To those involved with producing DSD & DSD+

Boatanchor · Nov 3, 2014

First, let me say a big thank you

Both of these packages are amazing tools for the growing SDR fraternity.

However, I have one gripe which I hope one day soon can be addressed.

Both of these software packages have bad (or awful) decoded audio dynamic range characteristics on P25.
I can't comment about the other DV modes, since I don't have any other nearby DV modes to check this with, but I wouldn't be surprised if they have similar audio characteristics.

DSD+ is by far the worse offender here.

I find I just cannot listen to DSD+ for any length of time because the decoded audio is so massively compressed that even the softest background noise, such as an operator typing on a keyboard, or a distant voice in the dispatch office is 'boosted' to almost the same level as the main operator. If a field operator speaks and there is any ambient noise present, the result is just painful to listen to.

It is almost as though there is some kind of savage software based audio compression going.
It definitely doesn't sound anywhere near as natural as a digital scanner or a 'real' P25 radio.

If you guys can address this issue, you would make my month

Cheers,
Boat

mmisk · Nov 3, 2014

DSD P25 Audio

The good news is that my P25 decoding works quite well, so I don't think your problem is with DSD, and you should also receive good decoded audio

What are you using for a receiver? Is it SDR software along with Unitrunker.

I agree with you about DSD and Unitrunker, both fantastic applications. Thanks to the people who spend many hours producing them for us.

Mike

EDIT: I just saw that you have a USB dongle so I assume you are using Unitrunker, so the problem may just be some settings.
Let me know.

Boatanchor · Nov 3, 2014

I get perfect decode with no error rate using DSD and DSD+.

My gripe is that when you compare the demodulated/decoded audio produced by DSD+ in particular, it is highly compressed compared to 'real' P25 radios.

The original DSD produces audio that is not nearly as compressed, but still is to a degree.

It is hard to explain if you haven't noticed the problem, but basically, any soft ambient noise sent along with the main radio operator, is amplified up to virtually the same level as the operator. This makes long term listening very tiring.

The software developers (you know who you are), will know what I'm talking about.

mmisk · Nov 3, 2014

frequency response

Here is something you can try.

Your sound card may have come with some sort of application that you can use to tailor the frequency response to your liking I have used this to vary my audio and it works quite well. Just the same as if you were listening to music.

And of course there are many audio applications available on the internet.

MM

slicerwizard · Nov 4, 2014

Boatanchor said:
My gripe is that when you compare the demodulated/decoded audio produced by DSD+ in particular, it is highly compressed compared to 'real' P25 radios.

The original DSD produces audio that is not nearly as compressed, but still is to a degree.

It is hard to explain if you haven't noticed the problem, but basically, any soft ambient noise sent along with the main radio operator, is amplified up to virtually the same level as the operator. This makes long term listening very tiring.

Don't think I got an answer the last time I asked - why don't you just disable DSD+'s AGC?

Boatanchor · Nov 5, 2014

slicerwizard said:
Don't think I got an answer the last time I asked - why don't you just disable DSD+'s AGC?

Sorry slicerwizard, I didn't/cant see your first post/response to my comments???

Hmm, just noticed you share the same location as user MMISK. Presumably, you are one and the same.

If you are referring to the RTL dongle AGC, then no, this is not the problem. The tuner AGC only effects the RF gain of the tuner. It has no bearing on the characteristics of the demodulated audio (assuming one has low BER).

Besides, I run only FCDP+ and discriminator taps. I don't like cheap RTL dongles as they are deaf, noisy and unstable

The problem is that the demodulated audio produced by DSD+ is too compressed and lacks any real dynamic range (compared to other DV receivers).

Hopefully, the software authors can address this in a future release.

mmisk · Nov 5, 2014

I am in Ottawa and Slicerwizard is in Toronto.

I am quite happy with my $20 dongle, I seem to get great reception and I don't have any stability issues like some have reported. I do have a 64 ft tower to get my antenna's above the tree line so that sure helps. I can use a tap from an old scanner or the $20 dongle and both work fine.

But back to your sound quality. Check all of your settings in Unitrunker as Slicerwizard suggested.
I don't know what else to suggest as my setup here works fine.

Some day I would like to get one of those FCDP+

Mike, in Ottawa

mmisk · Nov 5, 2014

Perhaps this will help. A screen capture of my UT settings:

slicerwizard · Nov 5, 2014

Boatanchor said:
Sorry slicerwizard, I didn't/cant see your first post/response to my comments???

You'd have to look back nearly a year.

Hmm, just noticed you share the same location as user MMISK. Presumably, you are one and the same.

No, last time I checked, we were wholly separate corporeal lifeforms. I have no idea how you came to that conclusion.

If you are referring to the RTL dongle AGC, then no, this is not the problem. The tuner AGC only effects the RF gain of the tuner. It has no bearing on the characteristics of the demodulated audio (assuming one has low BER).

No, I'm referring to DSD+'s audio AGC. Again, if you don't like how it sounds, why don't you just disable it?

Code:

Input/Output options:

  -g<num>     Output audio gain (0.001-999; 0=auto) [-g0]

rob12770 · Nov 6, 2014

Boatanchor said:
I don't like cheap RTL dongles as they are deaf, noisy and unstable
.

Nope....

Boatanchor · Nov 6, 2014

slicerwizard said:
You'd have to look back nearly a year.

No, last time I checked, we were wholly separate corporeal lifeforms. I have no idea how you came to that conclusion.

No, I'm referring to DSD+'s audio AGC. Again, if you don't like how it sounds, why don't you just disable it?

Code:

Input/Output options: -g<num> Output audio gain (0.001-999; 0=auto) [-g0]

Sorry Slicerwizard & mmisk, I apologize for mixing you two up.

Anyway, thanks heaps for pointing out the -g command.
I will give it a try this evening.

Cheers,
B

Boatanchor · Nov 6, 2014

rob12770 said:
Nope....

Really??

Oh well..

rob12770 · Nov 6, 2014

Boatanchor said:
Really??

Oh well..

Really

Boatanchor · Nov 6, 2014

rob12770 said:
Really

To each, their own..

Boatanchor · Nov 6, 2014

Unfortunately, the -g command only adjusts the decoded audio output level of the decoder.
As such, it has no effect on dynamic range.

It seems as though the audio compression characteristics are occurring further back in the decode chain.

Oh well, it was worth a try.

Back to our scheduled programming.

Boatanchor · Nov 28, 2014

I'm sorry, but DSD+ really does sound crap

I give credit where credit is due and the person or people that produced DSD+ have produced a software product that potentially allows enthusiasts access to SDR and discriminator tapped Digital Voice at little, if any cost.

However, the reproduced audio that DSD+ produces is pretty bad compared to virtually every other DV decoder product on the market.

Now, before anyone asks me what my error rates are, they are zero. Yep, zero error rate after running DSDTune and monitoring reasonably strong signals. The problem is not low signal strength or high error rates, or over-driven audio devices.

I have mentioned this several times previously and either I get blasted by the DSD Fanboys or told that I am simply doing something wrong with my PC audio setup. I assure you, I am not. Nothing I can do to my PC or sound card will correct the highly compressed, very low dynamic range audio that DSD+ produces.

I recently had the opportunity to test the latest firmware for the ADCR25 standalone, SDR P25 & DMR receiver produced by RU3ANQ. Believe me when I say that you haven't heard good quality P25 phase 1 audio until you listen to what the ADCR25 produces. This tiny little receiver, produces P25 audio unmatched by my BCD436HP and any of my GRE scanners.

So, yes it is possible to produce 'in house' software DV decoders that sound as good as a $2000 Motorola.

Hopefully, the DSD/+ authors can rectify the audio quality in their decoders in future versions..

RonnieUSA · Nov 28, 2014

Care to provide a link for these DV decoders?
I wasn't happy with the sound till I found a setting in my environment settings, it added more base, and now I'm very happy.

My sound driver is Realtek

Boatanchor · Nov 28, 2014

HAM RADIO WORKS -

Use google translate.

Andrey seems like a really nice guy and his English is actually very good when communicating via email.

The receivers are only available in VHF and 400-470Mhz at this stage.

His latest firmware adds trunk tracking too, although it seems there is a little more work to be done there to iron out a few bugs.

Basically, once you set the receiver up via the PC, all you have to do is plug it into a USB power supply and it runs by itself.

Boatanchor · Nov 28, 2014

I just noticed he has a pretty sweet Black Friday deal going on too... Need to get in quick though..

DSDPlus · Nov 29, 2014

Yes, you can get better sound by paying for it. The DSD+ developers are paid nothing, so requests like yours do not float to the top of the queue. Instead, these days, the developers are starting to work more on features or fixes that interest them or that they need instead of dealing with requests. And that is when they have free time to work on DSD+. The next DSD+ public release may be the last one for a long time, but I can't say for sure.

To those involved with producing DSD & DSD+

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