Introduction - BRUEL & KJAER 1022 Instructions And Applications

1. INTRODUCTION
The Beat Frequency Oscillator Type 1022 is a precision signal generator
using solid state circuitry throughout. It covers the range 20-20,000 Hz and
is designed for acoustical, vibrational and electrical measurements.
The 1022 works on the heterodyne principle using two high frequency
oscillators one of which operates at a fixed frequency while the frequency
of the other can be varied. The required audio frequency is then obtained
by mixing these frequencies to produce a beat frequency.
The instrument contains several features that aid experimental work. A
regulator stage is provided so that for instance constant sound pressure or
vibration level may be maintained.
The output signal can be automatically frequency modulated by an inter-
nal generator to produce a warble tone for use during reverberation mea-
surements. Alternatively the output signal can be externally modulated to
allow wider choice of modulation frequency and frequency deviation.
The output attenuator has a range of 100 dB in 10 dB steps and the
output impedance can be varied to give maximum power (2.5 W) in a load
of 6-60-600 or 6000Q.
The 1022 may be swept continuously through its frequency range by
means of an external motor drive. Alternately, parts of the frequency range
may be blocked with adjustable cams to suit any particular sweep program.
If it is driven by the Level Recorder 2305 it can also be automatically
synchronized with frequency calibrated paper.
Outputs of 100-120 kHz variable and 120kHz fixed frequencies are
available for use as control frequencies for the Heterodyne Slave Filter
2020.
Remote control facilities are provided to start and stop the scanning and
the oscillator and for instance to lift the pen on the Level Recorder when
the oscillator is sweeping outside the frequency range of interest.
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