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Radiosonde for Measuring Bovine Intraruminal Reticular Pressures

Dairy Science Department

A. J. Kurtenbach

Department of Electrical Engineering, South Dakota State University, Brookings

ABSTRACT

Radio telemetry transmitters for measuring intraruminal pressures have been described by Wallace (3), Rahm (2), and Dracy (1). All of these units were frequency-modulated transmitters. Their lack of reliability resulting from long term drift is undesirable. In addition, the repeatability of recordings is extremely difficult because of the need for two heterodyning stages in the receiver.

A more sophisticated AM/FM pressure transmitting unit has been designed and tested. This transmitter consists of three major components. The first is a potentiometric transducer which converts a change in pressure to a change in resistance. This resistor determines the frequency of an audio frequency oscillator. The audio frequency amplitude modulates a radio frequency in the range from 180 to 400 kc per second, in a manner similar to a broadcast radio station.

The outside dimensions of the unit are one and one-eighth inches in diameter and eight inches in length. This is large enough to encase the mechanism, yet small enough to pass down the esophagus of a large cow so that it can be implanted into the rumen without surgery.