BCD436HP: New BCD436HP will not pick up local P25 system

moparth

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I have a 436HP, 536HP and just got a SDS100 scanner and all work fine with our local P25 system ( Rockingham / Harrisonburg, VA). A coworker just bought a new BCD436HP and asked if I would program it with the exact same favorite lists as are in mine, I did and everything works except that system and I've done scanners for 2 other friends the same way and they worked. This scanner will never stop on that system and if I manually hold it on one of the P25 TGID's it will only get about 1 out of 25 transmissions if that. Any ideas on this ? I've tried clearing user data and starting from scratch but still the same result every time.
 

kruser

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Try changing the Digital Threshold Mode to Manual for that systems Site and then adjust the Digital Threshold Level starting with 6 and work higher and see if that helps.
I had an early model 536HP that needed a different Level to work while my other like models usually worked with it set to Auto.

Also, how does the signal strength look on this troubled 436 compared with those with no problem? Any signs of a signal difference between them.
You might need to enter the control channel in as a conventional entry to get an accurate signal level for that test.
 

Ubbe

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It could be that the scanners reference frequency are too much off from it's nominal value. It then will have more problem to decode a digital signal if it is more distorted. It's a bit difficult to test without a signal generator but a telltale sign could be if a FM setting instead of a correct NFM will improve reception, if the transmission are actually done in NFM.

/Ubbe
 

jonwienke

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Or it could be simulcast. What system?
 

whooey

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Try changing the Digital Threshold Mode to Manual for that systems Site and then adjust the Digital Threshold Level starting with 6 and work higher and see if that helps.
I had an early model 536HP that needed a different Level to work while my other like models usually worked with it set to Auto.
+1 on this, my 536 wouldnt pick up my local system and the SDS-100 was receiving perfect. Someone gave me the manual threshold tip, set it at 7 now my 536 performs as well as my SDS100, and it's a simulcast system too.
 

jonwienke

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Manual threshold helps with simulcast decoding sometimes. But it doesn't always solve reception issues. Take your SDS100 to your friend's place and see if it works where the 436 doesn't. If the programming is the same and the SDS100 works but the 436 doesn't, then your friend probably needs to upgrade to a SDS100.
 

kruser

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It could be that the scanners reference frequency are too much off from it's nominal value. It then will have more problem to decode a digital signal if it is more distorted. It's a bit difficult to test without a signal generator but a telltale sign could be if a FM setting instead of a correct NFM will improve reception, if the transmission are actually done in NFM.

/Ubbe
I had this exact thing happen on one of my states new VHF sites not long after the system went live in my part of the state.
The VHF sites here are all single tower non-simulcast sites. The site in question worked fine in NFM mode for a couple months after the system went live. Then one day I noticed no reception from one site. The nice signal level was still there but no decode of the CC.

I found I could still decode the sites control channel just fine with a GRE model but nothing on my x36HP models. The same x36HP models received the CC just fine from the other VHF sites within range. That pointed to an issue with the site.
I first changed the bandplan setting using Sentinel so the troubled site would use FM instead of NFM. That worked and the x36 was again decoding the bad sites CC just fine. The other sites using the same frequency range were also now using the bandplans FM setting but they still decoded fine.

After this worked for a week or two, I finally did a manual edit of the favorite list for that system and changed the mode to FM for just the one site with the problem so I could put the bandplan back to normal for the other sites. I needed that trick in place for another month or two before the problem was fixed at the transmit site.
I was able to put that site back to auto mode and all's been happy since. This was a couple or more years ago since that happened.
 

moparth

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Thanks for all the replies, I guess I never knew how many broadcasts I was missing with my old 436 until getting the SDS100 about a week ago, but my friends is even worse. It seems by changing the bandplan to FM from NFM and changing the the digital threshold to manual at 7 has really made a difference, but the SDS definitely outperforms on this system.
 

DellasWolf

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Check to make sure the System and Departments are turned on. I've turned on my fav and the system and department were turned off a few times when I copied something over from my SDS 200
 
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