Characteristics of the AN/PRC-70 Type of Set Portable tactical transceiver Type of Modulation CW, AM, FM, SSB (also supports FSK for data Communication) Type of Emission Voice, CW (morse code), data Number of Channels 74,000 Tuning Continous Frequency Coverage 2 - 76 MHz Modes of Operation FM - 40 km (VHF)- planning range CW - 2400 km (HF) - planning range AM and SSB Power Output FM, SSB, CW - 40 W AM - 10W Power Source NiCad or Metal Air Batteries Antenna Whip - 6 feet Whip - 15 feet Doublet Weight less than 25 lbs Note: the weight is different than the one listed in TMP TM 1-1 which uses 39 lbs. The characteristics of the AN/PRC-68A (from the orginal spec MIL-R-29401B - USMC) are: Type: Handheld VHF/FM radio Controls: Push to Talk Switch Volume Control Power Off/Power On/Squelch Disable Switch (Note: this swich will not stay in the squelch diable position without being held there. This radio uses a 150 Hz tone to break the squelch on the receiving unit. This means that you will not hear static unless you manually disable the squelch and hold it there) Phone/Mic/External Power Connector - a 5 pin connector compatiable with the standard military handsets (ie H-250) Earphone Connector - for standard earphones (ie H-281) - this connector disables the built-in speaker Built-in speaker Built-in microphone Channel Selector Switch (10 positions) Frequency Range: Operating Frequency Range 30-80 MHz (in 25 kHz) Number of Channels 2000 (Note: This unit will operate in one of four bands 30-40 MHz, 40-54 MHz, 50-64 MHz, and 60-80 MHz. Each band has between 500 and 800 channels each. Out of these channels, the channel selector switch can select 10. The band of operation and the ten channels are selected by programming switches within the unit. In my world, these ten channels are selected as 5 team channels and 5 guard (or regional wide) channels. The four bands are assigned to the four regional centers but the selected channels will be in the operating frequency range of the PRC-70 (again my world - your world my vary)) Planning Range With provided antenna 300 meters With long antenna (AT-892/PRC-25 (ie the VHF antenna for the PRC-70) 1.6 km (Note - when we discuss planning range we mean the range where reliable communications between two radios of the same type with the average operator over a wide range of terrain types - for the PRC-68A this includes the operator in the supine, kneeling, and standing position. This explains to some extent why the range is much shorter than that in the TMP TM 1-1.) Hours of Operation 36 hours with BA-1588/U (mercuric oxide battery) based on 1 minute transmit - 1 minute receive and 8 minutes of standby (squelched): probably much less with a NiCad battery (BB-588/U) but not stated RF Output Power - 1W Antenna - 12.7 to 19.7 cm long rubber covered - this antenna will be removable to allow attachment of external units. MTBF (mean time between failure) 1000 hours (at +65 degree C) Operating Temperature Range -40 to +65 C This unit will accept the standard Secure Voice Module (KYV-2 or -2A) Size: excluding the battery (as shown in TM 1-1) 23.7 cm by 9.6 cm (wide) and 3.86 cm thick add 5 cm to the height for the battery. Weight - 1.4 kg with BA-1588/U Battery Okay there is the equipment so let's discuss the various possible communication scenarios: AN/PRC-68 - AN/PRC-70 Since the PRC-68 (sometime PRC is pronounced 'prick') is VHF, both radios have to have "line of sight." This means that, in the absence of blocking vegatation, you should be able to see antenna of the unit to which you are transmitting. At these frequencies, vegatation does not cause a lot of problems. The range from the '70 to the '68 would be about 40 km while the range back would be about 1 km (the longer PRC-70 antenna gives us a gain in recieve with increases the range back). If the foot team would go too far from the vehicle, it could here the vehicle but not send back. Another interesting item is that two AN/PRC-70 can be connected into a retransmit mode (ie what is recieved by one unit is transmitted by the other). So two PRC-70 could be connected together and two nets of PRC-68 could be set up. This would allow one group on foot to communicate to another group. Each group is on a different frequency (separated by 10 MHz). This allows communications across blocking terrain (park the vehicle on the crest of the hill and team can check out both sides). It also increases the operating range overall but the vehicle has to be in the center of the area. Finally, in my would I have added the following piece of equipment: F2338 - Interlink Repeater System weight: 1.6 kg size 51mm high by 178mm wide by 242mm deep This links SSB HF and FM VHF/UHF radio for connecting nets. Thus a PRC-70 can be connected to the PRC-68 through the handset connector. This would allow PB to listen in on the group's VHF net (PRC-68s). AN/PRC-70 to PB The planning range in the CW mode is 2400 km (note the change from my previous post). The 4000 km range in TM 1-1 is probably based on the longest single bounce path obtainable on the earth. From some first order estimates (looking up the data and guessing the system performance at PB), the PRC-70 could probably do this with voice (single side band (SSB)) but this would require that the operator knew the best operating frequency for that time. I would expect that PB probably sent out the MUF (Maximum Usable Frequency) predication using CW (which would go farther) one per week or day. With a vehicular amplifier and larger antenna, this would not be as important. AN/PRC-70 to AN/PRC-70 - both in manportable mode It may be necessary for two teams each using AN/PRC-70s to communicate without the vehicle goodes. This can be done in HF in the heaviest terrain using NVIS (nearly vetically incident sky wave) propagation. The frequencies that are use in this mode are not receivable with the AN/PRC-68. Effectively we transmit up and receive the reflected signal. The planning range - pretty much without regard for the terrain - should be about 360 km (longer with trained personnel making an effort - maybe as far as 500 km but I don't have all the preformance information I need for the perdiction). Hope this helps. Bill William R. Garmer, PE Torrey Science Corporation 10065 Barnes Canyon Road Suite B San Diego, CA 92126-2777 Voice: 619/552-1052 Fax : 619/552-1056 email: bgarmer@tst.com