Re: [amsat-bb] Re: Fixed-uplink tuning (was: Eagle Launch Campaign)

[Paul Williamson <kb5mu@xxxxxxxxx>]

At 7:23 AM -0700 8/1/04, Scott Townley wrote:
>Horse-hockey!
>I have made and continue to make 100's of mobile--yes while 
>driving--QSOs on RS-12/13, FO-20, and FO-29.

But not while using the fixed uplink scheme that Mike proposed.

>There are a couple of ways to minimize the Doppler pain:
>1. Call CQ...then you only have to tune one radio (RX) to find replies.

In this case, the other station is doing the work by getting onto the 
same approximate downlink frequency, so he is not using the fixed 
frequency scheme. Or, if he is, there is only one other station. But 
for a single fixed frequency as proposed by Mike, it would be a 
multi-station roundtable most of the time.

With a single pair of stations in QSO, the tuning problem with the 
fixed uplink scheme is no worse than usual. In that case, the only 
disadvantage is that the QSO takes place on two different (drifting) 
frequencies, so it takes up more transponder room. As noted by Mike 
in his original proposal, this means that the section of the 
transponder used this way would have to be segregated from the normal 
users, to prevent interference.

And of course, if everybody calls CQ, no QSOs will be made.

>2. To answer a stn, rig up something where you only have to use one 
>hand to adjust your TX (I have a little switch on my keyer that 
>sends a string of 'dits').  Takes one (the same) hand to hit the 
>switch, tune TX until I hear my downlink, then off with the switch 
>and call.

That's practical, but it isn't using the fixed uplink scheme either. 
Nor is it possible using a '706 (which can't listen while 
transmitting), which was Mike's original motivation for proposing the 
scheme.

I never claimed it was impossible to tune Doppler mobile using all 
the standard techniques. What I claimed is that tuning a multi-way 
conversation with everybody on the same uplink transmitter frequency 
would make it very difficult.

That said, perhaps you should let us know what roads you're on while 
driving and operating at the same time. Those of us who believe that 
driving while distracted is unsafe would want to avoid those roads. 
Those of us who live where there's traffic might want to move to your 
town.

73  -Paul
kb5mu@amsat.org
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