Posts by pe1chl

    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.

    I only use a (modified) devcal utility from SvxLink package for calculating drift offset on second SDR stick.


    If i get GQRX working with rtl_tcp server then i only need one SDR stick for all. In the moment GQRX crashes if i want to use rtl_tcp.

    You could try to use SoapySDR as an intermediate between gqrx and rtl_tcp...

    I use this layer as well for my SDRplay RSP1a which is not supported by gqrx but it is supported by SoapySDR.

    (it all sounds a bit magic)

    DB2OS:

    I understand... DualBoot usually isn't the best way to become accustomed to a system, because when you boot Linux you probably are locked out of your information like e-mail, documents, etc (this of course depends on your setup) and it always is just a temporary excursion.

    I am from a Unix background, my first experience with computers was on a PDP11/40 with Unix version 6, and it is like "the normal OS" for me. At home, I had the usual 8-bit stuff and later the 68000-based Atari ST, but I never considered spending money on a PC clone as it ran only MS-DOS which had so much trouble with multitasking and memory management (although I helped lots of people setting up systems with my packet radio software, DesqView and F6FBB BBS, all cross-developed on my Atari ST).

    When Linux came out, this was like a godsend. I built a 486 system with 16MB RAM, high-end for that time, installed it and immediately had a 32-bit multitasking system with demand paging and a graphical window system. Microsoft was very far away from that. I was amazed at what the system could do at that time, after being in development only for a year or so (and of course running many programs that already were written for Unix).

    I ran a phone BBS, a packet radio system (with Z8530 SCC card), and the usual software all on the same system and without spending whole days on managing HIMEM space and debugging nasty crashes due to memory overwriting.


    So for me, Linux is just the natural system to run on my PC and Windows is only an alternative that came later. Of course I had a lot to do with Windows at work but that did not make me want to run it at home.

    When VMware came out (first version), I was very enthusiastic and bought a license and ran some Windows versions as VM (Windows NT4, 95, 2000, XP), mainly for experiments and to run some software only available for Windows.

    However that became less practical once Windows was past XP due to its resource usage on my machine. Today I still use VMware ESXi on server machines both at work and in the amateur network AMPRnet/HAMNET. Our systems on that network are almost all Linux with only an occasional Windows machine for backward things like YAESU Wires-X.


    Of course today Windows is much more stable than when it all started, and you can do a lot of useful things with it. However, now that locally installed software becomes less important and more environments are moving to cloud services with web browsers as the user interface, Linux is becoming more popular again.

    (and of course most people have several Linux systems even when they do not know that...)