A measuring and telemetry system is disclosed adapted to measure the ambient pressure and temperature in a downhole environment, and to telemeter signals representative of such measurements to the wellhead for demodulation and display. Only two wires are used in the system between the wellhead and the...http://www.google.com/patents/US4646083?utm_source=gb-gplus-sharePatent US4646083 - Borehole measurement and telemetry system
