[time-nuts] Need advice for multilateration setup

Bill Hawkins bill at iaxs.net
Fri Mar 27 12:01:06 EDT 2015

NASA uses the Doppler effect for deep space navigation, by integrating
the velocity.

You'd need a very stable oscillator, but you don't need a powered oven,
due to the short duration of the flight.
You only need one receiver. In fact, if it's possible for the rocket to
hear a ground signal and return it at some offset or fractional
frequency, you don't need an oscillator on the rocket.

But if you do need a stable oscillator, consider enclosing it in
aerogel, as we were discussing a few months ago. Bring it up to temp
with ground power and let it go.

There is still the matter of acceleration. If the oscillator can be
calibrated, then the frequency versus acceleration is known and can be
used to get the rocket's acceleration during powered flight. Double
integration yields position. Taking the Doppler shift out of the
integral could be tricky.

Disclaimer: The last time I had anything to do with a rocket was 1959,
with an Aerobee-Hi launched from White Sands, NM. We used Doppler to get
altitude for upper air density measurement. The rocket went off course
horizontally (determined by radar) and was destroyed before it crossed
the border.

Bill Hawkins

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