BCD436HP/BCD536HP: DMR Decoding Quality

[rocky28965]

listening to one particular DMR one frequency channel
I have tried SDS200e, UBCD536PT and TRX-2e
I am getting an excellent signal, but it is still hard to understand the voices.
I know who the licensee is but are trying to identify the user or type of business.
Is there any form of audio adjustment that may enhance this mode on any of those radios?

 

[Saint]

listening to one particular DMR one frequency channel
I have tried SDS200e, UBCD536PT and TRX-2e
I am getting an excellent signal, but it is still hard to understand the voices.
I know who the licensee is but are trying to identify the user or type of business.
Is there any form of audio adjustment that may enhance this mode on any of those radios?

What kind of signal are you receiving, how strong is it. what kind of antenna are you using, is the antenna inside or outside. To receive digital frequencies the stronger the signal you receive is better. If you're using only the rubber duck antenna that came with your scanner then you are probably not getting a strong signal, move your scanner around and find the best signal you can receive. The best is an outdoor antenna like a discone antenna. if your only getting 1 or to bars on the signal strength then you are getting a weak signal. Some digital audio is just bad on some systems and there is really nothing you can do about it, some of the audio is very bassy and hard to listen to.
Saint

 

[pb_lonny]

We have a DMR user here (I can see the TX site from my window) and I often have words that I miss or have sudden changes in the signal level. From what I have heard, the actual users of the network don't have these issues.

 

[rocky28965]

I using a discone and getting a full strength signal.
The repeater is only 10k's from my location.

 

[lamarrsy]

Maybe there is a proprietary « voice enhancement » option activated on users radios, that is perfectly compatible between them but that gets low-pitched, boomy / bassy with almost no high frequencies in the audio, when listened to with scanners.
That’s what I have in my area with one group of users : very difficult to follow conversations with my Uniden scanners not equipped with this voice companding thing…

 

[Ubbe]

but that gets low-pitched, boomy / bassy with almost no high frequencies in the audio, when listened to with scanners.

It should probably be the opposite if a compander feature are used to enhance the audio quality. This is digital signals that doesn't like to be overmodulated when it goes into the analog to digital converter. Low frequencies has the most energy so you would prefer to reduce those as much as possible and boost the high treble frequencies. Then at the other end in the digital to analog converter you restore the tone balance and get a much wider and useful dynamic range in the audio almost comparable to a pure analog system.

When you decode the digital signal using a scanner it should sound much brighter than normal without any bass.
If you loose high frequencies and it gets more bassy are an indication of a high amount of bit errors in the decode process, that results in a much less resolution and loose clarity and it's almost just the fundamental frequency left without the harmonics that identify a sound.

Usually a high bit error rate can be expected if you receive a system that use RAS, as the scanner then has to ignore the error correction function and you get a high number of bit errors even at a high signal strength. Both SDS200 and 536 can display its bit error rate.

/Ubbe

 

[lamarrsy]

Thanks Ubbe, your comments helps understand why the system on my part sounds « bassy », don’t know if it also matches the OP situation but it may very well be the case for him too.

 

[rocky28965]

That sounds about right, hence the last sentence in my post

"Is there any form of audio adjustment that may enhance this mode on any of those radios"

 

[Ubbe]

I've suggested, and always wanted, a tone control function in scanners to adjust the audio to better suit the speaker used.
Many Uniden scanners has a DSP that filters off frequencies below 250Hz when a frequency are programmed with a CTCSS tone and some scanners has audio AGC, so it wouldn't take much to add a global treble control, or a setting 1 and a setting 2 that can be set to each system, that can be programmed between -6dB to +6dB. And why not to also add middle and bass settings.

/Ubbe

 

[rocky28965]

I tried another couple of radios on the same channel and to my surprise, the USDS100 was the clearest of the lot.