Sondehub upload error when multiple balloons decoded

[Stan-K9SWX]

I installed an Airspy R2 on a spare Pi 4 today to compare it to my RTL-SDR and to see if it would decode multiple balloons at the same time. I used the KA9Q setup so I could decode all balloons between 400-406 MHz. 

My local balloon (ILX) was decoding fine and had a similar signal on both the RTL-SDR and Airspy R2 (KA9Q). I briefly picked up the DVN balloon while still decoding the ILX balloon on the R2. Then I noticed my data was no longer being sent to Sondehub. Once the DVN balloon went out of range, the ILX data eventually started making it to Sondehub again. 

Each auto_rx instance had its own unique Sondehub callsign. Is there something I can do to fix this? Thanks!

Here's a snippet of the error from the log during that time.

Feb 28 18:09:17 pi-balloon auto_rx[3685]: 2026-02-28 18:09:17,306 DEBUG:Sondehub Uploader - Payload data error: DFM radiosonde above 1000 and not enough data to perform z-check. Not adding DB to protect against double frequency usage.

Feb 28 18:09:17 pi-balloon auto_rx[3685]: 2026-02-28 18:09:17,306 DEBUG:Sondehub Uploader - Payload data associated with error: {'software_name': 'radiosonde_auto_rx', 'software_version': '1.8.2', 'uploader_callsign': 'K9SWX-AIRSPY', 'uploader_position': [40.112334, -88.288462, 225.0], 'uploader_antenna': 'N9TAX Slim Jim - 405 MHz', 'time_received': '2026-03-01T00:09:01.730826Z', 'datetime': '2026-03-01T00:09:00.000000Z', 'manufacturer': 'Graw', 'type': 'DFM', 'subtype': 'DFM17', 'serial': '25031052', 'dfmcode': '0xA', 'frame': 1456358940, 'lat': 39.92933, 'lon': -88.17673, 'alt': 17759.1, 'temp': -60.1, 'vel_v': 6.84, 'vel_h': 16.76, 'heading': 61.94, 'sats': 19, 'batt': 4.44, 'frequency': 405.01, 'ref_position': 'GPS', 'ref_datetime': 'UTC', 'snr': 7.3, 'dfm_failure': True}

Thanks!

Stan - K9SWX

[Mark Jessop]

This is an example of where the DFM 'z-check' is coming into play: https://github.com/projecthorus/sondehub-infra/wiki/DFM-radiosonde-above-1000-and-not-enough-data-to-perform-z-check

Basically, because the DFM telemetry is awful in a few ways, we require station to upload at least 10 packets of DFM telemetry in each upload bundle, so we can perform some basic checks on data sanity (e.g. no weird position jumps). If your station has only happened to receive one packet in an upload period (15 seconds, though this can be increased in station.cfg), then that will usually get discarded. 

Cheers,

Mark

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[Stan-K9SWX]

My main RTL-SDR Pi is set to 30 seconds but I had the Airspy R2 one on 15 seconds. I've changed it to 30 seconds so we'll see if that helps. Thanks!