Help me identify 452.175 / Cupertino area...

[b52hbuff]

I've been driving around with my BCD-396T in Close Call mode just to see what comes up. While I was driving around the intersection of De Anza and 280 in Cupertino, I got a CC hit on 452.175. It comes up as a digital signal. And after I disabled the tone search, I still couldn't get the signal to decode on my 396. So I safely assume that the digital encoding isn't P-25.

I was hoping someone more familiar with the sounds of digital data may be able to tell me what sort of mdulation it is. It is bursty, like voice. It doesn't sound like a control channel, (too many breaks in transmission). And it doesn't sound like telemetry (too random in length).

I went to the FCC database:
RadioReference.com - Scanner Frequencies and Radio Frequency Reference Database

There *is* an entry in Santa Clara County, and in Cupertino:
FCC Callsign WPVT344 Details
..but the designator doesn't show digital. 20K0F3E.

Anyway, if anyone has a clue, I'd be interested in hearing it...

 

[kg6nlw]

I have a few East Bay frequencies in the same way. the 20K0F3E but I'm getting data bursts at times and sometimes they are pure analog audio...

Regards,

-Frank C.

 

[SCPD]

sounds like an LTR trunking system?

 

[Stealthguy05]

I get it all the time while at De Anza, it's probably something from the college?

 

[inigo88]

I think posting an audio clip is in order.

 

[cousinkix1953]

sounds like an LTR trunking system?

You might be correct. I hear the same thing over the Summit. A similiar LTR system has a control channel on 151 mhz. I'm not sure if it's located in Santa Cruz or Monterey county.

 

[inigo88]

I doubt LTR in this case, even though the frequency looks like one used by the nearby Fisher Wireless Passport system (which has a site on Loma Prieta). Based on B-52s description of it sounding similar to P25 IMBE digital but not decoding, I suspect Moto TRBO or another company's new similar proprietary digital variant (NEXEDGE, etc) originating from or near De Anza college.

Since LTR uses purely sub-audible data, the idle bursts sound just like a repeater being keyed up with nothing said. There is no such thing as an LTR control channel per say (except in Multi-Net IIRC, which fell out of favor and is now seldom found). A pretty reliable way to differentiate between LTR Standard and Passport is by listening to the frequency of the idle bursts. Standard is usually set up to burst every 10 sec, or not at all, and usually only on the home channels. Passport systems usually increase the frequency of the bursts to once every 1 to 3 seconds on the registering channel and 5-10 seconds on all the other frequencies. The above could simply be system admin preference, but works reliably well in the Bay Area. Of course, the easiest way to tell Passport from LTR standard is that it won't decode on an LTR-capable scanner.

Hope that helps, and let us know if you can ever record and post it.

Inigo

 

[cousinkix1953]

You might be correct. I hear the same thing over the Summit. A similiar LTR system has a control channel on 451 mhz. I'm not sure if it's located in Santa Cruz or Monterey county.

typo fixed