Single Channel Air-Ground Radio System, commonly known as SINCGARS "sink-gars", FM or Fox Mike radio. SINCGARS and FM are used in conjunction with HF-SSB systems, UHF/SHF/EHF SATCOM and other communications systems for tactical military communications purposes.
VHF Tactical FM Land Mobile Air-Ground Military Communications
VHF-FM tactical radio system, with frequency-hopping and voice encryption/data encryption capabilities. Operating in the 30.000 to 87.975 MHz frequency band with 25 kHz channel steps. Uses 150.0 Hz CTCSS squelch system. Operates in single-channel (SC) and frequency-hopping (FH) modes for voice and data. Original generation SINCGARS radio such as the RT-1439 VRC set (VRC-87 configuration) and modern radios such as the Harris RT-1523 series offer +/5 kHz and +/- 10 kHz offset frequencies from the standard 25 kHz channels.
Single channel mode, also known as fixed frequency, is referred to as VULOS, or VHF UHF Line Of Sight. It is a catch-all term for VHF-FM 30-88 MHz, VHF-AM 108-150 MHz, VHF-FM 136-174 MHz, UHF-AM 225-399.975 MHz and UHF-FM 400-512 MHz fixed frequency clear (plaintext, or PT) or encrypted (ciphertext, or CT) simplex communications nets. Duplex or half-duplex repeaters (relay, retrans) or retransmission facilities may be used for VULOS nets. Frequencies in the 30.000 to 87.975 MHz range may be used for these nets in conjunction with SINCGARS, UHF SATCOM and UHF aircraft HAVE QUICK nets. PRC-148, PRC-152 and similar radios make reference to the VULOS radio net type. See also: PRC-150 HF/VHF radio (1.5-30 MHz SSB and various digital modes, 30-60 MHz [59.999 MHz] FM only. FM radios often have a "deviation" (bandwidth) setting. SINCGARS and fixed channel mode is generally set to 8 kHz deviation (36 kHz bandwidth) at 25 kHz steps. Land mobile settings include 5 kHz deviation (20 kHz bandwidth) and 2.5 kHz deviation (10 kHz bandwidth, regular narrow FM).
Most radios include repeater capability (called RETRANS or retransmit in military usage). Compatible with previous-generation FM radios such as the PRC-25, PRC-77, PRC-1077, HH7700 and dozens of other similar tactical handheld, manpack and vehicle-mounted radios operating in the 30-76 MHz (30.00 to 75.95 MHz in the original PRC-25/PRC-77 and VRC-12 channeling) or 30-88 MHz range. NATO military forces and many other military forces use similar frequencies for tactical purposes, almost always with FM voice. The US military fields radios that operate in the 30-174 MHz and 30-512 MHz ranges to support SINCGARS, regular VHF-FM, 136-174 MHz VHF-high band services like VHF marine, aircraft radios, SATCOM and interoperability with other radio systems that use VHF/UHF.
However, certain bands in the 30-50 MHz range (VHF low band) are allocated to exclusive government/military use. There are non-military government users of these frequencies, however most federal government agencies have moved to the 162-174 MHz and/or 406-420 MHz federal bands with the proliferation of trunking systems.
Federal Government and Military Only Bands 30-50 MHz
This list applies to the United States only. The US military will often use frequencies outside these bands on a non-interference basis. In Europe, CEPT standardizes the 30.300 MHz - 30.500 MHz, 32.150 MHz - 32.450 MHz and 41.000 MHz - 47.000 MHz band as "harmonized" military bands for NATO and allied military tactical radio use.
It is important to note that in SC mode or single channel mode, SINCGARS radios allow for -5 kHz / +5 kHz or -10 kHz / +10 kHz offsets, effectively changing the 25 kHz frequency step to 5 kHz frequency step, allowing for use of non-standard frequencies in single-channel mode. In FH mode or frequency hopping mode channels are 25 kHz frequency steps. US government (and some older-generation military) land mobile systems use 10 kHz or 20 kHz channel steps in the above-listed bands as well. Use of standard land mobile CTCSS or PL tones have been reported (cf. the TVA's 40 MHz land mobile system uses 203.5 Hz PL and 250.3 Hz PL with 20 kHz channel spacing, even though the same band is used for military communications. The TVA channels naturally avoid use of 40.500 MHz - the military tactical band FM emergency channel.)
|30.000 MHz to 30.550 MHz|
|32.000 MHz to 33.000 MHz|
|34.000 MHz to 35.000 MHz|
|36.000 MHz to 37.000 MHz|
|38.000 MHz to 39.000 MHz|
|40.000 MHz to 42.000 MHz|
|46.600 MHz to 47.000 MHz|
|49.600 MHz to 50.000 MHz|
It should be noted that military operations in single channel mode are found on any frequency between 30.000 and 87.975 MHz outside the government/military exclusive use bands on a non-interference basis. Use of the 150.0 Hz CTCSS or PL tone squelch allows for frequency sharing with other users. This, combined with the fact that civilian allocations in the 30-50 MHz band use 20 kHz channel steps, compared to the 25 kHz channeling used by military VHF-FM or SINCGARS systems. The 150 Hz tone squelch is close enough to the civilian 151.4 Hz CTCSS tone that many scanners or communications receivers will decode military VHF FM traffic as having 151.4 Hz CTCSS when in reality they are transmitting 150 Hz. Use of 150 Hz also permits the operation of "relay" (repeater) setups using two radios, the appropriate cables and filters and a high elevation location. Relay functionality has been included in FM tactical radios since the SCR-300 (BC-1000) series. It was not, however, heavily used until the Vietnam war. Most single channel battlefield relay sites use RC-292 (20-70 MHz) or similar high performance antennas. FH retrans sites use the more modern OE-294 broadband antenna system. The wide frequency range of modern FM radios allows for maximum flexibility in choosing frequency pairs.
Range control and air-to-ground communications will often be found on the VHF FM frequencies as well as the UHF airband frequencies. At larger military installations these bands will be connected via a cross-band system, often connecting VHF-FM (30-88 MHz), VHF-AM (108-150 MHz) and UHF-AM (225-400 MHz) frequencies together for air-to-ground coordination, close air support training, etc.
Background and History
SINCGARS evolved from basic simplex and duplex military systems operating in the low to mid VHF range (30.00 to 75.95 MHz) starting with the revolutionary PRC-25 radio. The PRC-25 (and associated VRC-12 vehicle radio set) utilized 150.0 Hz CTCSS squelch combined with indent channelization for frequency control vs. manual tuning with a VFO greatly simplified radio operation. The CTCSS system removed the need for adjustable squelch and made it easy for the average solider to use a radio with minimal training. The PRC-25 and PRC-77 (and dozens of clones, improvements, etc.) are considered hallmarks of battlefield communications simplicity and function. Their origin lies in WWII with the adoption of the SCR-300 (BC-1000) backpack (manpack) radio developed and manufactured by Motorola.
The US military pioneered the use of FM voice on the battlefield in World War II with the original "three band" system, allocating 20 to 27.9 MHz to armor (100 kHz steps), 27 to 38.9 MHz to artillary (100 kHz steps) and 38 to 54.9 MHz to infantry (100 kHz steps). The famous BC-1000 or SCR-300 backpack radio fielded in WWII operated in the 40 to 48 MHz range using 200 kHz steps and FM voice (falling within the 38-55 MHz "infantry band". Tank radios with FM provided vast improvement over AM-based systems on the battlefield. While the SCR-300 / BC-1000 did use a VFO, it featured channels labelled on the display instead of frequency and included a fine-tuning/adjustment signal generating function for battlefield fine tuning. Its use did require adjustment of the squelch and fine-tuning (meaning that the operator still needed to be trained in its use, compare to the PRC-25/PRC-77/VRC-12 family of radios, that are "soldier-proof"). With the adoption of the PRC-25/VRC-12 radios the "three band" system was abandoned, allowing cross-unit communications without the need for multiple radios. It also provided considerably more available channels (30-76 MHz in 50 kHz steps - 920 available channels vs. 20-55 MHz in 100 kHz steps - 350 available channels). Use of HF SSB and CW systems continued throughout the Vietnam war and up to the present day for long range communications and special operations uses.
The SCR-300 and similar high-HF/low-VHF radios developed in WWII and the Korean War revolutionized small unit tactics. First the capability for a platoon or similar level unit to communicate with its headquarters or commanding elements and then the capability for each man in a squad for fireteam to communicate with each other in addition to the longer-range communications capability for platoon-to-commander and platoon-to-platoon communications using FM radio have changed the battlespace forever. The SCR-300 radio provided 0.3 watts (300mw) power output, which provided anywhere from 2-5 miles of range, depending on which antennas were being used. The SCR-508 and SCR-608 family of FM tank radios featured significantly higher transmit power and more effective antennas, greatly improving range.
The basic military backpack radio (and now handheld radio) concept has been copied endlessly, to the point where even militias and guerrilla forces use similar VHF/UHF radios for similar purposes. For example, see Ukraine militia forces using Baofengs (UV-5R, UV-82 and similar VHF/UHF handheld Chinese radios) and fighters in Afghanistan using Icom IC-V8s and other 2 meter / VHF handheld radios for battlefield tactical purposes, often in conjunction with 26-28 MHz CB type equipment or other similar radios/bands.
Communist Bloc countries, including the Soviet Union (and former Soviet Union, now Russia), Poland, as well as Western and Central European military forces also use similar frequency ranges (for example, 26 MHz - 70 MHz or 26 MHz - 71 MHz is/was a popular frequency split for tactical radios, instead of 30-76 MHz). Various handheld and manpack radios covering these bands have been manufactured and used in various countries.
Captured radios from Iraq in the first and second Gulf Wars (Iraq Wars) indicate the 30-76 MHz (in 25 kHz steps, FM mode) band was used heavily by the Iraqi Army for tactical communications. The Iraqi military apparently used Italian made manpack and vehicle radios, as well as Soviet/Russian radios in the same frequency band. The PRC-638 manpack (backpack portable or transportable) radio made by IRET in Italy covers 30.000 MHz to 79.975 MHz in 25 kHz steps, with selector switches for 30 MHz/40 MHz/50 MHz/60 MHz/70 MHz, rotary decade switches for 0-9 and then a selector for 00 kHz, 25 kHz, 50 kHz or 75 kHz. For example, to select the frequency 31.575 MHz, the user would select "3", "1", "5" and then "75" on the radio's panel. This is very similar in operation to the PRC-25/PRC-77 and VRC-12 series of radios.
Evolution of military FM radio tactical radio bands
Evolution of military FM radio tactical radio bands World War II, Korea and Beginning of Vietnam War (roughly 1940-1960)
|Frequency Band||Use||Channel Step/Frequency Spacing|
|27.200 MHz to 33.300 MHz||German Armor Tank Radio Panzer Radio Band - sometimes listed as 27.0 MHz - 33.4 MHz or 27.2 MHz - 33.4 MHz||50 kHz channels - AM voice|
|42.000 MHz to 48.300 MHz||German Air-to-Ground Band (see also: 42.000 MHz - 47.8 MHz)||50 kHz channels - AM voice, close air support and tank command nets|
|23.000 MHz to 24.950 MHz||German Self-Propelled Artillery Band||50 kHz channels - AM voice - similar radios to the 10W.S.c. Panzer tank radios, different frequency range|
|32.000 MHz to 38.000 MHz||German Infantry Band (portable radios)||50 kHz channels - Feldfu d and KL.Fuspr.d manpack portable infantry radios|
|90.000 MHz to 110.000 MHz||German Infantry Band (portable radios)||Low power AM voice radios - tactical short range|
|120.000 MHz to 156.000 MHz||German Infantry Band (portable radios)||Low power AM voice radios - tactical short range|
|130.000 MHz to 160.000 MHz||German Infantry Band (portable radios) - considered ultra high frequency in the 1940s||Low power AM voice radios - tactical short range|
|22.700 MHz to 29.500 MHz||Japanese Type 97 Radio Set Walkie-Talkie 22.7 MHz - 29.5 MHz||Low power AM voice tactical radios (300-400mw, less than 2 mile range)|
|19.600 MHz to 30.600 MHz||Japanese Tank Mechanical Set Type TM Model 305 19.6 MHz - 30.6 MHz||30 watt - 50 watt AM voice mobile tank vehicle radio - 25 mile range|
|28.000 MHz to 80.000 MHz||TBY Series (TBY-2, etc.) US Navy USMC US Marine Corps tactical radios 28-80 MHz||Four "bands" - wideband AM receivers, combat radios used for beach landing nets, etc. heavily used in the Pacific|
|60.000 MHz to 80.000 MHz||TBS Series "Talk Between Ships" - Ship-to-Ship voice radio 60-80 MC radio - US Navy||Crystal controlled 20 kHz steps - TBS crystals for 65.74 MHz and 72.50 MHz have been found|
|20.000 MHz to 27.900 MHz||American Armor Band (tank radio, tank destroyers, tank command nets) (U.S. Army)||100 kHz (channels 200-279), PRC-8, PRC-8A, SCR-508, SCR-509, SCR-510, SCR-528, SCR-538, etc|
|27.000 MHz to 38.900 MHz||American Artillery Band (U.S. Army)||100 kHz (channels 270-389), PRC-9, PRC-9A, SCR-608, SCR-609, SCR-610, SCR-628|
|38.000 MHz to 54.900 MHz||American Infantry Band (U.S. Army)||100 kHz (channels 380-549), PRC-10, PRC-10A|
|40.000 MHz to 48.000 MHz||American Infantry Band - portable tactical radios - WWII vintage||200 kHz (channels 0-40), SCR-300 (BC-1000) manpack backpack radio|
Most of Vietnam War and Cold War (roughly 1960s-1980s) - although older-generation HF tactical radios and FM radios continued to be used.
|Frequency Band||Use||Channel Step/Frequency Spacing|
|30.000 MHz to 75.950 MHz||Tactical Band (30-76 MHz) (150 Hz CTCSS "new squelch" system) removes need for manual squelch control||50 kHz (channelized intent frequency control) PRC-25, PRC-77, VRC-12 and dozens of others|
1980s-present (starting in the 2000s and 2010s radios such as CB radios, amateur radios, and other COTS equipment has become more prevalent on the battlefield)
|Frequency Band||Use||Channel Step/Frequency Spacing|
|30.000 MHz to 87.975 MHz||Tactical Band (30-88 MHz) 150 Hz CTCSS (some radios allow use of other tones)||25 kHz step, single channel SC (fixed frequency) mode, frequency hopping FH or fast frequency hopping FFH (anti-jamming countermeasure) modes|
|30 MHz to 512 MHz||Tactical Band (30-88 MHz) combined with VHF/UHF bands, including the airband, VHF marine band, VHF land mobile bands||25 kHz step, single channel SC (fixed frequency) mode or frequency hopping FH (anti-jamming countermeasure) mode, 2.5, 5, 8.33 kHz steps|
|380-470 MHz||Intra-Squad Radio (ISR) and Improved Intra Squad Radio (IISR) systems||Various frequency steps and modes used for short range communications within squads/fireteams|
|2400-2500 MHz (2.4 GHz)||Intra-Squad Radio (ISR) and Improved Intra Squad Radio (IISR) systems||Various frequency steps and modes (including spread spectrum and frequency hopping) used for short range communications within squads/fireteams|
Commonly used VHF low VHF mid and HF high bands HF/VHF bands
Other common variations on the VHF low band/VHF mid band coverage for FM tactical radios include:
- 26.000 MHz - 69.950 MHz SEM-25 / SEM-35 and similar clones/variants used in Europe and elsewhere (26-70 MHz)
- 26.000 MHz - 71.950 MHz PRC-25/PRC-77 variants used in dozens of different countries (often listed as 26-71 MHz or 26-72 MHz)
- 28.000 MHz - 73.950 MHz PRC-25/PRC-77 variants used in dozens of different countries (often listed as 28-73 MHz or 28-74 MHz)
- 26.000 MHz - 71.950 MHz PRC-25-T PRC-25 variant developed by TADIRAN (Israel) for Greece. Greek military band 50 kHz steps
- 46.000 MHz - 57.975 MHz SEM-52 and similar radios, often listed as 46-58 MHz - 25 kHz channel steps
- 26.000 MHz - 70.000 MHz Radio Set 3600 - Dutch origin, used in various countries - RT-3600
- 30.000 MHz - 75.975 MHz VRC-4622 - Dutch successor to Radio Set 3600 / RT-3600 - 25 kHz channel steps
- 26.000 MHz - 70.000 MHz TRC-552 - French origin, used in Africa, etc. as well 25 kHz or 50 kHz channel steps depending on version
- 26.000 MHz - 76.000 MHz TRC-552 - variant with matching coverage for use with TRC-571
- 26.000 MHz - 76.000 MHz TRC-571 - French origin, used in Africa, etc. as well 25 kHz or 50 kHz channel steps depending on version
- 47.000 MHz - 56.950 MHz Radio Set 3610 - Dutch origin, used in various countries
- 30.000 MHz - 107.975 MHz Radio Set SPIDER - Dutch origin, used in various countries
- 53.000 MHz - 75.000 MHz PRC-614 handheld tactical radio (similar to PRC-68 series, 30.000 MHz - 79.975 MHz or 30.000 - 87.975 MHz)
- 36.000 MHz - 75.975 MHz Racal TRA-967 and various clones
- 37.000 MHz - 47.000 MHz PRC-349 Clansman portable radio
- 36.000 MHz - 57.000 MHz PRC-350 Clansman portable radio
- 30.000 MHz - 76.000 MHz VRM-5080 and various versions, 25 kHz steps with datalink, encryption mode, secure voice and frequency hopping
- 26.000 MHz - 71.950 MHz RV-3 or TR-PP-13B 50 kHz channel steps, 26.00 MHz - 48.95 MHz low band/49.00 MHz - 71.95 MHz high band (designed for export)
- 40.000 MHz - 48.000 MHz RUP-2 / RUP-2B Yugoslavian and Eastern European clone of SCR-300 / BC-1000 backpack radio
- 30.000 MHz - 79.975 MHz SEM-70 and similar clones/variants used in Europe and elsewhere
- 30.000 MHz - 79.975 MHz SEM-80 / SEM-90 and various clones/copies - 25 kHz steps (European version of the PRC-25/PRC-77/VRC-12 family)
- 30.000 MHz - 79.975 MHz numerous Russian, Chinese and similar clones/copies
- 30.000 MHz - 79.975 MHz R-158 (Russian/Soviet manpack radio) and various clones/copies (25 kHz steps, offset versions to 79.9875 MHz)
- 20.000 MHz - 51.500 MHz R-123 Russian tank radio (20.00 MHz - 35.75 MHz low band, 35.75 MHz - 51.50 MHz high band)
- 20.000 MHz - 49.975 MHz Type 889 radio - numerous Chinese and similar clones/copies (used in tanks, armored vehicles, etc.)
- 20.000 MHz - 49.975 MHz Often found in export-type vehicles and radio systems used in Africa, Middle East, etc.
- 27.000 MHz - 32.000 MHz Older-generation Russian (Soviet) manpack radios (FM voice) cf. 27.000 MHz - 38.900 MHz old PRC-9/PRC-9A bands
- 30.000 MHz - 80.000 MHz PRC-80, made in Israel, exported worldwide
- 47.000 MHz - 56.900 MHz PRC-239 designed in Italy - 100 kHz steps, exported to Middle East, etc.
- 40.000 MHz - 49.975 MHz PRC-439 designed in Italy - 25 kHz steps, exported to Middle East, etc.
- 30.000 MHz - 79.975 MHz PRC-638 designed in Italy - 25 kHz steps, used by Iraq and various other countries
- 30.000 MHz - 88.000 MHz Scimitar V - 25 kHz steps - FM voice or data, available with or without frequency hopping
- 66.000 MHz - 88.000 MHz Scimitar M - 25 kHz steps - FM voice or data, available with or without frequency hopping
- 68.000 MHz - 87.975 MHz Scimitar M Variant with slightly different frequency coverage for export use
- 30.000 MHz - 50.000 MHz A-53 portable manpack radio from South Africa
- 26.000 MHz - 77.000 MHz B-56 portable manpack radio/fixed radio from South Africa
- 30.000 MHz - 87.875 MHz HH7700, PRC-7700 and numerous other handheld and manpack radios cover this band
- 30.000 MHz - 87.9875 MHz Similar radios listed above, but with 12.5 kHz steps available, offset frequencies (narrowband)
- 27.500 MHz - 39.500 MHz Asian fishery radio systems, FM mode 25 kHz channels 27.5 MHz - 39.475 MHz FT-801 and clones
- 33.000 MHz - 49.000 MHz Various COTS Chinese VHF low band radios cover this band
- 43.300 MHz - 43.600 MHz 43 MHz Italy band radios - unmodified versions cover 43.3000 MHz - 43.5875 MHz in 12.5 kHz steps
- 42.300 MHz - 45.100 MHz modified 43 MHz equipment, 12.5 kHz steps to 45.0875 MHz - widely used in Eastern Europe, Ukraine and elsewhere
- 29.700 MHz - 36.000 MHz Various COTS VHF low band radios cover this band - see also 27-36 MHz, 29-36 MHz
- 36.000 MHz - 42.000 MHz Various COTS VHF low band radios cover this band
- 36.000 MHz - 59.000 MHz Various COTS VHF low band radios cover this band (for example, Alinco DJ-V17L, 36-58.995 MHz)
- 40.000 MHz - 60.000 MHz Various COTS VHF low band radios cover this band (for example, Alinco DR-135LH)
- 29.000 MHz - 49.975 MHz Various COTS VHF low band radios cover this band
- 42.000 MHz - 50.000 MHz Various COTS VHF low band radios cover this band
- 29.000 MHz - 37.000 MHz Various COTS VHF low band radios cover this band
- 30.930 MHz - 31.370 MHz Various COTS VHF low band radios - Nordic hunting radio - JAKTRADIO 31 MHz
- 35.000 MHz - 50.000 MHz Various COTS VHF low band radios cover this band
- 35.000 MHz - 48.500 MHz Various COTS VHF low band radios cover this band - see Soontone ST-45 handheld radio 35-48.5 MHz 5 watt
- 37.000 MHz - 48.000 MHz Various COTS VHF low band radios cover this band - Vertex FTL-2011 and similar (similar bands available)
- 37.000 MHz - 50.000 MHz Various COTS VHF low band radios cover this band
- 28.000 MHz - 40.000 MHz Various COTS VHF low band radios cover this band
- 66.000 MHz - 88.000 MHz Various COTS VHF mid band radios cover this band (for example, AnyTone AT-588HF 70 MHz/4 meter version)
- 25.615 MHz - 30.105 MHz Modern standard export radio 10 meter radio frequency coverage (25.610 MHz - 30.110 MHz) see Anytone AT-5555, AT-6666, Superstar 9900, CRE 8900, etc.
- 25.615 MHz - 28.305 MHz Export CB 11 meter 10 meter radio band 240 channel 6 band plan coverage (Superstar 3900 etc)
- 26.515 MHz - 27.855 MHz Export CB 11 meter 10 meter radio band 120 channel 3 band low mid high band plan coverage
- 26.515 MHz - 27.99125 MHz Export CB radio European UK band plan (see also: 26.510 MHz - 27.860 MHz, 26.565 MHz - 27.99125 MHz, 26.510 MHz - 27.995 MHz)
- 25.165 MHz - 28.755 MHz Export CB 11 meter 10 meter radio band 320 channel 8 band plan coverage see Galaxy DX 99, DX 99V2, etc.
- 26.065 MHz - 29.655 MHz Export CB 11 meter 10 meter radio band 320 channel 8 band plan coverage (modified)
- 24.265 MHz - 29.655 MHz Export CB 11 meter 10 meter radio band 480 channel 12 band plan coverage
- 26.065 MHz - 28.755 MHz Export CB 11 meter 10 meter radio band 240 channel 6 band plan coverage (modified)
- 25.615 MHz - 31.005 MHz Export CB 11 meter 10 meter radio band 480 channel 12 band plan coverage (modified)
- 25.615 MHz - 29.695 MHz Export CB 11 meter 10 meter radio band Magnum 257HP, etc (25.610 MHz - 29.700 MHz)
- 26.065 MHz - 30.555 MHz Export CB 11 meter 10 meter radio band 400 channel 10 band plan coverage
- 26.510 MHz - 27.860 MHz Export CB Russian CB band (see also: 26.515 MHz - 27.865 MHz)
- 25.615 MHz - 27.995 MHz Export CB Russian export band (see also, 25.610 MHz - 27.995 MHz)
- 26.000 MHz - 32.000 MHz Export CB band (cf. RCI-2950, RCI-2970 series of radios)
- 24.500 MHz - 30.000 MHz Export CB band, various 12m/10m radios
As discussed in previous paragraphs, there is a move to COTS equipment, including non-standard radios such as amateur radios, VHF marine band radios, CB/11 meter radios and other land mobile radios in the VHF/UHF band for tactical purposes. Unfortunately, VHF low and VHF mid band does not work well in heavily built up areas (i.e. urban warfare radios). High band VHF and UHF work considerably better in these environments. It is because of this that the modern PRC-148 and PRC-152 radios cover 30-512 MHz instead of just 30-76 MHz or 30-88 MHz. Chinese clones of Russian or Soviet combat net / tactical radios, including tank radios and manpack portable and mobile radios cover similar frequency ranges as well. 20-60 MHz, 20-50 MHz, 30-80 MHz and others are common. 30.000 MHz to 79.975 MHz is another commonly available band, using the 25 kHz channel steps. Western equipment generally favors 30.000 MHz to 87.975 MHz.
Easily acquired and widely available commercial off-the-shelf (COTS) communications equipment has introduced additional bands (as a replacement to or in conjunction with, or as a replacement for, the standard military bands as emerging threats in areas where asymmetric warfare, guerrilla warfare and insurgency tactics are used.
Improvements with radio technology allowed for all three bands to be combined and moved from 20-55 MHz to 30-76 MHz and eventually 30-88 MHz, reducing channel spacing from 100 kHz to 50 kHz (Vietnam War) to 25 kHz (SINCGARS and present day). With the addition of frequency-hopping (ECCM - electronic counter-counter measures or anti-jam) and voice encryption (COMSEC) the FM radio became the standard battlefield tactical radio for ground and air communications. In the United States, most military systems still use 50 kHz step compatible frequencies for range control (cf. Fort Hood Range Control on 30.450 MHz is often heard during 11m/CB/10m and VHF low band band openings). See the frequency bands above. The 30 MHz, 32 MHz, 34 MHz, 36 MHz, 38 MHz, 40 MHz, 41 MHz and 46/47 MHz bands are very popular for CONUS-based military communications.
Amateur Radio Operators Using Surplus Military Equipment
Because previous-generation, vintage or antique military radios with 30-76 MHz or 30-88 MHz frequency bands cover the 6 meter amateur band, and WWII and Korean War vintage equipment covers 20-28 MHz or 20-27.9 MHz and 27-38.9 MHz or 27-39 MHz amateur radio operators will often use surplus equipment in the 10 meter and 6 meter bands for FM communications. Vintage military radio equipment is also used by amateur operators in the HF bands and VHF bands above 6 meters where available. This includes the 4 meter band around 70 MHz, which is available in select countries for amateur use. The PRC-8/PRC-8A (20 MHz-28 MHz), PRC-9/PRC-9A (27 MHz-39 MHz), PRC-10/PRC-10A (38 MHz-55 MHz), PRC-25, PRC-77 and similar radios are very popular with amateur or ham radio operators who keep these vintage radios alive by operating them on the amateur bands.
51.0 MHz is the most common military amateur radio frequency on 6 meters, as this allows for compatability with 100 kHz channel steps, 50 kHz channel steps, 25 kHz channel steps and tunable radios such as the PRC-10 or PRC-10A. Before the adoption of the PRC-25 and VRC-12 family of radios, armor (tanks), artillery and infantry each had their own radio bands (20-28 MHz for armor/tanks, 27-39 MHz for artillery and 38-55 MHz [or some subset thereof] for infantry). For example, the famous walkie-talkie backpack or manpack radio SCR-300 (BC-1000) covered 40-48 MHz in 100 kHz steps while the PRC-6 "banana radio" handheld transceiver or HT covered 47-55.4 MHz.
With the adoption of the PRC-25 and VRC-12 family of radios (and associated fixed and aircraft radios), armor, artillery and infantry could all communicate using the same radios, greatly improving tactical battlefield communications in time for the Vietnam War.
See Radio Nerds for a large library of resources on military radio gear, including technical and operations manuals.
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