Unambiguous wide baseline interferometer

DETAILED DESCRIPTION I claim: 1.
In a system for receiving an RF signal having envelopes of RF carrier cycles, said RF carrier cycles having zero crossings, means for measuring the differential arrival time of said RF signal at two antennas spaced apart by a distance greater than one wavelength of the RF carrier, comprising first and second triggering means, one for each antenna, each said first and second triggering means having a digital output, said first and second triggering means being responsive to said zero crossings of said RF carrier cycles from its respective said antenna and providing outputs preserving RF carrier phase differential from said antennas, and timer means for measuring the time difference between said outputs of said first and second triggering means.
2.
The invention according to claim 1 comprising in combination means for detecting envelope arrival at said antennas to provide a coarse measure of said differential arrival time, and, in combination with said timer means, an unambiguous fine measure of said differential arrival time.
3.
The invention according to claim 2 comprising in further combination heterodyne mixer means for detecting RF carrier phase differential from said antennas to provide a further accurate fine measure of said differential arrival time.
4.
In a system for receiving an RF signal having envelopes of RF carrier cycles, means for measuring the differential arrival time of said RF signal at two antennas spaced apart by a distance greater than one wavelength of the RF carrier, comprising first and second digital counter divider means, one for each antenna, responsive to said RF signal from its respective said antenna and outputting one or more digital submultiples of said RF carrier and preserving RF carrier phase differential from said antennas, and means for measuring the time difference between said digital submultiples of said RF carrier from said antennas.
5.
The invention according to claim 4 wherein said last mentioned means comprises first and second zero-crossing detector means, one for each antenna, responsive to the output of respective said divider means, and timer means responsive to said first and second zero-crossing detector means for measuring the time difference between a zero-crossing from said first divider means triggered from said first antenna and a zero-crossing from said second divider means triggered from said second antenna