This read-only object reports the measured frequency offset (in Hz, 100 Hz resolution) of the carrier being demodulated, ranging from -200,000 to +200,000 Hz. A consistently nonzero offset here reflects either Doppler shift, LO drift at the transmitting end, or an inaccurate internal reference in this unit, correctable via cdd564InternalReferenceAdjust -- distinguishing between those causes typically requires checking whether the offset is stable and specific to this unit versus varying with a moving satellite or specific to one remote transmitter. A steady offset reading of around +5000 Hz on every carrier this unit demodulates would point to this unit's own reference needing adjustment, whereas an offset that only appears on carriers from one specific remote site points to that remote's transmitter LO instead.