RN-32 : Telemetry systems and signal analyzers for data transmission

Abstract

Data transmission is an integral part of any data acquisition system. The link between the sensor and the recording system can be physical or telemetric i.e. signal from the sensor is converted into radio signals and transmitted for subsequent recording at a recording site which could be far away from the sensor. Telemetry systems are suitable for long distance data transmissions, covering large aerial distances. Components of various telemetry systems, e.g. radio based , satellite-based , meteor-burst etc., have been reported. For efficient and reliable transmissions, generally data is converted into digital form and then initial analysis is performed on the signal. Pre-processing operations include amplification, filtering, trend removal, decimation, calibration etc.

In order to make the input signal compatible to the recording system, these processes are required for increasing the signal to noise ratio of the input. Improvement of accuracy and dynamic range of the system is also desired , which is obtained by processes such as conversion of the raw signal into appropriate units before proper analysis. The signal is transmitted in coded message format which is recovered and decoded at the receiver end. Various operations are available for signal analyses for use with these telemetry systems. These are briefly discussed in the report. Applications of these telemetry systems and associated signal analyzers in hydrology, water resources and related field have been reviewed.