GROUND MICROPHONES : GMA405
Ground Microphone Systems are available in a basic analogue and a high end digital range. In the higher end systems selectable filters and time of flight measurements are standard features.
PRINCIPLES OF OPERATION
The GMA305 Seismophone was originally developed to cater for the needs of cable fault location technicians where simplicity of use and high accuracy is of utmost importance in noisy environments.
The instrument is equipped with a number of filters, which greatly simplifies the acoustic pinpoint location of faults. It is also equipped with a number of other user-friendly features to simplify the procedure. Display of information is done in bar graph fashion.
Principles of Operation
The instrument embodies the very latest DSP (Digital Signal Processing) techniques, which greatly broadens the possibilities to upgrade and modify the instrument by simply updating the software.
This means that whenever a new technology is developed it will become available to you as the owner of the instrument. The acoustic amplifier employs five different filters to filter as much noise as possible before the signal is amplified. The magnetic amplifier is gain adjustable which allows the operator to attenuate the magnetic signal and then pinpoint exactly where the cable is. It also employs distance measurement techniques, which measure the time difference between the acoustic and magnetic amplifier.
The display is of a 128 x 64 graphic LCD display. Automatic Magnetic Gain Adjustment feature.
The instrument is set up in Auto Magnetic Gain mode by memorizing the cable depth. Auto power shut down feature – Instrument shuts down after 5 min of no user interaction.
Backlight also switches off after 30 seconds, if no user interaction.