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Transparent Tuning, WispDDE and SatPC32



Quoting Erich Eichmann <erich.eichmann@t-online.de>:

> Hello Bruce,
> when you want to steer the radio with SatPC32 you should do that by
> SatPC32
> directly via a COM port or USB-to-Serial adapter. That allows
> "transparent"
> tuning. Transparent tuning means, with SSB sats you can tune the radio
> with
> the VFO knob around the passband like you can with  terrestrial
> operation.
> When you stop moving the knob the program calculates and sets the
> corresponding new uplink frequency and the automatic Doppler correction
> continues with the new  frequencies.
> That requires, however, that the radio is steered directly by SatPC32
> via a
> COM port. SatPC32 polls the RX-VFO frequency  once per second. So it
> can
> recognize whether the user moved the VFO knob and then calculate the
> corresponding uplink frequency. That nis not possible, however, when
> SatPC32
> has no direct COM port access but sends its output via DDE to a further
> program that outputs it to the hardware. In that case the radio cannot
> be
> tuned with the VFO knob but only via the mouse or keyboard.
> 
> vy 73s, Erich,


Erich:

Thank your for your prompt replies, and for SatPC32, which is an excellent
package. It is especially valuable to be able to test its applicability
using a fully functional demo. As in many other fields, the software
developers are the ones who are driving so much innovation in satellite
operations.

Interestingly, I believe I *can* do full doppler tuning with WispDDE and
SatPC32. In any case, when I set this up with two FT-817s, the transmitting
radio's frequency does change after one changes the uplink radio's
frequency (via the tuning knob), and it seems that the resulting uplink
frequency is the one listed in SatPC32's main window. (This works with
Orbitron and WispDDE, too, as recommended by one member of this list; I'd
be interested in others' confirmation or refutation.)

You mention that one can do this directly, as well. But if I have
understood the instructions correctly, the two radio option in SatPC32
assigns one radio the role of transmitter and the other the role of
receiver. In this case, when switching from VO-52 to FO-29 one would need
to alter which radio plays the role of receiver and which transmitter. When
working with HRD, I do this by switching radios in the synchroniser;
WispDD, however, provides an added level of abstraction. It allows you to
assign a radio to a *band* (or selection of bands, or birds, or even
modes). Thus, when switching from VO-52 to FO-29, the 70cm radio becomes
the receiving one, and its dial is the master tuner, driving the 2m radio's
frequency. It will also change modes, though this seems not always to work
properly on the FT-817. 

The price to pay is that the tuning is less smooth. 

I think that a software-driven, easy two radio setup is a good way to get
people involved in satellite operations. Why is this? Well, a fair number
of operators have a 160m-70cm main rig on hand. If we can convince them
that an additional $380 second-hand FT-817 will be all it takes to have a
satellite station (sans antennas and preamps), I expect they will be more
willing to take the leap.

On this point, I note that saving the changes to doppler frequency (via the
CAT window) requires a radio be connected to SatPC32's COM port. This is
presumably to keep a user from altering these values when the radio is not
being controlled by the program. In my case, though, it means that I can't
make these changes when I'm connected via WispDDE. 

73, Bruce 
VE9QRP 

-- 
Bruce Robertson, 
Dept. of Classics, Mount Allison University
http://heml.mta.ca
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