Patent Document ID: 8442150
Application ID: 13404896
Patent Flag: 1

Claim One:
1. A method for determining I/Q impairments of a transmitter, the method comprising: configuring a local oscillator of the transmitter and a local oscillator (LO) of the receiver to be phase locked to a common reference and so that a frequency of the receiver's LO minus a frequency of the transmitter's LO frequency is equal to an amount ΔLO; performing a set of operations, wherein the set of operations includes: (a) directing that a complex exponential tone at frequency f be supplied to the transmitter; (b) supplying a pre-compensation transformation to a pre-compensation circuit of the transmitter, wherein the pre-compensation circuit is configured to apply the pre-compensation transformation to the complex exponential tone in order to obtain an adjusted complex signal, wherein the pre-compensation transformation is configured to pre-compensate for a current estimate of the I/Q impairments of the transmitter, wherein the transmitter is configured to transmit a transmit signal based on the adjusted complex signal, wherein a receiver is configured to receive the transmit signal and to capture a sampled complex signal representing the received transmit signal; (c) frequency shifting the sampled complex signal by the amount ΔLO to obtain a frequency-shifted signal; (d) computing raw I/Q impairments at frequency f based on the frequency-shifted signal; (e) removing a current estimate of a signal path from the raw I/Q impairments at frequency f to obtain path-compensated I/Q impairments at frequency f, wherein the signal path includes a path from an I/Q modulator of the transmitter to a demodulator of the receiver; and (f) updating the current estimate of the I/Q impairments of the transmitter at frequency f based on the path-compensated I/Q impairments at frequency f.