Apparatus and method for measuring the signal-to-noise ratio.

摘要

A signal source which provides a carrier signal (31) having a precisely set signal-to-noise ratio is provided. The carrier signal (31) and its sideband noise components (33) are attenuated below the equivalent thermal noise floor (35) of an attenuator (13). The attenuated carrier signal (31) and the equivalent thermal noise floor (35) are then amplified in an amplifier (15) having a known noise figure to produce a composite carrier signal having a usable power level and a precisely known signal-to-noise ratio. Since the equivalent thermal noise floor (35) is a function only of temperature, the desired carrier signal-to-noise ratio may be set by setting the power level of the carrier signal (31) and knowing the noise figure of the amplifier (15).