January 2008 - AMSAT-BB - mailman.amsat.org

Satellite mode on IC-821H
by ka8syx2003＠aol.com 02 Jan '08

02 Jan '08

Hi, Everyone -- Can?anyone who owns and uses an Icom 821H on satellites summarize for me how to put it into Sat mode and operate it in Sat mode?? I've had mine for several months, but have yet to use it for anything but listening to the odd pass of AO-7 or VO-52.? Maybe it's me, but I find the manual almost incomprehensible.? Other brands' documentation doesn't make me scratch my head like Icom's manuals, and the 821H isn't the only piece of gear of theirs I own, so I don't think that I'm just being dense. I also picked up a serial adapter on eBay for the CI-V I/O port on my rig with the idea of using my laptop to make Satscape 2.-something run my Doppler, but the manual is also too cryptic about this for me to figure it out.? Do I run the risk of damaging anything in either the laptop or the rig by just trial and error to figure it all out? Thanks very much! Perplexed, and 73, Ray KA8SYX Jacksonville, FL EM90ee ________________________________________________________________________ More new features than ever. Check out the new AOL Mail ! - http://webmail.aol.com

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Egg beater vs Quadrifilars
by Dave Guimont 02 Jan '08

02 Jan '08

Not to belabor the subject, but I had an RF engineer friend who had access to some very sophisticated signal measuring equipment, and we did many actual signal receive comparisons on several satellites...with both antennas Several leos and on AO40. We used coax switching for an immediate comparison, and the quadrifilar was superior.... Easy and inexpensive to build... See quadfilxxxxx on: http://home.san.rr.com/doguimont/uploads With detailed measurements for 2M, 435 and wx satellites....I scaled one for 2.4 gig feed on a 36" dish, and it worked very well, but not sure it was fully illuminated.... 73, Dave, WB6LLO dguimon1(a)san.rr.com Disagree: I learn.... Pulling for P3E...

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ICOM 910H
by Andrew Rich 02 Jan '08

02 Jan '08

Looking at an ICOM 910 H Does it work as two independant radios ? Can I be picking up ISS on 145.825 FM AFSK and also pick up AO-51 on 435.225 MHZ 9k6 ? ---------------------------------------------------------------------------- Andrew Rich VK4TEC vk4tec(a)people.net.au http://www.tech-software.net

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AO7b, FL-Brasil
by Dr. Jay Garlitz 02 Jan '08

02 Jan '08

I finally made an AO7b contact with PY4AJ in grid GH70un. I am on the fringes of the footprint with a few other stations in the south of Brasil/Northern Argentina and will report more success. Others deep in the SE might have a chance as I am in North Central Florida not far from Georgia. Check your coordinates for two observers. E-mail me at drjay(a)gatordental.com for more details. 73, Jay, AA4FL

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Automated station using PERL
by Andrew Rich 02 Jan '08

02 Jan '08

I have made a script that asks predict where GO-32 is. It runs once a second. It works out if it has to turn off the battery charger and engage the radio. The script also uses a file to simulate rotator position (till I get the hardware setup). It makes a diciscion to turn on and off any of 8 relays, hanging off the parrallel port. (Power ON/OFF , Rotator CW/CCW) I figured I have to have some sort of computer controlling the rotators, so push the process control back to the PC instead of the outboard controller. In this case, any old A/D would do for the rotator sense. Next after that will be frequency control. That is the beauty of LINUX, it is a one stop shop. -------------------------------------------------------------- sat_controller.pl ---------------------------------------------------------- ----------------------- #!/usr/bin/perl # # sat_controller.pl # # Andrew Rich VK4TEC - January 2008; # # Turn on and off power to rack and control a rotator # use Socket; my $port = 1210; my ($predict_server, $satellite); while () { open (sat,"/maint/scripts/sat_pwr_control.sat"); while (<sat>) { chop; $satellite = $_; } close (sat); # # Ask predict where the satellite is # $predict_server = "localhost"; my ($d1, $d2, $d3, $d4, $rawserver) = gethostbyname($predict_server); my $serveraddr = pack("Sna4x8", 2, $port, $rawserver); my $prototype = getprotobyname('udp'); socket(SOCKET,2,SOCK_DGRAM,$prototype) || die("No Socket\n"); $| = 1; # no buffering $SIG{ALRM} = \&time_out; #alarm(10); # Force exit if no response from server print "Satellite: $satellite\n"; send(SOCKET, "GET_SAT $satellite\0" , 0 , $serveraddr) or die("UDP send failed $!\n"); my $server_response = ''; # required by recv function recv(SOCKET, $server_response, 100, 0) or die "UDP recv failed $!\n"; my ($name, $lon, $lat, $az, $el, $aos_seconds, $foot) = split /\n/, $server_response; my $aos_time_date = gmtime($aos_seconds); close(SOCKET); print "Azimuth: $az\n"; print "Elevation: $el\n"; # # Work out if we need to power up the rack # if ($el =~ m/-/) { #system ("/maint/scripts/lptout 128"); print "Power Relay: OFF\n"; } else { #system ("/maint/scripts/lptout 64"); print "Power Relay: ON\n"; } # # Turn a rotator # open (rot_pos_file , "/maint/scripts/sat_controller.pos"); while (<rot_pos_file>) { $rotpos = $_; } close (rot_pos); print "ROT_POS: $rotpos\n"; $diff = $rotpos - $az; print "DIFF: $diff\n"; if ($diff > 5) { if ($diff =~ m/-/) { system ("/maint/scripts/lptout 1"); print "MOTOR: CW\n"; $rotpos = $rotpos +5; open (rot_pos , "> /maint/scripts/sat_controller.pos"); print rot_pos $rotpos; close (rot_pos_file); } else { system ("/maint/scripts/lptout 2"); print "MOTOR: CCW\n"; $rotpos = $rotpos -5; open (rot_pos_file , "> /maint/scripts/sat_controller.pos"); print rot_pos_file $rotpos; close (rot_pos_file); } } sleep 1; system ("/maint/scripts/lptout 0"); print "\n"; sleep 1; } sub time_out { die "Server not responding for satellite $satellite\n"; } ---------------------------------------------------------------------------- Andrew Rich VK4TEC vk4tec(a)people.net.au http://www.tech-software.net

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Re: Making your own rotator controller
by Henk, PA3GUO 02 Jan '08

02 Jan '08

Hi Andrew, Not exactly an answer to your question, but still: Some years (~1995..1996) ago I built my own tracker as well. Was the time when the LVB trackers etc were not available. Only the expensive Kansas City tracker (expensive). My system is still operational. Bertus, PE1KEH, wrote in PASCAL the tracking SW (input: kepler, output: sat position). I added to that the controlling of the rotors. All corrections mentioned below (overshoot etc) are done in PASCAL in the PC. That sends and integer value to the ST6 (like your PIC) which does only one thing extra: check if the integer exceeds the allowed maximum right or left position (in case max left is at 4.5V where your range maybe 0..5V). Items to consider next to straight degrees2voltage conversion: - overshoot (when you stop, the rotor actually moved still a tiny bit) - thresholds (to avoid oscillation & to much shaking) 8 bits give enough accuracy, I used a pot.meter to convert the voltage of the rotor voltage from eg 0..20V down to 0..5V. http://home.vianetworks.nl/users/hamoen/pa3guo/zb_rtr_ctrl.html (includes my poor PASCAL routines) Of course it took a terrible amount of effort/time, which I had only back then, so today I would buy an LVB tracker :-) Still - this was one of the most satisfying projects I ever did. Seeying you home-made system following the bright ISS in the darkness of the night is soooo cool ! Have fun & success Henk, PA3GUO http://www.qsl.net/pa3guo

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Re: 70cm Yagi and AO-51
by OZ1MY 01 Jan '08

01 Jan '08

Hi Andrew, That is exactly to be expected. 435.300 MHz is RHCP and 435.150 MHz is LHCP. Happy New Year 73 OZ1MY Ib ----- Original Message ----- From: "Andrew Rich" <vk4tec(a)people.net.au> To: "Amsat-Bb@Amsat. Org" <amsat-bb(a)amsat.org> Sent: Tuesday, January 01, 2008 10:12 AM Subject: [amsat-bb] 70cm Yagi and AO-51 > Gudday > > I tried a crossed offset yagi on the one boom. > > When I threw just one part of the yagi on the boom, AO-51 was really good, > > Now I am finding that with the second yagi on the boom I am seeing a big > drop between 435.300 and 435.150 voice / data. > > I think I might remove the second yagi from the common boom and add it to a > new seperate boom > > Comments ? > > I think I am getting -20db due to the cross polar RHCP LHCP with the data > > The voice is great , the data is down in the mud > > > -------------------------------------------------------------------------- -- > Andrew Rich VK4TEC > vk4tec(a)people.net.au > http://www.tech-software.net > > > _______________________________________________ > Sent via AMSAT-BB(a)amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb >

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Re: 70cm Yagi and AO-51
by OZ1MY 01 Jan '08

01 Jan '08

Hi again Andrew, Comments after your text. 73 OZ1MY Ib ----- Original Message ----- From: "Andrew Rich" <vk4tec(a)people.net.au> To: "OZ1MY" <oz1my(a)privat.dk>; "Amsat-Bb@Amsat. Org" <amsat-bb(a)amsat.org> Sent: Tuesday, January 01, 2008 4:54 PM Subject: Re: [amsat-bb] 70cm Yagi and AO-51 > If I have this correct. > > 1. LHCP recieved on a RHCP can knock your signal down by some 20dB OZ1MY: In theory it will be compleately attenuatet - in practice more like you say. > 2. LHCP matched with LHCP will result in a good signal. OZ1MY: Yes > > So how does a linear antenna equate when receiving a circular signal ? OZ1MY: In theory you loose 3 dB, which is not very much. > > And the other way around, a circular receiving a linear signal ? > OZ1MY: Same as above. > > BUT - all this is theory :-) For AO-51 the attitude of the satellite and the antennas in combination are fairly stabel, 435.300 MHz RHCP and 435.150 MHz LHCP. SO-50 have linear antennas on both up and downlink. In spite of that there can be a large difference between using RHCP and LHCP when listening to the downlink. That is one of the resons for at lot of us to have the possibility to switch between RHCP and LHCP. Even satellites with RHCP antennas may change polarity if the attitude of the satellite is not right. I can send you an article about it if you are interested. > -------------------------------------------------------------------------- -- > Andrew Rich VK4TEC > >

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New year
by CANDEBAT Christophe F1MOJ 01 Jan '08

01 Jan '08

Happy new year to all AMSAT members and all. Be well, be happy, be healthy, and be prosperous in 2008. 73 F1MOJ Christophe AMSAT-France Chairman

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Re: mode J filter / Comet CF416c
by K & R Yoksh 01 Jan '08

01 Jan '08

Thanks for all of the replies, both on and off the list. Happy New Year to all! 73, Kyle Yoksh K0KN Olathe, Kansas

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