System Test

[TinEar]

At 1401 someone tested a system that totally overwhelmed me across all freqs. I heard a warbling siren, then someone blasting saying, "This is a test of the _____ system. Since I wasn't on the actual freq they were using, it was kind of garbled and I couldn't pick out the name. They then went to scrambled voice for a few seconds and then someone said in the clear...Zero One copies. And that was the end. I had radios on in the 130, 143, 260, and 320 mHz ranges and the siren and voice completely swamped all of them. Anyone have any idea what this might have been?

[Edit] Heard it one more time about 10 minutes later with just one scrambled transmission. The thing is obviously close to my location in Glen Burnie to be able to swamp me across the VHF and UHF bands the way it did. I'm fairly close to BWI so it could have even been something airborne and almost directly overhead.

 

[TinEar]

I've been hearing this signal several more times. Each time it has been scrambled voice transmissions. The few times it hasn't been strong enough to swamp my entire frequency monitoring range, it seems to be centered around 143.8-143.9. That's about as close as I can estimate the actual freq. As long as they stay scrambled, there is no hope of identifying this thing. It's obviously very close to me to cause the damage it's doing.

 

[troymail]

Can you pick out any pattern to when they are active? Are they more active during the day verses the night or weekend?

The 396 has close call (which I learn durning the summer - works REALLY well*) -- I could get into the area of the airport and see what we can pick up....


*while on a cruise ship in the Gulf of Mexico in August, we encountered a small boat with 12 Cuban refugees on it... I used my 396's Close Call feature to find which freqs were being used by the ship and it's rescue boat... pretty cool. I wouldn't have known how to find them otherwise...

 

[Al42]

I've been hearing this signal several more times. Each time it has been scrambled voice transmissions. The few times it hasn't been strong enough to swamp my entire frequency monitoring range, it seems to be centered around 143.8-143.9.

When you say "scrambled", could it be SSB? It could be a local ham operating on MARS frequencies.

 

[fourwd1]

Yeah, 143.99 is a MARS freq.

And according to a 2000 MD/DC MARS map, Navy-Marine MARS station RVG appears to be in GB.

 

[TinEar]

No, it's not SSB. It's scrambled voice. Not a doubt. It has all the same characteristics as all the scrambled channels we hear on the digital trunked systems around us.

Troy, no I haven't been able to determine a pattern to the times they use the system - at least not yet. Perhaps after they've been at it a while longer I will.

I should also explain that I'm not sure the signal is confined to the 143.8-.9 range that I mentioned. It's so strong that spurs might be able to be found other places too. It's just that I happen to have freq 143.825 programmed for something else and when I hear it I tune to either side of that freq and that's the range I find it.

 

[TinEar]

Heard again today at 1319. Caught it on my programmed 143.825 freq and was extremely loud and strong. Scrambled voice...two transmissions and that was it.

And again at 1330. One speaker was in the clear and the other was scrambled. The one in the clear asked something about a vehicle. This almost sounds like the NSA scrambled net where you occasionally get a transmission in the clear. I'm too far away from them or Ft. Meade to be getting spurs though, right? I would think so.

1333: Another scrambled voice transmission

 

[Dougie]

....There is a trident scanner available with some sorta descrambler....