simulcast monitoring

[topcop1833]

All,
I have included a link to this same question below that I posted over at radioreference. some of the replies don't seem to add up, i can be hard headed sometimes so I thought I'd post it here too for some other perspectives.

Long story short, why does audio from a simulcast site decoded by a trunked radio sound better than it does when using a PSR500 trunk tracking or even an XTS while scanning conventionally. all three radios are with in inches of each other. my personal XTS was even programed as a trunking radio for a bit to show that the audio could be decoded properly.
i apologize if this question has been asked several times, no matter how i searched i didn't get any results.



http://forums.radioreference.com/genera ... ional.html

[RADIOMAN2002]

I noticed the same with our county's simulcast system also, but I have Spectra's and Astro Sabers that don't handle the phase distortion well, as compared to the XTS and XTL radios we have, so the only thing I can say is that the actual Motorola radio handles the handling of the data/audio differently, more than likely in the Vocoder board. Scanners and my older radios are not as up to date with their Vocoders.

[RADIOMAN2002]

I thought of this after I finished the last post, The receivers themselves are probably different also. More designed to handle the digital modulations than older radios, scanners usually have a compromise receive due to receiving so many formats across so many bands.

[Spiffy50]

This is a stab in the dark, but could it be that the frequency stability on a scanner isn't as good as the Motorola radio? From what I understand, for a simulcast system work work properly, frequency timing has to be bang-on with all radios involved. I could easily see a consumer grade radio not working so hot.

[kb0uxv]

If you are listening to simulcast in conventional mode , the modulator should be set to CQPSK. C4FM should only be used on single sites. CQPSK will work on both types. If you had a XTS/XTL set to scan the voice channels and had issues I suspect you were not set to CQPSK.

[Pj]

Is the system digital or analog? You only said trunked. In reality, it doesn't matter if its trunked or conventional. On the systems I have listened to in trunked/conventional, digital/analog I had the same results.

Just about everyone these days use a GPS reference for the timing, but that doesn't mean that the radio itself is in perfect alignment. So depending on your location, anything could be possible.

But as the poster above stated, if in digital you want to use the CPQSK (or whatever it is as I can't see it on edit) for a digital simulcast system.