Multi-Channel Telemetry Systems

Abstract

Publisher Summary This chapter discusses the multi-channel telemetry systems for the remote measurement of physiological parameters. The advantage of telemetry is that it permits the subject to move about freely without restricting cables. In studies of physiological and pharmacological responses on the central nervous system, this is quite important. Even if cables between the subject and the recording apparatus are permitted they can introduce artifacts by the change of the electrostatic charge of the insulating materials of the wire and induction of an emf in the wire loop as a result of its movement in the earth's magnetic field. The use of multi-channel systems permits simultaneous recording of several different parameters. In a multi-channel system, the low noise, broadband, and high-gain differential amplifiers provide signals of the proper level for the multiplexer. The function of the multiplexer is to combine the different signals from the amplifiers into a single signal that then modulates frequency modulation (FM) transmitter in the range 88–108 Mc. The received signal, after detection by an FM receiver, is divided into its original signals by the pulse shaper, the distributor, and the demodulators. The outputs can be connected directly to a pen recorder or an oscilloscope.