Test system measuring characteristics or FM radio comm. equip. - operates at both seventy and one hundred and forty mhz and uses transmitter and oscilloscope

摘要

The test system, for measuring the characteristics of FM radio communications equipment, consists of a transmitter feeding the equipment under test. The output of the test object is passed to a receiver whose frequency demodulator demodulates the FM test signal and displays the results on e.g. an oscilloscope. The demodulator input passes over two mixers to a frequency/voltage converter that drives the display. Two switches allow the two mixers to be bypassed and the input signal to pass via a frequency doubler to the same converter. The advantage of this switching lies in its allowing both 70MHz and 240MHz IF signals to be accommodated.