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ISS Cross band repeater comments



Hi all,

I have been getting several emails forwarded to me asking about the ISS and 
the cross band repeater.  Here are some tips and comments:

1.  Check with the ISS Fan Club webpage to see what the latest status is.  
Our friends there have an excellent webpage at:  http://www.issfanclub.com.  You 
should also check the ARISS (http://www.rac.ca/ariss/ )and AMSAT 
(http://www.amsat.org) webpages.  Our friends at these two locations have also put 
together great sites.

2. Kenneth Ransome N5VHO has been posting announcements to the various 
bulletin boards when he finds out the mode.  Please watch for his announcements.  
Kenneth is one of ARISS team members who is very up on the modes.

3.  Remember that the ISS radios are not able to correct for Doppler as the 
frequencies are channelized.  So it is up to the ground station to do the 
Doppler correction.  For 2 meters, the Doppler is about +3kHz at the beginning and 
goes to about -3kHz at the end.  For 70 cm, the Doppler is about +10kHz at the 
beginning and goes to about -10kHz at the end.  The 70cm Doppler is roughly 3 
times the 2m Doppler.  Many of the tracking programs have the ability to 
calculate the Doppler.

Also recall that the frequencies are:

Crossband voice mode (437.80 MHz up, 145.80 MHz down)
Public packet mode (145.990 MHz up, 145.80 MHz down), 
Public voice mode (145.20 MHz up for Region 1; 144.49 MHzup for Regions 2 and 
3; 145.80 MHzdown for all regions)
School contact mode (xx up and 145.80 MHz down)

These are the frequencies that are at the ISS.  So you will have to do the 
Doppler correction on the ground so that at the ISS the resultant frequency is 
that listed above.  For example, if you are on the public voice mode in Region 
2 and the Doppler is about +2kHZ, then you would transmit up on 144.488 MHz 
and listen on 145.802 MHz.  The ISS is not a transponder like the rest of the 
OSCAR sats.

4.  I have been asked several times how can one tell what mode it is in.  I 
wish I could tell you exactly but I think you will just have to check one of 
the webpages or better yet, dump your call in and try it.  Kenneth is doing a 
pretty good job of announcing any changes; so watch for his postings.

5.  The AMSAT Journal July/August 2004 Volume 27, Number 4 pages 12 to 17 has 
a pretty good article on the equipment presently in place as well as comments 
on the future.  We realize that everyone wants to have all of the goodies on 
board at once but that simply can not happen.  The equipment all goes up on a 
shuttle (hopefully they will be flying again soon) and all of it must be space 
qualified (they look at everything; not just electronic but materially, ie. 
plastics, paint, etc).  The qualification process takes quite a long time and 
we should all thank the hams who push to get that done.  Everyone should also 
realize that we will be going through some experimentation to determine exactly 
how the equipment is working and the proper setup.  Currently Mike Fincke 
KE5AIT is really getting into ham radio (recall his first ever contact was an 
ARISS school contact a few months back) and has been changing modes for us.  
Thanks Mike!  I know Gennady I. Padalka RN3DT has also been very active, so we 
thank him.  ARISS will keep everyone informed as the new equipment becomes 
available.

If you read the article in the AMSAT Journal, you will see that not all of 
the antennas are pointing at the earth.  There could be some times of signal 
dropout.  We have noticed this on some of the school contacts and believe that 
the signal is going through some of the ISS superstructure.  Don't forget, it is 
line of sight and so if the path from your antenna to that on the ISS is 
partially blocked by the ISS itself, there may be some signal dropout.  Give it a 
minute or so to see if the signal returns.

Hope this helps a little.  Good luck making an ISS contact and don't forget 
to check with a local school to see if they want to get on the waiting list for 
an ARISS school contact.

73,
Charlie Sufana AJ9N
One of the ARISS mentors
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