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Re: Features in FT-847 replacement, wish list



On Thu, 2005-12-22 at 15:11 -0800, Matt Bennett wrote:
>   My other suggestion for the next Yaesu sat rig would be the ability
> to control the SPLIT MODE tuning from the CAT interface. This is
> because many airborne cubesats and the ISS operate on the same band,
> and tuning must be performed by hand both cases. The necessity is not
> so critical for 2m ops as it it for 70cm.
> 

This can be done - the issue is addressed in my July 2004 paper at:

http://www.sunsunsun.net/kd4app/Full_Doppler_on_the_FT847.htm

Basically ...

Several people have looked at the Yaesu FT-847 CAT command set and
concluded it can’t do full Doppler control on “same-band” satellites
like ISS – I.E. those where the TX and RX frequencies are in the
same-band.  The premise of this belief was linked to a “10 kHz
limitation”. The FT-847 CAT “offset” command appears to offer 10 Hz
resolution, but anything entered beyond 10 kHz resolution is ignored -
this is the only CAT function which is limited to this resolution – in
fact all other frequency related commands offer as fine as 10 Hz
resolution. 

The FT-847 cannot be used to work “same-band” satellites in “satellite”
mode because the FT-847 satellite mode can’t have the same band for both
the TX and RX sides.  

My work in this document is based on using the “Main Frequency VFO”
rather than “satellite” mode. I will also utilize the “repeater shift”
function” and the “offset” function.   All of the examples in this paper
can be achieved using the existing CAT commands found on the FT-847.
While the FT-847 CAT commands may have some limitations, a little bit of
software can overcome these limitations and full Doppler correction can
be achieved on “same-band” satellites like ISS and PCSAT.

I will leave it as an exercise to the reader to implement this method to
achieve full Doppler correction.  A test of concept was performed under
Linux and the expected results were achieved – unfortunately I don’t
have the time to write a full blown same-band satellite Doppler
correcting program for the FT-847 – I’d rather see the various
tracking/tuner programs implement this in their code. 

73's

Don Woodward
KD4APP
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