Anyone know what the reverse S stands for? It's in the place of the reverse T and switches between them while scanning trunking systems.
WS1098: What is the Reverse S for?
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budevans
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On the TRX models it indicates an open Squelch for DMR or NXDN.
This is a 1098 but the display could be similar. Thing is this scanner won't do NXDN and there no DMR being scanned. The S does display even while manually sitting on a P25 system talkgroup, not scanning. My SWAG is that it has to do with P25 trunking as I don't recall seeing it before The system switched to P25 trunking.
Ubbe
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It sees an idle digital signal it can decode. If there's active calls in the site it will show a T.
/Ubbe
/Ubbe
Thank you Ubbe. The letter S as an indicator for an idle indicator seems a bit weird. I guess it's an S to indicate a valid Signal?
Ubbe
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baker50021
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A look at the display from Mark's scanner page...
Easier to Read Whistler WS1080/1088 Handheld Scanner and Software Manual
Easier to Read Whistler WS1080/1088 Handheld Scanner and Software Manual
I don't see the reverse S on there. See attached for what the reverse S looks like. Notice it's in the same position as the reverse T.
I see that on mine as well. It is usually a signal (or interference of types) that is stronger than the squelch threshold that is not a digital signal the radio can decode. Or a signal of a different mode than the system being scanned.
Turning the squelch higher will get rid of it at times. In my case, it was usually out of band signals, mostly from FM Broadcast stations. I needed FM Notch filter and then VHF paging band notch filters in order to filter out the noise or interference. Once I did all that, the reverse S is mostly gone now on all trunked and conventional systems I monitor.
By default these radios also need the squelch to be set at what seems to be a higher than normal level.
Try entering all the frequencies used by the system you see the Reverse S pop up into a new scanlist and programmed as regular analog conventional with no tones set. Scan those and see if just one or more of the frequencies shows a signal.
If you unhook the antenna now, does the Reverse S go away? If so, that is a sure sign the radio is picking up some kind of signal on at least one of the frequencies it is scanning.
Almost all GRE designed scanners in the last several years have bad front end problems with filtering out FM Broadcast stations mainly. It's almost like they don't have any out of band filtering to kill the strong signals from the FM radio band. An FM trap will help mitigate that. FM Traps are a must here for my GRE designs.
Hope you can figure it out!
Ubbe
Member
The normal S are the analog squelch indication and the reverse S is the digital squelch, it detects a signal that triggers the DSP into detecting a few data bits, could be an interfering signal with modulation in it, pehaps overmodulated FM broadcast music are a good candidate. To get the reversed S the received signal must first have opened the analog squelch. The front-end and squelch are the biggest negative points with these scanner models.
/Ubbe
/Ubbe
I don't think the reverse S indicates squelch. Remember this only shows when scanning a P25 trunking systems. It is located in the same position and alternates with the trunking indicator reverse T.
My guess is the reverse S indicates P25 control channel sync. But exactly how that is different than the reverse T is not clear to me.
My guess is the reverse S indicates P25 control channel sync. But exactly how that is different than the reverse T is not clear to me.
I have not seen the reverse S while scanning conventional frequencies. I don't think I have ever seen it except when scanning P25. I'll have to add a Motorola Type II system to verify that.
I see the reverse S a lot (and hardly ever see the reverse T) when scanning OC CCCS countywide. I get no reliable voice traffic on that system. On the other hand, when scanning OC CCCS southwest I see the reverse S flash occasionally and mostly see reverse T. Voice traffic is decoded pretty well on southwest. The CalTrans ASR site on Santiago Peak has a very reliable pattern with a short reverse S flash and a long, steady reverse T. Voice decoding is very reliable on the CalTrans system. I think I'm seeing simulcast interference on the OC CCCS countywide system, less simulcast interference on southwest (where I live) and none on the CalTrans non-simulcast system.
Based on that and what @kruser said about FM broadcast and VHF paging interference seeing a lot of reverse S is definitely a bad thing.
@kruser asked if removing the antenna eliminates the reverse S. It does and it also eliminates the reverse T as well. But that's not necessarily an indication of FM or VHF interference. I believe simulcast interference and perhaps a weak signal will also cause excessive display of the reverse S.
In another post I said that my guess is the reverse S in indicating P25 trunking sync but I was unclear of the relationship to the reverse T. It now appears to me that a short flash of the reverse S followed by longer display of reverse T is indicating the scanner sees a P25 trunking system and then immediately decodes it.
I see the reverse S a lot (and hardly ever see the reverse T) when scanning OC CCCS countywide. I get no reliable voice traffic on that system. On the other hand, when scanning OC CCCS southwest I see the reverse S flash occasionally and mostly see reverse T. Voice traffic is decoded pretty well on southwest. The CalTrans ASR site on Santiago Peak has a very reliable pattern with a short reverse S flash and a long, steady reverse T. Voice decoding is very reliable on the CalTrans system. I think I'm seeing simulcast interference on the OC CCCS countywide system, less simulcast interference on southwest (where I live) and none on the CalTrans non-simulcast system.
Based on that and what @kruser said about FM broadcast and VHF paging interference seeing a lot of reverse S is definitely a bad thing.
@kruser asked if removing the antenna eliminates the reverse S. It does and it also eliminates the reverse T as well. But that's not necessarily an indication of FM or VHF interference. I believe simulcast interference and perhaps a weak signal will also cause excessive display of the reverse S.
In another post I said that my guess is the reverse S in indicating P25 trunking sync but I was unclear of the relationship to the reverse T. It now appears to me that a short flash of the reverse S followed by longer display of reverse T is indicating the scanner sees a P25 trunking system and then immediately decodes it.
When monitoring digital trunked systems (or a conventional DMR channel programmed as a trunked system), a reverse T indicates active data decoding of a control or voice channel. As I see it, the reverse S simply means the receiver's squelch is open but no data is being decoded. It is akin to a normal S (open squelch) combined with the absence of a reverse T.
If I scan a digital trunked system with my antenna removed, both the normal and reverse S will simultaneously appear and disappear as I rotate the squelch knob open and closed, even though no signal is present. The reverse S can also appear if an interfering signal overrides the digital trunked signal.
With analog trunking, I've seen the reverse S appear while scanning LTR system as non-LTR signals are encountered, but only the regular S while scanning Motorola analog systems.
If I scan a digital trunked system with my antenna removed, both the normal and reverse S will simultaneously appear and disappear as I rotate the squelch knob open and closed, even though no signal is present. The reverse S can also appear if an interfering signal overrides the digital trunked signal.
With analog trunking, I've seen the reverse S appear while scanning LTR system as non-LTR signals are encountered, but only the regular S while scanning Motorola analog systems.
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