Posts by pe1chl

    No, that won't work, because the station that triggers LEILA won't even hear the LEILA. And afaik this LEILA system used on Eshail'2 is passive! That means that users *must* listen to their own downlink - running simplex would be outrageous ;-)

    Yes that is the issue. Some users decide not to abide by the regulations or recommendations, even when it comes down to something simple like "use your callsign as a username on the forum". Let alone to "only use fullduplex capable equipment on the satellite".

    What can we expect when it is recommended to them to use less power? They could just choose to "agree to disagree" and continue.

    However, we can assume that it will not be as bad as on the local 2m or 70cm repeater, because there at least is some effort to make to be on the satellite, not just "order a Baofeng at Aliexpress".


    Still, to remain ontopic, we have to be careful because we do not yet know the performance of the transponder when in full normal use, but the first tests indicate that we do not need to worry about "being able to receive it even with some de-sensing". If anything, the users of those huge dishes should worry about intermod in their frontend :-)

    Then LEILA comes to play :P

    But this makes the situation only worse... by adding more power.

    We have to hope that stations are cooperative and reduce the power even when they cannot hear themselves (e.g. because the QSO peer recommends it).

    Not exactly correct as I remember it.


    AO-40 also had a 2.4GHz receiver that was used a few times.

    Of course it had receivers and transmitters on every VHF and higher band, but after the major failure it was mainly used in L/S mode (23 up 13 down) so most people had 13cm downlink only. I had a G0MRF converter that was only for receive.

    (and no uplink equipment on 23 so I never worked over it)

    Honestly, did you ever hear so called alligators on L/S mode AO-40? at least DK2ZF never. 1269 MHz was hard to reach for most of the people in 2002

    No, I didn't, but it has changed quite a lot over those years. We will have to wait and see what happens.

    But anyhow, the level of a single station is of course a bit difficult to derive from the tests that they did. I saw both tests where they saturated the transponder and were very very strong, and tests which likely were at the normal operating point, where I could see the noisefloor of the transponder very clearly above the noise of my receiver (15-20dB).

    As long as that remains the case, we should not be to worried about receive performance.

    I never was able to achieve such performance on Oscar 10 and 13 with my "small" system (3m crossed yagis on 2m and 70cm) so I was more in danger of being an alligator because of not hearing enough (but I did not have much uplink power either).

    The main danger are the stations that cannot hear themselves (for whatever reason) and overdrive the transponder without knowing it.

    I guess we'll get a lot of experience with this once the transponder comes on.

    When the transponder was on the weekend before christmas, it was very very strong... we'll have to see how it will be when there are 50 users talking at the same time, and what it will be for "weak stations" when the "alligators" are cranking up the AGC, but it looked a lot like there will be no receive issues at all.

    Yes indeed, as I mentioned I also used the W3IWI "BASIC Orbits" program and modified it a lot, mainly to change it from a "prediction" type program into a "continuous tracking" program. I have made a version that showed the position of 9 satellites on screen simultaneously and then could track any one of them. Even automatically, so I could track a number of packet satellites using a priority list.

    Indeed a lot of typing from listings was going on back then, although I think I have not typed this particular program but received it on cassette from Eindhoven.

    I bought my TRS-80 in 1980 (easy to remember) but after initially starting with cassette tape (I even wrote an alternative loader that used a higher baudrate) I soon used floppies. My friends at the local club had systems with floppies and it was so much more convenient. Luckily I had another friend who had surplus floppy drives and diskettes and the only problem was they were 8". So I made a floppy controller that could support 8" (double the clock of 5") and used them. As I also needed a 5" drive to be able to swap programs with friends, I bought one Teac FD-55B. I still have the bill. Over 1000 guilders (or about 475 euro) in that time. But ready made drives with powersupply and enclosure from Tandy were about 1700 guilders. and those were single-sided while mine was double-sided. Well :-)

    Rene,


    As you already quoted and I also wrote before: the main effect is not signal strength of the wanted signal, but the attenuation of the opposite polarization.

    Some satellites have different transponders on H and V on the same frequency, and then it is somewhat important that you do not receive the V transponder when you have selected H polarization.

    So you look for the "null" in reception in H setting of a very strong V signal.

    But the strength of the wanted signal does not really vary much when you are off by like 15 degrees.

    The amateur transponder operates on non-overlapping frequencies for H and V, so this will not be very important.

    Of course by the time the skew is 65 degrees as in Brazil, it does become important.

    Ah that is a very interesting story to read Peter! Now we know how you became involved with AMSAT-DL :-)

    At that time I did not have a 400bps decoder, I only listened to the characteristic sound of the telemetry to align the antennas etc. And of course I was QRV on Oscar 10 a lot.

    I have only very few photos from that time, and they are all on negative and paper. I should scan them sometime, let's dig through the old photo boxes. But my shack looked similar to what I0LYL posted :-)

    (with other types of equipment)


    My involvement with satellites came mainly through knowing some people in Eindhoven who were also active in a local information roundtable led by Nico PA0DLO. So I became interested in that and we went to the colloquium etc.

    Nico is still very active in determination of object numbers of newly launched satellites, and he still has this roundtable on 2 meters but I no longer have the suitable antennas to be able to receive and join it.

    (that was possible with my AZ/EL rotated 2m and 70cm crossed yagi pair, but now I have only an omni)

    Those were the days :-)

    I left out my 8-bit times, but this was a little after that Altair system.

    I played with a couple of 6802 and 6502 evaluation boards, the kind of A4-sized PCB with a hex keyboard and 7-segment display and a monitor program in ROM, e.g. during internship at the TELEX exchange at our telecom company and at Philips, but my first own 8-bitter was a 4KB TRS-80 model 1 that I extensively upgraded and modified with homebrew boards using the same techniques :-)

    It was built up with 64K RAM, a SD/DD 5"/8" floppy controller (I had 3 surplus 8" floppy drives and two 5" drives I bought new), graphics, and in the end even a 5MB harddisk with SASI controller. It could run CP/M 80 2.2 besides the standard TRS-80 OS.

    Like you I spent thousands of guilders (~DM) on that :-)

    I programmed it mainly in Z80 assembler (as that was the only way to get some performance out of it), e.g. wrote a monitor program, the BIOS and even a command processor extension for CP/M that used overlays just like the original TRS-80 OS.

    With the Atari ST the fun was also in the homebrewing, I also built a harddisk interface for that (before Atari had it available in the shops) and then the Z8530 SCC interface for packet radio that I also used with the PACSATs and UoSATs (with G3RUH 9k6 and PSK 1k2 modem).

    (I wrote my own software for the PACSAT broadcast and file transfer protocols and automated my entire station to do all the tracking, uploading and downloading without me having to touch anything, much to the dismay of some users of the "official" software who always found me connected even at 02:00 before they could press their connect button...)

    This software was used for some time by the BBS systems that forwarded their bulletins via the satellite.

    But I did also an implementation of NET/ROM (after TheNET of course) on the Atari ST as part of KA9Q NET. All that software I could cross-compile for MS-DOS so others with a PC clone could use it as well, and a local amateur PA0HZP developed a Z8530 card for ISA bus and sold a lot of kits. Some others made similar cards. Most packet nodes and BBSes here used this setup.

    Those were fun times, but for me the computing really became interesting when I got my Linux system running and suddenly it was not a 1-program-at-a-time thing anymore. Before that, I had two Atari ST systems at home, one for running the amateur radio system (with a TRS-80 mini color computer, later an EPSON PX-8 alongside to run the W3IWI tracking program) and another one to do development. With Linux this was no longer required and everything, packet, tracking, BBS, and development, by then also internet browsing/mail etc, ran on one single system. But not so much homebrewing anymore, just standard PC hardware with some oddities attached via serial ports. E.g. the rotator via an AMSAT-DL tracking interface controlled via RTS and DTR of a serial port :-)

    The other systems more and more became relics that I never discarded because they had cost so much money, but are no longer in use. I still have most of it in storage boxes...

    You can twist it for optimal signal or for minimum signal on the opposite polarization. Not on the beacon signals because they are RHCP.

    I am not a fan of those "calculate the number of degrees" solutions (also for the direction) because it is so difficult to then set the thing to exactly that number of degrees... in my case the dish is on a rotor so I set the LNB vertical when the dish is pointing south (satellite position 5e) and the only skew I use is that caused by the rotation around the tilted axis used by the rotor to track the geo belt.

    I think that is not completely optimal, but the signal loss is not much. If anything, there would be more crosstalk from the other polarization.

    With my 3m dish i can just rx es'hail 1 transponder....

    That does not surprise me... with my 80cm I cannot receive it at all.

    At 26e I do receive a couple of transponders on Badr but these are on a European beam ('BSS') not the MENA or Africa beams of those satellites.

    As Es'hail-2 has only MENA beam according to their website, I do not expect to receive it at all (on DVB).

    Apparently the beacons are on a wider beam. And of course, so is the AMSAT transponder.

    I think the signal looks not so bad…. but the question is how strong will be the signals from the AMSAT transponder ??


    Are there any information available compared with the present beacon signals we see ??

    When the transponders were tested (the weekend before christmas) the signals were 10-20dB stronger here than the beacons at that time. Of course, as DB2OS explained, that does not tell the whole story as the patterns are different and also different patterns have been used on the beacons.

    However, it does not look like there will be receive issues.

    The next question of course is: what will the situation be on the uplink. We do not know yet.


    defintely not, Dec. 31st 23:28UTC on 25.88E now moved back to 25.72 and now again around 25 .80. Seems that Sat is looking for the right parking slot. 10.706 GHz is 20dB SNR

    I can confirm it is not (yet) at 26e but slightly west of it (2 clicks on my H2H rotor).

    Reception of 10.706 when pointing to 26e is becoming worse due to the noise from Astra2 at 28.2e DVB-S signals that are very strong here (probably a lot less in countries further away from UK).

    I even see an increased noise level on the amateur transponder frequency when pointing to 28.2e and dropping off around the position where Es'hail-2 is now.

    (not very much, and below the noise from the transponder I have seen before, so likely nothing to worry about)

    As Es'hail-1 is at 25.5e and there is no clear statement about the Es'hail-2 position on their website ("the 25.5e/26e slot") does anyone know if it in fact will be at 26e or at 25.5e?

    Does not really matter for the TV viewer but may give just a little more protection from Astra2.

    At my location (GG56tv, southern Brazil), the EB signal intensity on 10.706 GHz slowly dropped over the last few days. Today it is about 10 dB weaker than last Friday. My antenna is pointed at 24E. Tomorrow I will try realigning the antenna.

    The satellite has moved quite a lot the last two days! It is closing in on its final position. I have to choose a different pointing as well now.

    Is anyone aware of "standard crystal frequencies" in the 23.7-23.82 region that could be suitable for use?

    I have been searching for "stock" crystals but there does not appear to be anything in that area. 24 MHz is of course easy to get, but a bit lower would be more suitable.