Posts by s-band

    Very impressive, s-band, finding SR 71. :35:

    I think it was probably SR = 66 but it did not stay up for long enough to lock. I have no doubt it would have locked but it needs a fair bit of tweaking and a few re-scans to get the lower SRs. That is one problem with the software, the first guess is usually a bit off.

    Whist the Serit tuner has the same chip set as the 6903 etc, the software does not appear to be able to do much with GS. It will lock to a GS stream sometimes but I haven't worked out how to do anything with it. It would not lock to this stream on 7E even though I entered the SR manually. It doesn't display the full parameters, that are available from CS & IQ Monitor, when it does lock. The software is targeted at the ham market, QO-100 and very low SRs in particular.



    One important thing, that's worth mentioning, is that the frequency coverage is wider than the TBS cards at 143-2450MHz (vs 250-~2350MHz using CS). I guess this must be a driver limitation for TBS.

    Here's another test, this time on 16E with the group of 4 radio signals around 11070H. The first picture shows the initial scan where it gets close but does not lock. If left for a few minutes, it might lock one or 2 correctly.



    Clicking on each and leaving for 10-30 seconds, lock is achieved and the details in the right hand panel are updated. It doesn't seem to pick up the channel data on these stations.



    I did a few CS scans and it identified 1 to 3 of the stations. The LNB in use was an Octagon OSLO modified for external reference which was GPSDO locked.

    qwer  strannik Thick cloud here and a wet bag over the feed but here are some results from a beta release of Scan&Tioune using a Minitioner V2.0. It manages to blind scan and separate all signals including 21564. 21576 was just below lock and did not lock on the TBS6983 either. This set-up is great for identifying multiple, closely spaced, low SR, signals. It's a bit flakey but it is an early beta. You have to watch the SR display as it scans as it sometimes hangs on to a wrong value after displaying the correct one. It also gets the station names mixed up sometimes.

    No DX but some interesting features:

    The signals around 21540MHz and 21650MHz are mostly time dependent.

    The large spike 21627 has sawtooth shape. I haven't a clue what it is.

    The transponder noise appears to be visible and covers about 21510-21750MHz. It is surprisingly high considering the low level of most signals.


    Not a hope of getting pictures, especially as there is a leafless tree in the way. However, I can see something. I'm not sure why the individual spectra look the way they do but the processing gain was high and the tree was waving in the wind so treat the result with caution. The noise floor is elevated by about 1.5dB due to tree noise.


    strannik Thank you for the comparison all in one post. I sometimes scan sections in Crazyscan so in the example you showed it identified 8 automatically and 2 manually (21534 & 21564) and missed one all together (21541).


    Signals seem to come and go from this satellite and the relative levels seem quite variable. Tonight 21534 was not on. Here is the CS scan and a spectrum. CS identified 8/10 and still missed 21564 in the auto-scan.


    I must try IQMonitor again!


    I was having problems with a Gilat Ka band D LNB which I had modified to use with an external reference. I was using a reasonable signal generator at Flo/256 locked to a GPSDO as the reference. However, the constellation plots showed significant phase noise. Ignoring any synthesiser noise addition, the phase noise increases with frequency multiplication by 20 log10 (N) dB where N is multiplication factor. I changed the division ratio in the Gilat synthesiser from 64 to 16 (the mixer doubles again so the actual multiplication is twice those figures). The reference is now 625MHz for a 20GHz LO. The constellations show the reduction in spreading and improvement in SNR and BER on 16E, 21538H, 8PSK 1054ks/s.



    In this plot, the magenta trace is before mods (/64) and blue is after the mods (/16). It's hard to read accurately on that plot but the improvement is about 12dB


    I didn't know where this belongs but there are a lot of data sigs so it's here. The transponder bands show clearly. The beacon on 21402 is also visible.


    flie I have not seen that one before but it includes a DVB-T demodulator so may not be able to output the IQ stream needed. The best RTL sticks are the RTL2832 with R820 or R860 front end chip. THere's a list here which includes other variants: https://osmocom.org/projects/rtl-sdr/wiki/Rtl-sdr

    Try here https://www.ebay.co.uk/sch/i.html?&_nkw=rtl+sdr

    There were problems with some R820 chips which had a restricted upper frequency range. Take a look here for more info and background https://www.rtl-sdr.com/


    I think that the best value SDR is the ADALM-Pluto but the price has increased a lot since it's launch.

    Hi flie It is a little confusing. I think the improvements mentioned refer to version 2.1 which was to be released mid-December. v2.0.21 is the one I was using and it does not have the extra features it also has a problem with DVB-S1 that I found. It doesn't look like the author has been back to the Amsat-DL forum since the end of November.