Posts by EA4GPZ

Hi Peter,

Thanks for sharing this. I'm currently measuring the BPSK beacon frequency 24/7 for the next few days and posting updates on my Twitter ( EA4GPZ). Unfortunately I lost last night's worth of measurements due to a network problem. I find this weird wiggles quite interesting, since I haven't seen them before, and certainly they weren't present the last time that I made precise measurements, back in October 2019.

Mario DL5MLO tells me that the GPSDO at Bochum is not to be trusted 100%, since it is reporting some error (control voltage at limit) and people can't currently get in Bochum to check, due to the lockdown. I might also measure the engineering beacon at 10706 MHz to rule out anything having to do with the Bochum beacon. I think that beacon can be received in Madrid, since we're on the edge of the MENA beam, but it's been a while since the last time I tuned to it. Another idea is to put up a constant carrier myself through the NB transponder (with the appropriate CW id nearby, of course).

Interestingly it seems that the wiggles start at eclipse and half an orbit later. This is eclipse season, so the sun angle with respect to the orbital plane is small (this is the reason why there is eclipse in the first place). Depending on how the satellite attitude is controlled to aim its solar panels to the sun, it might need to do large yaw rates at eclipse and half an orbit later. The wiggles may or may not be related to this. We'll see how this evolves as the sun angle continues increasing and eclipses disappear (last night it was the last eclipse of the season).

I agree with all of the comments made so far.

I think that the main problem is that there are some people that are very conscious about the importance of signal quality, but there are many others in the don't know / don't care category. Examples of "don't know" include not having appropriate equipment to monitor their own transmissions, not having technical knowledge to look for or correct problems (some may not be so obvious). Examples of "don't care" include not realizing that QO-100 is a huge asset that we are extremely lucky to have and what we do with it is quite serious, as it gives the world an impression of what we care for as Amateurs, and also being too lazy to do a couple calculations for the uplink frequency and tuning with a TX signal across all the band instead.

The problem is not specific of QO-100. I think that it just makes it clearly visible in a worldwide scale. But I think that there are other aspects of Amateur radio where the problem is worse. For instance, I once did a study about IMD in the EAPSK63 contest, and the results were rather bad (something like 11th harmonics at only -10dBc with some of the stations). The contest organizers did nothing about it.

To try to improve this situation, I think that all of us concerned about the importance of signal quality should try to create a culture on the bands. I should apply these recommendations first to myself, but I'm going to list the aloud here: when you see someone on the bands doing something inappropriate, just tell them and stress why it is important. Examples of this include when you are calling CQ and see someone tune across trying to reach your frequency, working a station with visible spurs, too wide of a modulation, signal stronger than the beacon, splatter, also low audio quality because of compression (even if the signal is fine spectrally). Just tell them politely but stressing the importance.

Probably there are some people who will be offended by the comment and try to argue back, but I bet that many other will be either surprised or interested and will like to care or learn more. Several times I've had a station with some of these problems call me and I haven't told them anything. Now I realize that by not telling them anything I am just contributing to the problem. Also, if you see a station with a really horrible signal, just call them and tell them.