Really Important Question PLEASE HELP!

[FrankBarrett5]

How can I find out which areas of NJ use that CQPSK modulation I've been reading about that doesn't work well with Radio Shack scanners? I live in Bergen County.

 

[robbinsj2]

I've only heard of the very first version of the Pro-96 having trouble with CQPSK, as in it didn't support it. That was fixed by a user-upgradeable DSP patch over three and a half years ago, and all versions of the Pro-96 manufactured after that plus all versions of the Pro-2096 ever shipped with CQPSK ability built-in.

If you have read something more recent than 2003 which indicates problems with CQPSK, please share a link with me. My Pro-96 and Pro-2096 have performed well on any APCO P-25 unencrypted digital which I tuned them to, without regard for C4FM or CQPSK.

Jim

 

[wlmr]

I've only heard of the very first version of the Pro-96 having trouble with CQPSK, as in it didn't support it. That was fixed by a user-upgradeable DSP patch over three and a half years ago, and all versions of the Pro-96 manufactured after that plus all versions of the Pro-2096 ever shipped with CQPSK ability built-in.

If you have read something more recent than 2003 which indicates problems with CQPSK, please share a link with me. My Pro-96 and Pro-2096 have performed well on any APCO P-25 unencrypted digital which I tuned them to, without regard for C4FM or CQPSK.

Jim

Jim's right. Only the first issue Pro-96 scanners had this problem. They would track C4FM with no problem but would drop audio after a couple seconds when receiving CQPSK.

FYI, CQPSK is (as far as I know) only used with systems that have simulcast sites (multiple sub-sites synchronized together and all transmitting on the same frequency with the same info). C4FM is used at single location radio sites. Look in the database for your agency. The info on whether any of the site(s) are simulcast probably is listed there.

 

[robbinsj2]

Mercer County started out as CQPSK, before there was any outward indication of plans for a simulcast site. Maybe they planned a second site all along.

According to the wiki, the main functional difference seems to be bandwidth -- C4FM is 12.5 kHz and CQPSK is 6.25 kHz. But since all digital scanners on the market should handle CQPSK just about as well as C4FM, it doesn't really matter to a scanner enthousiast which kind the system uses.

 

[rdale]

All scanners have troubles with most CQPSK simulcast systems, the Pro96 is better than the 396 but it still suffers. Pretty sure there are none in NJ to worry about though.

 

[sacharoffm]

I have heard that Mercer County is trying to add a site in Hightstown to cover the dead zones on the edge of the county.

 

[Joseph11]

Jackson Township's system is simulcasted and has P25. I believe Manchester's system is also simulcasted.

 

[rdale]

If they use some digital audio, that's not the same. The problems are in dedicated P25 fully digital simulcast systems.

 

[Joseph11]

Thanks for the correction; I wasn't aware of that.

 

[robbinsj2]

All scanners have troubles with most CQPSK simulcast systems, the Pro96 is better than the 396 but it still suffers. Pretty sure there are none in NJ to worry about though.

As I indicated above, Mercer County is CQPSK, so add it to your list.

My Pro-96 and 2096 do as well on this system as on any other P-25 audio I've tuned. Perhaps that's because it is CQPSK but not (yet, as far as I know) simulcast.

Jim

 

[rdale]

Again - if it is not CQPSK simulcast, it is not a problem.

The issue isn't in the CQPSK, or the digital simulcast, but the combination.