A new three-frequency technique for obtaining geometry free, refraction-corrected, ambiguity-resolved, carrier-phase measurements has been described. First, the ambiguities on at least two wide-lane carrier-phase measurement differences are obtained by averaging the corresponding frequency weighted code measurements. These two ambiguity-resolved measurements are then combined into a composite refraction-corrected measurement. The resulting composite measurement is quite noisy due to the amplification of the multipath noise in the original carrier-phase measurements. But this noisy refraction-corrected carrier-phase measurement can be smoothed with another minimum-noise, refraction-corrected carrier-phase composite measurement. The minimum-noise, refraction-corrected composite measurement is constructed from the primary carrier-phase measurements prior to resolving their whole-cycle ambiguities. By smoothing the difference in the two refraction-corrected measurements, the noise can be reduced and the bias in the low-noise measurement (due to incorrect ambiguities) can be estimated and subsequently corrected.