DSD for dummies

Hello all! I stumbled across this DSD stuff by accident tonight. I have been searching the forums and other sites to try to get a beginners "dummy" approach and understanding. I get the basics that DSD allows you to monitor digital input and translates it to audio you can hear on your computer.

What would I need to monitor a P25 system? Is it as simple as feeding the program the over the air digital audio and allowing it to decode it? While both my wife and I have HP1s they stay mounted in the cars. Working for a public safety agency my wife might like being able to "keep tabs" on me while I am at work without having to get the HP out of the car.
Thanks for the assistance!
AW

In order for DSD to decode P25 Phase 1, it needs either:
1) Discriminator output from a tapped radio (or if you have a scanner that can output discriminator audio via audio cable)
---or---
2) RTL-SDR dongle.

If the system you are wanting to monitor is trunked, then 2 of either are needed.

Some newer scanners output the discriminator audio without the need to open them up and do any soldering. The HP-1 has discriminator audio put via USB if you have the Extreme Update, but I'm not sure if this would work with DSD.

In order to use an RTL dongle with only DSD+, you need to get access to the fast lane builds of DSD+ (Also note that DSD+ is different than the original DSD). Information about those builds can be found in the text files that accompany the downloads. However, UniTrunker can control SDR as well and you can output the audio (via another program) to DSD+ to decode without the need to utilize the fast lane builds.

The cheapest route would be to go with the dongle, they can be had for ~$20 on Amazon. You will probably need some antenna adapters and a real antenna as the one shipped with the dongles is probably not going to perform that great.

I second the DSD for dummies idea I donated for the fast lane and am completely lost. I have watched every youtube video I can find and have read the .txt files many times. I am just trying to run a basic setup of conventional P25 freqs and am missing something. I think like me most others who are having issues its related to getting the audio fed in correctly. I am using VB-Cable and am having a hell of a time getting it to work. I know the newest build I have uses TCP but there's not much documentation on setting it up. There are a lot of old how-to videos but not much on basic new build setup.Been scanning since 1981 and started on Unix workstations so I should be able to figure this out but the more I try to get it working the more confused I get. I know what I am missing is probable mind numbing simple but that's usually how it works.

I'll see what I can do tutorial wise. Stay tuned.

From our DSD page in the wiki - did you see this?

UK Radio Scanning Forum • View topic - DSD For Windows Basic Setup - Easy Instructions Noobs Guide

Mike

mrlindstrom said:

In order for DSD to decode P25 Phase 1, it needs either:
1) Discriminator output from a tapped radio (or if you have a scanner that can output discriminator audio via audio cable)
---or---
2) RTL-SDR dongle.

If the system you are wanting to monitor is trunked, then 2 of either are needed.

Some newer scanners output the discriminator audio without the need to open them up and do any soldering. The HP-1 has discriminator audio put via USB if you have the Extreme Update, but I'm not sure if this would work with DSD.

Click to expand...

An HP-1 can already decode P25 voice, so no point. It sounds like the original poster wishes to use a PC only.

In order to use an RTL dongle with only DSD+, you need to get access to the fast lane builds of DSD+

Click to expand...

Not true. All DSD+ versions work with RTL dongles. Usual interface is SDR#, FMP or UT.

(Also note that DSD+ is different than the original DSD). Information about those builds can be found in the text files that accompany the downloads. However, UniTrunker can control SDR as well and you can output the audio (via another program) to DSD+ to decode without the need to utilize the fast lane builds.

The cheapest route would be to go with the dongle, they can be had for ~$20 on Amazon. You will probably need some antenna adapters and a real antenna as the one shipped with the dongles is probably not going to perform that great.

Click to expand...

Yes, the OP should acquire two dongles and get UT plus DSD+ set up.

OHIOSCAN said:

I second the DSD for dummies idea I donated for the fast lane and am completely lost. I have watched every youtube video I can find and have read the .txt files many times. I am just trying to run a basic setup of conventional P25 freqs and am missing something. I think like me most others who are having issues its related to getting the audio fed in correctly. I am using VB-Cable and am having a hell of a time getting it to work. I know the newest build I have uses TCP but there's not much documentation on setting it up. There are a lot of old how-to videos but not much on basic new build setup.Been scanning since 1981 and started on Unix workstations so I should be able to figure this out but the more I try to get it working the more confused I get. I know what I am missing is probable mind numbing simple but that's usually how it works.

Click to expand...

To scan conventional P25 channels:

FMP and DSD+ should be installed/running in the same folder.

Edit the FMP.ScanList file with Notepad and add the channel information. Line format is just <freq> <protocol> <tag>, so something like:

451.0125 P25 Podunk PD
462.1 P25 Podunk EMS
etc.

Do not use VB-Cable. Your Fast Lane versions of FMP and DSD+ can communicate via a TCP link instead. FMP command line should be similar to:

FMP 20001 1 <PPMvalue> <initialFreq>

Point DSD+ at FMP's TCP port and lock protocol. Might as well enable per-call recording as well:

DSDPlus -i20001 -f1 -Pwav

Start FMP and DSD+. Press S in FMP to start scanner mode. You should see FMP scanning your scanlist. When DSD+ decodes digital voice, FMP should pause scanning until the voice ends.

If you hit a roadblock, please advise.

DSDPlus said:

Not true. All DSD+ versions work with RTL dongles. Usual interface is SDR#, FMP or UT.

Click to expand...

Hence my later statement:

However, UniTrunker can control SDR as well and you can output the audio (via another program) to DSD+ to decode without the need to utilize the fast lane builds.

Click to expand...

To clarify, I meant to use only DSD you need the fast lane builds, you can indeed bring SDR# or another RTL control software in to the mix.

mrlindstrom said:

To clarify, I meant to use only DSD you need the fast lane builds, you can indeed bring SDR# or another RTL control software in to the mix.

Click to expand...

Then you are not *only* using DSD+.

And FMP (included with DSD+ 1.074) is RTL control software, so... ?

Thanks for the replies all. I am wanting to monitor our p25 trunked system via computer only. My wife and I both have HP1s in our respective vehicles that are more or less "premanently" mounted. Not really wanting to drop another $400-500 on a digital scanner.

I am liking these dongles, will probably go that route. Have an older but in good shape laptop that would be perfect for this application.

DSDPlus said:

Then you are not *only* using DSD+.

And FMP (included with DSD+ 1.074) is RTL control software, so... ?

Click to expand...

Sorry, I had assumed FMP was developed by you guys and was part of the DSD suite.

KG4ERE, you mentioned wanting to monitor a trunked P25 system, so in addition to DSD+, you will also need to use Unitrunker and the free VB Cable to handle the trunking and to feed the output to DSD+ for decoding.

DSD+ will not currently trunk P25 on its own, and Unitrunker doesn't decode the digital output to voice, so you will have to use a combination of the two.

Here is my incredibly long winded walkthrough of getting an RTL-SDR installed, calibrated, and streaming to DSDPlus. I also show P25 trunking with Unitrunker and NXDN trunking with the fast lane DSDPlus.

https://www.youtube.com/watch?v=RvCchqKSrZI

mrlindstrom said:

Sorry, I had assumed FMP was developed by you guys and was part of the DSD suite.

Click to expand...

FMP is one of the programs we created and provide in the DSD+ zip files, but it is not DSD+.

Will check out your video. We need more of them!

Hit the roadblock

If you hit a roadblock, please advise.[/QUOTE]

I hit the roadblock, not getting freq list

(DSD .BAT FILE)
DSDPlus -i20001 -1 -f1 -Pwav

(FMP .BAT FILE)
FMP 20001 1 50.0 154.875

OHIOSCAN said:

I hit the roadblock, not getting freq list

(DSD .BAT FILE)
DSDPlus -i20001 -1 -f1 -Pwav

(FMP .BAT FILE)
FMP 20001 1 50.0 154.875

Click to expand...

What system are you trying to monitor?

Edit: nevermind, I see you are trying to monitor simplex P25

Are you able to tune that frequency on SDR#? If so can you try piping the audio to a virtual audio cable and then to DSD? My video above should get you through to that step.

No I am "trying" the TCP fast lane version, making some progress still missing something.

I don't see your FMP scope display, do you see that spike during transmissions?

Nope I get "No frequency data files found" I have freqs in the DSDPlus frequency file. It does report "Connected to TCP port 20001"
"Accepted Connection from localhost on port 61866"

Also reports output #1 <Speakers> initialized

I don't believe you would need to have anything in the DSDPlus.frequencies file if you are just doing simplex. You do not ever see anything similar to this when you launch FMP?

Note: I also show the "No frequency data files found" when I launch FMP, but it does not seem to be an issue.