[amsat-bb] Re: Doppler Tuning Convention Question (summary)

Tony Langdon vk3jed at gmail.com
Tue Jun 1 14:36:40 PDT 2010

At 05:53 AM 6/2/2010, Michael Tondee wrote:

>was fun. Not so if I came upon a station who was using manual tuning
>while I was trying to let my computer do the work. I had to chase him
>all over the passband and often lost stations completely that way. I
>didn't fare much better with manual tuning. I guess I never really
>learned it like some of the "old hands" have.

I have had quite a bit of success with manual tuning on the SSB 
birds.  It does require a lot of attention, especially on V/U and 
U/V.  On mode A, it's fairly straightforward, though adjusting the 
uplink on a radio that doesn't allow tuning on transmit is 
tricky!  One has to break their over into short segments of a few 
seconds long and make the uplink adjustment in steps. :)

On V/U, I was using an FT-847 at a hamfest, which was easier, 
provided I focused on keeping up with the Doppler. :D

>   When I can finally afford the V/U unit for my new Flex and get back on
>linear birds it would be my hope that everyone who was in a base station
>setup would be using full doppler control via computer. It baffles me
>why anyone wouldn't, it makes life so much easier.

In my past, it was simply because I didn't have the right 
radio(s).  Now I have an FT-736R, and the first accessory I bought 
for it was a CAT cable! :)  I can even dedicate a computer to the job.

>   I do understand why portable stations like Tim would not be using full
>doppler and I have no problem with that. I guess I just need to learn
>how to manually tune in that situation.

Yep, it can be fiddly, but rewarding.

>Michael W4HIJ
>On 6/1/2010 12:14 PM, John Belstner wrote:
> > Thanks to everyone that responded.
> > For those that have been on the list for years this thread may be 
> a dull rerun, but as a newbie, the information is useful.
> >
> > > From everyones responses, it appears that indeed there are 
> currently two conventions:
> > 1. Full Doppler CAT tuning
> > 2. Manually tuning the higher frequency while keeping the lower fixed
> >
> > I know that operators have been successfully using convention #2 
> for years so this is my lack of sat operating experience talking 
> here, but just looking at the math it seems that it would be 
> difficult for two stations with different velocity vectors to the 
> satellite to communicate without at least one of them adjusting 
> both TX and RX.  I need to try this for myself I guess.
> >
> > One thing I did notice is that when operating Full Doppler CAT 
> tuning I was only able to successfully track other operators who 
> were doing the same.
> >
> > Cheers,
> >
> > 73, John W9EN
> > DM13le
> >
> >
> > _______________________________________________
> >
>Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
>Not an AMSAT-NA member? Join now to support the amateur satellite program!
>Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

73 de VK3JED / VK3IRL

More information about the AMSAT-BB mailing list