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Trying (and failing) to receive IBP beacons on an SDR (fedia.io)

submitted 2 weeks ago by tiredofsametab@fedia.io to c/amateur_radio@lemmy.radio

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Hello! I just got an SDR and decided to start listening. As a teen, I bought a scanner from someone and used to fall asleep listening to all the various different conversations. I decided I should probably start again and get my license (for which I am studying).

The SDR I got is "RTL-SDR Blog V4 R828D RTL2832U 1PPM TCXO HF Bias Tee SMA Software Defined Radio with Dipole Antenna Kit " and I'm able to pick up some things (various shortwave, FM, AM, nearest airport, etc.), however I can't seem to get the IBP beacon nearest me. This could be in part due to literal mountains between us, I suppose (Japan problems), but I hear no beacons on any of the listed frequencies.

I am using the di-pole antenna included in the kit, fully extended, attached to the east side of my house (about 3km away from the pacific, but I have mountains west and some taller hills north and south). "2x 23cm to 1 m telescopic antennas." is what it says so I suppose It's a bit over 2m tip-to-tip oriented vertically.

Should I be able to receive any of the IBP beacons with my antenna, position, and orientation? Am I doing something obviously wrong? I'm happy to go fish if you point me in the right direction, but my searching hasn't turned up anything useful so far (probably user error in that I don't know exactly what to search for).

Thanks very much!

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[–] bigfondue@lemmy.world 2 points 2 weeks ago* (last edited 2 weeks ago) (1 children)

The problem might be your antenna, but it may just be the conditions right now. 14.100Mhz will have more consistent propagation than the higher frequencies.

I just went on KiwiSDR, which is a website that lets you access different SDRs around the world. I picked one of the stations in Japan and I wasn't getting much of anything on the 20 meter band (14 MHz range).

http://kiwisdr.com/public/

Check KiwiSDR. Just search for Japan and find the station that is closest to you. That will show you what you should be able to pick up if your set-up is working.

How big is you antenna? A dipole antenna works best when it is one half of the wavelength you are trying to receive. So you would want a 10m wide antenna for 14.100MHz.

Edit: I just saw that you are using a small antenna. That antenna will only really work for UHF/VHF. You will need a much larger antenna for HF. Look up random wire antennas. A lot of people use them to receive with an RTLSDR. I don't know how much space you have, I know Japan is pretty dense.

To receive the highest frequency beacon, at 28.200MHz you would want a 5m antenna. But propagation is very inconsistent on the 10m band. It only opens up occasionally.

[–] tiredofsametab@fedia.io 2 points 2 weeks ago (1 children)

Thanks very much. I had a feeling antenna size was at least part of the problem there. I appreciate the help and tools. Thanks!

[–] bigfondue@lemmy.world 2 points 2 weeks ago (1 children)

No problem and good luck! With your antenna now, you should be able to receive ADS-B, which is pretty cool. You can see what planes are flying overhead, how high they are etc.

[–] tiredofsametab@fedia.io 2 points 2 weeks ago

So far no luck, but I only seem to get flights when they are going to/from the nearest airport to places south of me; everyone else is going around. I'm not sure how far the range is meant to be　（EDIT: 370km or so per wiki). I can very faintly see something on the frequency, but Dump1090 isn't catching anything.

I have some parts coming today to try a ~20m random wire antenna. I got 2x20m copper wire in case I need to do a counterpoise on the other side (which seems to be like 1/4 length (so 5m) of wire?).

Edit: also apparently it's not required in Japan, so I'm guessing that's why nothing domestic at least has it. Maybe if I leave dump1090 running long enough, it might catch some international flight, but none seem to go that near me.

[–] tiredofsametab@fedia.io 1 points 2 weeks ago

I now have a random wire antenna ~16m long (though not straight and the very ends wind around the structure I'm using to hold it up which I'm sure is not ideal), a ~4m counterpoise-ish-thing, a 9:1 balun, and cable to the SDR.

I've gotten wefax (though in negative and spotty, so still some figuring out to do). Still no IBP beacons at all, though.

I have fldigi working to a degree using soundcard as input. No hits using a regex of the beacons' callsigns (including the one here in Japan) on any frequency I've tried. Not sure why that is yet.