IQ Offset (GSM/EDGE/EDGE Evolution)

IQ Offset (also called I/Q origin offset) displays the ratio of the power at the center frequency to the average signal power. This data result indicates magnitude of the carrier feedthrough signal. When there is no carrier feedthrough, IQ offset is zero (-infinity dB).

IQ origin offset is easily seen in the constellation diagram, as shown below:

In the above illustration, "x" is the center of the constellation diagram. When "x" occurs at the origin, the IQ offset is zero. When "x" is not at the origin, the IQ offset is the magnitude of the vector (in dB) between "x" and the origin.

IQ Offset is computed only at the symbol times (the instant in time when symbols are detected). The computation does not include points between symbols.