Posts by G0MJW

    Regrettably Andreas is right, it really is nearly all of them. The safe assumption is to assume there is a spike and take measures to prevent that being a problem. Otherwise you will keep the pre-amp suppliers happy with repeat business.


    Mike

    It is an approximation to the level of signal above the noise. To improve it, improve your receiver. Bigger dish, better LNB. Compare with others to make sure your setup is operating effectively. You will need a large dish for DATV, at least 80cm and preferably 1.2m.


    Mike

    Indeed - what would be good would be a IC705 with just a few milliwatts output and fully duplex and full coverage. Not impossible. Several SDRs already do that, they just lack the filter banks and integrated computer that generates the look and feel of a traditional radio. Then a bolt on amplifier would allow whatever was needed, from 1mW to 1kW. This will be an unpopular statement but I think the IC-705 is disappointing. The fact it can't do duplex means it is essential to have a second RX for the linear satellites. Even if Icom don't produce an update we can be sure someone in China will and it will be considerably cheaper with "good enough" performance for most people and yet bad enough performance to annoy VHF weak signal operators. Icom missed an opportunity, let's hope they fix it.


    So to the point. There has been several times now "I know my frequency comments". We don't have to just know our frequency but also our power and if not listening or looking at the waterfall of the downlink how do we know if we are not too low or too high power? I can imagine "I know my power" comments. Well, evidence seems to suggest far too many clearly don't know their power and ignore Lila as they don't hear it. Remember, the owner of the transponder probably doesn't care if you drift or have a poor signal, or trample on top of someone else, but they absolutely care when someone sends too much power. Too much too often and it will be switched off. So lets be clear about this. If you are not operating QO-100 duplex, you should not be operating at all, period.


    Mike

    It is really important to actively monitor your downlink, not just to be able too. When I mentioned this in the UK there was a lot of pushback. Out of the bad signals I see, almost none of them are from people using SDRs and almost all of them from people operating simplex. The IC705 is an SDR so hopefully it will be good, but I fail to understand why ICOM did not make the radio duplex! It makes no sense. The IC9700 is almost the same price and must have much in common in its design and is duplex.


    Mike

    Some of these SDRs use sound cards. These are not locked to GPS. An error of 130Hz in a sound card would be - shall we say - disappointing and quite obvious but it's possible. Meanwhile, does anyone know how to gold plate a Lily?

    Thanks to all for the responses. We are in an early stage of the project and your part is only to set up the antenna and RX/TX system. The communication part is done by someone else and we just know that part of it will be a high speed downlink on 13cm. To our calculations we are on the limit with a 2 m dish. So at the moment we are investigating the optimum for this setup regarding dish-size / rotator accuracy and speed / system costs. We also have to account for future developments as this institut will not be able to make a similar investment within the next 10 years.
    Anyway, further informations and reports are welcome.

    In that case, if you intend to use for professional missions I would strongly recommend a much larger dish - or X-band and a proper professional dish mount. They do come up second hand and if you have a mechanical shop then perhaps it could be refurbished. You might want to talk to TU Graz - experts in this area.

    130Hz in 10 GHz? Shocking. Don't think anyone said it was a standard frequency reference, but don't forget to account for Doppler and relativity.

    Hi PY2RN - I tested it last night and it works, but you need to power off the box when not using it or change it's IP as it sends multicast as you discovered. It does seem work with the new patch from M0DTS as H264 and H265. The audio via HDMI works fine for me. Video quality is quite good, not as good as you can get with an Nvidia graphics card encoder, but quite adequate at high bit rates - say above 125kb/s. These are very useful boxes.


    I found when switching between H264/5 and various rates the box crashed on occasion. It recovered but this prompted windows to re-arrange the open windows in that unique and unhelpful way windows is so fond of doing, so beware.


    Mike

    Wait a bit - I have been testing the same thing with issues. They are being worked on. You need to check the force compliant box. Audio via HDMI works for me.


    Mike


    PS, if you don't want the pluto to control the box and use your own settings, simply don't let the pluto know where it is. Configure the box to send UDP to the pluto, it won't know any different.

    What happened with ITU Resolution COM6/19 ? This problem was recognized in 2015 or earlier and should have been addressed at WRC 2019. :(

    Against the odds we were largely successful, due to a huge effort by many, in identifying spectrum for short duration missions. The result was:


    The frequency band 137.025–138 MHz may be used for short-duration missions, if they do not cause harmful interference and if they do not claim protection from other services. In this case, simplified filing procedures apply. For most countries, the coordination requirement Art. 9.21 was removed from the uplink band 148–149.9 MHz which enables it's use for these missions.


    It's not perfect but a good outcome given the circumstances.


    Mike

    I will raise this with my ESA contacts to find out what has really happened.


    Regardless of what the IARU say, they don't have a veto over administrations who will always be able to authorise what they wish. Normally administrations do follow IARU guidance, so for one to not do so, is quite a problem. However, if a university or individual has acted independently here and for example claimed a permission they did not have, that needs to be dealt with appropriately.


    You say 95% of cubesats have nothing to do with amateur radio. That's not really true. More like 95% of cubesats have been enabled to exist through the creativity and work of radio amateurs. It's a sign of the value of amateur radio that such a large market for them now exists and this is evidence that justifies our continued access to these bands more than anything else. In fact, I can't think of any satellite that has not had a radio amateur significantly involved in the mission at some point.


    Mike

    I expect you broke the tiny power chip. It can't be changed. If it is working with USB power via the power connector and USB data via the USB port then count yourself lucky and leave it like that. If not, have a look a the schematic to see how you can bypass it and feed 5V. That might work.


    Mike

    It would be better to make a complaint of interference via your administration - but I am afraid commercial startups are using the amateur bands because they can and it's cheap and their administrations are prepared to accept it, so your argument is really with the country.

    Very many - just google. Andreas Spiess has an excellent series on him getting on to QO100. He is local (as in in the same country) to you as well, Switzerland is not so large but I accept there is the odd mountain between people sometimes that frustrates ham radio contacts.


    Mike