CTCSS/DCS Delay

[Rleshane]

I recently purchased a GRE PSR-200U 200-Channel Base Station Analog Scanner : Scanners | RadioShack.com because it was the least expensive scanner I could find with CTCSS/DCS capabilities. I'm quite happy with it in general, but I notice when I have CTCSS/DCS codes programmed, I miss the first quarter second or so of each transmission. When I turn CTCSS/DCS off, I get the entire transmission. Is this a typical of CTCSS/DCS in general? Or would a more expensive scanner decode the signal faster?

Thanks!
Ron

 

[Laxplurr06]

I wouldnt say this is typical on my scanners, but I could see how this can be delayed considering the radio has to identify the tone so the scanner knows that is the station you would like to listen too. Someone else im sure will have some more insight, but I am sure it is because this is an older radio not a problem with it.

 

[fineshot1]

I recently purchased a GRE PSR-200U 200-Channel Base Station Analog Scanner : Scanners | RadioShack.com because it was the least expensive scanner I could find with CTCSS/DCS capabilities. I'm quite happy with it in general, but I notice when I have CTCSS/DCS codes programmed, I miss the first quarter second or so of each transmission. When I turn CTCSS/DCS off, I get the entire transmission. Is this a typical of CTCSS/DCS in general? Or would a more expensive scanner decode the signal faster?

Thanks!
Ron

Does this happen on one channel, some channels, or all channels you have programmed?

 

[Rleshane]

I'm only monitoring two local channels (police and fire in my city), but it appears to happen with both. One uses CTCSS and the other uses DCS.

 

[fineshot1]

As a test program in some other channels for another agency - perhaps the next town
over and see if it still happens with those. If it continues with them its probably a glitch
with the tone decoder in your radio. If not then its possible the agency transmitters may
need alignment as this should not happen. Typical tone decode and opening of the squelch
occurs in about 100 milliseconds(1/10th of a second) and should not take much longer,
that is of course when everything is setup and working properly.

Try the suggestion above and see what happens and post back and let us know.

 

[gmclam]

I have not used that exact scanner, but have had quite a bit of experience with CT/DC values and the GRE scanners.

My first thought was wondering if you *need* to use the CT/DC values. If there is an agency on the same frequency that you also receive, then I'd agree you need them programmed. Otherwise, I usually set a channel to CT/DC .. search and let it display a value, but not require it to open the squelch.

My second thought has to do with how you have your squelch knob set. You should make sure that your squelch would not be open if you were parked on a channel set to FM. Since both of your channels are using this decoding, you COULD run your squelch fully counter-clockwise, but that will actually slow down the entire process.

When I compare how all of the scanners I do use decode CT/DC values, some scanners are clearly SLOWER than others. The oldest scanner I have which performs this function, the PRO-92, is clearly the slowest of what I have.

The analog scanners use a dedicated IC to perform this function, and it requires time to determine the frequency. I could see that if you are changing modes (one channel is CT and the other DC) that it would slow it down. From what I've seen, the digital scanners use a function in their DSP to perform this function, it is much more elegant (faster). While I don't expect you to have to get a digital scanner to get faster CT/DC decoding, I'd bet the PSR-300 is faster than the 200 from what you're saying (at least the way I operate mine).

 

[RKG]

Any radio needs time to determine what the frequency of a PL or code of a DPL is. You can start an argument if you press for exactly how much time is required, but experience says in the neighborhood of 165 to 210 msec. That's just about your quarter of a second. This is the price of enjoying the advantages of PL/DPL.

Note that most public safety users won't notice the delay because they are using MDC, and their radio prevents them from talking until the MDC PTT-ID code has been sent. The time required for this to happen totally eclipses PL/DPL decode time.

 

[Rleshane]

Thanks guys. All good stuff.

My first thought was wondering if you *need* to use the CT/DC values. If there is an agency on the same frequency that you also receive, then I'd agree you need them programmed. Otherwise, I usually set a channel to CT/DC .. search and let it display a value, but not require it to open the squelch.

Without it, I don't pick up other agencies, at least not clearly. I do, however, get a good number of what I can only describe as "phantom mic key ups". I'm guessing it's stuff bouncing off the clouds or whatever because with the CT enabled I don't hear them.

I've been playing with the squelch as well. I'll keep tinkering. Thanks again all for the great info.

 

[N8IAA]

Thanks guys. All good stuff. Without it, I don't pick up other agencies, at least not clearly. I do, however, get a good number of what I can only describe as "phantom mic key ups". I'm guessing it's stuff bouncing off the clouds or whatever because with the CT enabled I don't hear them.I've been playing with the squelch as well. I'll keep tinkering. Thanks again all for the great info.

The new model 200U has no way to change how fast it hears the tone and decodes it like the more expensive radios can. As others have said, unless there is a great deal of interference, listen without the tone programmed in. Oh, those aren't 'phantom mic key ups', they're actually other cities or counties that use the same frequency. Usually found on VHF and UHF frequencies.
HTH,
Larry

 

[Nasby]

I have several top of the line Motorola radios I use for scanning. Even they have a slight delay on CTCSS/DCS before the squelch opens up as opposed to when they are set to "carrier squelch (no CTCSS/DCS)."

 

[gmclam]

Without it, I don't pick up other agencies, at least not clearly. I do, however, get a good number of what I can only describe as "phantom mic key ups". I'm guessing it's stuff bouncing off the clouds or whatever because with the CT enabled I don't hear them.

Are you only scanning these two frequencies? Are your local signals strong? If so, don't use the CT/DC values, instead adjust your squelch so that you don't hear "stuff bouncing off the clouds".