Odd Control Channel Behavior on Wake Simulcast System

KN4AQ

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This may just be a sanity-check post.

I'd been doing some revisions to the Favorites Lists for my Uniden SDS 100 and BCD536 scanners, when 'suddenly' things got too quiet. OK, not 'volume' quiet... 'missing talk groups' quiet.

After a while, I noticed that it was just the agencies on the Wake Simulcast system - I was still hearing Cary Fire on the Cary Simulcast system, NCSHP on VIPER, Durham on their system, etc. But most of the stuff on Wake was never showing activity. Most, but not all: I was still hearing the Raleigh PD's Northwest Dispatch talk group. Just that one... none of the others.

To shorten the story... checking things with my old Radio Shack PRO106, I found other RPD talk groups active. I'd hold the SDS100 on one of them and hear nothing, while audio was spouting from the PRO106 on that talk group.

Then I noticed that the 'idle' System Frequencies (the control channel frequencies) were different. The PRO106 was 'listening' to a control channel on 853.15, while the SDS100 was 'listening' on 853.9625 (or so said the display). Except when tuned to the RPD Northwest Dispatch... then both scanners were on the 853.9625 control channel (and the SDS100 received the transmissions). Both of those frequencies are listed as alternate control channels for the Wake Simulcast system. 853.9625 is in the list ahead of 853.15.

I temporarily deleted the 853.9625 frequency from the Site Frequency List, and wa la (as the kids say), I started receiving lots of stuff. I'd say 'everything' but who knows if something else is missing that I haven't noticed. But the other RPD dispatch, TAC and OPS channels, Wake Sheriff, EMS, Fire, etc. all made noise again, including RPD's Northwest Dispatch channel (with the scanner now telling me it was looking at the 853.15 control channel). I put 853.9625 back in the list, but moved it down 'below' 853.15, and things continued to work.

RF-wise, both channels are active with continuous data, like a control channel would be.

Um... WTF, over?
 

trumpetman

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If you hold on 853.9625 in search mode does it display any signal strength? They might have rolled the control channel due to interference or testing the new P25 system even.
 

KN4AQ

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If you hold on 853.9625 in search mode does it display any signal strength? They might have rolled the control channel due to interference or testing the new P25 system even.
There is a strong, continuous data signal on 853.9625 (and 853.1500)
 

trumpetman

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If anyone can run DSD or can recognize the signal as P25 you can run UniTrunker or Pro96Com to see what exactly it is. My bet is that you'll see site 2 of the Cary system and if so you will likely see the signal intermittent over the next few weeks as testing happens. Manually tune to the frequency on your PRO106 and see what it says. Or add 853.9625 as a P25 system and analyze it with your SDS and see what it says and we can go from there.
 

N1GAW

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If anyone can run DSD or can recognize the signal as P25 you can run UniTrunker or Pro96Com to see what exactly it is. My bet is that you'll see site 2 of the Cary system and if so you will likely see the signal intermittent over the next few weeks as testing happens. Manually tune to the frequency on your PRO106 and see what it says. Or add 853.9625 as a P25 system and analyze it with your SDS and see what it says and we can go from there.
I've tried running DSD+ and Pro96Com on the Wake TRS system without results as P25. Been watching for that switch.
 

N1GAW

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There is a strong, continuous data signal on 853.9625 (and 853.1500)
From just south of downtown Raleigh I am NOT hearing anything on 853.9625. Possibly testing on the Morrisville tower.
 
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N1GAW

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Been monitoring numerous Wake County voice channels today using DSD+, as well as listening to the Wake TRS Motorola system on the scanner utilizing the control channel. Including 851.4625, 852.9625, 853.2, 853.65.

While DSD+ still will not decode the CC for Wake TRS (as the CC is Motorola Type II) the voice channels are showing up with P25 traffic and the NAC of 383. Having earlier converted the Type II TGIDs to P25 TGIDs I'm noticing they are matching up based on the P25 traffic I'm hearing (IE 2282 is WCCortran 2504 is RPD SE 951 is GoRaleigh and encrypted channel 2540 for RPD INV 6.

The only CC I am receiving near downtown Raleigh is 853.150, but I might take a trip out to Cary/Morrisville area and check out 853.9625 in the next few days. Based on what I'm seeing in DSD+ it looks like the long awaited change may not be far off. @trumpetman your suggestion was spot on.
 

KN4AQ

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...add 853.9625 as a P25 system and analyze it with your SDS and see what it says and we can go from there.
I'm in fairly unfamiliar territory here, but I added a new Favorites list to the SDS100 with two Departments. One was 853.9625 as P25 and the other was 853.9625 as Motorola. I completed the steps to add a Site and one Frequency (853.9625) for each department, selecting P25 and Motorola as appropriate, and one talk group. And I put in the Rebanded band plan for the Motorola Department Site.

When I look at the channels in the Scan/Hold mode, the P25 does not show a Sys ID, while the Motorola shows
  • Sys ID: 6038h.
  • Site ID: 10

In Analyze:
  • the P25 Site shows a strong Signal, but no Q and no A, no System ID and no Site ID.
  • The Motorola Site shows strong S and Q, no A, and
    • System ID: 06038h-000
    • Site ID: 0012
Additionally, I deleted the 853.9625 channel from my Wake Sheriff Favorites List, so it's using 853.15 as the control channel. I see:
  • Sys ID: 6038h
  • Site ID: 10
And in Analyze for that Wake Sheriff (Wake Simulcast) site,
  • I see a moderate S, strong Q, and moderate A.
    • System ID: 06038h
    • Site ID: 0010
The PRO106, tuned manually to 853.9625 displays M36 99% CT:105.88 SID:6038 S12

The PRO106 tuned manually to 853.150 displays M36 90% CT: 90.00 SID:6038 S10
 

KN4AQ

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From just south of downtown Raleigh I am NOT hearing anything on 853.9625. Possibly testing on the Morrisville tower.
I'm near Weston Parkway, between Evans and Harrison, so I'm near the east side of Morrisville.
 

N1GAW

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I'm near Weston Parkway, between Evans and Harrison, so I'm near the east side of Morrisville.
This is the location (according to FCC license) of Morrisville tower listed on the P25 modified license grant for WC TRS


[TD]5216 NC#55 HIGHWAY
Morrisville, NC WAKE County [/TD]
[TD] 35-51-13.4 N, 078-53-38.6 W [/TD]
 
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trumpetman

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OK, with that tidbit of knowledge and now that I'm in front of a computer, it makes sense. While 853.9625 is shown as an alternate CC for the Wake Simulcast, it is also in use as the primary control channel for the Brier Creek site, which is a very small and low coverage IR that I believe only carries the RPD NWD TG. That explains everything. Take the 853.9625 frequency out and you won't have to worry about your scanner being tricked into following the Brier Creek site (#12) when it should instead be listening to the main simulcast site (#10).

I imagine it was easier to reuse an alternate control channel that is already programmed into subscribers for the fill-in site rather than retouch all the radios just to program a new temporary control channel. If 853.9625 is protected on the simulcast cell it will roll to the other 2 alternates first before using 853.9625 and causing interference with Brier Creek.
 

KN4AQ

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OK, with that tidbit of knowledge and now that I'm in front of a computer, it makes sense. While 853.9625 is shown as an alternate CC for the Wake Simulcast, it is also in use as the primary control channel for the Brier Creek site, which is a very small and low coverage IR that I believe only carries the RPD NWD TG. That explains everything.
Yay, thanks!

Where can I find site info for the various sites?
 

N1GAW

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N1GAW

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Okay, can someone explain to me the traffic pattern on this system and how it is actually working (patched to/from P25 or radios). The CC is Motorola Type II, but most of the voice channels are showing up as P25 with a NAC of 383.

Is it showing P25 because the new P25 radios are in use on a Type II system or is there a patch in there somewhere?
 

shoegazer

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Take the 853.9625 frequency out and you won't have to worry about your scanner being tricked into following the Brier Creek site (#12) when it should instead be listening to the main simulcast site (#10).
After wondering WTH was going on all evening; I tried this and, so far, it's working perfectly. Thanks!
 

JohnDistai

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I noticed the lack of activity in the past week, but thought there wasn't much going on, or the scan program was not hitting the channels in sync with activity. For whatever reason my 996XT was getting some hits, but the SDS 200 was quiet. Both have the same programming, same antenna, sitting in the same location.

I deleted that control channel, and now are both quite active. I'm near 70 and 540, close to Brier Creek.

Thank you for the fix!
 

pjb3589

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I'm also seeing some odd behavior. I listen to Wake using the FV IR site since I live in FV. I noticed my scanner is always listening to 853.150 which isn't even listed in the frequency list for FV. I've also noticed that I hardly pick up transmissions anymore on Wake.
 
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