"Oh No" wrote in message
...
Thus spake Spud
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gr-qc/0104064

Many thanks. If I understand Anderson correctly it is merely an
engineering constraint. With a (perhaps greatly) amplified signal it
should be possible to reduce integration times to achieve correlation so
that the signal can be returned without a substantial range delay.

The problem was more fundamental. Reading between the lines,
and from some personal correspondence, the rate of change of
the carrier frequency was I believe limited in choice by the
design of the exciter or correlator equipment. The narrow
bandwidth required to get an acceptable SNR at the craft
meant the minimum sweep rate was too fast and the craft lost
lock on the uplink. Increased gain at the craft wouldn't help,
only more transmit power, but that was in the 100's of kW
already and being routed through their largest (70m) dishes.

Anyway that is the basis on which I am working at the moment.

But I am not an engineer, and I was hoping this might be confirmed. My
arguments would take quite a different form if this was a fundamental
constraint.

It was purely an equipment limitation, possibly exacerbated
by radiation damage during the Jupiter flyby though that is
my speculation. BTW, I am a digital and systems engineer in
a company working significantly in HF comms.

George