Good cop, bad cop...

  • Dear All

    Everybody is aware of the amateur radio "policemen".

    They are on every band, on every mode and, of course, on QO-100.

    I don't want to discuss their reason to exist, but I want to say a few words about their activity.

    Today afternoon, one station was enjoying the first day of being active on this satellite. Unfortunately, the operator didn't not notice he was exceeding the typical SSB bw (3kHz).

    (Ok, we could argue that is not an excuse and all operators should operate according to the rules in all circumstances. Yes, fair enough. But we all know not all operators are young, bright, smart or tech savy. That is the reality and we can't ignore it.)

    As you can expect, It didn't took longer for a station to call the QO-100 newbie, not to welcome him, but to say he should reduce his bandwidth. He was not looking to make QSO, he didn't bother to gave his name, report or grid locator. No, he just asked to reduce the BW. He didn't asked if the newbie knew what he was talking about or offer any help/advice on how to fix the issue. No, he just asked to reduce the BW, again. (he did say his call, however. I aplaud that. Not all "policemen" identify themselfs)

    How do I know all of this? Because I heard that intereaction first, and then did QSO with the newbie station. He was clearly puzzled with the previous caller. So I explain him the problem and the usual ways to fix it.

    Having said that, I understand this is a cultural thing and I don't expect the "policemen" to be tolerant. But I would like them to be, at least, more helpful. Thank you in advance.

    See you on QO-100

    73 FCosta, CT1EAT/M0HOJ

  • Hallo Flo

    Thank you for the correction. You are a good cop ;)

    73 F.Costa, CT1EAT/M0HOJ

    P.S. By the way, "73" is "plural", so you don't need the "s".

    FYI, I did the same mistake 30 years ago (after I became an amateur) and I was corrected by an american ham :)

  • Headshaking Modus on

    What a strange discussion?
    Don't look at the bandwith. Take care about the audio frequency response to generate SSB with good readability. Many signals waste much power closed to the carrier. In the literature there is a clear information to increase audio gain with 6dB /Octave. In wireless communication the power densitiy spectrum must be filled everywhere constant to get good reports even with low power and noise. Another question is compression. One can found literature information there also. The readability increases with a specific degree of compression. I don't mean clipping but level control without additional distortion. At least the linearity of the transmitter chain should be good enough for a clear signal with the same bandwith as the SSB-Filter has. Carefully leveling and level control help a lot. All this is implemented in a SDR. Believe me or not, digital technology can be very senseful in transmitters.
    Of course there are newcomers. That is what we want. They need help to optimize their stations.
    Headshaking Modus off

    Let's be good Oms and give support in a friendly and hamlike way. To go forward as an example I wrote a paper (German) about my radio. Send me an email if you like to get it.


  • Would we send 73s in CW?

    There is a problem in with assumptions on bandwidth as not all driver radios have SSB filters able to meet a 2.7 kHz limit.

    So why wasn't the limit set to be compatible with the "standard" 300Hz-3.4kHz ? It's not as if there is a lack of bandwidth available with the extension to 500kHz.

    Rec. ITU-R BS.640-3 might have been more sensible.

    "The upper limit of the audio-frequency bandwidth (-3 dB) of the transmitter shall not exceed 4.5 kHz with an attenuation slope of 35 dB/kHz and the lower limit shall be 150 Hz with lower frequencies attenuated at a rate of 6 dB/octave."

    However that is for SSB broadcasting and even though QO-100 is a broadcasting satellite, amateurs don't broadcast.

    ITU Report M2478 which although related to the 6m allocation, does mention the bandwidths required for narrow band modes (CW/SSB/Digimodes) to be between 500Hz and 3kHz depending on the mode. So for 6m at least maximum of 3kHz.

    Then there is the handbook:…HDB-52-2014-OAS-PDF-E.pdf which is where I assume the 2.7 kHz comes from though the definition of SSB:

    SSB – Amateur single sideband suppressed carrier telephony has virtually replaced double-sideband amplitude-modulated telephony in the amateur service. The emission symbol is 2K70J3E, although there is some use of narrower and wider bandwidths. SSB is used on frequencies from 1.8 MHz through 47.2 GHz.

    So we see where it comes from and there's not hard and fast number. Most radios people might try to use from the (Yaesu, Icom, Kenwood, Elecraft) have filtering to 2.7 kHz or less at -6dB anyway.

    • Official Post

    I don't think the OMs with an errornous setting of 3.0 kHz in the TX modulation filter (SDR console for example) are the problem of this topic but rather the few gentlemen overdriving their PA and therefore generating up to 10 kHz wide splatter (which is actually IM3). Many operators have good to excellent signals, some of the overdrivers are reasonable once you explain the cause of their bad signal to them (actually, the readability of the voice does suffer considerably as well). The very small fraction of those who don't care, I have no idea what to do.

    • Official Post

    Regarding the 73s, I believe this comes from the Masonry culture of the 73 x 3 or triple fraternal 73 as they say.

    73 comes from "1859 Western Union '92 Code'" and means "Best Regards", also listed in "1864 Wood's Telegraphic Numerals". In the "92 Code" 88 means "Love and kisses".

    There was an article about it in our USKA journal from HB9DSB.

    73 & 88 ;)

  • Hallo,

    we don't need a qrp-day. I agree with Achim fully. Some guys don't know what intermodulation means and how to avoid it. That's it what we should talk about. All transmitters all amplifiers are not intermodulation free. As more stages are in the transmit chain as more intermodulation distortion can happen. Theory says a given stage should be 6 db better in intermodulation than the following one not to generate more distortion. If there are mixers and many amplifiers in a cascade, a correct leveling is important. SDRs and the software with a two tone option can do this easily. It is missing in many TRXs. May be an audio file with a two tone signal is possible like in the IC7300. This is not the best way but helps. An expensive spectrum analyzer is not nessecary. The satellit itself can show how the own signal looks like. If one don't have a duplex station which is strongly recommended, look to a WebSDR when transmitting to check the signal. It should show sharp limits without any products out of the filter in the water fall. I am afraid, stations with intermodulation products don't see a spectrum and probably don't work duplex. That's a pity. A free of charge WebSDR is a duplex receiver....

    Don't hesitate to ask if something is not clear. Good linear signals are our visiting cards.


  • Still regarding this exaggerating discussion regarding the audio going a little further than 2.7Khz or 2.8 (note that I am not extrapolating it to intermod which is a technical issue and must be fixed) , in the old times of AO-13, 10 and 40 this discussion was practically inexistent and everybody was happy.

    • Official Post the old times of AO-13, 10 and 40 this discussion was practically nonexistent and everybody was happy.

    absolutely agree.. and we were not complaining about Doppler shift, propagation delays, full-duplex operation, rules and operating guidelines, etc... ;)

    QO-100 is indeed the "easy satellite" and we have a lot of newcomers on the satellites too, which is good!

    Some of them just need a "good cop" who is able to explain to them what's needed to become a "good satellite user".

    Stay Calm and Listen: Everyone has to be open for comments, even criticism in a friendly way as well.. Unfortunately some operators take it as pure critics or simply ignore. Both sides need to be open and friendly...

    But I would also expect that new users shall try to educate them-self by reading trust-able and reliable sources first.

  • Hallo,

    if there are any ideas what we can do further to organize more and better knowledge transfer please publish it. This year all the meetings didn't take place and we missed the chance for talks and presentations. Probably there are many papers and informations we can share?
    Good cops help old Ladies crossing the street. Let's do this with the Newbees if wanted.


  • The main problem is, that, as Peter wrote, some user did not educate them-self by reading trust-able and reliable sources first.

    They work by try and error, did not respect the bandplans and regularity, partially they did not know about that, partially they don´t want to do that.

    How do we reach this part of users?