HIP
Member
Does anyone know how the 600 does on a simulcast system particularly the breaking up of the audio?This could be a good reason to add it to my list of radios.
600 and Simulcast?
- Thread starter HIP
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CQPSK? Depends MUCH more on the antenna than the radio.
You want a directional antenna pointed at your closest tower.
Look for an 800MHz yagi antenna, directional as Rob pointed out.
djg000111
Member
For scanners that have a problem with receiving voice from a CQPSK Simulcast System, does anyone have experience (or did some testing) that indicates a scanner problem is a CQPSK receive problem or a simulcast receive problem?
It's the receive - that's why it works very well if you have an antenna pointed right at one of the towers.
rdale said:
What would be different in a Motorola P25 hand-held that allows it to overcome this issue?
The extra $1000 you pay goes to something :>
Much tighter receiver, better able to get a contiuous strong signal.
Much tighter receiver, better able to get a contiuous strong signal.
rdale said:
How about dynamic range?
http://www.radio-electronics.com/info/receivers/dynamic_range/dynamic_range.php
djg000111
Member
Why do my scanners work better with C4FM than CQPSK Simulcast? The C4FM tower that I can receive is at a greater distance than several of the CQPSK Simulcast towers. Also, the C4FM signal is much weaker than the CQPSK Simulcast signal.
Are CQPSK Simulcast Systems not meeting the seller's performance specifications?
Are CQPSK Simulcast Systems not meeting the seller's performance specifications?
mikey60
Member
djg000111 said:
From my understanding, the modulation type isn't the main problem. The C4FM sites are a single transmitter on the frequency, and is much easier to decode.
The CQPSK simulcast sites are multiple transmitters on the same frequency. The issue comes in when you are receiving the signal from more than one site, and the phase of those received signals is off by even the slightest amount. When that happens, each site on the simulcast system begins to interfere with the others.
The radios on the system are probably better tuned receivers, and can pick out the differences a little better. Someone else can probably add to that, but even then there's only so much you can do to work around the multi-path.
Mike
wlmr
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mikey60 said:
If I recall correctly what I was told, the receivers have the ability to see the multiple simulcast signals and deal with the fact that they are being received out of phase. Somehow they reconstitute a single digital signal by treating anything that comes in within a window of time as being the same bit from multiple locations. Works well enough that helicopters have successfully had the radios installed and function fine. That includes fairly high and racing along at speed. (Not possible with analog simulcast!)
Hopefully the scanner manufacturers can keep fine tuning their products to better approach the same capability.
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