Computer Scanner using SDR

[screamin72]

I am using HDSDR as the voice radio. Just by watching the waterfall on a digital signal I noticed it is wider than a analogue voice transmission so 300khz wide on the audio is needed. I did have to widen the audio band pass for HDSDR to allow DSD+ to have enough audio to work with.

For those wanting to know how to use HDSDR for voice radio see this post
http://forums.radioreference.com/software-defined-radio/246308-how-link-unitrunker-hdsdr.html

 

[br0adband]

Just for the record: VB-Audio-Cable and Virtual Audio Cable are two entirely different products in spite of similar names. Virtual Audio Cable is the older and more established product and commercial by nature - it also allows for up to 255 "virtual audio cables" when configured properly which is part of the problem for some people (meaning the configuration as it's quite complex by nature).

VB-Audio-Cable is a donation-ware product (meaning you pay what you believe it's worth, basically), more or less, and much easier to install and get working properly but it only allows for a max of 3 "virtual audio cables" (VB-Audio Cable, then VB-Audio-Cable-A, and VB-Audio-Cable-B for a total of 3 distinct ones).

In my experience with SDR over the past 7 months or so, I never had much success with Virtual Audio Cable and SDR software even in spite of knowing I had the settings correct (using 48 kHz audio streams for all cables, etc) but with VB-Audio-Cable the first time I installed it it worked - I didn't have to do anything aside from install it and then alter the setting to 48 kHz, that was it, took like 3 seconds and it worked immediately with both DSD and DSD+ without a single issue from that point on and it still continues to work flawlessly.

I'd suggest VB-Audio-Cable, personally, but YMMV as it always does for individuals.

 

[nated1992]

I have the same problem with my setup. One thing I found is if I move the frequency in 100Hz steps up or down, can't remember which way it was, I will find that it will start scrolling data on DSD+
I find it hard to believe that my setup is so narrow, everything says I have it set to 6.25 kHz bandwidth in the SDR Sharp program but I still find myself moving the freq to make it start to scroll.
It is also extremely narrow, perhaps on 200 or 300 Hz wide then it stops scrolling on the screen again.

As far as this goes
"I am using HDSDR as the voice radio. Just by watching the waterfall on a digital signal I noticed it is wider than a analogue voice transmission so 300khz wide on the audio is needed. I did have to widen the audio band pass for HDSDR to allow DSD+ to have enough audio to work with."

This is a bit above my head and im not sure what your talking about widening the frequency ?!?!


I will look into that a bit however i think i got it pretty well tuned in,
DSD+ is now giving this " sync invalidated "
Hers is a picture of my setup

 

[rjdj2000]

nated... here is what I noticed....

1. There should be no audio output on the signal R820T, I have had the baseband agc turned on as well as the auto gain but YMMV here... May want to uncheck the deemphasis also. Might get better signal for control.

2. Turn off deemphasis on the voice. I have the auto gain turned off on my voice R820T.

3. Check in the main Unitrunker window in the options tab to make sure listen is checked.

4. For DSD+, what did you type in for any options?
try this ---> dsd -i1L -f1

you then have to adjust the level of line 1. It will be under your volume settings. if you are running windows 7, right click the volume icon at bottom of screen and click recording devices. then using the black arrow, make sure you are looking at Line 1. You should see unitrunker with the line 1. I put the line one @ 100% then put unitrunker to about 20% or so and then adjust from there.

Hopefully this will help you get things going to where you want them to.

 

[nated1992]

nated... here is what I noticed....

1. There should be no audio output on the signal R820T, I have had the baseband agc turned on as well as the auto gain but YMMV here... May want to uncheck the deemphasis also. Might get better signal for control.

2. Turn off deemphasis on the voice. I have the auto gain turned off on my voice R820T.

3. Check in the main Unitrunker window in the options tab to make sure listen is checked.

4. For DSD+, what did you type in for any options?
try this ---> dsd -i1L -f1

you then have to adjust the level of line 1. It will be under your volume settings. if you are running windows 7, right click the volume icon at bottom of screen and click recording devices. then using the black arrow, make sure you are looking at Line 1. You should see unitrunker with the line 1. I put the line one @ 100% then put unitrunker to about 20% or so and then adjust from there.

Hopefully this will help you get things going to where you want them to.

Eeehhh stil no luck

DSD is showing its getting sound sent to it but nothing is coming through my speakers nor is DSD showing that its decoding any thing, Have tried on two different systems in my area..

 

[nlurker]

What I did was to set the park frequency of the voice receiver to the control channel frequency. DSD+ should lock onto this and start scrolling numbers. If not, it could mean your ppm correction is not exactly right, so adjust it until you get a lock. This is how I got it going.

 

[nated1992]

What I did was to set the park frequency of the voice receiver to the control channel frequency. DSD+ should lock onto this and start scrolling numbers. If not, it could mean your ppm correction is not exactly right, so adjust it until you get a lock. This is how I got it going.

I did this and got DSD+ to start scrolling data but never got any audio any thoughts ?

 

[nlurker]

I did this and got DSD+ to start scrolling data but never got any audio any thoughts ?

You are getting closer! Does your Voice Receiver ever show that it has tuned to a voice frequency (last 4 lines under Listen)? I see that you set the Signal Receiver Listen priority to 11, try changing that back to 50.

 

[SCPD]

The screenshot shows a decode rate of 27%. Let's work on getting that fixed first.

Make sure the warp factor is correct. On the 'Scope tab, does the waveform look good? If the peaks or valleys are distorted, you're probably off frequency.

After nlurker can consistently keep the control channel signal near 100%, we can chase down any voice decoding problems.

 

[nated1992]

You are getting closer! Does your Voice Receiver ever show that it has tuned to a voice frequency (last 4 lines under Listen)? I see that you set the Signal Receiver Listen priority to 11, try changing that back to 50.

No I haven't noticed it switching to any voice frequency, I will try changing the priority.

As for the decoding rate. I have it staying above 80. I was tinkering with it when I took the screen shot

 

[screamin72]

Just in case, you cant use the same ppm for two dongles. I done tried it at first. Fail.

 

[nated1992]

Just in case, you cant use the same ppm for two dongles. I done tried it at first. Fail.

yep

 

[nlurker]

nated1992, you suddenly went silent. Did you get it working, or give up?

 

[nated1992]

nated1992, you suddenly went silent. Did you get it working, or give up?

No I haven't got it compltly work as of yet. And I haven't given up. Just busy.

Any more suggestions would be apreciated

 

[rosecitytransit]

No I haven't got it compltly work as of yet. And I haven't given up. Just busy.

Any more suggestions would be apreciated

Try adjusting the gain settings. The screenshots show the left, signal receiver gain set totally off and the right one set way high. If you haven't already, I would check SDR# (or equivalent) so you can actually see what gain does to the signal on both receivers. I know when I first started using SDR, I couldn't hear anything because the gain defaulted to zero.

Also, try to piping the audio from SDR# directly to DSD. You'll have to manually change the frequencies or wait awhile if you want actual voice (or try a scanner plugin or find a conventional P25 frequency), but you can see if audio decoding works OK. And make sure that when you turn the FFT Display resolution up and zoom in, the correct channel frequency centers on the signal in the waterfall for both devices.

You might be able to do the above in UniTrunker by setting the park or listen frequency to a voice frequency, but you won't have the ability to see if the frequency actually is being used.

Lastly, double check the virtual audio cable settings.