SDS200/100 Control Channel Only

[radiochuck]

By default, Sentinel programs all of the frequencies for a site, control and voice.

Is there any benefit to removing the voice channels so the radio doesn't have to scan through them for potential control data? Obviously the control channels are all that's needed, but do the voice channels being there cause the radio to scan more slowly?

 

[Hit_Factor]

You only need the control channel, and optionally the alternates.

Depends on your tolerance to fail over vs. Quickly acquiring the tower.

 

[hiegtx]

By default, Sentinel programs all of the frequencies for a site, control and voice.

Is there any benefit to removing the voice channels so the radio doesn't have to scan through them for potential control data? Obviously the control channels are all that's needed, but do the voice channels being there cause the radio to scan more slowly?

The scanner is only going to look for and use the control channel. Having all the frequencies (primary & alternate control channels, as well as voice) is not going to slow you down. Once the scanner finds the control channel, it ignores all the rest of them.

Remember that if you are dealing with a Harris P25 system, all of the channels should be programmed, as any of them can be used as control, and some systems rotate them regularly.

On the database scanners, such as the SDS100/SDS200, and others, there's no downside to including all of the frequencies for the site. For some of the older, non-database scanners, particular the GRE (now Whistler) object oriented scanners, which have a limit on how much can be programmed, then only the control channels (and alternates) are the best option.

 

[JoeBearcat]

...except that when a control channel is not found, the scanner will evaulate all programmed channels on that site, so that may slow you down some. As was mentioned, some systems need all the frequencies. Personally, my FLs only have the primary and alternate control channels since I have co-channel systems in range (voice channed used as a cc for another system), and I don't want the scanner locking on to the wrong control channel and ignoring the system I want to scan. That is also reason to not program voice-only channels unless you have to.

 

[radiochuck]

In this case, I'm dealing with a Motorola system and decided to delete the voice only channels and only leave in the primary and secondary control channels. Works like a charm. Don't know if I've gained anything as far as scanning speed is concerned, but it all works, so I'm leaving it that way.

Thanks for all of the info.

 

[tvengr]

I always program just the control channel and alternate frequencies. If you lose lock on the control channel, the scanner does not have to waste time searching through all of the voice frequencies to find the control channel again. As JoeBearcat mentioned, some systems require all of the frequencies since any can be used as the control channel and often rotate through the frequencies.

 

[MStep]

In this case, I'm dealing with a Motorola system and decided to delete the voice only channels and only leave in the primary and secondary control channels. Works like a charm. Don't know if I've gained anything as far as scanning speed is concerned, but it all works, so I'm leaving it that way.

Thanks for all of the info.

It is certainly a reasonable strategy. But I program everything in--- control, alternates, voice, data, the works. Occasionally, just occasionally, I've picked up "talk-around" unit-to-unit direct traffic on those voice channels that I would have otherwise missed. And of course it is usually in very close proximity to my own location, which makes it all the more interesting.

 

[hiegtx]

...except that when a control channel is not found, the scanner will evaulate all programmed channels on that site, so that may slow you down some. As was mentioned, some systems need all the frequencies. Personally, my FLs only have the primary and alternate control channels since I have co-channel systems in range (voice channed used as a cc for another system), and I don't want the scanner locking on to the wrong control channel and ignoring the system I want to scan. That is also reason to not program voice-only channels unless you have to.

That's where the ability of the SDS series scanners to utilize the site NAC comes in very handy. So duplicate frequencies in use on another system, that happens to be currently in range, are ignored.

 

[Ubbe]

Don't know if I've gained anything as far as scanning speed is concerned

It depends of how busy the system is. Each active voice channel will take something like 60mS to detect it to be voice data and not a control channel. Any voice channels currently not holding a call will add a further delay of 25mS for each channel. But if you lost the control channel then you probably lost all channels as they came from the same place, so it probably adds 25mS for each channel in a site until it goes to next site.

/Ubbe

 

[Hit_Factor]

...Don't know if I've gained anything as far as scanning speed is concerned, but it all works, so I'm leaving it that way...

You can program it in three different ways and then determine if it makes any difference in your use case.
CC only
CC & Alts
CC, ALTs, and voice

 

[mcjones2013]

Occasionally, just occasionally, I've picked up "talk-around" unit-to-unit direct traffic on those voice channels that I would have otherwise missed.

Please explain this a bit more. If programmed in a trunked system, the scanner is only looking for a control channel.

 

[GTR8000]

Please explain this a bit more. If programmed in a trunked system, the scanner is only looking for a control channel.

Exactly. It's not going to be stopping on traffic channels unless there are grants over the control channel.

 

[JoeBearcat]

Unless the system is programmed for conventional scanning. Then it might hear T/A channels. Of course it will not trunk when programmed that way. You will hear activity on the trunk system, but it will be mixed with other conversations if any are active at the same time.

 

[GTR8000]

A properly designed and implemented P25 system is not using the system frequencies for "off network talkaround channels". They may have unit-to-unit calls enabled (aka private calls), but those are still going through the control channel and getting grants.

 

[JoeBearcat]

A properly designed and implemented P25 system is not using the system frequencies for "off network talkaround channels". They may have unit-to-unit calls enabled (aka private calls), but those are still going through the control channel and getting grants.

Agreed. I was just trying to think of how the OP might be hearing T/A activity on voice-only channels. If it is programmed as a P25 system, you would never hear T/A activity.

 

[RRR]

Slightly off topic, but is Uniden going to address the phase 2 control channel systems?

 

[smithken]

In this case, I'm dealing with a Motorola system and decided to delete the voice only channels and only leave in the primary and secondary control channels. Works like a charm. Don't know if I've gained anything as far as scanning speed is concerned, but it all works, so I'm leaving it that way.

Thanks for all of the info.

If I understand Uniden trunking scanners correctly and you are monitoring one trunk system and nothing else then it doesn't matter what frequencies you program in as long as they are on the site you are monitoring. My understanding is that one the scanner finds the control channel it doesn't scan any more. The scanner seems to store the control channel frequency in memory so that when it is instructed by the control channel to switch to a voice frequency the scanner immediately switches back to the control channel when the voice traffic is complete and doesn't scan for the control channel.

 

[JoeBearcat]

Slightly off topic, but is Uniden going to address the phase 2 control channel systems?

I have made HQ aware of them. Whether the existing P25 Phase II scanners are going to be updated is a decision that is above my pay grade, but I will advocate to add support for it.

 

[RRR]

Yea, that's gonna be something that will be pretty widespread before too long. Harris is full speed ahead on it. Maybe Unication will address it if Uniden doesn't.

I mean, it's only been a few years since anything has happened with the SDS series. One can hope!