Sync Loss Issues

[David]

Hi everyone,

I just bought a Nooelec NESDR SMArt v4 Bundle and installed SDRTrunk. I have gotten SDRTrunk to recognize the Nooelec. 

I have imported all of the frequencies and talk groups for my area from RR. I have watched several videos to make sure I did it correctly. 

I have entered all 4 control frequencies provided by RR into a channel but when I start the channel, but I only get "Sync Loss - Bits Processes".

I have tried only using 1 control channel, adjusting the PPM, the gain. No luck so far.

Do I need a second RTL-SDR? I thought the only reason to get a second was if the monitored frequency didn't fit in the 2.888 sample rate.

Any tips to get it working with one RTL-SDR?  

Thanks for all your help.

[charley....@gmail.com]

What system?  How far do you live from the closest transmit site?  Are you sure that you have tuned an active control channel?  Can you post a screenshot of your spectrum monitor?  What is the signal strength indicated on the channels tab (or a screenshot of that value?)

[David]

I am running on Windows. I am not sure where the closest site is, but I don’t think that’s the issue due to more testing I did last night. I will detail that below. 

I was doing more testing last night and decided to try on a MacBook as well so before going to bed last night I decided to try on the MacBook just to see what happens. To my surprise using all the same settings with the antenna in the same place, I got it working within a couple minutes. I was receiving all traffic. I switched back to the windows computer, deleted SDRTrunk, extracted it again and set it back up with the same settings. Same issue. Sync loss.

[wemana...@gmail.com]

On Wednesday, May 18, 2022 at 12:51:22 PM UTC-4 David wrote:

I am running on Windows. I am not sure where the closest site is, but I don’t think that’s the issue due to more testing I did last night. I will detail that below. 

I was doing more testing last night and decided to try on a MacBook as well so before going to bed last night I decided to try on the MacBook just to see what happens. To my surprise using all the same settings with the antenna in the same place, I got it working within a couple minutes. I was receiving all traffic. I switched back to the windows computer, deleted SDRTrunk, extracted it again and set it back up with the same settings. Same issue. Sync loss.

Specs on computers?

As a test go to User Preferences , Tuner Channelizer, and change FROM Polyphase to Hetrodyne and retest it.. Does that improve things? Same????
 If you look at the screen shot, and what you are seeing Sync Loss and the occasional decode like that line at the bottom showing  a NAC and "CRC FAILURE" that indicates signal issues...  OR processing issues, ie: not enough computing power, but for a 2MHz SDR, that really shouldn't be an issue.. unless the one box is very under powered.

Show a screen shot of the spectrum and waterfall on the Mac, WITHOUT CHANGING ANY ANTENNA LOCATIONS or settings in either setup... Show a screen shot of the messages tab, and channels tab on each setup..

THEN ON the NON WORKING PC setup, for your control channel are you setup for C4FM or LSM??? Switch to LSM and save, and restart the channel. Any change???

Which antenna are you using? Where is it located? If inside, house construction? And the distance to the tower(s) for your setup.. If you don't know the locations, then use the FCC ULS site to look up your areas license and find out where they are located.
 
Which setting for bandwidth are you using??? 2.4 or something else... honestly I've never ever seen the 2.56, or 2.88 settings on the devices that offer it work RELIABLY 24/7/365... I've seen them work for a while and then they tend to drift off as being unstable and you get something like this with a control channel getting sync loss or lots of CRC errors.  Does setting it to 2.4 result in any change????

FYI: The number of SDR's needed is based on the formula:


# SDR = (Freq Highest - Freq Lowest) DIVIDED BY  BANDWIDTH OF the SDR

Example

X SDR = (853.850 - 851.125) / 2.4 = 1.13 = 2 SDR's , ALWAYS ROUND UP to a WHOLE NUMBER..

[David]

Just an update on my issue. Sorry for not answering all your questions but I was pretty sure the issue didn’t have anything to do with the antenna location and all the other things since everything worked on my MacBook with the same location and same settings.

After doing a bunch testing, it turned out to be an issue with my Windows VM. I’ll give some detail in case someone runs into this issue in the future. I am using Unraid to run my VMs. Since windows wasn’t working, I decided to try to do a Linux VM with all the same settings as the Windows one and it worked perfectly. So I went back to the my Windows VM and began to mess around with the configuration . It turns out that there some type of windows and SDR-Trunk compatibility issue with the default USB controller that Unraid selects. Once I choose the “3.0 Qemu Xhci controller” it started to work right away with no more sync loss messages.