KK7KA on DSP in EME.(II)

"Every time someone posts something innovative on this reflector, its overwhelmed by contrary or hilarius comments." ( IK5QLO )

>   From: "Ian White, G3SEK" 
>   Subject:      Re: Call-Puzzles and advanced coding
>   Stewart Nelson wrote:
>>  A number of the (mostly negative) replies to my original post on this
>>  subject used sports analogies, so I will continue in this vein.
>>  CW operation is like running - it's done mostly for fun, sometimes
>>  competitively.  EME is the Marathon.  I am not a good runner, so I am
>>  trying to build a bicycle.  Not knowing much about bikes, I outlined
>>  what my first one would look like, hoping to receive suggestions for
>>  superior designs.
>   OK, it's a good analogy to use, so let's pursue it.
>>  Instead, most folks told me to continue running, many explained why
>>  cycling is not a satisfying sport, one chastised me for failing to
>>  attempt the Marathon,
>   You have a right to decide what you - individually - find enjoyable
>   about amateur radio. I'd support that, and defend it against people
>   trying to make you enjoy it their way. But...
>>  and one even suggested that bicycles do not
>>  belong on the course!
>   In a sense, they don't - at least, they don't belong on the same course
>   that the runners are using.
>   Nobody "owns" the EME path, but we do have to share the amateur bands.
>   These so-called ultra-weak-signal modes still involve very strong TX
>   signals in the immediate locality (read: anything up to 50-100 miles
>   radius). What worries me even more is the fact that these signals will
>   be controled by computers that take no account of the other band users.
>   If the cyclists want to enjoy their own sport, they must find a
>   different course that won't interfere with the runners. In particular,
>   the cyclists have no right to decide what is and isn't OK for the
>   runners.
>   Us cyclists and the runners had better decide to work together.
>   Otherwise, we'll all be mown down by the motor-bikers and the 4x4s!

    How True,
    Good analogy!  Here in Alaska it would be: "Us x-country (Nordic) skiers
    and dog mushers...else we're run over by the snow machiners (snow-mobile or
    snow-go, depending on the local term in use).  So some would prefer to
    stretch their own muscles, others would prefer to train some dogs to do it,
    while others would prefer to just enjoy the ride (maybe being physically
    unfit to do the other methods) and letting the machinery do all the work!
    Hopefully there is room for all.

    Just a little disturbed at the reaction of some to an attempt to
    innovation.  What has attracted me to eme is: (1) the technical challenge,
    and (2) the pursuit of technological excellence.  Am I wrong to expect to
    find kindred souls in the eme community?  I know my status is still
    "wanabee", but I'm working toward joining you all.  After I master the
    proven approach(es) to eme, I'd like to explore some new frontiers.  Hoping
    I'll find others out there will a similar inclination!

    Proud owner of eleven Alaskan Huskies and a dog musher for 20 years.  Prior
    to that, a Nordic skier for 10 years and an alpine skier for 20 years,
    until badly breaking an ankle in 1978.  Some day I may have to retire to a
    machine...or a rocking chair!
    73,   AL7EB, Ed 
    Analog Satellites: RS, AO-10, FO-29, AO-27...QRV very soon.
    2m-eme: FT-847-MGF1302-4xM2xpol-20 (V/H)...building 8877
    23cm-eme: DEMI xvtr & preamp-K9EK(7211)-OE9PMJ(TH328)=500w
       ...building power supplies and 5m dish (Summer 1999)
    21cm-Radio Telescope: under design for 5m dish
    13cm & 3cm: 2.5m dish...Rx for 2401 & 10,368 (Fall 1999)
    ARRL-AMSAT*-SETI*-SARA...*Alaska Coordinator

    Just a simple proposal :  given that the EME subband doesn't seem to suffer from
    overcrowding problems, why not reserve a slice of it for experimental modulation schemes
    other than CW ?
    This way, both the romantic fascination of decoding by ear a faint murmur coming from
    the silver lady of the night and the sensation of self-accomplishment deriving from
    tackling a technical challenge could be both preserved.

    73,  Alberto,I2PHD 

    On Sun, 20 Jun 1999, Ian White, G3SEK wrote:

>   Also, as I3LDI has said, for most of us the modulation/detection method
>   is part of the basic choice we have already made about the style of
>   operating. The present "EME" sub-bands belong to that style of
>   operating, as well as to the EME path.

    Hm, if the modulation method is really optimized for the path, I doubt
    that you can even detect these (hypotethical) signals (low power, wide
    bandwidth). Lets not worry about problems before there are problems. I
    think the same frequencies can be shared like gentlemen and solve any
    conflicts if they become real.

    Please go ahead with experimenting, after all, that's what ham radio is

    Cheers,   Kaj, OH6EH 


        Koellner Guenter  Guenter, DL4MEA 
     DL4MEA's WEB Page 

    Hi there,
    I read last messages of Leif (SM5BSZ) and Juergen (DL8OBU) and I strongly
    appreciated the technical opinion of Leif (his proposal of "coherent" CW on
    base of high frequency stability and a loop of 3 frames of the same message
    - I still use a ECC83 xtal oscillator + triplier with a large amount of
    freq. drift but this don't prevent me to explain my opinion - I'pe!) and
    the ideas of Juergen, particular:

    1) Understanding the importance of EME and MS procedures (simply to obtain
    the maximum fun in the radio ham activity, i.e. a great number of C QSO!)

    2) Freedom in the choices of activity (don't mean that I can transmit on
    beacon sub_bands or other damaging acts!) like use or misuse of a PC to
    have maximum performances, QRP or QRO (matching EME ARRL rules or for
    terrestrial qso),etc.

    Really I think that everybody want improve his EME performances (increasing
    G/T of antennas, noise figure of receivers, quality of analogic or digital
    filters - last but not least power output), it's true that everbody use own
    ears to solve a QSO but it's also true that there is'nt any kind of natural
    activity by using radio equipments (even if analogic) and some (or many)
    accessories to send a "low rate of information" by the moon!!
    Maybe I'm biased to digital techniques (so I wrote this message) but maybe
    also that freedom  is the key to continue this funny experience.
    73   Claudio, I4XCC 




     Subject:  Re: EME procedure

     On 1296 sometimes signals were peaking 30 dB over noise , but very much
     distorted. i could not find out if it was OE9XXI or OE9ERC. The only way to
     discover who it was, was to call  him on SSB.
     I would like to see a computer in such a case.

        GL, 73 Paul, WA6PY 

      "Charles R. MacCluer" wrote:

>      In regards to the following"
>      "But you must realize that, in spite of any advances in DSP or other
>      digital techniques, a majority of attempts at EME communication will
>      still fail."
>      I strongly disagree.  Most EME QSO's (at least on 432 & 1296) are made
>      just like on 20M you call CQ and answer whoever come back.  On 1296 a
>      significant number of QSO's are made on SSB.
>          Steve, K1FO

      Kaj Wiik wrote:
>     Hm, if the modulation method is really optimized for the path, I doubt
>     that you can even detect these (hypotethical) signals (low power, wide
>     bandwidth).

      There's no worry about detecting them on the downlink from the moon -
      it's about detecting the *uplinks* from stations up to 50 miles away, or
      more. Even if they are 10dB down from "EME power", those signals are
      STRONG, and capable of causing a lot of wide-bandwidth QRM.

      The other problem with the under-the-noise modes that rely totally on
      computers for decoding is that operators have no reason to actually
      listen on the band. Nobody should ever transmit unless they know that
      the frequency is clear... but if a station hasn't got the "ears" to copy
      weak CW on the EME downlink, how can they know that? The only answer is
      to wait for up to 2 or 2.5 minutes in case a local uplink signal
      appears, and I don't think most operators would do that.

>     Lets not worry about problems before there are problems.

      Having some practical experience in band planning in Europe, where VHF
      population densities are extremely high, I fear that's bad advice. It's
      true that the first few experiments cause little QRM to existing users
      of the same frequencies, but if the experiments are successful and lots
      of people get involved, it's already too late!

>     I think the same frequencies can be shared like gentlemen and solve any
>     conflicts if they become real.

      The European VHF band-plans always keep a frequency area where new modes
      can start up, so that they can avoid conflicts with existing uses of the

>     Please go ahead with experimenting, after all, that's what ham radio is
>     for!

      Absolutely - but only with complete respect for other band users.

      73 from  Ian G3SEK 

                             Editor, 'The VHF/UHF DX Book'
                            'In Practice' columnist for RadCom (RSGB)
                              G3SEK's Web Page 

        Leif Asbrink SM5BSZ  ( remove .sm5bsx from address )

     Hi all,

     I have to admit that my previous posting on this subject was strongly
     biased. My interest is RANDOM contacts, and there are underlying
     assumptions because of that.

     Taking a pro sked attitude just for once I would like to propose a sked to
     some Oscar Class -6dB station, for example Stewart, KK7KA with
     appropriately reduced power. I suggest 75 W to compensate for my use of
     four yagis rather than one.

     I suggest the following procedure:

     My sked partner suggests the day, the hour and a 10kHz frequency band and
     sends the proposal to me.

     At some 1 minute interval within the first 10 minutes of the hour my sked
     partner starts by transmitting a full minute of continuous carrier,
     starting the first second of the selected minute.

     If I can "hear" the signal I will respond during nearly 3 minutes by
     transmitting call signs and OOO at the frequency I received with a
     polarisation that is optimum for my sked partner. It will take some time
     for me to adjust the frequency and polarisation so one minute is not
     enough. Two minutes is no good in case my partner likes to make a second

     If my sked partner can hear my answer on the frequency he calculates from
     the doppler shifts, he should transmit one minute of continuous carrier at
     a new frequency somewhere between 0.5 and 1.5 kHz away from the first
     frequency (up or down).

     If I can "hear" the confirmation I will answer by transmitting calls and
     RRR at the new frequency I have received during nearly 3 minutes.

     If my sked partner can hear my confirmation he should transmit a
     confirmation by transmitting a 1 minute carrier without frequency change.

     I will record the signals and make the recording available as a gif file
     and some spectrum graphs that allow determination of bandwidth and S/N.

     If the "QSO" is successful my sked partner will know for sure that I can
     actually detect him. I will have no chance to select correct minute and
     frequency just by luck or by detecting something else. (Actually this
     procedure is far more safe against mistakes than the standard procedure as
     any station that has some experience in listening to other stations skeds
     must know)

     This test "QSO" must be done without ground reflections at both ends to
     make the result really interesting. Any suitable time with degradation
    (loss + sky temperature) below 3dB and the sun 20 degrees away or more is

     Stewart, KK7KA wrote:
     >4) We are comparing "once in a lifetime" conditions with "good" ones.

     In my experience with cross yagis there is no such thing as exceptional
     conditions. Unless something is wrong, the signals are always the same.
     The bandwidth changes from time to time but the maximum S/N is always
     nearly constant if the degradation according to popular programs is
     subtracted. Things that may go wrong are mainly:
     1. Local QRM.
     2. Thick ice layer on antennas.
     3. Error in azimuth or elevation.
     4. All other possible (and impossible) operator errors.
     5. Very strong aurora.

     The EL2RL signal was in fact weaker than it was during the first attempt.
     I failed to work them then because they disappeared (due to extremely bad
     weather making it impossible to track the moon as I learned later)

     In my collection of QSL cards I have the following:

     call         date    time(UTC)  single ant     pwr      degradation
     K1FJM     02 oct 94   1328          17M2       280W          1.3dB
     W7OE      19 oct 97   0418          2M8WL      350W          3.7dB
     SP2JXN    15 nov 97   1957          17M2      4CX250B        3.8dB
     F8ZW      16 nov 97   1830          17B2       600W          3.8dB

     These were regular random contacts during contest. There was some
     contribution from ground gain. K1FJM was before I had any digital
     processing at all, just analog filters and polarity switching in 45 degree
     steps. The other three were DSP aided, but only adaptive filtering and
     polarisation, no coherent processing.

     By use of ground gain at both ends, medium power single yagi stations can
     already work each other (but it takes patience and good understanding of
     EME) Add 4dB for ground gain for K1FJM, one more for lower degradation and
     increase the power by 1dB to 350W to get the signal level I had in our qso
     using a normal analog filter. It is generally accepted that a qso is
     possible at lower signal levels by use of skeds so take that as a bonus!


      leif.asbrink@sm5bsz.MBOX300.SWIPNET.SE  ( remove sm5bsz from email address )


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