Posts by SV1BDS

    Hi i2NDT again,

    You must take into account that each spectrum analyzer has a minimum of phase noise that can measure. In order to have a valid measurement you must determine the minimum phase noise that you instrument can measure and don't expect to measure anything less than this.

    Hi i2NDT Claudio

    FSEK30 Rohde & Schwarz and Prologix Ethernet interface. With the ethernet one is possible to work even from internet if you port forward the port.

    Hi George,

    did you measure the phase noise?

    Best regards,

    Detlev

    No, but using this method does not increase phase noise. I can measure phase noise but only when it is large. I evaluate it from the LNB performance in QO100. I used this method until now with good results. If you need more info please tell me.

    Hi,

    It seems that a working setup can be done using GNURADIO for Tx and a mix Minitioune & GNURADIO for Rx using gr-dvbgse module.

    The only that have to be done is F6DZP extract data after BBScrabler and before BBheader. A GRC is attached that it seems OK for Tx at 500Ks.

    Link : it is implemented...

    Hi,

    A GNURadio generic SNR calculation routine is built as an extended Python block. It takes a IQ data stream (usually a narrow one - a few kHz) and gives SNR as a real number. It takes one optional parameter FFT size ( 1024 seems a good value). The way of doing it is to log power FFT input signal and then take the difference of the max and the mean values.

    Files

    • bdssnr.py.txt

      (842 Byte, downloaded 16 times, last: )

    Hi,

    I have a nice FDX QSO with DL2GRC Nina using SDR Console. For me to avoid confused by my own voice I use the Full duplex option together with Receiver mute enabled in Transmit options at 75%. To avoid PTT, VOX was used and it was possible to talk and hear full duplex without problems. We have to overcome the half duplex way of operating (saying over etc).

    The progress in developing code in GNURadio showing that in order to have results, the CPU power is not enough.

    The next step is to try to schedule a more than two persons QSO in order to see it in practice. If any one is trying it lets share with us it's experience.

    Congratulations !!!

    It seems that the reason for not yet received by me is that I try to decode signals without pilots on. I have sent a IQ dump of the WB beacon (pilots off) to Igor and he promised to see why I can not decode it. Also I notice good SNR in your Rx.

    Hi,

    In order to align my portable system dish (but not only to this), a ICOM Q7 used as a portable 739.5 or 740 MHz FM receiver seems suitable to do the job. A set of a 10 dB and a 20 dB attenuators give proper S meters readings used in any combination. Any similar experience?

    Hi,

    I am in direct contact with Igor. When I have successful results I will post it here.

    It seems that his effort is supporting pilots on, so maybe code with pilots off is not working so good.

    The problem now is to successfully decode LDPC packets.

    Thanks for the answer hb9dug !!!

    Hi,

    After a lot of tests the solution to Winzel low phase noise GPSDO, which have big frequency variations due to thermal stabilization internal circuit, was to run the Lars original software with TC = 16. The Alan deviation was improved, but most important it stopped to unlock as big TC leads to PLL unlock.