Posts by s-band

    SBIRS-Geo 2 is now around 27W.

    WFOV (USA 332) TLEs are available and it's around 25.7E and heading west. Unlike the SBIRS satellites, it's inclination is very small.

    I can't see anything 17.5-20.7G RHCP.

    In my opinion - Nilesat 301 is moving to the east, away from IOT - regarding 12499 at about ~09.2°W

    Agreed, within 0.2 degree. It looks about 0.1 deg high but that's beyond the my position accuracy. N2YO still shows 10.21W using AFSPC TLE

    I left the analyser recording the maximum level for over an hour. The capture shows the peak on 11977MHz V. Most of the time the highest level is around 8dB lower. I'm not sure if the ~35MHz wide signal is transponder noise or a test signal. It looks like noise on CS.


    The signals at 11950 & 12450 are local to me. The 12498 beacon is just visible on the right of the trace.


    The peak CW signal is about 30dB SNR in 50kHz which equates to about 3dB in 25MHz.


      


    I only get indications on the 2 lower TPs as I'm using a linear feed. However, the beacons are now at different levels to those recorded here RE: Beacon Levels & Spectra

    12694.5 is now ~9dB below 12698.5 whereas it was about 6dB above. That was using the same linear feed as the linked plots. I suppose it's possible I did not peak fully for the earlier plots, I don't have real time tracking.


    Latitude 16.7 deg N (47 deg elev.) at the time of this post.

    flie Unfortunately the BWEI LNB has quite poor image rejection and I think you may be seeing image responses. Can you peak the dish on the beacons or their images to check that the signals you see are in the correct position?


    It is strange that you should have many narrow band signals in either the wanted or image bands that you show. It's possible that you have some 13GHz terrestrial links nearby. I have one around 13.15GHz but that looks like DSSS (spread spectrum) and is only 'seen' as noise on CS.


    I peaked on the beacons 12501H & 12501.5V and could not see anything in the band 13.4-13.65G. The odd spikes on the plot are just noise (I checked looking close in on a couple).


     

    Thanks Capitan_Uncino I was looking for this earlier and could not find it since NSSDCA TLE had not been updated. The level is very variable with some fast (<10 second) and some very slow (>30 minute) cycles. It's hard to tell what's going on as it will relate to the TX antenna pattern. However, it does not look stable yet.


    These plots were were close to a maximum (12498MHz = 21.4MHz):


      


    This is a 2k second plot of the IF signal level in 2kHz:



    About an hour after the plot above, the short term variations have reduced but the long term no longer seems to be repeating at the same rate.

    Therefore, if you disassemble the LNB and carefully remove the partition, then without it it will be possible to receive only one linear polarization on both L and R channels simultaneously.

    Ah, yes, my mistake, I should think more clearly before posting. I still had 'squeezed pipe' polariser in my mind. Here is a very good article on septum polarisers: http://www.w1ghz.org/antbook/conf/SEPTUM.pdf


    This is the septum from an AN8024 ODU:



    It rotates through 180 degrees to set the polarisation. The TX guide feeds one side and RX the other. This is the WG output:


    Is it possible to modify this lnbf to linear polarization?

    If it is the same design as their Saorsat band B LNB, then it will have a septum plate. The picture shows one which had the feed removed. I would not recommend the Saorsat LNB as there are much better options unless you want upper band B circular. Note that Saorsat itself on 9E has a very tight beam covering only Eire, some of NI and a small part of western England/Wales.


    The plate is part of the casting and could be removed with care but the electronics should be removed first.