Apparatus for testing microwave radios having 35 MHz if using test equipment designed for 70 MHz IF
AssigneeAEL Microtel, Ltd.
InventorsLarry Y. Onotera, Leonard Dueckman
Life of this patent
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Abstract
A 70.+-..DELTA.f MHz sinusoidal test signal from a standard radio link test set is down converted and shaped to obtain a 35.+-..DELTA.f/2 MHz sinusoidal test signal to be applied to the radio set under test. The output of the radio set is applied to an up converter in which a multiplier is used that maintains the amplitude information as it doubles the frequency. The 70.+-..DELTA.f MHz test signal from the up converter is then applied to the input of the radio link test set, and the characteristic is measured as if the radio set under test employed a 70 MHz IF, rather than a 35 MHz IF.
Claims7
Apparatus interposed between a standard radio link test set, which is designed to test radio sets having an IF bandwidth .DELTA.f centered at 70 MHz, and a radio set having an IF bandwidth .DELTA.f/2 centered at 35 MHz, so as to permit testing by the standard radio link test set, which comprises:
- a down converter having an input terminal adapted to receive a 70 MHz sinusoidal test signal from the radio link test set and having an output terminal adapted for connection to the input of the radio set under test, said down converter comprising:
- means to square up the sinusoidal signal from said radio link test set;
- means for dividing the squared up signal to obtain a fundamental frequency of 35 MHz;
- means for substantially reducing spurious frequencies present after the squaring and dividing of said sinusoidal signal to obtain a relatively harmonic-free 35 MHz test signal;
- and
- means for adjusting the level of the test signal as required for the test to be performed to provide an adjusted level test signal at said output terminal;
- and
- an up converter having input terminals adapted to receive output test signal from said radio set, and having an output terminal adapted for connection to an input terminal of said radio link test set, said up converter comprising:
- means for multiplying said output test signal by itself without squaring the amplitude thereof so as to obtain a fundamental output frequency, f.sub.o =K'E.sub.2 (1+cos 2.omega.t), where K' is a constant of proportionality, E.sub.2 being the amplitude of the output test signal and .omega. being the angular frequency;
- means for conditioning the output signal from said multiplying means to substantially remove spurious frequencies and compensate for group delay;
- and
- means for adjusting the amplitude of the signal output from said conditioning means to obtain a level equal to that at the up converter input terminals, and applying this level adjusted signal to the input terminal of said radio link test set.
Dependencies are inferred from the claim text.