Satellites

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STATUS

  • GO-32 - RX at 9600 baud via TS-2K, AWGPE and Orbitron, RX only
  • VO-52 - I was able to hear my CW downlink on VO-52, minimum of 5 watts
  • NO-44 - Decoded packets on NO-44 and my APRS packets were reported via IGATE (found on findu.com)
  • AO-51 - RX FM Voice
  • Software Combo:
    • Ham Radio Deluxe
    • AWGPE - Packet Engine
    • UISS - GUI for sending packets
    • WispDDE - for controlling Rotor
38 27 19.52N   77 24 56.43W
3827.34N       7724.95W

Notes

  • Joined AMSAT mailing list. (Interesting stuff.)
  • AMSAT Web site is nice, but a lot of old news.
  • TS-2000 has an internal TNC (1200/9600) but only one serial port. Either CAT or TNC via serial port, not both. (Menu 55)
  • TS-2000 - use COM1 - DB9F === DB9F - TS2K (i.e. straight through F-F cable, no Null Modem adapter)
  • TS-2000 able to do both 9600 and 1200 baud via ACC2
  • http://www.amsat.org/amsat/archive/amsat-bb/200509/msg00368.html - note about WISP/TS-2K
  • http://issfanclub.com/ - ISS latest status

Usable Satellites

I looked at all the satellites for possibilities. The FM transponders are useless for FD because of the capture affect and so many people are trying to use them. So I'm going to limit the possibilities to Packet and Linear transponders. If a satellite isn't mentioned on this page, it's not operational or only provides telemetry. Information was gleaned from: http://www.amsat.org/amsat-new/satellites/status.php

Probably FD Choices: 1) 9600 baud packet (GO-32) or 2) Linear Transponder (VO-52).

AO-51

Packet - 9600 BPS - schedule varies. So it's risky to rely on this one. I can't tell from the web pages if there is packet operation.

Mode V/U (J) PacSat BBS: Operational
Uplink: 	145.8600 MHz AFSK 9600 BPS
Downlink 	435.1500 MHz AFSK 9600 BPS

FM Repeater, V/US
Uplink: 145.920 MHz FM, NO PL Tone
Downlinks: 435.300 and 2401.200 MHz FM 

2/15/08 - scratch this one. According to a message on one of the ham web pages (eHam,) the BBS is dead. I was able to receive a voice pass this evening. Signals were not super strong, but readable - above about 20 degrees.

2/27/08 - I see more conflicting data. The digital link is supposed to work, but I think it may not be active. I will keep my eye on the AMSAT reports and give this another go. Although, after my good luck with GO-32, I tried listening for the digital downlink on 435.150 and didn't hear anything. The voice link was strong, but it's crowded. Obviously, not the place to be on FD.

NO-44

Packet 1200 BPS - this may be the only usable packet satellite. I was able to decode packets and get my position reported via APRS. Used UISS and AWGPE with the TS-2000 on 145.8270. No Doppler correction.

Mode V APRS: Semi-Operational
Simplex: 	145.8270 MHz AFSK 1200 BPS
 
Mode U/V (B) APRS: Non-Operational
Uplink: 	435.2500 MHz AFSK 1200 BPS
Downlink 	145.8270 MHz FM 1200 BPS

ARISS

Don't count on this one. I think the schedule is too volatile.

Mode V APRS (Worldwide APRS Digipeater): Operational
Simplex: 	145.8250 MHz FM 1200 BPS
Downlink 	145.8250 MHz FM 1200 BPS

GO-32

9600 baud packet - maybe we should try this one. The satellite is operational. It's a PBBS and the want to limit automatic APRS reporting.

Mode V/U (J) APRS (Set Path to be via 4XTECH): Operational
Uplink: 	145.9300 MHz FM 9600 BPS
Downlink 	435.2250 MHz FM 9600 BPS
 
Mode V/U (J) PacSat BBS: Operational
Uplink: 	145.8500 MHz FSK 9600 BPS
Uplink: 	145.8900 MHz FSK 9600 BPS
Downlink 	435.2250 MHz FSK 9600 BPS
Uplink: 	145.9300 MHz FSK 9600 BPS

2/25/08 - FINALLY! Logged a massive number of packets from GO-32 at 9600 baud on 435.225 +/- doppler. I used a square, horizontal loop with a AG-1 ICOM preamp and TS-2K with Internal TNC at 9600 baud. Doppler was corrected by hand (slowly) based on the output from Orbitron. Pass ended around 8:15. Signal strength was as high as +60db. I copied from about 20 degrees through 20 degrees. The pass was to the west. Did not copy packets when signal strength was less than S9. Here is a clip from the pass. TNC had MCOM, MCON, MONITOR and PASSALL set to ON.

4XTECH-12>BEACON <UI R>:>Tue Feb 26 01:09:20 2008 :UTC| Gurwin Techsat1B (V9.87)

4XTECH-12>BEACON <UI R>:BBS(V9.87 beta) 2Users/8BCasts.

4XTECH-12>BEACON <UI R>:Upl:145.89,145.93,1269.8,1269.9

4XTECH-12>BEACON <UI R>::BLN1 GO32:cu APRS!!Use pth via 4XTECH

4XTECH-12>BEACON <UI R>::BLN2 GO32:APRS msgs and clients use 145.85 Upl

4XTECH-12>BEACON <UI R>::BLN3 GO32:D7&D700 posits use 145.93

4XTECH-12>BEACON <UI R>:
4XTECH-12>BBSTAT <UI R>:Open:AB1C23:
4XTECH-12>STATUS <UI R>:>B:61970116
4XTECH-11>PBLIST <UI R>:PB: VE4NSA\D

2/26/08 - Observations, I was able to receive another great string of data tonight. I noted the following:

12 deg - S3
16 deg - S5
20 deg - S7 1st packet
29 deg - S9 More packets
35 deg - S9+20 packets rolling in
52 deg - S9+60 many packets

So I need at least S9... meaning > ~ 25 degrees. The preamp matters.

To solve the doppler, TNC issue on the TS-2K, I tried a combination of AWGPE, Orbitron and WISP. In a late pass, elevation < 20 deg, max signal strength, S8 I received one packet! So it works. I set the TS-2K:

46 - Built in TNC, Sub
47 - Built in TNC, 9600 (shouldn't matter)
48 - TNC BAND, DCD (shouldn't matter)
50A - Packet Filter Bandwidth (no affect on 9600)
50B - AF Input Level (6)
50C - Main Band AF Output Level (9)
50D - Sub Band AF Output Level (6)
50E - External TNC, Main
50F - 9600 baud external TNC
55 - Packet Operations - OFF (Turns off TNC)
Rig was in Satellite mode, 435.225 on VFO A, 145.850 on SubBand.
PTT over subband (Important! Don't blow preamp) CTRL over Main

UISS and AWGPE worked OK for RX! AWGPE = 9600 baud, sound card TNC (Options under KISS to select rate) Use COM5 (RTS) for PTT. In MicroKeyer - set up COM5 for PTT and COM4 as - no radio digital. This allows WISP to use COM4 for control without interference. Audio Mixer tab - none and none for REC MIC and RX/Recording. Used Wave for TX VOICE. Note, I had to increase TX volume in Mixer to make sure there was enough TX volume with the TS-2K in 9600 baud mode. Master and Wave were set at 3/4.

VO-52

The best of the current linear transponder satellites. Listen to the beacon to figure out which transponder is active. Before FD2009, the Indian transponder was on. The beacon is really an unmodulated carrier. Note the AMSAT site lists the Downlink frequency incorrectly for the Indian transponder. (i.e. they have the lowest frequency listed first.) The transponder is inverting, so I listed the downlink as 145.930 to 145.870; high to low. Hopefully, this will eliminate my confusion in the future.

Here is a picture of the antenna configuration for FD 2008. http://picasaweb.google.com/stutwo/HamRadio#5235631387331535858

Mode U/V (B) Linear Transponder (Inverting) (Indian Transponder): Operational
Uplink: 	435.2200 - 435.2800 MHz SSB/CW
Downlink 	145.9300 - 145.8700 MHz SSB/CW
 
Mode U/V (B) Linear Transponder (Inverting) (Dutch Transponder): Operational
Uplink: 	435.2250 - 435.2750 MHz SSB/CW
Downlink 	145.9250 - 145.8750 MHz SSB/CW

Indian transponder - unmodulated carrier on 145.936MHz.
Dutch Transponder - CW message on 145.860MHz.

2/27/08 - Received my signal through the 21:45 pass this evening. Signal was pretty strong. Used CW. RX antenna was my 4 element beam, pointed north (fixed) and TX was the 435 Omni Squares. When the pass was overhead, I was able to reduce power to 5 watts and have a fine signal. The highest signal strength was S-2. I do not have a 2 meter pre-amp installed.

Need to get a better handle on the doppler control. Once I found my downlink, I used the TRACE function and REV function on the TS-2K to move around the band. This works well, as long as you stop every 10-15 seconds and resync.

Question - which frequency should a person adjust RX or TX? At one point, the computer was doing it all for me!

I was able to hear my signal all the way to the horizon. However, I think it may be worth steering a small array, just to give strong signals AOS-LOS.

FO-29

This has a inverting linear transponder, but the signals are much weaker than VO-52. The downlink is on 436 and you really need a preamp. Note - this satellite is NOT available during eclipses.

Mode V/U (J) Linear Transponder (Inverting): Operational
Uplink:  	145.9000 - 146.0000 MHz SSB/CW
Downlink 	435.8000 - 435.9000 MHz SSB/CW

Mode U Beacon: Operational
Downlink 	435.7950 MHz CW

I was able to make a contact through the satellite using my resurrected Texas Potato Smasher and the 4 element 2M beam (pointing North.) Signals were weak and for Field Day, I would want to use a preamp. VO-52 is easier to work, but the uplink/downlink frequencies are reversed from FO-29.

Software

Tracking Programs

I have tried a lot of different tracking programs, so far, these are the best:

  • Nova for Windows - works well, AZ/EL but no doppler
  • Orbitron for Windows - Az/El + Doppler, but no 'Until AOS' Hasn't been updated in a while, but still nice program
  • Ham Radio Deluxe - WOW! It has doppler correction and DDE. So use WispDDE for rotors.
  • gpredict for Linux - simple, works, but no rotor/rig interface yet. Watch this one. I may be able to do the whole ground station on Linux
  • WiSP DDE Client - provides Doppler correction under Orbitron, works well
  • SatPC32 - not free

Packet Programs

Use the sound card! I tried AGWPE and XASTIR (aprs) via a network and it works pretty good.

Was able to do 9600 and 1200 with the AWGPE software. This is the way to go. No TNC required. The TS-2K only has a single serial port. With AWGPE, I can have Orbitron or Ham Radio Deluxe correct for Doppler.

Analysis Software

Hardware

While the ominis worked, they are limited to > 20 degree passes. I will investigate a set of small beams attached to the G-5500.

  • Kenwood TS-2000 - verified for 9600 baud (RX), 1200 baud (RX/TX) and CW (RX/TX)
  • G6LVB tracking interface works.
  • Yaesu G-5500 rotor and controller
  • Antennas
    • Small Yagi in the attic for 2M
    • 432 Omini Squares in the attic
    • 435 Texas Potato Smasher (needs preamp, signals are weak without one)
    • Make a Lindenblad (Sure wish I could find my original paper on the Lindenblad. Search for WD4ECK and you'll see references to the my work. Designed a 50 ohm feed using folded dipoles and a phasing line. Similar to the one at http://www.arrl.org/qst/2007/08/monteiro.pdf)
    • Make this Arrow style antenna - http://ve2zaz.net/Arrow_Ant/Arrow_Style_Ant.htm
  • Preamps - ICOM AG-25 and AG-1, replaced 3sk121 with 3SK183, measured 15 db gain. Note, these preamps require a sequencer. They ARE NOT RF Switched. The AG-25 worked well with the ICOM 471 because the rig sequenced the voltage. I bought a couple of 3SK183s from http://www.xs4all.nl/~barendh/Indexeng.htm.

Ham Radio Deluxe Notes

This is very, very cool. The satellite planning functions are the best I've seen. Here are a few notes about using HRD for satellites.

6/21/09 - the satellite program was updated. It can run on a separate computer and pass commands via TCP/IP from the satellite module to the HRD radio control module. While the graphics have improved, it lost the text listing for future predictions. I also can't figure out how to select several satellites and let the software sequence through them unattended. That is, you have to manually select the the satellite you want to track.

Manual Tuning - You can manually tune the receiver and have the doppler correction added automatically as the satellite goes overhead. Click in the RX frequency dialog, under Satellite, in the Tuning section of the Ground Control tab. Check 'Enable' under Manual Tuning in the radio tuning strip. Turn the radio knob control and the RX Satellite frequency will change. When you stop turning the knob, HRD will start correcting for doppler at the new frequency. Very cool.


RX/TX Deviations

The following shows the deviations between the actual RX/TX frequency and the calculated frequency. Once I changed the frequency at the satellite to these observed frequencies, HRD accurately corrects for the Doppler.

Beacons:
Sat     Nominal       Observed        Delta       Pass           Notes
AO-16   437.026 000   437.025 490     -0.000 51
CO-55   436.837 500   436.836 700     -0.000 800
CO-57   436.847 500   436.848 600     +0.001 100
CO-58   437.465 000   437.464 681     -0.000 319  3/2/08 ~11:00  Freq still changed over pass
RS-22   435.352 000   435.353 169     +0.001 169  3/2/08 ~10:35
VO-52   145.936 000   
FO-29   435.795 000   435.797.116     +0.002 116  6/21/09 ~08:25

Sat     TX Nominal    TX Observed     TX Delta      RX Nominal    RX Observed   RX Delta
VO-52   435.250 000   435.250 200     +0.000 200    145.900 000   145.901 580   +0.001 580
FO-29   145.950 000   145.948 711     -0.001 289    435.850 000   435.850 867   +0.000 867

Testing this procedure:

Use the transponder Frequency adjustments in the Radio Tuning strip of the satellite tracking window. Set the transponder downlink frequency to the center of the passband. Set the uplink 1600 Hz higher. (e.g. VO-52 - DL 435.850 UL 145.951 600) During a pass, load the frequency into the tuning strip and check RX and TX so the program will correct for doppler. Adjust the XIT slider until you find your downlink signal. Now, the doppler offset should be correct.

Using Spectrum Laboratory to look at the passband. Key - 50F - needs to be set to 1200baud. Don't forget to set it back for 9600 satellites! Here's an image. See how the RX frequency increases during the transmission. Doppler corrections do not occur while the TS2K is transmitting.

Doppler

For inverting transponders, the calculation goes like this:

Rx + Tx = Fcd + Fcu 

where:

Rx = Receive Freq at transponder (downlink)
Tx = Transmit Freq at transponder (uplink)
Fcd = Center freq of downlink transponder
Fcu = Center freq of uplink transponder

Here is an example:

Using VO-52

Uplink: 435.220MHz - 435.280MHz
Dwlink: 145.930MHz - 145.870MHz

The passband is 60KHz wide. The centers are:

Fcu = 435.250MHz
Fcd = 145.900MHz

So if the frequency at the satellite is 435.220, the transmitted downlink will be at:

Tx = (435.250 + 145.900) - 435.220 = 145.930MHz

The computer corrects for the doppler on the transmit side, so the frequency is constant as seen by the satellite. The downlink frequency is converted as above and then experiences a doppler shift on the way back to earth. The computer calculates the shift and adjusts the receiver. The doppler formulas are listed here:

http://en.wikipedia.org/wiki/Doppler_effect - Formulas are on the Wikipedia.

Frequency Errors

Ideally, I should be able to set the uplink and downlink frequency - as seen at the satellite - according to the above formula. However, I noticed there is an offset. For example, if I set the download frequency for VO-52 at 145.900 as seen by the satellite, I have to adjust the uplink frequency to 435.251 780. That's 1780Hz higher than expected. What is the source of the error?

  • Position errors which would affect the doppler calculations
  • Transponder frequency errors
  • TX/RX frequency errors (dial doesn't read the actual frequency)
  • Adjustment error - RX tone frequency of the CW signal doesn't match the side tone of the CW monitor. (not zero beat)

I think the satellite transponder stability is better than my Kenwood TS-2000. So the errors are probably on my end. Using a spectrum analyzer, I discovered my TS-2K reads 593Hz high on 432MHz and 162Hz high on 145Mhz. So the actual frequencies I'm transmitting and receiving are lower than the read out on the dial.

I also may be adjusting the pitch of the RX signal differently than the side tone frequency of the TS-2K. If the side tone frequency is set to 600Hz and I adjust the VFO so the tone sounds like a 600 tone, then the readout on the dial is the carrier frequency. If I adjust the VFO for a 1KHz tone, the readout will indicate a frequency that is lower than the actual frequency.

The best way to sort all this out is to view everything from the satellite. (CW)

Account for the rig's frequency error. In my case, the TS2K reads 593Hz too high. If we want the frequency at the satellite to be 435.250 000, we need to set the rig to 435.250 593MHz. The computer will tell the rig to TX at 435.250 593, but the rig will actually transmit at 435.250 000. The computer will then calculate the doppler based on relative position and make further adjustments to the TX frequency.

The transponder will convert the signal to the downlink frequency. However, since there is an error in the TS2K RX (dial reads high) we need to tell HRD (computer) to expect the downlink on a frequency that's higher than the actual signal transmitted by the satellite. So I would set the dial to 145.900 162 to receive a carrier on 145.900 000.

So taking into account TS2K frequency errors:

Fcu = 435.250 593
Fcd = 145.900 162

It's possible to add the offset to one side.

After another pass this evening (6/22/09) the offset must be 1750. So I still haven't accounted for all the errors, yet.

Operating Practice

I found this:

"The convention on the linear birds is that the lower half of the downlink passband is for CW, and the upper half is SSB. So, you should pick an uplink frequency that will place your downlink in the appropriate half of the passband, and then adjust the higher of the two for doppler. In the case of VO-52, that means picking a frequency in the LOWER half (435.2200 - 435.2500) of the uplink passband in order to appear in the UPPER half (145.9000 - 145.9300) of the downlink passband (VO-52 uses an inverting transponder), and adjust only your uplink to keep your downlink frequency constant. And it's LSB on the uplink to give USB on the downlink.

The ideal situation, if you have a radio that is CAT ready, is to use something like SatPC32 that will adjust BOTH your uplink and downlink for doppler, as well as automatically setting the uplink frequency that corresponds to your chosen downlink.

Enjoy! VO-52 is an awesome satellite!

George, KA3HSW"

Another view:

  • Tune to your desired RX frequency.
  • Adjust the XMIT frequency until you hear your downlink
  • Tweak the frequency of the HIGHER band during the QSO

Rotor Control over the Network

It's possible to use the auto tracking feature over the network. I used WiSP DDE, com2tcp and N8VB virtual com port. This lets me control the rotor over an ethernet link. I wanted rotor remote control for another project. So you can find the technical details here.

The general idea is to

  • hook up a linux box to the G6LVB tracker (serial port)
  • run socat on the linux box to link a TCP/IP address/port to the serial port
  • run N8VB virtual com driver on the Windows machine to link two com ports together (e.g. COM3 - COM25)
  • run com2tcp on the Windows machine to link COM25 to the remote socat session
  • configure WispDDE to use COM3

Now, HRD will send/receive commands via WispDDE. WispDDE thinks it's connected to COM3. Through the magic above, COM3 is patch to COM25, which is connected to the linux computer over the network. All commands go over this virtual serial port to/from the G6LVB tracker.

Some Notes:

  • WispDDE only allows COM1 - COM4. I use COM4 to control the radio, via a virtual port in the MicroHam package, so I chose COM3 for the rotor.
  • Make sure the radios are set to 'None' otherwise HRD fights with WispDDE for radio control.
  • Choose GS-232 command set for the rotor in WispDDE