• Effective immediately we will be deleting, without notice, any negative threads or posts that deal with the use of encryption and streaming of scanner audio.

    We've noticed a huge increase in rants and negative posts that revolve around agencies going to encryption due to the broadcasting of scanner audio on the internet. It's now worn out and continues to be the same recycled rants. These rants hijack the threads and derail the conversation. They no longer have a place anywhere on this forum other than in the designated threads in the Rants forum in the Tavern.

    If you violate these guidelines your post will be deleted without notice and an infraction will be issued. We are not against discussion of this issue. You just need to do it in the right place. For example:
    https://forums.radioreference.com/rants/224104-official-thread-live-audio-feeds-scanners-wait-encryption.html

DSD for Dummies

Status
Not open for further replies.

druhe

Member
Premium Subscriber
Joined
Feb 18, 2003
Messages
525
Location
Southwest Pa
Is there a step by step document in layman's terms on how to get DSD for Windows up and running ? Between the wiki and multiple discussion forums, I've wasted the better part of the afternoon and I am no further along than when I started.

Thanks for any assistance
 

br0adband

Member
Joined
Apr 8, 2005
Messages
1,568
Location
Springfield MO
Think of using DSD as a signal pathway:

- you need a source signal aka baseband audio (unfiltered) and up till recently that meant the good old discriminator tap to provide the baseband audio for decoding purposes, but nowadays (within the past 2 years) there's a new way of getting such source material and that's by using "cheap USB TV tuner sticks" made specifically for use outside the US (because the rest of the world typically uses DVB-T technology for digital TV broadcasts while here in the US we just gotta do our own thing so we use ATSC technology and they're incompatible with each other)

- you'll then be routing that through some software on a computer (Windows being the most popular operating system overall so Windows apps, but Linux has a strong showing with respect to software defined radio and other aspects related to decoding digital communications modes)

- the decoded signal is then sent to your computer's audio subsystem for translating it into something you can actually hear

So point A to point B to point C, or more less, the idea being the source goes through all that, ends up at DSD's door so to speak, and DSD decodes it as needed and then outputs to your computer's audio subsystem and voila, magical voices from the Ether!!! MUAHAHAHA (ok, a little overboard there, I admit it)

With DSD, it can be run entirely by itself if you have a discriminator tap on a receiver/scanner and you can feed that into the computer's sound card (preferably into the line-in but mic-in can be used with very very careful attention to the input levels so you can keep the signal useful but not distorted or overloading the input). So with a discriminator tap and DSD you can decode digital comm formats that DSD supports basically with just that program alone.

Now, if you happen to have one of those "cheap USB TV tuners" you'll need software to control/tune the stick (commonly referred to as RTL devices since they tend to use a Realtek control chip - Realtek doesn't make the tuner chip on such hardware, just the RTL2832U chip that controls the USB interface and data pump for connecting to a computer). For most people that I'm aware of, the popular software is known as SDR# (SDR-Sharp) and it's pretty awesome for what it can do and also considering that - like most SDR software these days - it's completely free of charge. How cool is that? :D

I don't use any other SDR software except SDR# but there are different ones available such as RTL-SDR, GNU Radio, SDR-Radio, and HDSDR to name the ones I'm aware of, so because of that I can't offer anything in terms of instructions for all those other ones. Because SDR# tends to be the most referred to hence most popular (at least as I read it) that's what I'd suggest for starting out aka "getting the damned thing to work."

Before I do a full write-up to help, I need to know what your setup is:

- do you have a discriminator tapped receiver/scanner + DSD on a computer already attached by way of some patch cord, or...

- are you using some RTL device + SDR software + DSD on a computer

Once you describe what hardware/software setup you have, then I/we can answer some more questions or provide more info.

And just as a final note, there is now another digital speech decoder program known as DSD+ or DSDPlus, it's only been around for about 2 weeks (first release) but even so it's proven itself to be quite remarkable in terms of how solid it is, the ability to decode even weak digital signals with relative ease by comparison to DSD (for most people based on what they're reporting), and a lot of options like the ability to actually record a given weak signal (raw recording of the actual data as a WAV file) and then go back with another piece of software called dsdtune (from a different author, for the record) and "tune" the decoding potential. You then feed the decoder tuning parameters back to DSD+ and it will amaze you at just how well it's able to clean up what was previously almost not listenable at all.

Just something to make a note of, try DSD and DSD+ and then figure out which works best for you, sometimes you may discover that one works better for a given system, so use both.
 
Last edited:

druhe

Member
Premium Subscriber
Joined
Feb 18, 2003
Messages
525
Location
Southwest Pa
Think of using DSD as a signal pathway:

Before I do a full write-up to help, I need to know what your setup is:

- do you have a discriminator tapped receiver/scanner + DSD on a computer already attached by way of some patch cord, or...

- are you using some RTL device + SDR software + DSD on a computer

Once you describe what hardware/software setup you have, then I/we can answer some more questions or provide more info.

And just as a final note, there is now another digital speech decoder program known as DSD+ or DSDPlus, it's only been around for about 2 weeks (first release) but even so it's proven itself to be quite remarkable in terms of how solid it is, the ability to decode even weak digital signals with relative ease by comparison to DSD (for most people based on what they're reporting), and a lot of options like the ability to actually record a given weak signal (raw recording of the actual data as a WAV file) and then go back with another piece of software called dsdtune (from a different author, for the record) and "tune" the decoding potential. You then feed the decoder tuning parameters back to DSD+ and it will amaze you at just how well it's able to clean up what was previously almost not listenable at all.

Just something to make a note of, try DSD and DSD+ and then figure out which works best for you, sometimes you may discover that one works better for a given system, so use both.
First let me say Thank You for the reply. I have a Uniden 780 with discriminator tap HOWEVER I was given a "USB TV tuner stick" that I have never taken out of the package, so I have both options (the one I did not know I had) available. With that said, let the learning begin.
 

mtindor

OH/WV DB Admin
Database Admin
Joined
Dec 5, 2006
Messages
7,369
Location
Carroll Co OH / EN90LN
First let me say Thank You for the reply. I have a Uniden 780 with discriminator tap HOWEVER I was given a "USB TV tuner stick" that I have never taken out of the package, so I have both options (the one I did not know I had) available. With that said, let the learning begin.
I'd suggest using the tapped scanner first. Not only will it be easier, but if the tap was done properly [and I bet it was] you'll likely have a signal from the start that requires no adjustment, versus using a dongle + SDR# and having to do a bunch of tuning and configuring to get it going.

Get used to DSDPlus [or DSD if that is your bag] first. Then once you are comfortable with it, test out your dongle setup with it.

Mike
 

br0adband

Member
Joined
Apr 8, 2005
Messages
1,568
Location
Springfield MO
Are you already using the discriminator tap with some other software, like Unitrunker to be able to keep track of trunked talkgroups and radio IDs, 'cause if you've already got that set up I'd prefer not to spend a lot of time explaining how to get the audio inputs working.

Basically I need to know a little more I suppose. If you have the discriminator tap functional and ready to go - already connected and known to function, especially if you already use it for other purposes (trunking info, pager data, etc), that's what I need confirmation on.

The basic gist of this whole process is simple:

Get a digital data stream to DSD (or DSD+) and it should/will be able to decode it as required and then it will synthesize the content back into an analog and audible format, aka "people talking on their radios."

With a working and functional discriminator tap (meaning all the way into the computer and audible through the speakers if so desired), all you require is DSD (or DSD+) and that's it.

With an RTL stick, it's just a bit more complex and more time consuming so for the time being let's just focus on getting things working with the discriminator tap - if you want more info about using the RTL stick, that would best be directed to the Software Defined Radio subforum specifically.
 

frazpo

Member
Joined
Jan 14, 2007
Messages
1,264
Location
SW Mo
DSD cliff notes

With a working and functional discriminator tap (meaning all the way into the computer and audible through the speakers if so desired), all you require is DSD (or DSD+) and that's it.
.
Get your feet wet within minutes. Go DSD+.
Download DSD+
https://mega.co.nz/#!dxBEES5T!URN1d1aqbIX8wCqHCKpCuiI0J-VB7GaF9oP_42vUHaE

Download the Lame Encoder. Go here. Not a "get a dll file" site
Audacity: How do I download and install the LAME MP3 encoder?
Place the Lame enc.DLL file within your dsd+ directory.

Plug your patch cable in from your tap to the "mic in" on the computer
Open the squelch on your scanner
run dsd+
 

rrbum

Member
Premium Subscriber
Joined
Feb 28, 2012
Messages
154
This thread is right on time. I will be piggybacking along here as well. It is much appreciated you guys paying it forward and taking the time to explain things to us newbies.
I am just now going to start installing the programs and hopefully in a little bit (if I can find a strong digital signal) attempt to feed some "audio" from a tapped scanner into this old computer.

druhe, do you mind if I ask questions in this thread if need be?
 

SCPD

Member
Joined
Feb 24, 2001
Messages
65,126
Location
Virginia
Funny this, I'm ending up posting a link to the same video twice within the space of 5 minutes. Nobody on this forum appears to have seen this video, its definitely relevant though. Watch it and I'm sure it will answer some of your questions.
https://www.youtube.com/watch?v=sPrSyfu_nvg
 

druhe

Member
Premium Subscriber
Joined
Feb 18, 2003
Messages
525
Location
Southwest Pa
This thread is right on time. I will be piggybacking along here as well. It is much appreciated you guys paying it forward and taking the time to explain things to us newbies.
I am just now going to start installing the programs and hopefully in a little bit (if I can find a strong digital signal) attempt to feed some "audio" from a tapped scanner into this old computer.

druhe, do you mind if I ask questions in this thread if need be?
Sir: Have at it, I have no problem with anyone asking questions or jumping in. Glad to see I'm not alone
 

druhe

Member
Premium Subscriber
Joined
Feb 18, 2003
Messages
525
Location
Southwest Pa
Are you already using the discriminator tap with some other software, like Unitrunker to be able to keep track of trunked talkgroups and radio IDs, 'cause if you've already got that set up I'd prefer not to spend a lot of time explaining how to get the audio inputs working.

Basically I need to know a little more I suppose. If you have the discriminator tap functional and ready to go - already connected and known to function, especially if you already use it for other purposes (trunking info, pager data, etc), that's what I need confirmation on.
I am not running Unitrunker or anyother program requiring a discriminator tap. We're on virgin turf here
 

cg

Member
Premium Subscriber
Joined
Dec 13, 2000
Messages
3,001
Location
Connecticut
That video looks to be OK for DSD but is not for DSDPlus (which is a bit easier to start using).

chris
 

rrbum

Member
Premium Subscriber
Joined
Feb 28, 2012
Messages
154
Very interesting so far. Many questions though. Not how I thought it would be. Unable to squelch noise between transmissions. Wondering if any way to tweak voice quality. I would like to know what the scrolling information means as well. Perhaps in time I will understand just what the program is doing :)
 

rrbum

Member
Premium Subscriber
Joined
Feb 28, 2012
Messages
154
As to the above post of mine, I have figured out where I went wrong and am no longer hearing the raw audio between DSD outputs, as those of you who are familiar would know I had the speaker volume for the line in not set to zero. ;)
 

frazpo

Member
Joined
Jan 14, 2007
Messages
1,264
Location
SW Mo
Very interesting so far. Many questions though. Not how I thought it would be. Unable to squelch noise between transmissions. Wondering if any way to tweak voice quality. I would like to know what the scrolling information means as well. Perhaps in time I will understand just what the program is doing :)
What kind of voice quality are you getting?
and what are you decoding?
 

druhe

Member
Premium Subscriber
Joined
Feb 18, 2003
Messages
525
Location
Southwest Pa
Progress !!

Well I've made significant progress, I now have DSD+ decoding a NXDN and TRBO system. I have yet to hear any voice transmissions, as I do not know how busy these systems are. Now to my question, is there a way to filter or mute the raw data ? This is all I hear through the speakers
 

br0adband

Member
Joined
Apr 8, 2005
Messages
1,568
Location
Springfield MO
If you're monitoring through DSD+, you shouldn't be hearing anything from the speakers because DSD+ won't be audibly decoding the control channels or the basic data stream itself. The only thing that comes to mind is somehow one of your audio outputs is set to be monitored with the "Listen" option on the devices tab under the Recording devices dialogue box (example image attached). Deselecting or unchecking that box will prevent the raw audio stream (which is what DSD+ is listening for and decoding) from being passed directly to the speakers or whatever output you're using to audibly monitor.

DSD+ will show activity whenever it's decoding "something" - if you feed it raw static (squelch is disabled completely) it's not going to pass that to the output; it only passes content that's being decoded for content which it then synthesizes back into an audible format. If everything is set up correctly on your system, you should never hear a peep from DSD+ at all unless it's got something to actually decode - if you're hearing the static (no squelch) or raw data streams (DMR/MOTOTRBO/NXDN streams, P25 streams, trunking control channels, etc) then you've got something basically hooked up wrong and that usually means something with the virtual audio cable setup.

For a DMR/MOTOTRBO as well as NXDN there are two basic types of data streams: the actual control channels of a given system (with respect to it being a trunked system of those types, because there is still conventional as well) which are near-constant streams of data as seen on the waterfall, and there are the actual times of data/voice content being transmitted which:

- for DMR/MOTOTRBO content will end up being decoded as data or voice calls and will show as such on the DSD+ window based on the headers (and if it's voice you should hear the decoded/synthesized results) - using DMRDecode at the same time will help identify what you're listening to (as in which slot/channel is being utilized as well as group info, data calls when they happen, and other various DMR/MOTOTRBO info. When a DMR/MOTOTRBO channel is "at rest" you'll see the typical data burst activity every 2 seconds, that's what makes that type of system easy to spot; in fact on a somewhat busy system you may find several frequencies across the waterfall or spectrum display with data bursts every 2 seconds which could mean several DMR/MOTOTRBO systems in the same range

- for NXDN you should see the DSD+ display showing just short bursts of activity but it doesn't show anything for channels at rest like DMR/MOTOTRBO will, it's key up the mic, transmit whatever, release and you're done so it's about as short and quick as it gets, no preamble tones, no talk permits, no "roger beeps," nothing

I've included a few screenshots to show what DMR/MOTOTRBO and NXDN transmissions "look like" on the waterfall so they're easier to spot. I don't honestly know why so many people leave their waterfall so completely loaded with noise (and the noise floor in the spectrum so prevalent all the way down to -120 dB or whatever), I've never understood that at all but then again maybe I'm doing things wrong, who knows. All I know is two things:

- the noise floor of these RTL devices that most of us use (not the Funcube dongle or anything else of a higher quality) is roughly -60 dB so anything below that isn't going to be of much use and in many respects it'll get drowned out by the noise itself so you might as well adjust the FFT range so you don't have to stare at anything -60 dB or below (I usually have mine at -50 dB so nothing below that is visible since it's meaningless

- adjust the waterfall so it's not quite so "complicated" for lack of a better word; the idea, at least for me, is that I want to see signals, not noise, so I have my waterfall adjusted most of the time so it looks similar to what you see in the screenshots below: I see the signals, not the noise. I've never found an instance of needing to see all that extraneous noise, but then again I'm still somewhat new to this type of monitoring activity using spectrum displays for bandwidth and waterfalls for activity.

YMMV, of course, just some suggestions that might make this work better for you (or anyone else), maybe not.



EDIT:
Just noticed I have the Filter audio box checked which I normally do not do - before I took those screenshots I was doing some testing for audio quality with respect to what I hear in the headphones. By default the recommendation is to uncheck that box when using DSD+ (or DSD) since they seem to work better with the truly unfiltered audio being passed to them. A few people have said they've encountered better decodes with the filtering enabled, so who knows, it might do better for you as well. Try everything at least once I suppose, you might end up with something working better overall. You'll only find out by experimentation I suppose.
 
Last edited:

druhe

Member
Premium Subscriber
Joined
Feb 18, 2003
Messages
525
Location
Southwest Pa


EDIT:
Just noticed I have the Filter audio box checked which I normally do not do - before I took those screenshots I was doing some testing for audio quality with respect to what I hear in the headphones. By default the recommendation is to uncheck that box when using DSD+ (or DSD) since they seem to work better with the truly unfiltered audio being passed to them. A few people have said they've encountered better decodes with the filtering enabled, so who knows, it might do better for you as well. Try everything at least once I suppose, you might end up with something working better overall. You'll only find out by experimentation I suppose.
I'm using Windows XP, looked at every possible setting I can find and there is nothing that I can find that says "listen to this device".
 

br0adband

Member
Joined
Apr 8, 2005
Messages
1,568
Location
Springfield MO
I'm using Windows XP, looked at every possible setting I can find and there is nothing that I can find that says "listen to this device".
As XP works just a bit differently, the specific thing you need to check on is obviously found a bit differently as well. It's been so long since I've used XP I'm not sure I'm gonna be of much help to be honest. I could have sworn I had XP Mode (for Windows 7) installed but I suppose I don't, go figure - and I'm on a Wi-Fi connection right now that doesn't take too kindly to me doing big downloads (the XP Mode install files are roughly half a gig) so there goes that idea.

Honestly I just can't even remember how to manage the audio subsystem in XP anymore, guess I'm getting way too old, who knows. ;)

If you're hearing the raw audio that DSD+ is working with then somewhere in the system the audio is being "tapped" before it's getting to DSD+ itself because as I noted earlier, DSD+ (nor DSD before it) will bot output any audio directly aka pass-through - those apps only output synthesized audio when it's got something to decode from the data stream into an audible format meaning you shouldn't be hearing the raw audio off the tuner. The issue isn't with DSD+ (or DSD for that matter), it's something in the XP audio mixing subsystem and I can't even begin to help there, sorry.

Maybe someone else that's using XP to this day can assist with that aspect as you only want to be hearing what DSD+ (or DSD) happens to be outputting. Maybe it will end up with you using some virtual audio cable software of some kind so you have more control over things than the XP system mixer is allowing, I don't know for certain.

You could try one thing just in case: for however you're doing the discriminator tap input to the computer - whether it's Line-in or Mic-in - bring up the Windows mixer and mute it on the playback side, not the recording side. I know it sounds weird but, even if you mute it on the playback side DSD+ should still be able to get that signal from the recording side of how the Windows audio subsystem works.

What I mean is this:

- If you're using the Line-in on the soundcard (or laptop, like mine does line-in through the mic-in depending on what I select), when you left-click the speaker icon in the System Tray (the volume) it'll bring up the Windows audio mixer for playback; if you are using Line-in you should see an individual mixer for line-in right there; if not then you need to enable that mixer to show up under Properties - once it's available and it specifically says "Playback Control" in the titlebar of the window itself, check the Mute box on the Line-in mixer - that will mute it as far as pushing that audio directly to the speakers and should be what you want

- Now if you access the Recording mixer (says "Recording Control" in the titlebar of the window) and find the Line-in mixer, you'd select it with a check in the appropriate box because it needs to be the source of the audio signal coming from the discriminator tap

It's tough to explain with words and since I'm not using XP I can't really do screenshots. Your basic principle is the Recording input needs to be active on the Line-in so DSD+ can find the signal, but you want that signal muted for Playback so you don't hear the raw signal through the speakers - when DSD+ is running you can then use DSD+'s ability to direct the audio to a specific output device; in this case we'd want to use. Say on your machine when DSD+ runs it shows a line like the following:

Code:
audio output device #1 = 'Speakers / Headphones (IDT High'
it should default to that device but if not, you can force it to output to that device with the -oX switch where X matches the device number. That should get you some audio output from DSD+ given it's got something to decode and synthesize, of course. Control channel data for DMR/MOTOTRBO rarely has any voice traffic but I have found a few systems where it does happen; as for NXDN I've yet to hear any voice comms on a channel that is transmitting data near-constantly as a control channel typically does.

Hope this helps in some respect...
 
Status
Not open for further replies.
Top