The ISS radio system currently supports only one mode at a time. The current L/v configuration is scheduled to be active until Saturday, Jan 3.
And I don't think you can't get into the 1.2 GHz uplink without a yagi ;)
The most important thing is proper Doppler compensation. At 1.2 ghz the Doppler is from -25 KHz to plus 25 KHz or so, and you have to be within a few KHz, or your splatter will not open the squelch of the repeater.
With 11 full Doppler steps during a pass, you have to nail it exactly or you dont get through he 12.5 KHz filter. Plus I bet even being 2.5 KHz off between each step and speaking fully, will splatter so much as to keep the squelch closed.
So in that case, there are 22 discrete windows of opportunity, only half of which are useable, so it takes real care to get through. Of course, I am only kibitzing, since I have not tried it, but all the signals I have heard do NOT seem to be suffering power limitation, but all seem to be suffering off-frequency splatter and therefore squelch unreliability.
Maybe setting narrow band deviation (as used in europe) will reduce the spaltter and keep the squelch open better.
Good luck! Bob, WB4APR
I'd suggest setting narroband deviation too, to help prevent
From: bruninga@usna.edu Subject: Re: [amsat-bb] Re: ISS Repeater To: Kenneth.G.Ransom@nasa.gov; ko6th_greg@hotmail.com; w5ggw@wonderly.org CC: amsat-bb@amsat.org Date: Tue, 30 Dec 2008 22:09:02 -0500
The ISS radio system currently supports only one mode at a time. The current L/v configuration is scheduled to be active until Saturday, Jan 3.
And I don't think you can't get into the 1.2 GHz uplink without a yagi ;)
The most important thing is proper Doppler compensation. At 1.2 ghz the Doppler is from -25 KHz to plus 25 KHz or so, and you have to be within a few KHz, or your splatter will not open the squelch of the repeater.
With 11 full Doppler steps during a pass, you have to nail it exactly or you dont get through he 12.5 KHz filter. Plus I bet even being 2.5 KHz off between each step and speaking fully, will splatter so much as to keep the squelch closed.
So in that case, there are 22 discrete windows of opportunity, only half of which are useable, so it takes real care to get through. Of course, I am only kibitzing, since I have not tried it, but all the signals I have heard do NOT seem to be suffering power limitation, but all seem to be suffering off-frequency splatter and therefore squelch unreliability.
Maybe setting narrow band deviation (as used in europe) will reduce the spaltter and keep the squelch open better.
Good luck! Bob, WB4APR
I'd suggest setting narroband deviation too, to help prevent
Yeah, I think it's going to be one hand on the mike and the other on the uplink tuning knob, adjusting it real-time by ear. I can use the computer to keep the antennas and downlink radio on track, but the rest is going to be up to me.
Greg KO6TH
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Bob,
Plus I bet even being 2.5 KHz off between each step and speaking fully,
will splatter so much as to keep the squelch closed.
That is exactly my experience, reported in an earlier message. Frequency control, including knowing what your transverters is really doing, are necessary but not sufficient to get in.
Alan WA4SCA
participants (3)
-
Alan P. Biddle -
Bob Bruninga -
Greg D.