JH2184
Member
How do you adjust the P25 threshold on the BCD396XT?
BCD396XT P25 Adjustment
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sjlamb
Member
You don't.... it's strictly automatic (w/ a default setting of "8"). There is, however, settings for the P25 LP Filter and Wait Time.
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You do have some control over the P25 adjustment... If you press and hold the "hold" button and turn on the scanner the screen will flash colors and allow you to get into the P25 settings. Then press menu and go to settings and then go to P25 adjust level. You will notice it is set to 50 for the default auto setting. If you change it to 200 (press 200 enter) now the default level will always be 8 and if you change it to 100 the default will be set to 11. You can check this when scanning by pressing Func then volume, Func then volume to watch the threshold. Auto works well for me but setting it to 200 isn't bad because most of the digital systems level off around 8 using the auto setting anyway. If you find that the default setting works best just set it back to 50 by pressing 050 enter.
Mike
Mike
sjlamb
Member
Learn something new everyday. I stand corrected.... thanks
I did what you stated about and I was adjusting the p25 adjust settings. I set it at 200, but when I check the screen to monitor the err rate it still says "8 Auto" is that what the unit is supposed to be reading. I thought 50 was auto?
Mine can be set to any value between 1 and 200 and my error screen still shows 8 Auto as well. It does appear to widen or sharpen the allowed autotune threshold however.
I do know the "AUTO" setting cannot be changed so even if you get it to start at say 11, it will still be in auto mode. This is something I wish Uniden would have made the same as the "T" series. The Manual mode. I have a simulcast system here that works the best for me with a setting of 5 or 6. My old BCD996T tracks it 99% when set to manual and a 5 or 6 decode rate while a 996XT hooked to the same antenna system only hits about 65% and will not auto tune down below 8 very often. When it does, it tracks fine but only until that transmission is ended and then it jumps right back to 8 again.
So Uniden, if you are listening, please bring back the Manual mode for P25 decode rate in the XT series! It worked great for those that need it in the T series.
While typing this replly, I've been playing with this setting and it seems if I set it to a value of 1 (or something low), I then get an Auto rate that bounces between 6 and 12 or so as it tracks the system. This makes for horrible reception. However, if I set the setting to 200, I then get what appears to be a fixed rate of 8 Auto. No value gives me a fixed rate. So a setting of 1 lets it adjust between 6 to 12 or so while a setting of 200 seems to lock it at 8 although it still shows Auto. This is reverse of what was stated by the other poster.
My system actually tracks fairly well while set to 200.
So a low value like 1 allows the threshold to search acoss a range and attempt to self adjust while a setting of 200 appears to narrow the threshold down and lock it at 8.
I'd think if you set yours to 1, then watch the decode screen, you should see yours bounce around as it attempts to lock onto the correct threshold. Set tit oa high value like 200 and it should stay on 8. I did notice with mine that when monitoring a system with a good signal that the setting does not bounce around much, if at all, regardless of this setting. But on my poorer signal simulcast system, it does make a big difference.
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Mine allows adjustment from 3 to 15 but I can't determine what it changes.
I tried varying the setting across the entire range on poor signal systems as well as high quality signal systems (all P25 of course) and I cannot tell a difference at all.
The older 996T also has both these settings available when powered up while holding the Hold button.
I wonder if this setting is just an old menu item no longer used in the XT series that was not removed when the XT was developed.
Of course this setting may work in parallel with the P25 Adjust Level and only make a difference if that setting is at certain values. I'm clueless on this one other then I can't see any difference regardless as to what value I set it too.
rmosier
Member
KB8RVP,
Thank you! I took your advice, and by consulting this website
P25 audio decode level adjustment (BCD396T - The RadioReference Wiki)
was able to determin the proper threshold for Morris County's trunk system, as well as Parsippany PD, Monville PD etc. is 1.60 which is equal to "Manual threshold 7" on the 396T, which is the equivalent to entering 160 as the default on the 396XT. Now they all sound crystal clear. And I too wish that Uniden would include the manual setting in the next update.
Thank you! I took your advice, and by consulting this website
P25 audio decode level adjustment (BCD396T - The RadioReference Wiki)
was able to determin the proper threshold for Morris County's trunk system, as well as Parsippany PD, Monville PD etc. is 1.60 which is equal to "Manual threshold 7" on the 396T, which is the equivalent to entering 160 as the default on the 396XT. Now they all sound crystal clear. And I too wish that Uniden would include the manual setting in the next update.
MarMatthias
Member
Hi,
I've spent way too much time playing with these values. I was dumb enough to sit and try every combination. My experience is that the 396XT always degraded when I changed the values away from the default. There may be, and there probably is, special circumstances that require these values to be changed, but for the most part, I believe the 396XT , and probably the 996XT, does better on its own in adjusting itself.
I've spent way too much time playing with these values. I was dumb enough to sit and try every combination. My experience is that the 396XT always degraded when I changed the values away from the default. There may be, and there probably is, special circumstances that require these values to be changed, but for the most part, I believe the 396XT , and probably the 996XT, does better on its own in adjusting itself.
My local system is simulcast and my 396XT works better with the setting at 100. My 396T has fewer digital dropouts than the XT when the T is set on manual with a level of 11.
I would like the option of setting the XT manually as well.
I would like the option of setting the XT manually as well.
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Correct me if I am wrong but I believe that value has nothing to do with the decode levels. I was always under the impression that this value represented the mili volts of the incoming signal needed to have the scanner begin the auto adjust threshold. Meaning the higher the number, the stronger the signal required for adjustment. This is set so if you are in a fringe coverage area with digital pixelation the scanner will not run a correction algorithm thus changing the level it already detected to be the best level.
ka3jjz
Wiki Admin Emeritus
The wiki has an extensive article on the subject...
P25 audio decode level adjustment - The RadioReference Wiki
73 Mike
P25 audio decode level adjustment - The RadioReference Wiki
73 Mike
This isn't documented very well but I believe you are correct. That is the problem I have with the 396XT. I can't set the actual levels like I do with the 396T. No matter what the setting is on the 396XT, it eventually ends up auto adjusting to a level of 12, my errors climb to the double digits, and the digital garbage starts. With the manual setting at 11 on the 396T, I usually see a lower error rate and have better audio. It's not perfect but definitely better.
The wiki article is a good summary of the threads I have found here and does state that the only adjustment to P25 level on the 396Xt is an adjustment to the minimum RSSI level at which auto adjustment of the actual decode levels can occur on the 396XT. This doesn't help my situation at all because I have a multipath distortion issue caused by simulcast that occurs at full signal levels.
I have had times if I left the setting of 50 (default) that I would not pick up anything sitting right next to my Pro-2096 working just fine. I then changed it to 200 which set the decode rate to 8 then it would work all day long. This was on the Genesee Simulcast system. Using the 396XT on the state towers that are non-simulcast with a setting of 50 or 200 both work well but I still think it is a little better set to 200. You can watch it decode and check the error rate as I mentioned above and see which setting keeps the error rate closest to zero.
Mike
Boatanchor
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There is at least one other serious issue at play here, which has to my knowledge, not been documented anywhere and it affects every scanner tested so far.
If a control channel becomes 'active' (for want of a better term) with a voice call and it sends the scanner to a voice channel that is close in frequency to another very strong control channel, or even another voice channel, the scanners IF filtering is not sufficient to prevent overload from the adjacent strong signal and this will prevent the scanner decoding the voice channel.
I have seen this occur on local non-simulcast trunking networks.
The problem occurs when voice channels fall within 50Khz of another very strong control or voice channel. In practice, you get 100% decode rate on the control channel, but the voice channel breaks up or doesn't decode at all. This occurs on every scanner I have tried including the PSR600 and the UBC996xt. It is a flaw in the scanners IF filters that allows strong signals to break through and interfere with nearby channels.
One way you can see if this is occurring is to open the squelch and tune +-50Khz from a very strong local control channel. Do you hear a strange 'silent' channels just up or down in frequency from the control channel? This is the control channel signal breaking through the cheap IF filters and blocking that/those frequencies. If the voice frequencies fall within ~50Khz of the strong signal, it is highly likely that you will not decode the P25, even if not a simulcast channel.
The only way to eliminate this problem is to try and reduce the strength of the strong interfering signal and this is where paperclips or yagi's can be of benefit
The fact is that the IF filtering in a $500 scanner is just not up to scratch on narrowband trunking networks, let alone ultra-narrowband systems with 6.25Khz steps..
Sorry..
If a control channel becomes 'active' (for want of a better term) with a voice call and it sends the scanner to a voice channel that is close in frequency to another very strong control channel, or even another voice channel, the scanners IF filtering is not sufficient to prevent overload from the adjacent strong signal and this will prevent the scanner decoding the voice channel.
I have seen this occur on local non-simulcast trunking networks.
The problem occurs when voice channels fall within 50Khz of another very strong control or voice channel. In practice, you get 100% decode rate on the control channel, but the voice channel breaks up or doesn't decode at all. This occurs on every scanner I have tried including the PSR600 and the UBC996xt. It is a flaw in the scanners IF filters that allows strong signals to break through and interfere with nearby channels.
One way you can see if this is occurring is to open the squelch and tune +-50Khz from a very strong local control channel. Do you hear a strange 'silent' channels just up or down in frequency from the control channel? This is the control channel signal breaking through the cheap IF filters and blocking that/those frequencies. If the voice frequencies fall within ~50Khz of the strong signal, it is highly likely that you will not decode the P25, even if not a simulcast channel.
The only way to eliminate this problem is to try and reduce the strength of the strong interfering signal and this is where paperclips or yagi's can be of benefit
The fact is that the IF filtering in a $500 scanner is just not up to scratch on narrowband trunking networks, let alone ultra-narrowband systems with 6.25Khz steps..
Sorry..
cpetraglia
Member
This sounds by far the best explanation I have yet to hear for poor P25 reception. I live in the middle of the county system I am trying to listen to and have nothing but trouble. What I have noticed after many observations is that whan the outdoor humidity rises my reception improves to a point when it rains, everything goes to 100% including voice reception. I have a high end yagi on a rotor and it dosent seem to matter where I point it. Maby someone can explain the anomally with the rain and there would be some wiring/electronic fix for this. I have tried many different pre-amps, filters, indoor antenna setups. They might as well go ENC for all I have done with very little luck. Pray for rain.There is at least one other serious issue at play here, which has to my knowledge, not been documented anywhere and it affects every scanner tested so far.
If a control channel becomes 'active' (for want of a better term) with a voice call and it sends the scanner to a voice channel that is close in frequency to another very strong control channel, or even another voice channel, the scanners IF filtering is not sufficient to prevent overload from the adjacent strong signal and this will prevent the scanner decoding the voice channel.
I have seen this occur on local non-simulcast trunking networks.
The problem occurs when voice channels fall within 50Khz of another very strong control or voice channel. In practice, you get 100% decode rate on the control channel, but the voice channel breaks up or doesn't decode at all. This occurs on every scanner I have tried including the PSR600 and the UBC996xt. It is a flaw in the scanners IF filters that allows strong signals to break through and interfere with nearby channels.
One way you can see if this is occurring is to open the squelch and tune +-50Khz from a very strong local control channel. Do you hear a strange 'silent' channels just up or down in frequency from the control channel? This is the control channel signal breaking through the cheap IF filters and blocking that/those frequencies. If the voice frequencies fall within ~50Khz of the strong signal, it is highly likely that you will not decode the P25, even if not a simulcast channel.
The only way to eliminate this problem is to try and reduce the strength of the strong interfering signal and this is where paperclips or yagi's can be of benefit
The fact is that the IF filtering in a $500 scanner is just not up to scratch on narrowband trunking networks, let alone ultra-narrowband systems with 6.25Khz steps..
Sorry..
rjschilder
Member
Sorry to kick up an old thread but I just had a similar issue and it turned out my squelch was set all the way up...turned it back down and all my problems disappeared.
Ryan kc9gmy
Ryan kc9gmy
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