WSPR 22 m ISM Band Wrong Centre Frequency [fixed in v1.542]

edited June 18 in Problems Now Fixed

Just a quick note. The KiwiSDR 22 m ISM WSPR (ISM_13) band centre frequency is wrong. It should be 13555.400 kHz +/- 100 Hz but it's showing up as 13554.500 kHz (I assume +/- 100 Hz) in the KiwiSDR status display and on the WSPRnet station activity list. Looks as if two digits were transposed.

If there's some way that I can manually tweak this value could someone please let me know? I don't use Linux so it has to be via the web browser admin user section.

73 and thanks



  • jksjks
    edited June 15

    I think you're correct. As mentioned in the original thread below I used the frequencies for ISM_6 and ISM_13 as requested by the UK balloon-mobile people. But I see now on the page, top left, that they specify a frequency of 13553.9 (dial) + 1.5* (BFO) = 13555.4 (CF), a CF 900 Hz higher than than what the Kiwi is currently using. This is verified on the activity page as you noted.

    I have to change this in a release. You can't tweak it from the admin page.

    Does anyone object to this proposed change? ISM_13 was added in v1.446 back in March 2021. How come there were no complaints about this until now?

    *1.5 kHz BFO: Note that by default the Kiwi uses a WSPR BFO of 750 Hz instead of the usual 1500 Hz. I think the lower tone is easier to listen to. That's why the dial freq for, say, 30m shows 10140.2 (CF) - 0.75 (BFO) = 10139.45 (Kiwi dial) and not the 10138.7 ( dial). If you want, you can change the Kiwi WSPR BFO (in 750 Hz steps) on the admin page, extensions tab, WSPR section.

  • edited June 15

    I think the problem is that WSPR is, in fact, an FSK mode and FSK modes are always specified by their centre carrier +/- x Hz. But SSB AFSK use of FSK modes screwed that since you can use different audio tones added to the side band carrier to create the same difference as you noted with *1.5 kHz BFO... . The reason that the frequency error was probably missed, and this happened to me, is that 13554.5 and 13555.4 are easily misread. It took me quite a while to figure out what was wrong. Like spotting the the second "the" in this sentence. I'd like to add the ISM_13 band to my list of the Amateur Radio WSPR bands that I currently monitor now that we can spot to the server.

    The 22 m ISM band is an experimental band for secondary users (non ISM users) and no license of any kind is required so even "civilians" can transmit herein, but it's restricted by a maximum radiated field strength measured at 30 m, which after doing the mathematics works out to 4.7 mW transmitter power to a standard dipole or 2.35 mW using a standard vertical. No high-gain antennas (Yagi, et al) are allowed. This specific 22 m ISM segment (13555.4 kHz +/- 100 Hz) is called the "Sweet Spot" and is shared with WSPR and QRSS FSK CW users so you also need to get on the webpage to see who's transmitting what and where within this 200 Hz segment to avoid any conflicts. The entire band is much larger and used by other QRPp modes farther up the dial. The U.S. Part 15 regulations that apply to this ISM band are in alignment with Canadian unlicensed low power transmitter regulations and the 22 m ISM band has world-wide allocation/use, but I don't know if the same rules here apply to "over there".

    My main interest is transmitting remotely located fixed 24/7 telemetry-over-WSPR beacons and the 22 m ISM experimental band is ideal for this purpose. So if you see any WSPR type 1 call signs starting with "0", "1" or "Q" you know it's a telemetry packet or a non-Amateur Radio call being used in this band. We aren't supposed to use our government assigned Amateur Radio call signs in this band because it's not an Amateur Radio band but many do. I used "ROM" for 22 m QRSS FSK CW beacons, which is okay, but used "VA3ROM" for 22 m WSPR beacons, which is not okay, as I later found out. 22 m shouldn't be listed on the website with the other Amateur Radio WSPR frequencies seeming to imply that it's a new Amateur Radio band without noting that it's really a old ISM band with a totally different set of operating rules, IMHO.



  • Seems good to change the default, though I've switched to using Robs 'daemon to do WSPR decodes and it works great with my Kiwis.

    I think the reason folks use their call on 22M wspr is to ensure that they get picked up on the WSPR aggregators. I'm not sure the FCC really cares about use of the call there, even though it may technically be against the rules (much in the same way they don't seem to care about balloon beacons at 30,000 ft on 20M without a control operator). There's only a small handful of 22M wspr and QRSS ops there anyway, and a slightly larger handful with CW beacons.

    There's a lot of fun stuff on 22M. I regularly copy 4mW WSPR from Oregon here in NC .

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