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Thread: [EE] Phase locking DRO's
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face picon face BY : Alan B Pearce email (remove spam text)



How about the following scenario for your phase locking - I am thinking along
the lines of TV studio camera genlocking.

If each dish can have a DRO as a local oscillator to down convert the signal to
an IF frequency, and each DRO can be phase locked to a stable source. The stable
source is fed by coax or other suitable means - exactly how is unimportant so
long as it is still a stable signal at each dish. The local phase locked loop at
the dish has a means of injecting a stable DC voltage into the loop to provide a
constant phase offset to the oscillator signal. The control of this voltage is
done from a central point to get the IF signal received back at the central
point phase correlated to one of the other dishes which will be used as a
reference signal.

The control point will need a means of correlating each IF signal to the one
being used as a reference, and sending a command out to the phase control
voltage of all the other dishes. If the reference dish has an identical phase
control loop to the other dishes, it may also be possible to use this to adjust
for ageing or some other parameter which may make some of the other loops go
outside control range at extremes of phase angle difference. The Shera
electronics with modified control software would probably be the way to go.

P.S. I just received a couple of D/A converters from Analogue Devices (AD1861)
which are the equivalent of the Burr Brown ones Brooks Shera used, as I want to
build a copy of his frequency standard. I managed to get them as samples N/C!

Also using PICs in the control system, you could drop the OT.

<00de01bfc491$37a95710$5dbdf682@ssdwkiwi.AG.rl.ac.uk> 7bit

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Subject (change) [EE] Phase locking DRO's

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