proprietary to Motorola however there are a number of other manufacturers that market radios capable of DMR. The TYT MD-380 is one, however at the time of writing most DMR capable radios are single band, typically UHF. Up until May 2016 there were no scanners on the market capable of listening to DMR signals, however Whistler recently produced one and I’m sure other scanner manufacturers will follow. While commonly used in commercial business radio systems there are Amateur Radio DMR systems around the country. Colorado has one of the most extensive Amateur Radio DMR networks in the country, providing communications along most of the Front Range from Cheyenne, Wyoming to Albuquerque, New Mexico.
D-STAR (Digital Smart Technology for Amateur Radio) is another digital mode found in ham radios. While it was developed by Icom in Japan it is open source. Kenwood has recently come out with a D-STAR capable radio (TH-D74A), prior to that only Icom produced D-STAR capable radios. D-STAR utilizes UHF, VHF, as well as the 23 centimeter (1.2GHz) bands, D-STAR transmissions cannot be received by any commercial scanners at this time.
Radio frequencies cover a whole spectrum. They are broken down into bands, with each band having different characteristics. Low bands, (high frequency – “HF”), aka. short wave, tend to bounce off the atmosphere and therefore are good for long transmissions around the world. Because they bounce, places between the transmission point and reception point cannot hear the transmissions very well, if at all. This has obvious advantages to COMSEC but can be a disadvantage when attempting to communicate locally. Time of day, and even time of year, change the characteristics of HF bands. The low bands, 160 meters (1.8-2khz) are good at night but almost unusable during the day, this band is similar to the long distance AM stations, and is better during the winter, with transmissions possible over thousands of miles. Whereas 10 meters (28Mhz-30Mhz) is best during the day (CB is the 11 meter band). Some bands between these (such as 17, 20 and 40 meters) are good during the day and into the evenings.
Transmissions in the VHF and UHF bands are considered ‘line-of-sight’ as they travel in almost straight lines and therefore do not follow the curve of the earth, we usually refer to these as tactical COMMS. Terrain, like hills, can block transmissions in the UHF and VHF range. Tactical COMMS equipment tends to be smaller and lower in power. “Line of sight” transmissions can be easily intercepted with direction finding equipment (“DF’d” or “DF’ing” – the art of direction finding).
Antenna selection plays an important part of getting your signal out, and receiving. Near-Vertical Incident Skywave (NVIS) antennas are used to take advantage of the ability to bounce of the atmosphere and used to communicate with a station out to about 200 to 300 miles. Bouncing the signal also makes it difficult to DF.
Selecting the most appropriate band for the type of COMMS is essential. Selecting the lowest possible power to get the message through and making transmissions very short helps prevent “DF’ing”.
Continuous Tone-Coded Squelch System (CTCSS)
CTCSS is a sub-audible tone that can be added to a frequency to help reduce interference from other users of the frequency. In most cases it is used to eliminate interference getting into a repeater system. CTCSS is also know by vendor names such as Private Line (or PL tone) (Motorola), Channel Guard (Bendix King & and GE), Quiet Talk (Kenwood) and Tone Guard (TG) or CallGuard (CG) (EF Johnson). Generally, in ‘radio speak’ the generic term “tone” is used.
There is an industry standard list of tones. In most cases the actual number of the frequency is listed, i.e., 127.3, or a two-character code utilized by Motorola, such as 3Z (for 127.3).
The use of tones does not provide any security or privacy on a channel.
In “bubble-pack” radios, typically FRS radios, the vendors assign a number (not the actual frequency) to a tone, these are not consistent between different manufacturers.
Digital Coded Squelch (DCS)
DCS is a digital version of CTCSS that puts a continuous stream of digital data on the transmitted signal. As with CTSCC the different vendors have their own names; Motorola calls it Digital Private Line (DPL), GE uses Digital Channel Guard (DCG), and Icom uses Digital Tone Squelch (DCS).
A repeater is basically two radios, one on a receiving frequency and one on a transmitting frequency. The user radio transmits on the repeaters receive, or input, frequency and the repeater retransmits on the output frequency. Typically, a repeater is located on a hill top or a high building. A low power radio is then ‘repeated’ on the higher power, or at least higher antenna, of the repeater and can be heard over a considerable distance. Depending on the location and frequency this can be as much as 50 miles.
There are three basic pieces of information required to program a radio to use a repeater in the Amateur Radio service. First is the frequency; It is common to refer to the repeater by the output frequency of the repeater (the receive frequency of your radio). When programming, most radios require you to enter the receive frequency.
The second piece of information is the difference, commonly called the offset, between the receive frequency and the input frequency of the repeater. There is a standard in Amateur Radio; 2m is 0.6mhz and 70cm is 5.00mhz. Again, depending on the radio you then enter the shift, whether the offset is negative (when transmitting the input is less than the output) or positive. Some radios, especially Icom, Yaesu and Kenwood, are programmed with the standard offset and shift for a given frequency.
The third piece of information you may need is the CTCSS or DCS tone in order to access them. Not all repeaters require an input tone, but most do. In some radios in addition to a menu setting for the tone there is an additional setting to turn the tone on, in others you merely need to select the correct tone.
Some repeaters also send a CTCSS or DCS tone on transmit. This is usually listed as TSql (for tone squelch) or RcvT (for receive tone). You can program this into your radio if you have local interference. This means that the radio must receive the correct tone otherwise you will not hear anything. In most cases it is best to leave the receive tone off.
Repeaters can be linked together by radio, microwave or internet. Some connections are permanent and some can be selected by the radio user.
Internet Relay Linking Project (IRLP) is a method of linking repeaters using the internet. The audio is converted to a digital stream and sent to the distant repeater. Simple DTMF codes are used to link a repeater to the distant repeater or to a reflector. A reflector is a server with sufficient bandwidth to support multiple connections, allowing a large number of simultaneous connections.
Echolink is very similar to IRLP, however Echolink allows a licensed ham to run an application on a computer or smart phone that will access other Echolink users and repeaters.
Automatic Link Establishment (ALE)
Is where the radios automatically find the best frequency for the transmission. The radio can be programmed to scan a number of different frequencies in different HF bands. When one user wishes to communicate with another the user selects the ID for the other radio and the radio determines the best frequencies and “calls” the other radio. Amateur Radio service operates ALE, with both voice and data channels, using computer software interfaced with HF radios (see hflink.com for more information). Both Codan and Motorola manufacture ALE radios which can operate on the Amateur Radio bands however their price is prohibitive for most individuals. Programming is also a challenge without training.
LICENSED BY RULE SERVICES
Licensed by rule services do not require the individual user to have a FCC issued license. There are a number of radio services that are ‘license by rule.’
Family Radio Service (FRS)
The Family Radio Service is a ‘licensed by rule’ service, under Title 47 Code of Federal Regulations (CRF) Part 95 subsection B. The FRS is 14 frequencies in the UHF range with a power limit of 500mW and 11.25khz spacing of the frequencies. This limits their range to about ¼ mile up to 1 mile depending on terrain, a more unobstructed terrain permits greater distance. FRS radios list the channels by channel number and all vendors follow the standard labeling of the channels. Different manufactures make their radios available in differing CTCSS capabilities, usually list them by a number that does not correspond to the actual tone. Unfortunately the vendors do not all use the same tones or numbering system which can make communicating between different vendors radios a little difficult. FRS radios are sometimes referred to as “bubble-pack” radios due to their packaging in stores.
One of the rules for type acceptance of FRS radios is that they cannot have detachable antennas, thus they cannot be connected to an external antenna, such as one mounted up high, to increase the range. The Baofeng and similar programmable radios will operate in the FRS and GMRS bands do not meet type acceptance, as the antennas are detachable. Also, note that the low power setting on most of these radios is 1 watt, twice the permitted legal power for the FRS service.
Channels 1-7 are the same as GMRS channels 9-15. GMRS radios are permitted to use higher power but an operator can only use the higher power GMRS channels if they hold a GMRS license. (see GMRS below). In Europe a similar service to the FRS service is called PMR 446. It should be noted that these frequencies are in the U.S. Amateur Radio service band.
Multi-Use Radio Service (MURS)
MURS is another ‘licensed by rule” service which does not require an operator to have a license. The FCC rules for MURS are contained in 47 CFR Part 95 Subpart J. MURS is five VHF channels with 11.25khz spacing or 20khz spacing and 2 watts of power. Range can be up to 10 miles in ideal conditions.
Business may use the MURS frequencies and these are commonly seen as a colored dot on the radio to delineate the frequency. All of the MURS frequencies are simplex only, so a repeater is not permitted. MURS channels are not assigned a channel numbering system so generally the frequency is used to identify the MURS channel.
Citizens Band (CB)
I would assume that almost everyone has heard of CB radio, if not go watch Smokey and the Bandit or Convoy. CB radio has 40 channels in the 27Mhz range (11 meter band). Power is 4-watts AM and 12-watts for single side band (SSB). Not all CB radios are capable of SSB transmissions. SSB transmissions cannot be picked up by a scanner but can by some short wave radios. Being in the 11-meter band and close to short wave radio signals can travel considerable distances, especially overnight. Of all the radio services available to the public CB is probably the most common, with truckers providing traffic information along the nation’s highways. It is also probably the most abused radio service, with people running illegal amplifiers, jamming and using profanity. There are a large amount of slang terms used on CB. CB mobile radios require 12v DC and antennas tend to be long, around 9ft. Portable CB radios are available but their range is limited due to the practical length of the antenna needed for good communications.
LICENSED RADIO SERVICES
In order to use frequencies in the services below the user must have a licensed issued by the FCC within that service. A license in one service does not permit use in another service. In some cases a license applies to all family members and others apply to the individual only.
General Mobile Radio Service (GMRS)
GMRS is regulated by 47 CFR Part Part 95 Subpart A. GMRS is assigned 15 channels in the UHF band with 8 being assigned in pairs, for repeater use. The other 7 are shared with channels 1-7 in the FRS service. A user is required to have a FCC license, usually issued upon completion of an application and a fee currently set at $85. The license is valid for 5 years and a single license entitles the license holder and immediate family members to use GMRS frequencies. Power on the non-shared frequencies is 50-watts and limited to 5 watts on the frequencies shared with FRS. Repeaters are authorized on the GMRS paired frequencies and can increase the effective range to 20 or more miles depending on the location of the repeater and antenna. A search of www.mygmrs.com will usually reveal local GMRS repeaters. It is customary to contact the owner and get permission prior to using a GMRS repeater.
When programming a radio low power should be used on any simplex channel you plan on using for tactical comms. When accessing a repeater it will usually be necessary to program a CTCSS tone with the transmit frequency, sometimes a tone is transmitted by the repeater and can be used to reduce interference on the signal coming into the radio.
Most ‘bubble-pack’ radios are now available with both FRS and GMRS frequencies, these use AA or AAA batteries. Unfortunately, the use of FRS and GMRS channels in a single radio tends to result in the use of the GMRS frequencies by people without a license.
Amateur Radio Service
The Amateur Radio Service (aka “ham” radio) is regulated by 47 CFR Part 97 rules. Individuals must possess a license issued by the FCC. The Amateur Radio Service has more frequencies in more bands than any other service available to the general public.
How to obtain your ham radio license was covered in a prior article.
The most common frequencies used by those with a Technician license are in the UHF and VHF bands. Dual band (UHF & VHF) radios type (Part 97) approved are readily available, with some including a third band such as 6 meters or 1.2 meters (“220” band). Note: many people are purchasing the Baofeng UV5 series, or similar, radios which cost as low as $35. While these radios are capable of being programmed to transmit in the VHF & UHF Amateur bands, as well as FRS, GMRS, MURS and Marine bands, the radios are only labelled as Part 90 (Public Service) approved. However having tested one of these radios they seem to work well on the Amateur bands. They are an inexpensive way to start out in ham radio while also having the capability of FRS/GMRS to talk to your non-ham friends and members of your CPT. Selecting radios will be the topic of a future article.
Radios type approved for use in the Amateur Radio Service allow the user to directly enter the frequencies on which the user wishes to operate, this is a feature usually only found in ham radios, most commercial radios must be programmed using software and the user can only change to a pre-programmed frequency. Aircraft radios are the one notable exception, where the user changes to specified frequencies.
Hams can utilize many modes of voce transmission, including AM, FM and SSB. In addition to voice modes Amateur Radio utilizes many different forms of data transmissions, including morse code, fax and video.
There are agreed band plans, designating what frequencies are used for within each band, i.e., only morse code can be operated in some parts of the HF bands, some frequencies are reserved for digital communications and some for satellite.
Hams continue to experiment and utilize a huge variety of communications modes in addition to ‘basic’ voice communications. Most of these other modes cannot be picked up on a scanner or other conventional equipment unless you have the same equipment. While voice is best for tactical comms these other modes provide the users lots of different ways to communicate, including spread spectrum, frequency hopping and ALE, without being easily intercepted. However, you should never assume communications are secure and the use of encryption or other codes designed to disguise the message are prohibited by the FCC rules on ham, FRS, GMRS, CB and all radio services available to the general public.
OTHER RADIO SERVICES
Marine Radio operates under 47 CFR Part 80. Recent changes no longer require boats to have a FCC license. Marine radio operates in the VHF band and with an internationally agreed plan of about 80 channels most of which are simplex. FCC rules explicitly prohibit use of a Marine radio while on land. In the U.S. the Coast Guard monitor channel 16 and other channels and have considerable direction finding capabilities.
Communications is essential to be able to respond to emergencies in your community. It is highly probably that cell phone service will not be available in a widespread emergency. Practicing using radios is important; being able to make an accurate, concise transmission that are received and understood by the recipient without the need to repeat is essential. One of the best ways to improve this skill is getting involved with your local Amateur Radio group that is part of the ARRL National Traffic System, where they send practice messages on a regular basis.
I trust that this article has explained some of the terms that you may have come across while taking your Technician license and the rules for the various radio services. Following the rules for the various services is important so that undue attention is not brought on your CPT.
Tags: amateur radio
, cpt commo
, marine band
, marine radio
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