DERIVATION AND ERROR ANALYSIS OF ECHO PHASE PARAMETERS FOR THE DYNASONDE

Ionospherically reflected echoes are received with a four-element mult iplexed interferometer array and two phase-matched receivers in implem entations of the National Oceanic and Atmospheric Administration dynas onde. From these data, six phase parameters (Phi(0), Phi(x), Phi(y), P hi(t), Phi(p) and Phi(f)) are obtained and used to derive echo locatio n, Doppler velocity, wave polarization, and virtual range. Since 2 pi aliasing is an inherent feature of interferometric spaced antenna phas e measurements, the phase parameters cannot be derived directly from t he measured phase values using the method of least squares. in this wo rk, we introduce a general procedure for the derivation of these param eters that (1) employs a ''zero-freedom'' technique to derive initial estimates of the phase parameters, (2) derives shifted values of the m easured phases from the six estimates, and (3) uses the method of leas t squares in conjunction with the shifted phases to improve the phase parameter estimates. This procedure minimizes the phase ambiguity inhe rent in interferometric phase measurements and derives phase parameter s that approach the ideal least squares result. Furthermore, the ionos pheric echo ''quality'' is quantified by two error parameters, defined as (s) over cap, the least squares of the measured phase errors, and EP, the RMS phase error. It is also shown that the value of (s) over c ap relative to the square of the standard deviation of measured phase is equal to the number of degrees of freedom in the phase parameters. Applying these techniques to data acquired with the Utah State Univers ity dynasonde, we derive a standard deviation of <2 degrees in the mea sured echo phase.