On 8/20/11 6:40 AM, Ronald G. Parsons wrote:
With these two changes, although the Doppler correction may drift off,
it does so very smoothly, which I assume allows the decoding of the BPSK
data to be more accurate.
Yes, the closer you keep it the better it'll work. Errors of up to +/-
50 Hz
One thing I've discovered which makes things go more smoothly is to reduce
the minimum Doppler tuning interval.
I am using SatPC32 V12.8a. There are two parameters in the CAT menu -- the
Speed which I changed to 5x (which is not sticky) and the minimum Doppler
tuning step for SSB which I set
Ron,
That behavior is common around TCA, Time of Closest Approach. At that time
everything is changing rapidly, and slight errors in QTH position, system
clock, and Keps can be magnified. I have seen a few hundred Hz shift at
that time with new satellites whose Keps have not fully converged.
Ron,
Alan's points are spot on. That being said---I see something similar to
what you are seeing and blame the Keps :)
In the first few days, the manual freq. correction at TCA was over 1,000Hz
(seems like I had to shift it down, so -1,000) as compared to AOS and
LOS...which were on frequency.
I found it quite noticeable last night too, I'm 150 miles or so North of
Ron's QTH.
In my experience, the marker on ARISSatTLM was moving down rapidly as the
satellite approached. After TCA (which was at about 68 degrees elevation,
I believe) it reversed back to normal.
I was using the latest
On 8/18/11 6:59 AM, Alan P. Biddle wrote:
Ron,
That behavior is common around TCA, Time of Closest Approach. At that time
everything is changing rapidly, and slight errors in QTH position, system
clock, and Keps can be magnified.
As everybody knows, even tiny errors in the Keplerian mean
