Monitoring, ranging and locating devices

Ranging apparatus comprising first and second transceiver units, each said transceiver unit containing an RF transmitter, RF receiver and control circuitry,

• said control circuitry including means of determining the distance between said first and second units independent of the received RF field strength of the transmitter of the other unit,
• said control circuitry of said first unit including reference frequency generator means for causing its associated transmitter to transmit a modulated RF pulse, the control circuitry of said second unit including phase lock loop means for frequency and phase alignment with said RF signal transmitted by said first unit and received by said RF signal transmitted by said first unit and received by the second unit, upon receipt of said modulated RF pulse by the receiver of said second unit the control circuitry of said second unit causing its associated transmitter to transmit a reply RF pulse modulated in accordance with said received signal and in phase therewith,
• said control circuitry of said first unit including means for between said transmitted pulse and said received reply RF pulse to thereby determine the distance between units display means connected to said control circuitry for indicating the determined distance between the units.
• said control circuitry including means for pulsing the transmitter and receiver of each unit in time coordination with each other to thereby conserve power
• said pulsing means of said first unit including means for generating a reference frequency, said reference frequency driving said transmitter of said first unit, said receiver of said second unit receiving said reference frequency signal and generating an internal reference signal which is used to provide a time aligned periodic pulse for energizing the transmitter and receiver of said second unit, said first and second units thereby being actuated simultaneously, said control circuitry of said second unit begins time alignment between said first and said second units by its associated transmitter transmitting an RF pulse independent of said receiver of said first unit, said receiver of said first unit including means to enable said receiver of first unit to remain in a receiving mode including means for time alignment when said transmitter pulse from said second unit causes said receiver from said first unit to time align when said pulse from said second unit is received by said receiver of said first unit.

Ranging apparatus comprising first and second transceiver units, each said transceiver unit containing an RF transmitter, RF receiver and control circuitry,

• said control circuitry including means of determining the distance between said first and second units independent of the received RF field strength of the transmitter of the other unit,
• said control circuitry of said first unit including reference frequency generator means for causing its associated transmitter to transmit a modulated RF pulse, the control circuitry of said second unit including phase lock loop means for frequency and phase alignment with said RF signal transmitted by said first unit and received by said RF signal transmitted by said first unit and received by the second unit, upon receipt of said modulated RF pulse by the receiver of said second unit the control circuitry of said second unit causing its associated transmitter to transmit a replay RF pulse modulated in accordance with said received signal and in phase therewith,
• said control circuitry of said first unit including means for between said transmitted pulse and said received reply RF pulse to thereby determine the distance between units display means connected to said control circuitry for indicating the determined distance between the units
• said control circuitry including means for pulsing the transmitter and receiver of each unit in time coordination with each other to thereby conserve power
• said pulsing means of said first unit including means for generating a reference frequency, said reference frequency driving said transmitter of said first unit, said receiver of said second unit receiving said reference frequency signal and generating an internal reference signal which is used to provide a time aligned periodic pulse for energizing the transmitter and receiver of said second unit, said first and second units thereby being actuated simultaneously
• said control circuitry of said second unit begins time alignment between said first and said second units by its associated transmitter transmitting an RF pulse independent of said receiver of said first unit, said receiver of said first unit including means to enable said receiver of first unit to remain in a receiving mode including means for time alignment when said transmitter pulse from said second unit causes said receiver from said first unit to time align when said pulse from said second unit is received by said receiver of said first unit, said control circuitry including means for triggering an alarm signal when said first and said second units are not time aligned.