Sentcom radios???

[scannerman200]

There is a national guard base here in my city and there appears to be a spider shaped antenna on the top of the base. I was informed that the frequencies used here are called something like "Sentcom radios" and that the frequencies used hop around on each transmission. What frequency range could I search to pick up these transmissions?

 

[prcguy]

Could it have been "Satcom"? How big was the antenna? If it was less than 2ft in diameter and looked like it was aimed skyward, its probably UHF Satcom. There is also "SINCGARS" radios which hop in the 30 to 90MHz range and they might use anything from a large Discone or Bi-Cone with 3 8ft elements sticking up and 3 down or there is an older "stressed wire" log periodic that might resemble a spider depending on your state of mind. Check this link for a picture of that stupid thing: http://www.american-milspec.com/p-50-as-2236grc-dorne-margolin-log-perodic.aspx
prcguy

There is a national guard base here in my city and there appears to be a spider shaped antenna on the top of the base. I was informed that the frequencies used here are called something like "Sentcom radios" and that the frequencies used hop around on each transmission. What frequency range could I search to pick up these transmissions?

 

[ff-medic]

I was informed that the frequencies used here are called something like "Sentcom radios" and that the frequencies used hop around on each transmission. What frequency range could I search to pick up these transmissions?

You are not going to pick up anything.

Quote = "a. SINCGARS hops or changes frequencies about 100 times per second. The radio uses digital processing to control the hopping sequence and the pattern so that the RT arrives at the same frequency at the same time. This ensures the information sent is received and can be decoded. If the sequence were truly random, the receiver could not predict what frequency to hop to next, so the actual sequence is developed in a pseudorandom fashion. The RT uses identical sequencers so the receiver can predict what frequency the transmitter will hop to next. SINCGARS uses the following four variables to synchronize the hopping sequence:

Hopset.

TSK.

Net identifier.

Julian day/zulu time.

Unless the receiver has all four identical variables, the sequence appears random to a radio outside the network. FH degrades enemy detection capabilities because the output is basically a random pattern. Additionally, several different networks operating in the same area prevent identifying a particular frequency or hopping pattern with any one network. "

" Frequency Hopping" think of the old radio scanners that had the 10 or so lights on the front. The lights lit up from left to right. Well...While an individual is talking......The radio is "Scanning" ( the lights are moving from left to right and checking numerous freqs - as quoted above...at about 100 times per second ). It don't transmit on one single frequency, you transmit on numerous. The kick is.....everybody else on the net has to have their radios in the same sequence.

The NCS ( net control station ) sends a radio signal out to everyone in "Their" net to syncronize their radios, in able to transmit. When I was in the service...way back when..we still had a single freq to transmit priority and flash radio traffic on. This was in the event something happend in Freq Hopping mode. But that info was still transmitted in secure mode ( encrypted ).

Satellite traffic...Most usually the ground antenna is pointed directly at the satellite, and unless you are in the sky betwen the transmitter and the receiver...you still are not going to hear anything. Most all Military satellite communications are encrypted to prevent foreign agents and foreign governments from intercepting the signal, especially on the downlink. Alot of confidential info is given over satellite, and satelite communications is not in every unit such as the vhf lowband - highband and UHF. Think of satellite , for teh best part, as specialized commo..for specialized units.


FF-Medic - - - - -


FF-Medic - - - -

 

[prcguy]

To further complicate things, in the hopping mode the SINCGARS audio is a digital waveform at 16kpps. Good luck with all that.
prcguy

You are not going to pick up anything.

Quote = "a. SINCGARS hops or changes frequencies about 100 times per second. The radio uses digital processing to control the hopping sequence and the pattern so that the RT arrives at the same frequency at the same time. This ensures the information sent is received and can be decoded. If the sequence were truly random, the receiver could not predict what frequency to hop to next, so the actual sequence is developed in a pseudorandom fashion. The RT uses identical sequencers so the receiver can predict what frequency the transmitter will hop to next. SINCGARS uses the following four variables to synchronize the hopping sequence:

Hopset.

TSK.

Net identifier.

Julian day/zulu time.

Unless the receiver has all four identical variables, the sequence appears random to a radio outside the network. FH degrades enemy detection capabilities because the output is basically a random pattern. Additionally, several different networks operating in the same area prevent identifying a particular frequency or hopping pattern with any one network. "

" Frequency Hopping" think of the old radio scanners that had the 10 or so lights on the front. The lights lit up from left to right. Well...While an individual is talking......The radio is "Scanning" ( the lights are moving from left to right and checking numerous freqs - as quoted above...at about 100 times per second ). It don't transmit on one single frequency, you transmit on numerous. The kick is.....everybody else on the net has to have their radios in the same sequence.

The NCS ( net control station ) sends a radio signal out to everyone in "Their" net to syncronize their radios, in able to transmit. When I was in the service...way back when..we still had a single freq to transmit priority and flash radio traffic on. This was in the event something happend in Freq Hopping mode. But that info was still transmitted in secure mode ( encrypted ).

Satellite traffic...Most usually the ground antenna is pointed directly at the satellite, and unless you are in the sky betwen the transmitter and the receiver...you still are not going to hear anything. Most all Military satellite communications are encrypted to prevent foreign agents and foreign governments from intercepting the signal, especially on the downlink. Alot of confidential info is given over satellite, and satelite communications is not in every unit such as the vhf lowband - highband and UHF. Think of satellite , for teh best part, as specialized commo..for specialized units.


FF-Medic - - - - -


FF-Medic - - - -