Posts by G0MJW

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    I am completely agree with your opinion for 333ksym DVB-S2 and 100% support this idea and all the people who share this idea !!!

    But we all know that there are still many pensioner among us who want absolutely nothing to do with a computer, they just want to TX a switch to ON, turn ON the camera and send !!

    Translated by google.

    This is exactly what Portsdown is. A transmitter without computer features. It is based on a PI of course but can order an SD card image. All controlled from a touch screen. G8GKQ and his team have developed an incredibly flexible system anyone can use.


    Hi Laurent

    Most of these Ethernet not working problems are due to the USB to Ethernet adaptor, either not being compatible or not getting sufficient power. The problem is adaptors that look identical might not have the same hardware inside. First thing to do is try another and the other thing to do is ensure it is powered and that normally means a Y cable or hub.


    I am not sure I agree. It's the 21st century and DVB-S is 20th century technology and getting old. Such a system might be easy to use but there are not so many wide channels. 1Ms DVB-S requires much higher power than say 333ks DVB-S2 and generating power is the most difficult bit.

    A more modern solution is the BATC Portsdown project. This does all that and much more and arguably does it better because it also does low SR, DVB-S2. H264 and can be made to receive as well. The transmitting hardware is not challenging, a Raspberry PI, a touch screen, a webcam and a Lime Mini. Perhaps we need to translate the instructions into the German language to make this project more accessible.


    We can calculate pretty much exactly what the SNR should be. I don't think we are going to discover anything new here so it's more around helping new users determine how well their equipment is working. In full duplex you optimise your uplink by looking at it's spectrum and making sure it's clean. Regrettably there are many people who were sold black box solutions who frankly have not a clue about how satellites should be operated and because they are incapable of monitoring their own uplink because they decide to use an HF radio as driver they transmit excessive power, splatter all over the place and call off frequency. If the same station is also deaf, they don't see their splatter, but everyone else does. Such is life.

    They are not visible to anyone. You need to work with it under a magnifier. The gain in dexterity with the feedback from the magnification is remarkable. So you can do it. You just need to practice on something less costly first.

    I was sending DATV last night with 15W and a 1m dish. Don't think because you are QRP you can't play. While you can't send 4K video in a 1MS transport stream with such low EIRP you can send perfectly viable video at low symbol rates.


    If you are interested you can look at the models for rain attenuation in ITU-R Recommendation P.837. with specific attenuation described here and its application to satellite links here - I wrote a tutorial a while back - anyway if you look at the maths it's clear why 10 GHz is much more impacted than 2.4 GHz.

    Specific attenuation γ = kRα dB/km where R is the rain rate in mm/hr

    Surely "Full Duplex operation is mandatory" means you should operate full duplex, not simplex, not occasionally checking but always full duplex? The key words here are mandatory and must. Very strong instructive terms. Rules are what they say, not what we might like them to mean, not necessarily even what we intended to mean. You can interpret rules as much as you like but you should obey them as they are written.

    Now what might be open to interpretation is the status of these rules. If they are in guidelines they are not enforceable rules in a legal sense like say the speed limit, but nevertheless everyone is expected to follow them.

    I find hearing myself 1/3 of a second later distracting, so I operate full duplex but with reduced RX volume on TX so while I can still hear myself, it's not quite so distracting. Also an SDR waterfall to check the signal quality and level. I think this meets the guidelines.


    Interesting. I am not sure what an Orange PI is but that's a useful tutorial on how to use gnuradio.

    There is also the option of using an Adlam-Pluto and an Ethernet adaptor. Not sure using a HackRF is a good idea for new designs in 2020, plus you only need one Pluto as it does Duplex and it works out quite a bit cheaper.

    Colin G4EML has developed some software, also Gnuradio based, for the PI that makes a stand alone transceiver, not just for QO-100 but all bands from 4m to 6cm. It's not duplex yet, but can be.

    On a PC Simon's excellent SDRConsole can drive the pluto and several other network based SDRs.

    Thanks Michel

    A useful link. Question still remains what would be better for low rates. The examples assume something like 1 Mb/s whereas we are looking at more like 30-300kb/s. I was testing at 66k earlier and the video was OK but not great - like an 80s VCR on LP. I am sure it is possible to do better. The 333ks is fine but again, perhaps could be improved.


    The box doesn't do very low rates, at least not well - when on my main PC I will send the profile for low bit rates for OBS. I can only find an out of date one from 6 months ago on my archive and there are better ones now


    FFVCustom=preset=slow profile=main10 tier=high level=6.2 rc=cbr_hq


    FFVCustom=profile=main level=4.0 rc=cbr_hq rc-lookahead=10 surfaces=2

    Tomorrow if I remember I will find the newer profile

    It's Tomorrow - or rather was but is now today, or would have been if now was then, whatever...

    The attached seems to work for 66ks 8PSK 5/6 - please ignore the muxer settings which are not right - they are largely ignored by the pluto but matter for other recordings. The important line is the one under video encoder settings. Also not the lower resolution helps, if you want to do good quality full high definition you really need to be using 333ks 3/4 or at least 250k 5/6. It also helps to reduce the frame rate if you can - see the video tab. Keep audio at 32k. OBS Record is used to send the data via UDP to the Pluto.

    Here are settings for 333ks 3/4 I am using this at 1920x1080.

    It's possible to go higher, especially with 8 PSK but 4K video only really benefits from higher bit rates. Static images are fine in 4K but anything moving isn't which undermines the quality. As the transponder is a shared resource high bandwidth needs only to be used when not causing trouble for others. Besides, who want's to see the average ham's mugshot in such high detail?

    Hope this helps.

    Please add better settings if you have them.


    I am using Nvidia. Don't know if there is support for AMD stuff, probably. You set OBS up to record and set appropriate parameters. This is complex. See the BATC magazine and Wiki. What are you setting in OBS?

    An alternative is to use a hardware box like the H264/H2265 encoder that Evariste F5OEO's firmware supports.