978 Mhz decoder

Hi,

I left the 978 decoder running for an hour with no luck to get anything on the screen.

any hint?

$ rtl_sdr -f 978000000 -s 2083334 -g 48 - | ./dump978
Found 1 device(s):
0: Realtek, RTL2838UHIDIR, SN: 00000001
Using device 0: Generic RTL2832U OEM
Found Rafael Micro R820T tuner
Exact sample rate is: 2083334.141630 Hz
[R82XX] PLL not locked!
Sampling at 2083334 S/s.
Tuned to 978000000 Hz.
Tuner gain set to 48.00 dB.
Reading samples in async mode…


END

I’m using the same a VHF/UHF antenna that works fine for 1090 Mhz on the same dongle.


Regards,
Antoine

Antoine,
Wait for the new dump978-fa to be announced on Friday.
It should be a lot more reliable than the older dump978 (I have to restart mine every hour).

Mostly low flying, GA aircraft use UAT 978. The range is considerable lower than ADSB-1090Mhz.

This is my airspy setup on 1090 Mhz

This is my rtl-sdr setup on UAT 978 (I’ll change it to airspy shortly)

The Antennas are basically in the same location. Both setups use hab/nevis amps with cavity filters and LMR400 coax.

Had UAT running here with a home-made antenna tuned for 1GHz, maybe received 1-2 flights per day a few months ago. Interesting was picking up some weather data from the nearby airports I wasn’t expecting. Had an earlier dump978 running on an RPI2b, needed to be re-started every day so added a chron. Was expecting more traffic being close to the US border, might be more traffic now though and looking forward to checking out the new software release when available.

1 Like

Thank you Jon for the details. appreciated.

Gents,

Anyone in Greater Seattle Area managed to get a single 978Mhz message?

I don’t understand what could be the issue!!

@jonhawkes2030 Did you manage to get the Airspy working with UAT 978 ? I can’t get mine to work successfully.

It sort of works. The application works but I don’t get any aircraft. I’ll try again in a clean RPI 4 setup soon.

There is some sort of soapysdr driver problem i would assume.
It got basically no signals when the equivalent setup with an rtl-sdr compatible dongle worked flawlessly.

I’m not inclined to debug this either, too niche sorry.

My guess would be either the sample conversion doesn’t work correctly or the soapysdr gives dump978-fa the wrong sample format or something along those lines.

So i would just recommend running an rtl-sdr compatible dongle and avoid the hassle.

@obj might be able, not sure if inclined to debug it, if maybe @prog would send him a sample airspy for testing? :slight_smile:

2 Likes

Of course. Where to send?

I’m sure @obj will get in touch in case he is interested in one for dev purposes :wink:

I appreciate the offer! But I don’t want to have it just sit on my desk for a couple of months while I try to find time, so let me get back to you once I can actually make use of it.