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eHam Forums => Software Defined Radio => Topic started by: N3KXZ on November 16, 2022, 09:55:52 AM

Title: Trouble getting local repeaters in CubeSDR with RTL-SDR dongle
Post by: N3KXZ on November 16, 2022, 09:55:52 AM
I finally got CubeSDR software to use with my RTL-SDR dongle, running under Linux. For reception only I am using a homebrew dipole (hung high in my shack). I do not have any 2m equipment- this is just for listening.

I can receive local FM commercial broadcasts just fine.

But I can not get any audio from any of my local repeaters- should be FM somewhere between 143-148Mhz. I can see a few carrier signals, but I get no audio. This morning I tried during my local club's net meeting, and I got nothing on either the call frequency or the offset freq.

Is there some other setting that needs to be set?

I have direct sampling turned off. I'm varying the bandwidth but I figure it should be between 3000Hz and 6000Hz? Bandwidth for the local broadcast FM stations is of course much higher.

Could my problem have something to do with the repeaters needed PL codes? I have played with the squelch settings with no joy. What else to look at?

Thanks,
Keith
Title: Re: Trouble getting local repeaters in CubeSDR with RTL-SDR dongle
Post by: K9AO on November 16, 2022, 11:16:36 AM
PL tone would not matter for receiving. For NBFM it's 10-15 KHz bandwidth. The repeaters will be vertically polarized. Look between 146 and 148 MHz. You will look at the repeater output frequency, not the input (offset).

A screenshot might help if you are still having trouble.

Have you tried SDR++? That is available for Linux (and Windows). Make sure to get the latest nightly build of it should you decide to try it.

https://www.sdrpp.org

Rick Kunath, K9AO
Title: Re: Trouble getting local repeaters in CubeSDR with RTL-SDR dongle
Post by: N3KXZ on November 16, 2022, 01:25:21 PM
Hi Rick K9AO-

Thanks. Yea, I did forget about vertical polarization, but has made no difference yet. Could be there just isn't any activity to hear? Except this morning I tried during a time for the local net with similar results. No problem receiving commercial broadcasts in the 98-105Mhz FM range.

My local club repeater is at 147.180 with 600Khz offset- so I was bouncing back and forth between 147.180 and 147.780 trying to find audio from either.

I had tried both FM and NBFM, as well as varying the bandwidth just to see if I could hear anything at all. I did get noise quieting when on top of the carrier.

Here is a screen shot:
https://card16.com/screenshot-cubesdr-11-15-22.png

That was last night. I think you can see there appears to be some activity (top left modem section) but could be just noise? Or maybe my antenna just isn't pulling them in enough?

I did get to tune into a conversation last night in the general range of 146Mhz (can't recall) but I'm guessing that was simplex... just two guys ragchewing back and forth with no station ID... but at least that confirmed my antenna was doing OK in the range.

I looked at github for sdr++ , not going to try that at this time since I don't run Docker.

Keith
Title: Re: Trouble getting local repeaters in CubeSDR with RTL-SDR dongle
Post by: N3KXZ on November 16, 2022, 06:35:48 PM
Well, tonight I received two local repeaters. Evidently I just can't, for some reason, reach my own club repeater.

I had to wait until I could find a repeater in the area that was actually in use in order to tell if I had things setup correctly, and evidently I do. I just need either a better antenna or better placement for it...

Thanks Rick K9AO for your comments, which were helpful. It was good to get confirmation that the PL tones were irrelevant in this context, to make sure about vertical polarization, and to use NBFM. As I am new to SDR these things were unclear in my mind. I also have been active in Ham radio for more than 10 years so I have forgotten a few things...

Keith
Title: Re: Trouble getting local repeaters in CubeSDR with RTL-SDR dongle
Post by: W1VT on November 17, 2022, 06:32:34 AM
The biggest variable is the location of the repeater.  In densely populated areas it can be impossible to coordinate a repeater with a huge coverage area as there may not any "clear channel" frequencies available.  But, a repeater coordinator may be able to squeeze in a limited coverage area repeater with minimal impact on the existing repeaters.
Title: Re: Trouble getting local repeaters in CubeSDR with RTL-SDR dongle
Post by: AI5BC on November 17, 2022, 07:30:34 AM
First thing to do is go to Repeaterbook.com and find all the repeaters in your area. Program those frequencies into your radio and scan them. What you will find, there is almost no traffic, but don't let that discourage you. Every 10 minutes those repeaters have an auto identification, typically broadcast in morse code so you can get hours of enjoyment listening to the ID's all day long. I find it double exciting to go outside during summer and watch grass grow while listening for the station ID's. You will get so excited; you will find it hard to contain yourself.

Perhaps someday you will get a lost baby boomer ham passing through the area asking for local information because they do not know how to use their cellphone map program to find their way.
Title: Re: Trouble getting local repeaters in CubeSDR with RTL-SDR dongle
Post by: AC2EU on November 17, 2022, 07:32:10 AM
Maybe they are using Dstar or DMR digital instead of analog?
Title: Re: Trouble getting local repeaters in CubeSDR with RTL-SDR dongle
Post by: AC2EU on November 17, 2022, 09:10:01 AM
First thing to do is go to Repeaterbook.com and find all the repeaters in your area. Program those frequencies into your radio and scan them. What you will find, there is almost no traffic, but don't let that discourage you. Every 10 minutes those repeaters have an auto identification, typically broadcast in morse code so you can get hours of enjoyment listening to the ID's all day long. I find it double exciting to go outside during summer and watch grass grow while listening for the station ID's. You will get so excited; you will find it hard to contain yourself.

Perhaps someday you will get a lost baby boomer ham passing through the area asking for local information because they do not know how to use their cellphone map program to find their way.

  8) ;D

The only time repeaters are active around here is when there is a net, in which I have no interest .
VHF is helpful, however, in the winter or during bad storms when the ARES guys start reporting conditions.
Otherwise it's a waste of time...