A Noise Figure Meter Having Large Dynamic Range

This paper describes an automatic noise figure indicator having a range of 0 to about 40 db and a frequency range extending from tens to tens of thousands of megacycles. Gas-discharge noise generators are used as standard sources of noise power. To provide the large dynamic range, the noise generator is modulated, and a cross correlator is used to determine the magnitude of the modulation component in the output noise, The noise figure reading is presented on a direct reading meter with a tolerance that varies from about 0.2 db to about 1.0 db. Methods are given for correcting indicated noise figure readings for the effects of spurious pass bands, non-standard temperature, and non-standard noise generator power.