September 27, 2021, 01:46:31 pm

Emergency A/G COMMS

Started by blackrain, March 11, 2021, 01:38:02 am

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Quote from: etodd on March 12, 2021, 08:31:41 pm
Quote from: Fubar on March 12, 2021, 06:54:39 pm
Quote from: Eclipse on March 12, 2021, 06:24:40 pm
Quote from: blackrain on March 12, 2021, 05:58:52 pmIf frequencies are officially designated and people know that official assets now have the capability to operate on those frequencies would people carry a capable radio?


Think of all the common sense precautions a person can already take to prevent the likelihood of them being in a situation where they need to be rescued. Adding one more precaution of carrying a two-way radio won't reduce the amount of people who ignore common sense precautions.

Exactly. Blackrain is thinking nobly with good intentions, but he is a techie and thinks in those terms. The group of teenagers that get lost in the forest, or the old person with alzheimer's who wonders off, or any number of examples ... will simply not be carrying a radio.

Never underestimate the unpreparedness of our civil SAR "customers". Combat SAR is another story, of course, with CSELs and so forth, but even there that field is evolving (doing away with DF, etc.).

It would be a serious error to invest in the belief that we should equip and train to a cooperative target when the vast majority of them are not. (Cite?  Well, the majority of them are incapacitated or gone by the time they are found, for one, which is why TSOc91A exists).


Quote from: blackrain on March 12, 2021, 02:07:40 pm
Quote from: SarDragon on March 12, 2021, 09:48:38 amI just looked at the specs for the MURS radios, and the A/C FM radio. I see two incompatibilities: the output power of the A/C unit exceeds the permissible power for the frequency set, and the bandwidths for individual frequencies don't match, causing audio intelligibility issues.

MURS has specified operating parameters, and adapting our A/C radios to meet those specs on a small number of channels is impractical at best, and expensive if even doable.
Actually I was wondering about that. Our power settings at least on the TDFM 136 are 1 and 10 watts (low/high power setting) if I remember correctly and MURS is limited to 2 Watts. Also on the Bandwidth (narrowband vs wideband issue) is what I understand you are referring too? Can the TDFM 136 utilize Marine Band Channels which are still wide band? Anyone out there know the TDFM 136 and the programming capabilities? Can we set bandwidth and power settings for individual channels/frequencies? Our GT handhelds are another question.

MURS bandwidth is 11.5 kHz; TDFM bandwidth is either 12.5 kHz or 25 kHz. I have programmed TDFMs. It is certainly something I would not want to be doing in flight.

As for your later Q about marine freqs, we already have them in our CAWG channel plans. Each channel has its own set of parameters regarding frequency, bandwidth, squelch/tones, conventional/digital mode, and a few other things.
Dave Bowles
Maj, CAP
AT1, USN Retired
50 Year Member
Mitchell Award (unnumbered)
C/WO, CAP, Ret


Thanks for the Noble Techie title etodd! My son won't believe it though.  I've tried 25khz to 12.5 kHz with different radios and there is definitely a loss. I didn't notice the odd bandwidth of the MURS radios and what the 20khz to 25khz distortion would be I can only imagine. Interesting fact is the most reliable means of comms in most 3rd world localeles is the cell network and in Afghanistan we actually bought cheap local phones with scratch card minutes. They would often work where other means didn't. Go figure. Certainly not secure but in an emergency the bad guy's probably knew where we were and at that point we wanted the good guys to know too. Spent about $150 or so on the phone and minutes and we all agreed it would seem mighty cheap if things ever went south. Don't get me wrong and I agree that most who get into trouble are there because they aren't the plan ahead types anyway.
"If you find yourself in a fair fight, you didn't plan your mission properly" PVT Murphy


Apparently NC Wing has the TDFM 9100 and on page 20 they address the use of contacting individuals in distress via FRS. I had no idea and our radios aren't even capable of UHF. Hopefully we'll get the upgraded radios.
"If you find yourself in a fair fight, you didn't plan your mission properly" PVT Murphy