SDRTrunk SDRTrunk - Tuner Unavailable - Phase 1 Channel Grant

[SpectralContent]

Trying to monitor Howard County, MD's Simulcast Phase 1 system using one RTL-SDR dongle on SDRTrunk ver. alpha6 . While it looks like all calls are being recognized by the tuner, 99% of them have a Group Call - Rejected "Tuner Unavailable - Phase 1 Channel Grant" error. As a result, there is no audio from those calls.

I am not sure what the problem is. I was able to monitor Baltimore City's P1 system extremely well with one RTL-SDR. Anyone have thoughts on a solution or what could be going wrong?

Thanks!

 

[mattwillson]

You need a second dongle. The frequency range of that system is spread out further than what a single dongle can cover (2.4 MHz of bandwidth).

 

[SpectralContent]

You need a second dongle. The frequency range of that system is spread out further than what a single dongle can cover (2.4 MHz of bandwidth).

Kind of figured it had to be a dongle limitation. Thanks! So I'm guessing I have to split the antenna cable into two separate feeds to input into both dongles?

Is there other SDRs that can cover a wider bandwidth that could mitigate this issue?

 

[GTR8000]

Airspy R2

 

[awasser1]

Airspy R2

airspy R2 on sale now they say. but you can probably just buy another regular rtl/sdr for less. SDR-Trunk works very well once you have it configured.

Alec
N1AJW

 

[JimD56]

I use 2 RTL-SDR Dongles for my P25 Phase II "Simulcast" Systems with great results.
If you look at the SDRTrunk tutorials on YouTube they all even say a second dongle is needed for optimum reception.

 

[boatbod]

Kind of figured it had to be a dongle limitation. Thanks! So I'm guessing I have to split the antenna cable into two separate feeds to input into both dongles?

Is there other SDRs that can cover a wider bandwidth that could mitigate this issue?

Airspy Mini does 3/6Mhz

Alternatively there are different sdr software apps that can tune any P25 system with a single dongle

 

[SpectralContent]

I use 2 RTL-SDR Dongles for my P25 Phase II "Simulcast" Systems with great results.
If you look at the SDRTrunk tutorials on YouTube they all even say a second dongle is needed for optimum reception.

Thanks for the info! I've bought a second dongle.

 

[awasser1]

Thanks for the info! I've bought a second dongle.

Wow that was quick. Should work lots better

 

[SpectralContent]

Should be coming today. Amazon isn't THAT quick (yet) 👍.

Wow that was quick. Should work lots better

 

[maus92]

Airspy Mini does 3/6Mhz

Alternatively there are different sdr software apps that can tune any P25 system with a single dongle

He will need the R2 version if he decides to go the Airspy route - Howard County has a 9 MHz channel spread.

 

[SpectralContent]

He will need the R2 version if he decides to go the Airspy route - Howard County has a 9 MHz channel spread.

Yea they have a huge freq spread. I tested it with the 2 RTL-SDR dongles yesterday and it does great. The one stays around the control channel and there isn't enough channel traffic so the second one is able to rotate between the other "bands"

 

[maus92]

Yea they have a huge freq spread. I tested it with the 2 RTL-SDR dongles yesterday and it does great. The one stays around the control channel and there isn't enough channel traffic so the second one is able to rotate between the other "bands"

TBH, the R2 is probably not quite wide enough to capture all channels. For practical purposes, its bandwidth is closer to 8 MHz, so the two dongle solution is best. A HackRF is considerably wider, but it is expensive and I'm not sure if SDRTrunk supports it.