Rugged IQ receiver based RF gain measurements

A method for measuring a complex gain of a transmit path comprising:

• modulating a quadrature radio frequency carrier signal using a quadrature test signal;
• down-converting a down-converter radio frequency input signal to provide a quadrature down-converter output signal using the quadrature radio frequency carrier signal, such that the down-converter radio frequency input signal is based on the quadrature test signal and the complex gain of the transmit path;
• frequency converting the quadrature down-converter output signal to provide an averaged frequency converter output signal, which is a quadrature direct current signal that is representative of an amplitude and phase of the quadrature test signal and the complex gain of the transmit path, such that the quadrature down-converter output signal is synchronized to the quadrature test signal;
• and
• extracting the complex gain of the transmit path based on the amplitude and phase of the quadrature test signal and a magnitude and phase of the averaged frequency converter output signal.

Antenna facing circuitry configured to operate in one of a test mode and a normal operating mode, and comprising:

• an IQ to radio frequency modulator configured to, during the test mode, modulate a quadrature radio frequency carrier signal using a quadrature test signal;
• and
• a radio frequency to IQ down-converter configured to, during the test mode, down-convert a down-converter radio frequency input signal to provide a quadrature down-converter output signal using the quadrature radio frequency carrier signal, such that the down-converter radio frequency input signal is based on the quadrature test signal and a complex gain of a transmit path,
• wherein baseband facing circuitry comprises a digital frequency converter configured to, during the test mode, frequency convert the quadrature down-converter output signal to provide an averaged frequency converter output signal, which is a quadrature direct current signal that is representative of an amplitude and phase of the quadrature test signal and the complex gain of the transmit path, such that the quadrature down-converter output signal is synchronized to the quadrature test signal.