SDRTRUNK spectrum edges

[davejl2001]

I have noticed that frequencies at the edges of the tuner spectrum have poor performance. What is the best way to keep SDR Trunk from the unstable edges?

 

[mtindor]

Typically, the usable bandwidth is somewhere between 85% and 90% of the total set bandwidth.

I think that for somebody to give you a good answer, they would need to know:
1. how many dongles are you using
2. what is their bandwidth set to in SDRTrunk
3. What is the lowest freq you are monitoring and the highest freq you are monitoring

 

[dave3825]

1. how many dongles are you using
2. what is their bandwidth set to in SDRTrunk
3. What is the lowest freq you are monitoring and the highest freq you are monitoring

And also, what dongle are you using? Different dongles have different bandwidth limitations.

 

[davejl2001]

6 dongles - Nooelec v5
Monitoring a system with 6 mhz bandwidth.
Each dongle is set at 1.2mhz - The reason I have this set at 1.2 MHz is that I monitor a very busy system and when one tuner has more then 4 active voice channels in use the audio becomes distorted.

 

[dave3825]

Monitoring a system with 6 mhz bandwidth.

3. What is the lowest freq you are monitoring and the highest freq you are monitoring

 

[davejl2001]

769.19375 low
774.78125 high

 

[mtindor]

769.19375 low
774.78125 high

Do you have a link to the system (in the RRDB) ? If not, what are the primary/alt CCs?

 

[davejl2001]

New Jersey Interoperability Communications System (NJICS) Trunking System, Statewide, Multi-State

New Jersey Interoperability Communications System (NJICS) Trunking System Profile

www.radioreference.com

Monitoring site #1 West Orange

 

[mtindor]

I have noticed that frequencies at the edges of the tuner spectrum have poor performance. What is the best way to keep SDR Trunk from the unstable edges?

If you were using just one device (like an Airspy), it's pretty easy to do by creating two dummy P25 channels, 0 max voice channels on each one. Set those two dummy channels to start before any of the trunked systems you are monitoring. Those two P25 dummy channels would be the max low and max high freq. But I don't know how that will work in an environment with 6 dongles, since you are really wanting to limit the scope of each dongle. Perhaps you'd have to set up 6 pairs of dummy channels, one pair for each dongle.

An example of my setup (Airspy 10 mhz, perhaps 8.5 mhz usable):

Lowest freq on systems I monitor: 851.1625
Highest freq on systems I monitor: 858.4625
Total bandwidth required: 7.3 mhz

P25 dummy channel 1: 850.8125 (no signal ever present on it) - this one starts first
P25 dummy channel 2: 858.8125 (no signal ever present on it) - this one starts second
Two P25 trunked system sites: these start after the dummy channels

This keeps the Airspy pretty much in the center of the "good area".

With you having multiple dongles, I think it's a different story. And in my mind I can't wrap my head around what you may need to do. Hopefully somebody else will chime in with some ideas.