NB Transponder - Received Signal Level

  • I have recently (accidentally !) re-aligned by antenna for QO-100. I have an 85cm dish with Bullseye LNB.


    I am currently receiving the upper & lower CW beacons around +33db above the noise floor - which for my station is the best i have seen.


    I'd be interested to know from other operators what signal levels they are seeing for the CW beacons, relative to the size of their antenna...?

    Vielen Dank !


    G0TKZ

  • Here ~39 dB SNR @150cm PFA.

    Edit: Zoom level (sdr-console) a tad below mid , meaning i see the entire transponder on my screen . If i zoom in totally, SNR goes up to 50dB. Zoomed out totally, SNR is 42dB. Bandwith of my RTL-dongle is 2.048MHz.

    73, Martin

  • Hallo,

    please don't compare levels shown by the Console without looking to the zoom of the spectrum. The level is changing dramatically while zooming. The IS0GRB receiver shows approx. 18dB SNR of the beacons. It seems to be realistic. To compare dishes or receiving situations it's more useful to look to the basic noise floor of the transponder. If this is above the LNB noise all is ok. No further improvement is possible. It is good for dish adjustment also. Because of the unknown LNB gain, S-Units as absolute levels say nothing. Very often discussed but hard to do.... I've forgotten to talk about the bandwith of the receiver. 2,4 KHz is a kind of standard.
    73
    Andreas

  • Hello Andreas,


    I agree the readings of SDR-Console are not precise. Thats why I mentioned having used SDR-Console for the "judgement"
    but I should have rather refrained from ...


    Hello G0TRZ,


    if you see 3dB transponder noise that means that the transponder noise is equal to your receiver noise

    (1/2 the noise is coming from the satellite, 1/2 the noise is coming from your receive system).


    With your 85cm dish you might get up to 3dB transponder noise (max. 4dB).


    Kind regards


    Matthias


    http://www.dd1us.de