Design of an Ultrasonic Telemetry Information Transmitter for the Downhole-Wellhead Communication Channel

The problem of creating an energy-efficient and compact downhole telemetry system in the ultrasonic operating frequency band is relevant but currently not solved. The investigations are aimed at finding possibilities to transmission of telemetric information that provide the better noise immunity and data transfer rate. An ultrasonic transmitter designed as part of the study of the ultrasonic communication channel is presented. A MA40S4S transmitter was used to convert the acoustic signal into an electrical one. The signals are transmitted at a frequency of 40 kHz. The “Manchester-II” coding system is used, implemented in the PIC18F2455 microcontroller. The paper presents the results of testing equipment using amplitude and frequency modulation. It is shown that amplitude of the transmitted signal is significantly reduced when frequency modulation is used due to the narrow frequency band of the receiver and transmitter. The paper presents the electrical circuit of the transmitter with a detailed description. It was found that an AC voltage occurs between the transmitted data packets. This problem was solved using a key. The electrical circuit is powered by 12 V batteries, because it is no 220 V power supply in the field.