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I question why they couldn't buy COTS P25 radios for tactical communication in a hardened form factor - I'm sure Motorola (or whomever else) would have gladly w

by Aloha 11y ago

I question why they couldn't buy COTS P25 radios for tactical communication in a hardened form factor - I'm sure Motorola (or whomever else) would have gladly whipped up a extra durable version of an XTS3000 or XTS5000 - P25 by its nature supports pluggable encryption, so you can use just about anything with it. For Lower than 30mhz - there are many COTS solutions using well proven technology, even supporting digital encrypted audio available.

rayiner 11y ago
What do you do when the enemy deploys a jammer? One part of the military's broader cognitive radio strategy is/was radios that could avoid jamming by hopping to different parts of the spectrum.
- Aloha 11y ago
  Building a simple durable FHSS system isn't hard either, you could then effectively send a P25 data stream on top of it - the radio access channel and data stream are reasonably divorced in P25. Even then, its hard to build an effective broadband jammer - you simple move to another part in a say ~120MHz band.
elithrar 11y ago
No doubt part of it was trying to "have it all". They wanted radios that could act as VSAT terminals (for field to base comms), data terminals (for which P25 is poorly suited) and for operational voice with fallback (UHF, VHF, HF). Otherwise yes, you can buy (today) hardened P25 handsets with IP66+ rated fist microphones and all that. (my opinion is that the project was madness on a hardware level: all of those filters and FPGAs were competing with size, battery life, cost and complexity)
- Aloha 11y ago
  Oh agreed - and P25 can do packet data sorta anyhow, as you said, not well suited to integration with the existing military radio systems. I think the P25 datastream however is a useful construct to build a larger radio system around however. They wanted it all, and got nothing, the usual ending when you try to build something around a "grand unified model" there is always an edge case.
kayfox 11y ago
I think the main issue with the project is more the software outside the SDR software, they wanted these radios to do everything to the point of absurdity, just look at the list: https://en.wikipedia.org/wiki/Joint_Tactical_Radio_System#Waveforms https://en.wikipedia.org/wiki/Joint_Tactical_Radio_System#Wa... This requires a significant amount of software outside of decoding a radio signal from a bitstream into another bitstream. You have tons of software to interface to all the little dingus and do-dads you want to plug in. Some of this is standardized. Remember, the military connector category on Mouser is 500,000 parts large.

by Aloha 11y ago

rayiner 11y ago

What do you do when the enemy deploys a jammer? One part of the military's broader cognitive radio strategy is/was radios that could avoid jamming by hopping to different parts of the spectrum.

Aloha 11y ago
Building a simple durable FHSS system isn't hard either, you could then effectively send a P25 data stream on top of it - the radio access channel and data stream are reasonably divorced in P25. Even then, its hard to build an effective broadband jammer - you simple move to another part in a say ~120MHz band.

elithrar 11y ago

No doubt part of it was trying to "have it all". They wanted radios that could act as VSAT terminals (for field to base comms), data terminals (for which P25 is poorly suited) and for operational voice with fallback (UHF, VHF, HF). Otherwise yes, you can buy (today) hardened P25 handsets with IP66+ rated fist microphones and all that. (my opinion is that the project was madness on a hardware level: all of those filters and FPGAs were competing with size, battery life, cost and complexity)

Aloha 11y ago
Oh agreed - and P25 can do packet data sorta anyhow, as you said, not well suited to integration with the existing military radio systems. I think the P25 datastream however is a useful construct to build a larger radio system around however. They wanted it all, and got nothing, the usual ending when you try to build something around a "grand unified model" there is always an edge case.

kayfox 11y ago

I think the main issue with the project is more the software outside the SDR software, they wanted these radios to do everything to the point of absurdity, just look at the list: https://en.wikipedia.org/wiki/Joint_Tactical_Radio_System#Waveforms https://en.wikipedia.org/wiki/Joint_Tactical_Radio_System#Wa... This requires a significant amount of software outside of decoding a radio signal from a bitstream into another bitstream. You have tons of software to interface to all the little dingus and do-dads you want to plug in. Some of this is standardized. Remember, the military connector category on Mouser is 500,000 parts large.