Quick question on modulation for SATCOM,

[NS9710]

Is Satcom AM or FM modulation. Just want to ensure I’ve set the scanner properly, thank you

 

[SA_tx_88116]

FM remember AM bounces off the ionosphere while FM continues in to space until hitting something

 

[10-43]

Its the frequency not the modulation mode most affected by the atmosphere. AM or FM at UHF satcom frequencies will behave pretty much the same as far as propagation, but FM is more suitable for other reasons. The reasons are a bit complicated. AM broadcast band frequencies 540 to 1700 Khz are much more affected by ionospheric deflection or absorption. If the AM broadcast band used FM mode the propagation would be mostly the same.

What you can listen to on UHF Satcom frequencies can be demodulated with FM mode.

 

[merlin]

It depends entirely on the service, the frequencies involved and type of spacecraft.
Off hand, I know of about 16 different modulation schemes from simple AM/FM through complex quad amplitude digital.

 

[10-43]

It depends entirely on the service, the frequencies involved and type of spacecraft.
Off hand, I know of about 16 different modulation schemes from simple AM/FM through complex quad amplitude digital.

I thought maybe there was some AM, but I am not familiar with it and couldn't find a reference for it. Any reference for AM?

I am familiar with a few of the digital modes. I have deployed AN/PSC-5 DAMA as a part of command and control for larger systems. A long time ago in a galaxy far far away.

 

[prcguy]

FM remember AM bounces off the ionosphere while FM continues in to space until hitting something

Modulation has nothing to do with bouncing off the ionosphere or passing through it. It’s all about the frequency. Most UHF satcom modulation is digital and there are many formats of DAMA spanning several bit rates and for US based comms probably 99% encrypted. Pirates use FM and you might hear an occasional mil user on FM but it’s rare or by accident.

 

[TDR-94]

DAMA is now a legacy SATCOM waveform.

 

[RichardKramer]

I thought maybe there was some AM, but I am not familiar with it and couldn't find a reference for it. Any reference for AM?

I am familiar with a few of the digital modes. I have deployed AN/PSC-5 DAMA as a part of command and control for larger systems. A long time ago in a galaxy far far away.

Back in the 80s & 90s there was a Canadian ATC UHF AM freq that was on an uplink freq to one of the AFsatcom/Fleetsatcoms which was downlinked in the AM mode in the 262.xxx range. The freq has since been changed.

 

[10-43]

DAMA is now a legacy SATCOM waveform.

It isn't a waveform, and still very much alive. It's a protocol to handle channel access and allocation. Modulation is BPSK and QPSK.

 

[TDR-94]

It isn't a waveform, and still very much alive. It's a protocol to handle channel access and allocation. Modulation is BPSK and QPSK.

L3HARRIS defines DAMA as a waveform in their terminology.They also define DAMA as a 'legacy' waveform, like the aging SINCGARS and soon to be replaced Havequick waveforms

 

[10-43]

Back in the 80s & 90s there was a Canadian ATC UHF AM freq that was on an uplink freq to one of the AFsatcom/Fleetsatcoms which was downlinked in the AM mode in the 262.xxx range. The freq has since been changed.

Interesting. Well the AN/PSC-5 operates AM, FM and PSK modes and of course has DAMA with the possibility of encryption. I don't remember much about the transponders. I dont think they are anything but RF translators so AM is possible. I never ran into it. Transponder were in the training materials, but I never had to be concerned about that. It looks like maybe the D versions are still produced.

 

[10-43]

L3HARRIS defines DAMA as a waveform in their terminology.They also define DAMA as a 'legacy' waveform, like the aging SINCGARS and soon to be replaced Havequick waveforms

Defining it as a waveform is weird. Definately not a waveform.
Maybe legacy as in old and still used.
And Havequick isn't a waveform, but also a protocol. The waveform or modulation is FM or AM.

 

[10-43]

Defining it as a waveform is weird. Definately not a waveform.
Maybe legacy as in old and still used.
And Havequick isn't a waveform, but also a protocol. The waveform or modulation is FM or AM.

It appears SINCGARS radios are just being phased out in favor of the newer radios with coverage from 30 to 512 or up to 2000 MHz. I read up on the AN/PRC-117G. Harris did list DAMA within the narrowband waveform section, but that was probably just for inclusive reasons. DAMA isn't a modulation or waveform. Also looks like Havequick is still alive and well. I couldn't imagine it going away. The primary purpose being ECM. Havequick by itself isn't approved for secure communications, but due to radios on the same net using TOD and WOD it's virtually impossible to track the hopping to monitor if you are not on the net.

I'd sure like to get my hands on an AN/PRC-117G. Talk about a do everything radio. There is also a P25 option.

 

[prcguy]

It appears SINCGARS radios are just being phased out in favor of the newer radios with coverage from 30 to 512 or up to 2000 MHz. I read up on the AN/PRC-117G. Harris did list DAMA within the narrowband waveform section, but that was probably just for inclusive reasons. DAMA isn't a modulation or waveform. Also looks like Havequick is still alive and well. I couldn't imagine it going away. The primary purpose being ECM. Havequick by itself isn't approved for secure communications, but due to radios on the same net using TOD and WOD it's virtually impossible to track the hopping to monitor if you are not on the net.

I'd sure like to get my hands on an AN/PRC-117G. Talk about a do everything radio. There is also a P25 option.

Why not a PRC-152, should do everything the 117 does but slightly lower power.

 

[10-43]

Why not a PRC-152, should do everything the 117 does but slightly lower power.

Yeah. That one would be fun too. Slightly different coverage. Data sheet implies P25 Phase 1 trunking included. Since base comms are P25 trunking makes sense to include it. Those were not available back when I last served. Neither it or the PRC117.

 

[10-43]

Yeah. That one would be fun too. Slightly different coverage. Data sheet implies P25 Phase 1 trunking included. Since base comms are P25 trunking makes sense to include it. Those were not available back when I last served. Neither it or the PRC117.

I bet there's a ton of them was left in Afghanistan Sept 2021.

 

[prcguy]

Yeah. That one would be fun too. Slightly different coverage. Data sheet implies P25 Phase 1 trunking included. Since base comms are P25 trunking makes sense to include it. Those were not available back when I last served. Neither it or the PRC117.

I've seen a few and P25 seems to be a rare option.

 

[TDR-94]

Havequick is sheduled to be completely phased out of all US branches of service by October 2024. It's been replaced by the SATURN waveform.SATURN also uses M-Code GPS as it's primary TOD acquisition.

I believe the SINCGARS waveform was to be replaced by the Soldier waveform or WREN.

The only AN/PRC-152 radios that support the P25 waveform with P25 Phase 1Trunking are the AN/PRC-152A version radios. The AN/PRC-152(C) version radios, only support P25 conventional. In either case, it's rare for the P25 waveform option to be installed in any of the AN/PRC-152 radios, or even any of the L3HARRIS export military handhelds, that have support for it.

The ability to configure the P25 waveform parameters also requires the programming software application and the radios have to still be TYPE-1 Initialized to be able to use the programming application.The P25 waveform paramaters can not be configured through FPP.

Some of the export variants support their own variations of tactical sattelite waveforms, but none support the SATCOM DAMA waveforms.