I still think the best way around all of this is to make a "box" to were ground ctrl sta's can cmd each rig. This way the crew would not be tired up .. this has been done in the past with several of WA4APR's experiments and has work just fine ..
----- Original Message ----- From: "MM" [email protected] To: "Eric van de Weyer" [email protected]; [email protected]; [email protected] Sent: Wednesday, May 02, 2007 8:15 AM Subject: [sarex] Re: Future ISS amateur radio modes, Marex
I agree with your analyses on the Doppler / PL Tone shift. With a Doppler of less than 2 kHz, the PL tone should be passed with little or no degradation. The FM Capture effect locks on to the signal and compensates for some of the frequency error. At a higher Doppler values, you do see noise and other distortions begin to creep in. The PL tone suggestion just needs to be tested to get a realist feel on what to expect. We have had issues in the past, with putting stuff in space that was not properly tested end to end. Whenever I hear of a good idea, I try thinking about the environment where it will be used.
Packet is affected by Doppler when it begins to get above 2.0 kHz. The amount of error is also dependent on the Signal level at the receiver. At a signal level of S9 and a 2.5 kHz Doppler you will see very few data errors (Retries caused by check sum errors). At S2 and 2.5 kHz Doppler your receiver will have a harder time decoding the data. That's why, at the beginning and End of ISS packet passes when the Doppler is the greatest, I adjust my TX and RX for Doppler.
On a related note, I did test the Icom ID-800 digital voice mode with a Simulated Doppler. The results were very good. The ID-800 uses a 2.4 kbit digital data stream for Digital Audio. When this data stream was subjected to simulated Doppler of 2.5 kHz, at an indicated receiver S-meter level of S1, the audio stream decoded perfectly. This means that some of the narrow digital modes can be used from FM satellites when the Doppler is less than 3 kHz (depending on received signal strength).
--- Eric van de Weyer [email protected] wrote:
think about it, the percentage shift of the carrier frequency of the modulating tone compared to the carrier will be negligible and therefore the effect on the tone itself will also be virtually zero. If the Doppler affected it significantly, our voices through the system would also be changed significantly. Also, packet wouldn't work either and we know that it works fine.
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of MM Sent: Wednesday, 2 May 2007 22:42 To: [email protected]; [email protected] Subject: [sarex] Future ISS amateur radio modes, Marex
ISS Amateur Radio Status: May 2, 2007
Future Projects on ISS By Miles Mann WF1F,
MAREX-MG News www.marexmg.org
Manned Amateur Radio Experiment
Future Projects on ISS:
There are a lot of good ideas regarding how to use Amateur Radio equipment on board ISS. I like the suggestion from Darrell Bellerive va7to of using a Downlink PL tone from ISS for the voice channel.
I am not sure how much the Doppler will affect the PL tone. I am intrigued by the idea and will try some terrestrial experimentation to if there is much of an effect.
Current In-flight projects on ISS include: Packet, Voice (mono-band), Cross-Band Repeater and SSTV.
Each of these projects has shown good results from manned platforms such as Mir and ISS. The projects that the space agencies like the best are the ones that do not use very much crew time. The projects Packet, Cross-Band and SSTV are the highest bang for the buck projects because they do not take up too much crew time. And as we know, free crew time for ham projexts is very very limited.
Cross-Band Repeater generates a lot if good interest from the amateur radio community. There are a few down side issues to cross band that have to be taken into consideration. Not all countries allow amateur radio on the 440 band (sometimes called 70cm). There is more Doppler on 440 (+ and - 10khz) Some of these and other issues can be overcome with experience. I wold be nice if someone could design a small frequency agile cross repeater that could work on any combination of 10 meter, 2-meter and 440. That way we would have the maximum flexibility based on project needs. We have the existing antennas on ISS, let's use them.
Existing ISS Antenna counts: Module FGB One Sirius 2-meter antenna tuned for approximately 147 MHZ. Dual one-quarter wave co-phased antennas mounted externally. Currently connected to the Ericsson Ht.
Service Module, Three Tri-Band antennas, that support 2-meters, 440 and a patch antenna supporting 1.2 - 2.4 GHz. (The patch antenna has high coax losses, > 8 dB at 1.2 GHz) One 10-meter whip and 1.2-2.4 GHz patch combination. One of these Tri-Band antennas is conneced to the D700. The others are not currenlty used.
Grand total of currently installed Amateur Radio antennas on ISS 4 antennas for 2-meters 3 antennas for 440 4 antennas for 1.2-2.4 GHz 1 antenna for 10 meters
MAREX is focusing on the entry-level projects for beginners such as Slow Scan TV and Packet Email. We have had excellent results on Mir project with both SSTV and Packet. And last summer experimented with SSTV from ISS with some very good down linked images.
The long term plans, hardware and crew time permitting is to place SSTV on a 10 meter down link, continuously streaming images from ISS.
And place a continuous presence Packet Email system on 2-meters, running 24/7. MAREX has received initial approval to use a Kantronics KPC-9612 TNC as the data engine. This modem supports all the standard features of most TNC's built, including: Full Multiple user simultaneous Email users. Simultaneous dual speed support 1200 and 9600 baud. Un-proto modes, Text messaging and APRS beacons.
Some unapproved projects Marex is working on are to provide a full plug and play solution for a new system. New style easy to use transceivers, Analog and digital voice capabilities, Bolt on heat sinks and fans to compensate for zero gravity cooling issues, standardized plug in DC headsets and more. Your support for these projects would be greatly appreciated. http://www.marexmg.org/
ARISS Web page and other great Space projects http://www.rac.ca/ariss/
73 Miles WF1F MAREX-MG
Until we meet again
DOSVIDANIYA Miles WF1F
Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
Sent via [email protected] Opinions expressed are those of the author. Not an AMSAT member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/sarex
__________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ---- Sent via [email protected] Opinions expressed are those of the author. Not an AMSAT member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/sarex