Hey all! I am trying to get my SDR setup perfected, but it seems like I am still missing a lot of transmissions and reception is somewhat spotty. I was hoping someone who knows a lot more than me could offer some advice on my setup and give me tips or pointers on how I can improve it. I have seven dongles right now running SDRtrunk on Windows on the 9th floor in downtown Saint Paul. I don’t understand Linux. I will pay for your time and knowledge. Thanks in advance!
Any SDR “Experts” that can help me out?
- Thread starter signguy10
- Start date
Describe your antenna setup across those seven dongles please. If you have a typical tv coax type splitter with seven outputs, you are really reducing the signal strength significantly.
I have seven separate USB dongles with seven USB extension cables plugged right into the computer. Each dongle has a 800mhz antenna individually attached. The antennas are indoors, however.
Power wise (not data) the usb might be overloaded and not supplying 5 V. Try fewer dongles (2?) and see if they work.
The max current rating on every USB wall supply I’ve tested is a lie, they drop well below 5v at half the stated current rating. I have a cheep adjustable USB LOAD tester that I’ve verified with good external metering. (The curse of being a retired calibration tech…)
The max current rating on every USB wall supply I’ve tested is a lie, they drop well below 5v at half the stated current rating. I have a cheep adjustable USB LOAD tester that I’ve verified with good external metering. (The curse of being a retired calibration tech…)
7 USB ports (minimum)? Are you running a PCIE-to-USB card or something? I know there are a lot of PCs with a lot of USB ports, but 7 ports seems like an extreme number to have on a default PC. So I'm wondering if you added ports via a card.
johnmoe1
Member
I used to be fairly SDR proficient ( Experiment: Build Your Own Stream ... wow, it has been almost a decade!). I've never used SDRtrunk, but why are you using seven dongles? That just seems like a never ending hassle. A single HackRF One (or whatever is popular these days) seems like it would be so much less hassle.
I used to run 6 RTL-SDR when they were turning up and transitioning a new P25II system in King Co (WA).
Why 6?
To log and document all TG activity on the new system.
And also monitor the old system during the transition.
I suggest using a multi-coupler.
Example: Stridsberg MCA208M
Why 6?
To log and document all TG activity on the new system.
And also monitor the old system during the transition.
I suggest using a multi-coupler.
Example: Stridsberg MCA208M
Good thought. I’d be worried about data too if all 7 usb ports are on same bus.
No, it's not an additional card. There are 4 USB 3.0s and 4 USB 2.0 ports. I have one USB 2.0 for a wireless mouse and keyboard.
I am trying to monitor 3 systems. I've been told before that I should have three for each system. I'm not sure how true that is though?
johnmoe1
Member
I'm curious which 3 systems are you trying to monitor? For example if you were trying to monitor ARMER and trying to use the rtl-sdr type dongles, I would think you would need something like 5 of them. Probably at something like 852, 854, 856, 858 and 860 MHz to cover 851 - 861 MHz. A single HackRF can listen to a 20 MHz range, so you could just tune it to 856 MHz or something and be done.
(Repeated disclaimer: I have never used SDRtrunk.)
How about providing a link to all three systems / sites that you are wanting to monitor. We can then tell you exactly how many dongles you would need to use. And as long as your USB subsystem can support those dongles without issues, there is no reason not to use what you already have.
But if we know the systems/sites you want to monitor, we can be more precise on how many you need to have installed.
Ubbe
Member
Power shouldn't be a problem as USB 2.0 can supply at least 500mA and USB 3.0 at least 900mA and a dongle like RTL-SDR takes 350mA. I notice that my dongle only gets 4,6V. I use a 1-4 splitter from one USB 3.0 port to power a lot of other things at the same time so probably get voltage drops along the way but the dongle works fine on that voltage.
You would need two dongles for one site if you need to keep track of if one important priority TG gets active while monitoring another. But if that priority function are not necessary, or you don't need to log every call, than one dongle can sit on the control channel and then move to the voice channels when needed to trunk track calls.
A RTL-SDR dongle can sample at least a 2,5MHz spectrum, so if all frequencies of a site fall within that range then a trunk track program could manage with one dongle and still monitor the control channel while at the same time monitoring a conversation. But the program needs to support that kind of function.
/Ubbe
You would need two dongles for one site if you need to keep track of if one important priority TG gets active while monitoring another. But if that priority function are not necessary, or you don't need to log every call, than one dongle can sit on the control channel and then move to the voice channels when needed to trunk track calls.
A RTL-SDR dongle can sample at least a 2,5MHz spectrum, so if all frequencies of a site fall within that range then a trunk track program could manage with one dongle and still monitor the control channel while at the same time monitoring a conversation. But the program needs to support that kind of function.
/Ubbe
If you are trying to receive the Armer, I’m guessing you want Ramsey County site, Minneapolis city center and Minneapolis N S simulcast. (I’m just guessing looking at RR database); then you would probably need 3 dongles dedicated to city center and another 3 dedicated to BOTH ramsey county and NS simulcast. That is 6 in total to cover the bandwidth you need.
If you want to simply your life sell or give away the rtl dongles, and get 2 airspy minis. One will cover city center and the other will cover NS simulcast. Now you only have 2 antennas to mess with. But before you make any major changes it sounds like a bit of testing is in order to see how well you are able to receive these different sites from your location and if their is a “sweet spot” for each of the sites.
Posting your spectrum view may be helpful, again and clarifying what sites exactly you want to receive.
If you want to simply your life sell or give away the rtl dongles, and get 2 airspy minis. One will cover city center and the other will cover NS simulcast. Now you only have 2 antennas to mess with. But before you make any major changes it sounds like a bit of testing is in order to see how well you are able to receive these different sites from your location and if their is a “sweet spot” for each of the sites.
Posting your spectrum view may be helpful, again and clarifying what sites exactly you want to receive.
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