Wideband sondes out of Boulder

Brendan Curley

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Mar 5, 2025, 1:47:10 PMMar 5

to radiosonde_auto_rx

I'm wondering if NWS Boulder is launching wideband iMet sondes at 402MHz. Each week, I often see a wideband signal at 402MHz that is either not decoded at all by radiosonde_auto_rx, or intermittenttly decoded. I thought these were phased out, but they seem to be using them a lot. Sometimes these iMet are launched in conjuction with an RS41 at 401MHz, but sometimes they are solo. Today, I noticed one of these iMet sondes (s/n AD53FB23) and my system was having a hard time decoding it until I changed my config to set "wideband_sondes = True" under the demod/decoder tweaks. Link to I/Q recording: https://drive.google.com/file/d/1iKIYUi2QTZL8zFCnriy5vLT5pgcnTvt5/view?usp=drive_link

73,

KF0JNG

Jim MacDonald

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Mar 5, 2025, 1:48:46 PMMar 5

to Brendan Curley, radiosonde_auto_rx

Did you ask them?

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Brendan Curley

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Mar 5, 2025, 1:49:09 PMMar 5

to radiosonde_auto_rx

But I understand that enabling the wideband setting might inhibit decoding other narrowband sondes. Thoughts? Wouldn't there be a way to enable decoding both narrowband and wideband sondes at the same time?

I'm running radiosonde_auto_rx 1.8.1 with KA9Q on a Raspberry Pi 5 and AirSpy R2.

Screenshot before I enabled wideband mode:

Mark Jessop

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Mar 5, 2025, 4:25:42 PMMar 5

to Brendan Curley, radiosonde_auto_rx

Wideband and Narrowband at the same time is something I haven't spent much time on, hoping the wideband imet sondes would have gone the way of the dodo by now... but it seems there's still universities hanging onto them.

If you enable wideband_sondes, it will:

- Increase the reception bandwidth for iMet sondes, allow reception of the wideband imet sondes, but will reduce performance on the narrowband imet sondes.

- Widen the detection bandwidth when scanning. Other sonde types will probably still be detected, but not at as low SNR.

I'll look into adding a IMETWIDE option into the 'always on' decoders, so you can at least set up an always-on decoder if you know there are launches happening.

73

Mark VK5QI

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Brendan Curley

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Mar 5, 2025, 4:28:44 PMMar 5

to Mark Jessop, radiosonde_auto_rx

That's kind of what I was thinking. That would be great! Thanks for the consideration.