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

[Jerome Blaha]

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