Posts by g7iii

  • 'The frequency'

    Hi Peter


    With regards to perhaps someone will write an SDR code which will automatically track the beacon while receiving other signals:


    I now have gnuradio code that measures a carrier frequency down to 1Hz in a 250kHz bandwidth. Tests have been carried out using terrestrial sources, some strong, some weak(MSF on 60k, DCF on 77.5k TDF on 162k, RBU on 66.6667k , and RWM on 4996 and 9996kHz.)


    Without a 10MHz reference my USRP N200 appeared to be up to 6-10Hz off at 9996kHz (although some of that may have been atmospheric of course). Multiply that up to 10GHz and you get 6-10kHz. With a 10MHz reference, 0Hz off!


    RWM is very weak here on certain frequencies at certain times of day, but I can still get a 'Lock' even then, next steps are to test with space sources (AO-73, Nayif-1 are targeted for later this week, and maybe JYSAT-1 as well once she launches.)


    I also have some early ranging code (Sorry Achim, only carrier at present, Spread Spectrum will be have to wait), that I'm hoping to test to at least some degree with the same spacecraft assuming I can confirm a good uplink to them


    The carrier measurement code has also been modified to measure to 1kHz rather than 1Hz. That version can run on a Raspberry Pi 3! I am planning to see how accurate I can reliably go with a Pi 3 (I do not expect to get to 1Hz, but fully expect to be able to manage somewhere between 100 and 10Hz)


    Also working on separating the different sources of frequency drift (Lack of GPS lock on uplink, LNB drift, doppler (due to dinuaral effects from the Moon) etc, and am hoping to measure the figure of eight "wobble"



    73s


    Iain

  • Simplex operation

    Just as aside, a LNB+RTL dongle+ Your chosen SDR software should suffice for the downlink, even providing a nice waterfall so you can _see_ as well as hear that you are no stronger than the beacon, and not transmitting over others.


    This would then let you use a single single-band trx just as an uplink.


    I certainly intend to have at least one dongle constantly monitoring at least one beacon just as an extra receiver

  • Suggestions For A 1 Watt 2.4GHz Linear PA ?

    Hi Folks,


    I have plenty of equipment that will generate 2.4GHz, and can acquire a 1W in, 10W out PA easily enough. The problem is that all my 2.4GHz gear is 1-10mW out. Anyone have any suggestions of a 1mW in 1W out 2.4GHz PA ?


    I do have an alternative, as I have a spare 144->2.4GHz transverter that has 1W output, but I'd rather use all the 2.4GHz gear that I have if possible...



    Iain

  • 23cm transverter for 1267-1269

    Great News, I was wondering when I saw an article saying that there were now only 64 cubesats onboard, but the full compliment of 15 microsats


    It looks like it's going to be an exciting November! I must acquire a 23cms PA :)



    Iain