Software Defined Radio - SDR, any HAMs doing this? Listen to LEO radio.

[Glass]

We've spoken about SHTF communications before. I've heard of SDR before, however the systems I've seen are multi $ thousands just to get started. Things like WinRadio cost a bomb IMO.

Modern radios are merely computers anyway. Specific purpose computers with specifically coded software to run them.

You could get a transceiver card and a PC. The SDR software on the PC runs the transceiver card just like a radio would.

OK enough background. Someone was progamming a Linux driver to run a TV Tuner USB dongle and they discovered something interesting. These TV Tuner dongles are cheap. About $20 in the US. They also receive FM Radio (usually in DAB format but it's FM) on top of TV signals. They have fairly wide bandwith. Below 100Mhz and upto 2000Mhz.

So there is a software out there that enables you to use one of these $20 digital TV tuner dongles to scan and record frequencies in that range. It can even record several frequencies to a hard drive at one time. It doesn't have transmit abilities only receive.

Has any one set this stuff up or heard about it? Is anyone out there a Linux Guru? I've been putting something together over the weekend but I have some obstacles. I'm not a linux guru.

It's called GNURadio.

Reason? There is a SDR application out there that deals with P25. P25 is the encryption sytstem the LEO etc are using on their signals. This OP25 program runs in conjunction with the GNURadio program to decode the encrypted signal.

It does require the encryption key to do this. That is obviously something they don't share.

There is at least 2 hours of Sandy Hook LEO radio traffic out there. It's recorded to a file. This OP25 can do it's thing to a saved file. As long as it's fed via the audio input.

I'm thinking there is a fair bit of garbled radio traffic on that 2 hours of audio. Some of it is going to be encrypted. I'd like to know what it is that is being said.

I admit the encryption is an obstacle I haven't looked into yet but I'm figuring someone out there has something to deal with that.