Posts by G0MJW

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?

Quote from OE3GBB

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.

You should be using 10m dishes on s-band. This is to allow for the many missions there are to co-exist. Narrow beams are necessary. Amateur S-band is different of course.

I am sure he knows. I will ask next time. The reasons for these errors are probably interesting and subtle.

See http://g4jnt.com/QO100_Stab.pdf

Quote from DJ0VL

Hi all,

Half a year later, the issue remains unchanged. The Goonhilly WebSDR now seems to be off by around 130Hz. Apart from the offset, there is a visible jitter of quite a few Hz.

The screenshot below shows the same audio signal as received simultaneously by the Brazil WebSDR (trace at the left side), the Goonhilly WebSDR (trace at the right side) and by my own receiver (trace at 762Hz).

The Brazil WebSDR (http://appr.org.br:8902/) is shown just for comparison as Thomas mentioned it above and I guess it uses a simple TCXO as a reference. Both offset and drift are heavily dependent on the time of day.

73 Jean DJ0VL

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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.

Quote from HB9SKA

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

Oh dear.

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's a still from a broadcast made this afternoon for several hours on QO100 DATV transponder. Copyright material. Music.

I wonder what we need to do about people persistently violating copyright and amateur regulations? It's true it is not doing any harm, that is until some administration perhaps not so supportive of amateur radio objects and we are taken off air permanently.

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

Quote from hb9hci

Thank you for your helpful contributions.

Ok - so feed back to BaMaTEch and I back to the start: What would you recommend as an inexpensive dual feed with an integrated Dow converter?

The intermediate frequency is not critical: beginning and end is an ADALM-Pluto,

There is no such thing - you have to do some work I am afraid. QO-100 is not plug and play. I think there is a German ham selling already converted LNBs and several selling feeds of various designs, including Hans http://www.hybridpretender.nl/ and of course BaMaTech. There is also the AMSAT DL transverter and hardware from Khune but it would fail the inexpensive test to go that way.

Incidentally, you don't actually have to convert the LNB at all, you can just use a standard PLL LNB and an SDR. SDRConsole software will lock to the beacon keeping the frequency stable.

Mike

Yes I saw that. Very interesting and why not as it is open source. However, unless it's an Analog Devices unit it should not have their logo on it.

I don't see a GPIO connector. It's a pity they didn't take the opportunity to provide a proper 5V input.

I took the risk on the original pluto ordering it will in advance of release. Someone else's turn to be guinea pig.

Mike

Quote from DJ7TH

If you want to use the ADALM-PLUTO DATV controller to set the parameters of the Pluto, you have to send the OBS data to the Pluto via UDP stream. Above you can see what has to be entered in OBD under "Output" "Recording". But what do you have to enter under "Stream" in the line "Server" and "Stream Key"?

In my case nothing because I am not using streaming or recording. I am using the virtual webcam output and converting that with ffmpeg in a batch file.

Mike

Quote from PA3FYM

[user = '533'] SM7PNV [/ user] Those LNB's have been found months / years ago; -) (and also in use at several QO-100 stations & locked to GPS etc.)

Point is, most fora don't have 'a memory' (it's more like a labyrinth), so everyone starts his own thread and invents his wheel: -)

But this is useful - we would not want to forget how to make wheels.

Try tuning to the 10 GHz frequency. I suspect it is fine but you are tuned still to the IF. I.e. enter a 10 GHz frequency.