[time-nuts] Very Accurate Delta Time RF Pulse Measurements

Brooke Clarke brooke at pacific.net
Fri Jul 29 13:45:21 EDT 2016

Hi Jerome:

The Vietnam era Radar Warning Systems used 4 wide band antennas (nose, tail & wing tips) and displayed the bearing, 
rough distance & threat type on a CRT.
Near the antenna was a crystal video receiver using a multi channel filter driving Schottky diode detectors.  The output 
from each detector fed a video log amp.

The Fenwick antenna patent based on time delay beam steering is far superior to a phased array in that it's frequency 
I think the basis of TOA.

Can you say more about the specifics of what you are trying to do?

Have Fun,

Brooke Clarke
The lesser of evils is still evil.

-------- Original Message --------
> Hi Guys,
> This is a little outside of time-nuts scope, but not by much.  I'm interested in finding the time between two rising edges above a set threshold with preferably nS or high ps timing accuracy.  Can this be simply done with a few programmed Microchip PICs or with a good short term OCXO clock?  The issue I see is that a 10Mhz timing reference with 1 cycle difference in time yields 100ns resolution, which is far too large, so maybe a PIC can solve this.
> This weekend project would be a multi-element antenna array, each with a super-fast response log peak power detector fed into several PICs for time of arrival.  Whenever a nearby high energy RF pulse is detected, the time of arrival between two antenna elements and hence the direction toward the TX could be roughly computed.  Some typical log peak detectors have an 8ns input pulse response time, so I'm hoping that rise times are similar between multiple detectors, negating the delayed response.
> There are time of arrival/AoA systems out there with synthetic doppler, phased arrays, correlative interferometers, and phase comparators, but it would be interesting to accomplish super wideband AoA timing on two rising pulses with relatively cheap parts.
> Thanks,
> -Jerome
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