BCD536HP Threshold

[USASA]

Hi All!

I have 6 digital scanners, only the BCD536HP have I had to change the Threshold to manual and go from 8 to 7. Now the voices of the dispatchers and officers sound natural. I know some of the dispatchers and officers so it is easy for me to compare. Has anyone else had tis occur. This is the first time I have ever had to do this. Also the AGC on this radio leaves a lot to be desired. Turn it on and there is no constant level up/down like a ping pong ball. Is it me, my radio or is it a common problem? The AGC on the Whistler (GRE / Radio Shack) radio are even and smooth. Odd!


Al
USASA

 

[Ubbe]

It almost sounds as if you have a faulty scanner. The AGC usually have very little impact on the audio level and definitly not a big ping-pong effect. Adjusting threshold one step up or down also have little impact and are a way to finetune the digital decoding when you have a weak signal. It is assumed that setting it to the lowest setting of 5 will let it pass thru signals with more biterrors, that could give robotic voices but also will let you monitor those weak signals. I assume that setting it to 13 will work as a squelch and only pass signals that are strong and without any interference or distorsion.

Make a backup and then do a total reset (hold 2-9-dept while powering on) of the scanner and write that backup to the scanner.
Also try to do a new firmware update to set everything straight again.

/Ubbe

 

[jonwienke]

Adjusting Threshold to get best digital decode is normal. It's the whole point of the adjustment. Auto works OK on many digital systems, but not all.

The fluctuation in audio level is because the x36 audio AGC is next to useless. It's bad when it's on, but even worse when it's off. Upman once described its effect as "subtle", which is exactly what AGC is NOT supposed to be. Evidently Uniden has some really stupid audio engineers.

 

[jonwienke]

It is assumed that setting it to the lowest setting of 5 will let it pass thru signals with more biterrors, that could give robotic voices but also will let you monitor those weak signals. I assume that setting it to 13 will work as a squelch and only pass signals that are strong and without any interference or distorsion.

None of those assumptions are accurate. Threshold is not a squelch setting. Threshold defines the modulation levels used for logic 0 and 1 when transmitting digital data. That varies by system site, depending on how the transmitter is adjusted. Setting Threshold too high or too low will increase the decode error rate.

 

[marksmith]

Adjusting Threshold to get best digital decode is normal. It's the whole point of the adjustment. Auto works OK on many digital systems, but not all.

The fluctuation in audio level is because the x36 audio AGC is next to useless. It's bad when it's on, but even worse when it's off. Upman once described its effect as "subtle", which is exactly what AGC is NOT supposed to be. Evidently Uniden has some really stupid audio engineers.

I find it's best when it is off.

Not necessarily because the AGC is bad... I think it's the same AGC that has been in Uniden scanners for a long time.

But because the newer modern trunking systems, particularly digital ones, have their own system AGC, and the one on the radio seems to fight with it.

If you are monitoring older non-trunking systems, then the AGC works fine.

And your comment about the audio engineers is probably a little strong.

536/436/ws1095/996p2/996xt/325p2/396xt/psr800/396t/HP-1/HP-2 & others

 

[jonwienke]

And your comment about the audio engineers is probably a little strong.

The whole point of AGC is accept input signals that vary by 10-20dB or more, and adjust them so that they output within a few dB of each other. That is not "subtle". Engineering a "subtle" AGC function makes less sense than trying to engineer "dry" water. Uniden's audio AGC either has a gross bug that nobody has ever bothered to fix, or was engineered by someone who has no understanding of basic audio recording/mixing principles.

 

[rbrtklamp2]

Thank You Jonwienke. I wish this site had a like button you always explain things very well when it comes to the Uniden scanners. And just FYI for the OP Jonwienke was one of the original reporters of the capacitor problem and one of the great people on this site to help find help find the solutions both temporary and permanent. Listen to him he knows what he's saying when it comes to uniden and these scanners.

Sent from my SM-N910V using Tapatalk

 

[jonwienke]

I'm not the first person who reported the UHF noise issue from the battery compartment, nor was I the one who discovered the link between C1 and the noise. But I have done a lot of testing with units that had C1 installed vs. not, and the noise effect on various antenna configurations. Doing the GPS mod on 436 and other Uniden scanners has given me the opportunity to go hands-on with a bunch of 436s representing all of the main board revisions.

 

[DeDawg]

And your comment about the audio engineers is probably a little strong.

I disagree, the P25 PII decoded audio varies from unintelligible to unlistenable for the system in my area.. This is on a non simulcast system, very strong signal. I truly wonder if the engineers ever listened to voice or just used O-scopes and BER detectors for development.

Threshold does not change the useless voice audio in the slightest, probably because it is already a strong signal.

 

[marksmith]

Since you guys think the engineers at Uniden are stupid, you should stop buying the product. Your arguments would carry more weight. I don't know of anybody doing it better, and don't think it's very useful to call someone stupid.

536/436/ws1095/996p2/996xt/325p2/396xt/psr800/396t/HP-1/HP-2 & others

 

[ChrisABQ]

DeDawg, maybe that is exactly your issue, a very strong system. Maybe try to dial it back a bit with less antenna, if possible.

 

[jonwienke]

Since you guys think the engineers at Uniden are stupid, you should stop buying the product.

Not all of them, just whoever designed and/or QCd the audio AGC function. There are a lot of products that do audio AGC far better than Uniden--they have AGC functions that actually work. There are a lot of things Uniden scanners do right, but that particular thing is definitely not on the list.

 

[jonwienke]

I disagree, the P25 PII decoded audio varies from unintelligible to unlistenable for the system in my area.. This is on a non simulcast system, very strong signal.

In Uniden's defense, that is something they got mostly right, in the sense that it works as designed in the majority of cases. There are more than five P25 systems within monitoring range, and I can monitor all of them clearly, including the ones that do Phase II. If the signal is extremely strong, attenuating it a bit might help. What antenna are you using?

 

[DeDawg]

DeDawg, maybe that is exactly your issue, a very strong system. Maybe try to dial it back a bit with less antenna, if possible.

Tried the built in attenuator, switched to an outside antenna with much less gain Even tossed in a FM broadcast notch filters, just in case this was intermod.

Nothing changes, just wretched audio. Headphones at low level are almost tolerable, but too soft to understand.

 

[DeDawg]

IWhat antenna are you using?

A coaxial/sleeve dipole of my design, like 20 years ago, my version of a "Ventenna"

Took apart a Ventenna, measured VSWR, and saw a mediocre swag. Thought about it and made my own.

 

[USASA]

AGC

Hi All!

Well on the AGC issue, G.R.E / Whistler do it right! Their AGC works very well. Uniden has never had a good AGC. I have had Uniden scanners from the time of crystals. The volume is low then the next signal is over powering. You run the gambit from perfect audio to WTF was that! They do make a great radio that is the only fault I find, that is why I buy them so often. I also buy GRE/Whistler, it has some faults also. I wish Uniden would fix the AGC issue that is all. The problem is at it's worst in DMR. I just started monitoring DMR signals to include Ham. The hams also complain about the Ping Pong volume on their radios, very expensive and cheep ones. The issue for DMR is DMR and how it was written and programmed! The U.S.A. going to DMR is just to make a buck selling new radios, P25 now works well. Stick with what works! My 2 cents, or no cents.


Al
USASA

 

[jonwienke]

Tried the built in attenuator, switched to an outside antenna with much less gain

Try the stock antenna. Any outdoor antenna is going to pick up way more signal than any indoor antenna. The change in signal strength due to antenna gain is far less than the change i nsignal strength you'll get by moving the antenna outside.

 

[Ubbe]

None of those assumptions are accurate. Threshold is not a squelch setting. Threshold defines the modulation levels used for logic 0 and 1 when transmitting digital data.

Modulation levels are the exact same on all DMR systems. It would create chaos if they weren't.

I understood threshold as something that you have to climb over to be able to pass it, I.E a squelch level.
My BCD536HP have it's DMR threshold work as a squelch for the bit error level. Set it at 5 and it holds on to very weak signals, sometimes without being able to properly decode the data. As long as the signal is saturated with no bit errors it doesn't matter what threshold level is used.

Uniden changed that setting in a later FW release so that the range where dropped down 2-3 steps so that the old level 5 where more like 2 or 3 when set from Butels ARC software and where more usable.

/Ubbe

 

[jonwienke]

Modulation levels are the exact same on all DMR systems. It would create chaos if they weren't.

The exact frequency deviation used to represent zeroes and ones varies from radio to radio, just like the analog FM frequency deviation induced by a given audio signal varies from radio to radio. You hear significant differences in audio volume from one radio to another listening to analog FM, the same principle applies to digital. Auto looks at the min and max transmitted frequency, and attempts to use that as the 0/1 reference. That works most of the time, but not always.

 

[DeDawg]

The change in signal strength due to antenna gain is far less than the change i nsignal strength you'll get by moving the antenna outside.

That would depend on the antenna, no?

Back of set antenna improved nothing, same horrible muffled or overmodulated voice audio. BER is higher as well, not a surprise. Never got any improvement adjusting the threshold anyway, no shock there.