Last night I went outside with my tape measure antenna and attempted to receive the 2-meter downlink of the AO-92 amateur radio satellite, was I successful? have a look in the video attached and find out.
73 de M0WNU
Ban PLT
Showing posts with label satellite. Show all posts
Showing posts with label satellite. Show all posts
Friday, 7 August 2020
Saturday, 10 August 2019
setting up receive for QO-100 at my QTH
The Es'hail-2 geostationary satellite, the first of its kind to carry an Amateur radio payload, designated QO-100, has been in orbit for some time now, and I listen to it now and again on the BATC WebSDR hosted at Goonhilly Earth Station in Cornwall and have got a rough idea of when it is active, I've had a look at how to receive it and it would appear it can be received with a Sky UK 60cm Minidish and LNB connected into the RTL-SDR, however the RTL-SDRs that can power accessories on the coax only can do so with 5v, a satellite LNB requires either 12v or 18v, the polarisation is selected using these two voltages, 12v for vertical, for the narrowband transponder, which I am interested in here, 18v for horizontal, this calls for a Bias-t which essentially supplies voltage to an accessory up the coax however at the same time prevents that voltage going into the receiver (or transceiver in some cases), a Bias-t simply has a capacitor to block voltage and an inductor to block RF).
LNBs generally have a LO of 9.75 GHz unless a tone is fed to them as well, which is not required for QO-100 as the 9.75 GHz LO is suitable, the downlink frequencies being around 10.4 GHz (though generally these LNBs specify a minimum frequency of 10.7 GHz), so on the RTL-SDR for me to receive the narrowband transponder requires me to take it's frequency of 10489MHz and deduct 9750MHz, this should be around 739MHz.
As I already have an LNB, which is designed for an oval shaped dish, the Sky UK Minidish, the biggest size they are in is 60cm for the north of the country is what I need, though there is a dish and LNB already on the building for my flat I cannot use this as it needs to stay set for the Astra 2 Satellites used for Sky UK and Freesat, so I need to buy another dish and this is what I had in mind as the LNB I have, a quad-output Visiblewave unit with Sky branding on the sticker, will fit this with no modification, this gives me an option to receive both transponders as the unit had a length of twin cable terminated in F male connectors, which I intend to splice and fit a Bias-T inline for each, powered at 12V and 18V respectively, however I'd need two RTL-SDRs of good quality, the NooElec NESDR SMArt is a perfect choice as it is more frequency stable than the standard stick, as reference I'll use the Goonhilly hosted WebSDR to ensure things are on frequency, LNB skew and dish alignment is obtainable from BATC.
There should be a YouTube video of my success (or failure) of receiving QO-100 with a Sky Minidish, nice to experiment with, if not I've got a portable satellite dish to take camping with me for television use.
73 de 2E0EIJ
LNBs generally have a LO of 9.75 GHz unless a tone is fed to them as well, which is not required for QO-100 as the 9.75 GHz LO is suitable, the downlink frequencies being around 10.4 GHz (though generally these LNBs specify a minimum frequency of 10.7 GHz), so on the RTL-SDR for me to receive the narrowband transponder requires me to take it's frequency of 10489MHz and deduct 9750MHz, this should be around 739MHz.
As I already have an LNB, which is designed for an oval shaped dish, the Sky UK Minidish, the biggest size they are in is 60cm for the north of the country is what I need, though there is a dish and LNB already on the building for my flat I cannot use this as it needs to stay set for the Astra 2 Satellites used for Sky UK and Freesat, so I need to buy another dish and this is what I had in mind as the LNB I have, a quad-output Visiblewave unit with Sky branding on the sticker, will fit this with no modification, this gives me an option to receive both transponders as the unit had a length of twin cable terminated in F male connectors, which I intend to splice and fit a Bias-T inline for each, powered at 12V and 18V respectively, however I'd need two RTL-SDRs of good quality, the NooElec NESDR SMArt is a perfect choice as it is more frequency stable than the standard stick, as reference I'll use the Goonhilly hosted WebSDR to ensure things are on frequency, LNB skew and dish alignment is obtainable from BATC.
There should be a YouTube video of my success (or failure) of receiving QO-100 with a Sky Minidish, nice to experiment with, if not I've got a portable satellite dish to take camping with me for television use.
73 de 2E0EIJ
Sunday, 17 February 2019
ISS SSTV - 15th to 17th February 2019
Yesterday I stumbled, merely by chance, on what I thought might be a potential SSTV transmission from the International Space Station, which I did tweet about, confirmed by Trevor M5AKA, and I had a look on the Amsat UK website, my home shack radio for 2-meters is still the QYT KT-8900D and the antenna is currently just the 2/70 TX capable magnetic mount scanner antenna, with rubbish thin coax feeding it, on top of a radiator by the window and received the ISS no problem at all.
Today knowing about this, I was able to decode it, thanks to Carl 2E0EZT who mentioned the Robot36 SSTV app in one of his videos on YouTube (a channel I ended up finding out about thanks to Callum M0MCX of DX Commander fame so both are being credited for this), using nothing more than my phone's inbuilt microphone I was able to decode an image from the ISS when it passed over between 1350 and 1400UTC, my first successful attempt at SSTV rx from the ISS, and pleased is an understatement.
When I initially stumbled on the transmission yesterday purely by chance I had mounted the radio onto something to allow air to circulate around it, and also allow it to be raised a little higher, I have the ISS and a few local repeaters along with both 2-meters and 70cm simplex channels all programmed into the radio, and was turning the dial when I heard the transmission, bearing in mind I was unaware that the ISS was overhead at that time so it really was just luck, and on tweeting about it I got my confirmation.
Though I do plan to do some ATV (Fast Scan) I have for a while wanted to play with SSTV but lacked facilities, turns out to receive it all I need is a mobile phone, perhaps the same to TX it too? we'll see
And this is a screencap from Robot36 of what I received today
Today knowing about this, I was able to decode it, thanks to Carl 2E0EZT who mentioned the Robot36 SSTV app in one of his videos on YouTube (a channel I ended up finding out about thanks to Callum M0MCX of DX Commander fame so both are being credited for this), using nothing more than my phone's inbuilt microphone I was able to decode an image from the ISS when it passed over between 1350 and 1400UTC, my first successful attempt at SSTV rx from the ISS, and pleased is an understatement.
When I initially stumbled on the transmission yesterday purely by chance I had mounted the radio onto something to allow air to circulate around it, and also allow it to be raised a little higher, I have the ISS and a few local repeaters along with both 2-meters and 70cm simplex channels all programmed into the radio, and was turning the dial when I heard the transmission, bearing in mind I was unaware that the ISS was overhead at that time so it really was just luck, and on tweeting about it I got my confirmation.
Though I do plan to do some ATV (Fast Scan) I have for a while wanted to play with SSTV but lacked facilities, turns out to receive it all I need is a mobile phone, perhaps the same to TX it too? we'll see
And this is a screencap from Robot36 of what I received today
Not too bad for a first attempt and with equipment that is certainly not the best.
A good reason to get into the hobby, you aren't limited to receiving communications from stations here on good ol' planet Earth, the challenge with the ISS is, of course, knowing when the astronauts are on air and knowing when it will be passing over, and normally you only have a window of a few minutes. in my case it was 10 minutes and I made that count to receive the SSTV image here.
In some cases it is possible to talk to the astronauts but during this weekend the ISS 2-meter station was being used for SSTV so that would not have been possible.
73 de 2E0EIJ
Sunday, 11 December 2016
Amateur satellite
After watching a segment of episode 12 of TX Factor about operating through satellites I thought I would give this a go myself as all I need to do this is a suitable dual-band HT, as all mine are Chinese one would think they wouldn't be suited, as they can do what the offerings from the big names can do then they are fine for the purpose.
The satellite I am interested in, and as noted on the TX Factor episode referred to above, is SO-50, as it has an FM transponder, with uplink on 2-metres and downlink on 70cm, as it would be massively impractical to use the -600kHz split on a satellite due to the size of the cavity filters used at 2-meter repeater sites that achieve this so the signal goes up on 2-metres and comes back down on 70cm, but it isn't that straightforward as the Doppler effect has to be compensated for, programming the HT with the frequencies for the satellite beforehand will save you trouble here, the frequencies for SO-50 and other Amateur satellites are available on the Internet.
Knowing when the satellite is to pass is another thing you need to know, I have already gone ahead and downloaded two pieces of software for this purpose, on my Android phone I have AmsatDroid Free, and for my laptop I have Orbitron, the latter software being mentioned in the same TX Factor episode noted above, and this runs fine on Windows 10, so now I know where SO-50 is at any given time the next bit requires I be able to transmit from my HT through the satellite and my HT's rubber duck antenna simply will not do, for this a Yagi is the best antenna to use, but it needs to be of a design that will work on both bands, the most popular antenna appears to be the "Arrow" antenna, the original of which is actually made from arrows for the antenna elements, and because we're doing cross-band operation we also need a diplexer (this is correct, it is not "duplexer"), which from what I can tell is simply two passband filters, one high-pass for 70cm and one low-pass for 2-metres.
The Arrow antennas are not cheap, so in the spirit of Amateur radio it makes perfect sense to build one using bits from the junk box, and from a DIY store (B & Q in my case as it is the closest one to the home QTH), and I like to build rather than buy antennas where I can to save money, and considering that one may simply use their arm to move the antenna with the satellite it needs to be lightweight, wood for the boom would work well here, but if you do use wood it should be varnished to protect it should you be out on that hilltop and the heavens open, waterproofing the coax connections is also advised.
Once you have all the information regarding your chosen satellite, an antenna, a programmed HT, go out and make some contacts, but be aware that satellite QSOs through SO-50 are similar to contesting, usually callsign, location (locator square) and signal reports as the satellite passes for a short duration and is often very busy, listening before keying up is well advised, as is the use of headphones so you can hear the satellite better, also run the radio with an open squelch.
As a foundation license holder I am restricted to 10 watts, as is anyone with a foundation licence, antenna gain may push your actual radiated power beyond this level so dropping the radio to a lower power setting may keep the foundation licencee within their power limits and still legally use the satellite, gain and other such factors are beyond the scope of this blog, and from what I understand SO-50 doesn't need more than 10 watts anyway into it and by the time the signal gets there it probably falls well below that.
Having a second person on hand to assist with the operation may also be a good thing, as they are not transmitting they do not need to be licensed, adding a second pair of headphones for the assistant to help with logging may be a good thing too, the assistant can also help position the antenna leaving you free to carry out the QSOs.
And finally, building the antenna simply requires a search on Google as there is a lot of information on the subject and many designs are available, and you could further this and build the diplexer as commercial ones are about £30+ depending on where you go, and you get the pleasure of building the entire thing yourself if you do, and save money.
I look forward to working some stations through a satellite very soon, just got to get the festive season out of the way first.
73 de M6RSQ
The satellite I am interested in, and as noted on the TX Factor episode referred to above, is SO-50, as it has an FM transponder, with uplink on 2-metres and downlink on 70cm, as it would be massively impractical to use the -600kHz split on a satellite due to the size of the cavity filters used at 2-meter repeater sites that achieve this so the signal goes up on 2-metres and comes back down on 70cm, but it isn't that straightforward as the Doppler effect has to be compensated for, programming the HT with the frequencies for the satellite beforehand will save you trouble here, the frequencies for SO-50 and other Amateur satellites are available on the Internet.
Knowing when the satellite is to pass is another thing you need to know, I have already gone ahead and downloaded two pieces of software for this purpose, on my Android phone I have AmsatDroid Free, and for my laptop I have Orbitron, the latter software being mentioned in the same TX Factor episode noted above, and this runs fine on Windows 10, so now I know where SO-50 is at any given time the next bit requires I be able to transmit from my HT through the satellite and my HT's rubber duck antenna simply will not do, for this a Yagi is the best antenna to use, but it needs to be of a design that will work on both bands, the most popular antenna appears to be the "Arrow" antenna, the original of which is actually made from arrows for the antenna elements, and because we're doing cross-band operation we also need a diplexer (this is correct, it is not "duplexer"), which from what I can tell is simply two passband filters, one high-pass for 70cm and one low-pass for 2-metres.
The Arrow antennas are not cheap, so in the spirit of Amateur radio it makes perfect sense to build one using bits from the junk box, and from a DIY store (B & Q in my case as it is the closest one to the home QTH), and I like to build rather than buy antennas where I can to save money, and considering that one may simply use their arm to move the antenna with the satellite it needs to be lightweight, wood for the boom would work well here, but if you do use wood it should be varnished to protect it should you be out on that hilltop and the heavens open, waterproofing the coax connections is also advised.
Once you have all the information regarding your chosen satellite, an antenna, a programmed HT, go out and make some contacts, but be aware that satellite QSOs through SO-50 are similar to contesting, usually callsign, location (locator square) and signal reports as the satellite passes for a short duration and is often very busy, listening before keying up is well advised, as is the use of headphones so you can hear the satellite better, also run the radio with an open squelch.
As a foundation license holder I am restricted to 10 watts, as is anyone with a foundation licence, antenna gain may push your actual radiated power beyond this level so dropping the radio to a lower power setting may keep the foundation licencee within their power limits and still legally use the satellite, gain and other such factors are beyond the scope of this blog, and from what I understand SO-50 doesn't need more than 10 watts anyway into it and by the time the signal gets there it probably falls well below that.
Having a second person on hand to assist with the operation may also be a good thing, as they are not transmitting they do not need to be licensed, adding a second pair of headphones for the assistant to help with logging may be a good thing too, the assistant can also help position the antenna leaving you free to carry out the QSOs.
And finally, building the antenna simply requires a search on Google as there is a lot of information on the subject and many designs are available, and you could further this and build the diplexer as commercial ones are about £30+ depending on where you go, and you get the pleasure of building the entire thing yourself if you do, and save money.
I look forward to working some stations through a satellite very soon, just got to get the festive season out of the way first.
73 de M6RSQ
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