Doc# 0296-0018 • REV R (July 2017) Page 8 of 61
Capabilies (connued)
The Signal Generator
The signal generator produces a variable frequency sine wave which becomes the source of
the driving signal to produce the vibraon at the shaker head. The amplitude of this sine
wave signal is controlled by the front panel AMPLITUDE dial controller. The frequency is also
con trolled by the front panel FREQUENCY dial controller.
The Power Amplier
The power amplier is designed to provide the current required to drive the coil in the Elec-
trodynamic vibrator through an impedance matching circuit. The frequency and amplitude
of the shaker are controlled by and are proporonal to the frequency and amplitude of the
oscillator signal applied to the amplier input.
The Electrodynamic Amplier
The electrodynamic vibrator funcons by means of the interacon between the magnec
eld in the air gap and the oscillang current owing in the moving coil. This current gener-
ates a force at right angles to the liens of ux in the air gap and to the conductor carrying
the current. This force is proporonal to the product of the instanta- neous current and the
magnec ux density.
The Reference Accelerometer
The reference accelerometer is used to measure and set the level of vibraon at the shaker
head (which is the mechanical interface to the test transducer) for calibraon. The reference
accelerometer is an integral part of the shaker head. It’s sensing element is a ferroelectric
ceramic crystal that outputs a voltage proporonal to compression and extracon forces
imposed by a precise mass that is xed to the crystal assembly. This signal is condioned and
factory calibrate to 50 mV/g. A calibraon “standard” is maintained that is used to calibrate
the TTS and provide NIST traceability.
The vibraon levels can be read in English or Metric units as set by the setup program. Fre-
quency can be read in Hz.
The Microcomputer
The microcomputer manages the operaon of the TTS by interpreng external commands
entered from the front panel keys, monitoring operang parameters, measuring the built-in
reference accelerometer and the transducer under test, performing calculaons and driving
the display and printer. A signicant benet in having a microcomputer is its ability to run self
tests to insure the TTS is funconing properly.
To Next Page
Loading...
Need help?
General
