" I know the TSA uses it (purely encrypted end to end)"
What makes you say that? I can hear TSA all the time on my PSR-500 and my tapped BCT-15 thru DSD 1.6. Clear as can be. 172.9
Ok, my mistake then, I was under the impression that the TSA has a system in place that's P25 encrypted at McCarran - I saw mention of it here in the past and that's what I was going on. I never put a lot of interest in it overall because of the P25 nature; I'm just now getting into being able to monitor that kind of traffic since I've never owned a digital capable scanner. I still don't own one but I've got RTL sticks now for SDR and can decode that stuff with DSD+ but even so, there's just not much here in our area using P25 that matters even now.
I've been listening in on the range from 163 to 174 here in Vegas for years now and I swear I've never picked up a single transmission of any kind, ever. Since I got into this SDR kick I've put time into that range and I'm still getting Jack Squat in there, absolutely nothing (ok, I get an image of a lower frequency from time to time but that's about it). I can't believe we live in a "dead zone" with respect to Federal activities so I just chalk it up to me not being able to receive a damned thing, go figure.
If you have any specifics I should be looking for and wouldn't mind dropping them into a PM or whatever I'd appreciate it. I see plenty of lists with "Federal frequencies" and stuff listed for our area as well as general frequencies in use by some agencies in that range but, again, no matter what I'm doing with respect to antennas I'm just deaf in that area. Right time at the right frequency I suppose. That's one thing I figured SDR and the spectrum display might help instead of just scanning a range hoping to get a hit - kinda hard to do that since I don't own a physical scanner at this point.
I'll punch in 172.900 and go from there. My location in downtown Vegas + having a huge brick and steel building blocking my direct LOS to McCarran could be a big part of it more than likely. I built one of those 1/4 wave VHF groundplanes using an SO-239 chassis mount and radials made from coat hangers and it's been exceptional in terms of yanking in stuff for the most part, still planning on building an OCFD here when I can get the parts together too, might make a difference.
EDIT:
Well I'll be damned, it works...
Punched in 172.900, brought up DSD+, gave it a minute or so and wham, W00T!!! Awesome, and it sounds great through DSD+ too. Signal peaks around -25 dB so it's fairly strong, guess it really was being in the right place at the right time (and with the right hardware, of course).
Ok, so... guess I need to focus on that 163-174 range a bit more now so again, any frequencies that I should specifically target would be appreciated, thanks for the tip on 172.9. I'm not new to scanning in general as I've noted before, but I can honestly say I've never bothered with that range in all my years, the "Fed files" and Federal monitoring has never even been a hot topic for me.
Now it seems that was probably a mistake so, now I'm going to get into it just a wee bit more.