Comment on "Short-Delay Multipath Mitigation Technique Based on Virtual Multipath"

It is shown that in the above letter by Z. Zhang and C. L. Law (vol. 4, pp. 344348, 2005) the virtual multipath (VM)-based technique for GPS multipath mitigation is only fit for some certain situations where the first multipath signal is the strongest among the direct and all the multipath signals, which hardly agrees with the real propagation circumstances. Two multipath cases are illustrated to invalidate the VM-based technique.