Feds on close call??

[pro106import]

Ah but you don't need or particularly want a dongle. Basically this:

Uhf receiver tuned to an active signal in wide FM mode

Tap the wide FM discriminator chip (not the discriminators you see for decoders) the WIDE FM chip

Route that tapped unfiltered wide FM discriminator into the microphone port of the PC

Set the sound card to to at least 120 kHz bandwidth (up to 190 is fine) but 120 is perfect

Use SDR# or similar with the sound card set as the receiver

The signal will appear as a series of vertical thin stripes. Those are the 2600 Hz off hook tones

Voice signals will appear every 8 kHz alternating LSB USB etc...

To get real fancy edit the SDR# config file and add in 8 kHz tuning step below the 8.33 step.

Add in one of the frequency manger plugins and create voice channels at every 8 kHz

That's it.

Crystal clear audio every time.

I suppose virtual audio or VB cable would work to route wbfm audio from a dongle into another instance of SDR# but I haven't tried that yet. I will have to experiment with that.

Makes sense. The scanner is the receiver. The software is the decoder. Maybe I'll break out that old Bearcat 9000XLT sitting in a box somewhere and tap the chip on that one. I have the schematic around somewhere too. Don't want to mess with my newer radios if I don't have to. See, I told the wife I would use all of that "junk" someday...:lol:
PS , sorry moderator for getting off topic here

 

[rbm]

Here's a photo of the Navy E-6B, tail # 167284.

Click on the thumbnail to see the big photo.

Mancow, I've never tried the method you mention.

However, there have been a few times when I've tuned across the wideband signal and could just barely hear some voice but it was extremely difficult to make out what was being said.

Sometime when I have time to fool around I'll have to give it a try.

Rich


162784 Boeing E-6B Mercury (707-300) US-Navy
162784 Boeing E-6B Mercury (707-300) US-Navy Picture

 

[krokus]

It's a system that dates back to the beginning of the cold war. Basically it's a doomsday comms system. They are thousand watt transmitters that use frequency defined multiplexed signals that carry a dozen voice channels. Ground receivers referred to as GEPs route the comms back to silos or command centers or wherever. The signals often carry data as well. The system works like a phone system. It's full duplex and traffic on it sounds like a phone call rather than the two way stuff we are used to.

Sounds like a similar setup to the multiplexer, in the analog microwave system I used to maintain.

Sent via Tapatalk

 

[mancow]

I think it's pretty much that system in UHF.