What transmitter performance parameter does a two-tone test analyze?

A two-tone test specifically analyzes the linearity of a transmitter's amplifier, primarily in single sideband (SSB) operations. Linearity refers to how accurately an amplifier reproduces the input signal at the output without adding distortion. When two non-harmonically related tones are fed into the transmitter, a perfectly linear amplifier will only output those exact two frequencies. If the amplifier is non-linear, it will cause the tones to mix, generating unwanted intermodulation distortion (IMD) products at new frequencies. While other parameters like carrier suppression and sideband suppression are important for SSB transmitters, they are measured differently. The two-tone test is uniquely designed to reveal IMD, making it the standard method for evaluating amplifier linearity.