Patent Document ID: 8699552
Application ID: 13886986
Patent Flag: 1

Claim One:
1. A method for determining I/Q impairments of a transmitter, the method comprising: performing a set of operations, wherein a local oscillator of the transmitter and a local oscillator (LO) of a receiver have been configured to be phase locked and so that a frequency of the receiver's LO minus a frequency of the transmitter's LO is equal to an amount ΔLO, wherein the set of operations includes: (a) 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 a complex exponential tone in order to obtain an adjusted complex signal, wherein the complex exponential tone is at frequency f, 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; (b) computing raw I/Q impairments at frequency f based on a frequency-shifted signal, wherein the frequency-shifted signal is a result of frequency shifting the sampled complex signal by the amount ΔLO; (c) 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 (d) 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.