WB TRANSPONDER TESTS

  • Plots below show receiver spectrum with dish not pointed at the satellite to show reference noise level, and dish pointed at the satellite. Both NB and WB transponders visible. Dish is 3m, feed position possibly not optimised, and DU4BC preamp. HB downconverter. Polarisation is midway between V and H. WB transponder about 10dB above noise floor. Edges of spectrum have some intrinsic slope owing to SDR/software.





  • I honestly have no idea what the activity will be in the future. It'll increase, for sure, when more commercially available equipment may become available for relative low prices. On the other hand, the whole transponder design lies in the 'microwave area' and (at least here in The Netherlands) activity on and above 23cm is very poor and not many HAMs are (primarily) interested. They prefer repeaters or short wave.


    I reckon this is another issue of the category: "Let's wait and see" ?

  • I always wondered about the limited bandwidth of the NB transponder. The designers have something in their minds that I don’t.

    Excellent question but rather simple answer: Power. If you do the whole math (which is easy.. antenna gains, path loss and so on) and add some secret sauce (aka values under NDA we cannot share) the completed dinner dish will be something like 250 kHz BW for the NB transponder if you ask for reasonable SSB capability with small size antennas. You only have so much power from the satellite transmitter. Bigger transponder BW = more QSOs = less power per QSO = less signal per QSO.


    On the other hand, I would be thrilled to see the transponder filling up.. which means microwave activity and the ultimate proof that microwaves are easy. Something James Miller G3RUH postulated long ago..

  • On the other hand, I would be thrilled to see the transponder filling up.. which means microwave activity and the ultimate proof that microwaves are easy. Something James Miller G3RUH postulated long ago..

    Well, in the old days when the use of microwaves was first coming up for satellites, it was not so easy. I remember the designs (never built one) for linear amps with tubes like the 2C39 and others. Lots of mechanical work that either took a long time or was expensive. I also still have a klystron for 10 GHz in the junkbox. And experimented with gunn-diode modules intended for automatic door opening (doppler radar movement sensors).

    But a lot has changed since then. Of course due to the same developments that at the same time are a hazard to our microwave bands: large deployments of consumer-oriented devices that stimulated the development of devices and brought down the cost.

  • @DH2VA The majority of non technical minded hams want new countries, new bands for DXCC and new squares for VUCC. I’m sure that the next DXpeditions will be equipped with P4 earth stations. Not bad but alligators will grow rapidly...

  • Frankly I am not so afraid of "alligators" in the original meaning (big mouth, small ears) as they were known on Phase3 satellites. There was a real reason for them - poor receiver and not hearing themselves back, increasing power until they did.

    On Es'hail-2 it will be very difficult to make a bad receiver setup so everyone should essentially hear the same thing (the transponder noise floor).

    So everyone should be able to hear themselves and judge the level well.

    Also, the advent of SDR technology and panoramic receive display with waterfall should enable everyone to see what is happening.


    Of course there is still room for "antisocial" stations but maybe we should attach another animal name to them?

  • Hallo all ...


    first stations received today with commercial TV-Cards in the PC... and

    tweaked streamreader.ini


    F5OEO, DL50AMSAT, PE1ASH

    RX: Dish 60cm + OCTAGON TWIN LNB


    Screenshot ATTACHED...


    73 to all de dg0opk


    Update: 21:45UTC ON4BHM is now seen with strong and best quality signal

    ... S/N 8dB SR:1000

  • dl4sdr Good morning Herbert I have here MiniTiounerExpress from DATV and TT-s2-1600 Cards from Technotrend inside a PC with PCI Slots. This I will try today with the EBSpro SW.