Radar range lock loop

Claim 2

A search and track range indicating system wherein interrogating pulses are transmitted and transponders receiving such interrogating pulses transmit coded reply pulses comprising: a means for generating and transmitting a series of interrogating pulses having a predetermined repetition rate; means for receiving a series of coded reply pulses from one of such transponders in response to said interrogating pulses, said reply pulses each having leading and trailing edges; means for initiating a range measurement substantially coincidently with the transmission of each of said interrogating pulses; sensing means effective at the time of said range measurement initiation for generating a gating voltage pulse a predetermined time after transmission of each of said interrogating pulses, said gating voltage pulse having a leading edge and a trailing edge; gating means responsive to the coincidence of said gating voltage pulses and the leading edge of the first of each one of said coded reply pulses for generating a stop pulse; means responsive to said stop pulse for terminating said range measurement; and means responsive to variations of the leading edge of each one of said coded reply pulses away from the center of said coincident gating voltage pulses to change said predetermined time for bringing the leading edge of the first one of each of said coded reply pulses toward the center of said coincident gating voltage pulses.

Claim 3

The search and track range indicating system according to claim 1 wherein the means responsive to variations of the leading edges of the first coded reply pulse away from the gating voltage pulse comprises a range lock loop including analogue means responsive to variations between the said leading edges of the reply pulses and the said trailing edges of the coincident gating pulses for locking the said reply pulse to the coincident gate pulse, and said analogue means include a capacitor, a constant current charging circuit for said capacitor, and means for diverting current from said capacitor in response to the said difference between the leading edges of the reply pulses and the trailing edges of the gating pulses.

Claim 4

The search and track range indicating system according to claim 2 including means for supplying the voltage on said capacitor to said means for generating a gating pulse voltage for varying the predetermined time thereof for generating said gating pulse voltages.

Claim 5

A search and track range indicating system wherein interrogating pUlses are transmitted and transponders receiving such interrogating pulses transmit coded reply pulses comprising: means for generating and transmitting a series of interrogating pulses having a predetermined repetition rate; means for receiving a series of a coded reply pulses from one of such transponders in response to said interrogating pulses, said reply pulses each having leading and trailing edges; means for initiating a range measurement substantially coincident with the transmission of each of said interrogating pulses; a range lock loop including sensing means effective at the time of said range measurement initiation for generating a gating voltage pulse a predetermined time after transmission of each of said interrogating pulses, each of said gating voltage pulses having a leading edge and a trailing edge; said range lock loop including gating means at the entrance thereof responsive to the coincidence of said gating voltage pulses and the leading edges of the first of each one of said coded reply pulses at said entrance gate for generating a stop pulse, and for determining the time of generation of said gating voltage pulse, and means responsive to said stop pulse for terminating said range measurement.

Claim 6

A search and track range indicating system wherein interrogating pUlses are transmitted and transponders receiving such interrogating pulses transmit coded reply pulses comprising: means for generating and transmitting a series of interrogating pulses having a predetermined repetition rate; means for receiving a series of a coded reply pulses from one of such transponders in response to said interrogating pulses, said reply pulses each having leading and trailing edges; means for initiating a range measurement substantially coincident with the transmission of each of said interrogating pulses; a range lock loop including sensing means effective at the time of said range measurement initiation for generating a gating voltage pulse a predetermined time after transmission of each of said interrogating pulses, each of said gating voltage pulses having a leading edge and a trailing edge; said range lock loop including gating means at the entrance thereof responsive to the coincidence of said gating voltage pulses and the leading edges of the first of each one of said coded reply pulses at said entrance gate for generating a stop pulse, and for determining the time of generation of said gating voltage pulse, and means responsive to said stop pulse for terminating said range measurement.

Claim 7

The search and track range indicating system according to claim 4 wherein the range lock loop includes analogue means responsive to variations between the leading edges of the first coded reply pulses and the trailing edges of the gating pulses for locking the first coded reply pulse to the coincident gating pulse, includes means at said entrance for disabling the loop after the receipt of each one said gating voltage pulses and said first coded reply pulses in coincidence with each other, includes means for causing said disabling means to ignore subsequent disabling signals for a predetermined time following each enabling signal, includes means for storing information corresponding to the receipt of a predetermined coded reply pulse, and includes means for enabling said range lock loop upon sensing the storage of said predetermined coded reply pulse.

Claim 8

A search and track range indicating system wherein interrogating pulses are transmitted and transponders receiving such interrogating pulses transmit coded reply pulses comprising: means for generating and transmitting a series of interrogating pulses having a predetermined repetition rate; means for receiving a series of coded first and second reply pulses from one of such transponders in response to each of said interrogating pulses; each of said first and second reply pulses having leading and trailing edges; means for initiating a range measurement substantially coincidently with the transmission of each of said interrogating pulses; a range lock loop including sensing means effective at the time of said range measurement initiation for generating a gating voltage pulse a predetermined time after transmission of each of said interrogating pulses, each of said gating voltage pulses having a leading edge and a trailing edge, and including gating means at the entrance of said loop responsive to the coincidence of said gating voltage pulse and the leading edges of the first of each one of said coded reply pulses at said entrance gate for generating a stop pulse, and for determining the time of generation of said gating voltage pulse; means responsive to said stop pulse for terminating said range measurement; decoder means responsive to the receipt of said coincident signals for determining the validity of the coded reply of said first and second pulses and if valid storing said coded reply as valid; means for receiving and storing said valid reply; means at said entrance gate for disabling the loop after the receipt of each one of gating pulses and said first one of said reply pulses in coincidence with each other; means for enabling said range lock loop upon the subsequent sensing of the valid pulse in said storage means; analogue means responsive to variations between the leading edges of said reply pulses and the trailing edges of the gating pulses for locking the reply pulse to the coincident gating pulses; and means responsive to a predetermined time interval for energizing means for reading the range information.

Claim 9

A search and track range indicating system wherein interrogating pulses are transmitted and transponders receiving such interrogating pulses transmit coded reply pulses comprising: means for generating and transmitting a series of interrogating pulses having a predetermined repetition rate; means for receiving a series of coded first and second reply pulses from one of such transponders in response to each of said interrogating pulses; each of said first and second reply pulses having leading and trailing edges; means for initiating a range measurement substantially coincidently with the transmission of each of said interrogating pulses; a range lock loop including sensing means effective at the time of said range measurement initiation for generating a gating voltage pulse a predetermined time after transmission of each of said interrogating pulses, each of said gating voltage pulses having a leading edge and a trailing edge, and including gating means at the entrance of said loop responsive to the coincidence of said gating voltage pulse and the leading edges of the first of each one of said coded reply pulses at said entrance gate for generating a stop pulse, and for determining the time of generation of said gating voltage pulse; means responsive to said stop pulse for terminating said range measurement; decoder means responsive to the receipt of said coincident signals for determining the validity of the coded reply of said first and second pulses and if valid storing said coded reply as valid; means for receiving and storing said valid reply; means at said entrance gate for disabling the loop after the receipt of each one of gating pulses and said first one of said reply pulses in coincidence with each other; means for enabling said range lock loop upon the subsequent sensing of the valid pulse in said storage means; analogue means responsive to variations between the leading edges of said reply pulses and the trailing edges of the gating pulses for locking the reply pulse to the coincident gating pulses; and means responsive to a predetermined time interval for energizing means for reading the range information.

Claim 10

The search and track range indicating system according to claim 6 wherein said analogue means includes a capacitor, constant current charging circuit for said capacitor and means for diverting current from said capacitor in response to the said variations between the leading edges of the first pulse of said coded reply pulses and the trailing edges of said gating pulses.

Claim 11

The search and track range indicating system according to claim 7 including means for supplying the voltage on said capacitor to said means for generating a gating pulse voltage for varying the predetermined time thereof for generating said gating pulse voltages.

Claim 12

The search and track range indicating system according to claim 7 including means for dumping the current in said capacitor.

Claim 13

The search and track range indicating system according to claim 6 including means for displaying said readings of said range information.

Claim 14

The search and track range indicating system according to claim 10, including means for inhibiting the display of range information.

Claim 15

The search and track range indicating system according to claim 6 including means for disabling said range reading means unless at least a predetermined number N out of every twenty successive time frames had valid reply indications.

Claim 16

The search and track range indicating system according to claim 12 wherein N is equal to five.

Claim 17

The search and track range indicating system according to claim 12 including a valid reply memory storage apparatus from which said valid reply indications are taken.