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US 5,847,559 AGranted
Spectrum Analyzer
AssigneeAdvantest Corporation
InventorsHiroaki Takaoku, Takayoshi Fukui
Life of this patent
Estimating the term…
Abstract
An improved local oscillator for use in a digital step sweep is capable of minimizing dynamic spurious which is an inverse of the unit step time T.sub.step. The local oscillator includes a random clock delay 12 which provides a random clock 12.sub.rndclk to the DDS 40 to modify a time length of the unit step time T.sub.step for sweeping the local oscillator to be random.
Claims5
A spectrum analyzer for analyzing frequency spectrum of an incoming signal, comprising:
- a local oscillator which is digitally swept by a DDS (direct digital synthesizer), said DDS generating a reference signal for said local -oscillator based on a sweep signal formed of a plurality of unit step time (T.sub.step);
- and
- a random clock delay (12) for generating a random clock (12.sub.rndclk) having a random step time whose average time is significantly the same as said unit step time (T.sub.step) and providing said random clock to said DDS (40) so as to modulate said unit step time (T.sub.step) by said random clock, said random clock delay (12) comprising:
- an address counter for generating an address signal by counting a reference clock;
- a table memory for storing random data for generating a pseudo random signal when accessed by said address signal from said address counter;
- and
- a divider for dividing said random signal from said table memory to form said random step time.
4 more elements
Dependencies are inferred from the claim text.