[Dana, N1OFZ]

I’m ordering the needed hardware to get this project started today. While thinking about what radios I am going to use the question popped into my head as to if it would be possible to use a sdr dongle for the receive side?

Once I have my own system running I will investigate it but I figure maybe it has already been considered. Once the rtl packages are installed it should not be difficult to pipe the audio stream to your code.

Why would I want to do this? One reason is that I’m in a very hilly area and even though we have a repeater at the highest point there are still significant dead zones. What if we had multiple receive sites via these inexpensive dongles to cover the dead spots? The whole voting process can be external to open repeater if it’s not something that is of interest to the group.

There would be some other benefits as well. With multiple receive sites it could be possible to triangulate signals. This could be valuable if you have issues with jamming, etc. I could eventually envision a map overlay where you could see the locations of the people using the repeater in realtime via the web interface. Inbound signals can be stored as IQ files and analyzed better than just a regular audio recording. Finally, being able to split the receive could be a big money saver from having to purchase cans/diplexers/coax.

Thoughts?
Dana
N1OFZ

[Aaron, N3MBH]

Hello Dana,
Thanks for the interest in the project and I hope you have fun with it. Yes, the SDR receiver thing has been brought up before. Unfortunately at this time it is not on the immediate road map. Reason being because many of those SDR receivers are pretty low end. They also have a wide receive range which makes them highly susceptible to noise and desensitization. This makes them a poor candidate for a repeater site or in high RF environments. We would also have to solve the COS issue for switching as VOX squelch is a poor solution for a repeater. At this point and time, I would say you’d be better off which a cheap radio. to server those purposes.

I certainly understand the appeal, but until someone wants to invest the time to fully develop, test, and document the inclusion of SDR dongles the prospect looks bleak. ORP is open source, and so is the SVXLink core, so anyone can tackle this if they have the time.

For the time being, I have a list of other improvements to work on to make it more functional as a standard repeater controller. Thanks for the input and good luck with your deployment.

73,
Aaron – N3MBH / WRFV871

OpenRepeater is offered free of charge. Find out how you can support us.

[Dana, N1OFZ]

I wouldn’t dream of using the dongle at the primary repeater site! Frankly I’d be wary of using a low cost radio. I’d spend some money and try to get something as bullet proof as possible. I envision the remote sites as places where there is little rf.

I’ve downloaded the svxlink code and am getting ready to compile it on an extra machine that I have so I can play around with it while waiting for my stuff to show up next week. I read the post from last year regarding the extra receive port so I’m going to start there and see what’s involved.

Edit: it looks like the voter and remote receive ports are already supported in svxlink. I’m going to try getting that working. When my Pi is up and running I’ll look into how it works in open repeater. Don’t want to clutter the forums here with my learning process 🙂

Thanks!

[Dana, N1OFZ]

So while waiting for my gear to arrive I set up svxlink on a PC and have been playing around with it. Used a sdr dongle for the receiver and speakers for the output. Learned a lot.

My RPI came in yesterday and in under an hour I had it up and running with OpenRepeater. Even linked in the sdr dongle as a remote receiver. Had to temporarily set up the local receive as vox even though it’s not recommended but for testing at my house it’s not an issue. Once my GM300’s come in tomorrow I’ll be able to switch to COS. My little repeater project is coming along nicely!

Going to start reviewing the OpenRepeater code and seeing what is going on. Thanks for the great image and instructions for getting it up and running.

[Aaron, N3MBH]

No problems glad to see that you are coming along and that you are getting your hands on some decent radios. ORP is not setup to do everything, but it is a great spring board into SVXLink where you can do much more one you learn the ins and outs.

73,
Aaron – N3MBH / WRFV871

OpenRepeater is offered free of charge. Find out how you can support us.

[Dana, N1OFZ]

So the next day after getting the radios I started building code to handle the voter. I created a line in the openrepeater.db settings table called voter_enabled. Then added a slider to the general settings page under modules to set the value to true/false.

Then I copied the Echolink page and used it as a template for my voter.php page. I couldn’t decide how to handle the rx/tx. I started creating something and then thought maybe I’d tie it in with the ports page. After reading the notes on the ports page I was not sure what the status is of the development of that area so I decided to just create my own page for now.

I add a new table to openrepeater.db called voter. There is a column for receiver and value. I input values for DdrRx (local sdr), NetRx (remote sdr), Rx1 (GM300) and a couple of spare local receivers Rx2 and Rx3. When voter.php loads it reads the table values and creates a list of receivers enabling the check box if the value is true. It works well for now allowing me to turn on/off receivers. I was not sure where to go next. Cosmetically I was going to make the check boxes sliders like in the general page or do something to match the look of the ports page. I also toyed with trying to parse the svxlink.conf file to create the entires in voter rather than them being hard coded. I ended up just deciding to hold off until the next release to see where things stand before deciding what to do next.

I’m now focusing on the hardware side for a while. I spent hours trying to get a usb serial dongle working so I could program the GM300’s. I ended up digging up an older machine that had a physical serial port and I have been able to program the radios with Radio Doctor. However it looks like the COS pin may not be enabled on one of the radios and I’m struggling to get RSS via DosBox to talk to the radio. So it’s off to creating a bootable usb stick with FreeDOS. This has led me down another path where I’m considering picking up a Pi expansion board that adds an RS232 port so I can program the GM300’s via the repeater controller. That would be pretty slick!

• This reply was modified 7 years, 8 months ago by Dana, N1OFZ. Reason: trying to get image to show
• This reply was modified 7 years, 8 months ago by Dana, N1OFZ.

[Aaron, N3MBH]

Yes, I have heard that Motorola software is a bear to get working. I think I had run across a YouTube video in the past of something successfully using DosBox to run it, but they had to slow it down to a specific number of cycles.

73,
Aaron – N3MBH / WRFV871

OpenRepeater is offered free of charge. Find out how you can support us.

[Dana, N1OFZ]

I did finally get it going. DosBox works fine if you drop the cycles down to 191 as you mentioned. However the issue was that the com port still didn’t work. The final solution was that VT needs to be enabled in the bios to enable the serial port to be accessed by 16 and 32 bit programs. This took a loooong time to figure out!

The other thing to note is that if you have GM300 only the 16 channel version allows you to modify the COS settings via software for hi/low. With the other GM300’s the external COS pin will always be low. It’s not a huge deal as it’s easy to pick up the high side in the radio if needed but figured it was worth mentioning to save someone headaches in the future.

[Aaron, N3MBH]

Glad you got it working and thanks for taking the time to describe you experience for others.

73,
Aaron – N3MBH / WRFV871

OpenRepeater is offered free of charge. Find out how you can support us.

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