The inphase and quadrature data is processed independently for each transmitted frequency. Covariance averaging is performed between pairs of pulses separated by T1 and T2 (denoted R1 and R2). This process gives zeroth lag power for both PRT's:

The following spectral moments or associated products are computed for the staggered PRT: unfolded velocity, velocity for PRT#1, velocity for PRT#2, reflectivity, spectrum width, and NCP. The phase of each vector is determined as follows:

Velocity unfolding for ELDORA is done in vector space. This is advantageous because the signal processor can unfold the velocity without any knowledge of the PRTs or transmitted frequencies. Given T_{2}/T_{1} = f_{ 2}/f_{ 1} = K_{2}/K_{1}, where K_{1} and K_{2} are relatively prime integers and K_{2} > K_{1}, there exists K_{1} + K_{2} regions where the difference, D = (K_{2}/K_{1})f_{ 2} - f_{ 1} is unique. For K_{2}/K_{1} = 5/4, nine such regions exist. Associated with each region is a constant phase offset which is added to the average phase, f = ((K_{2}/K_{1})f_{ 1} + f_{ 2})/2 to place it in the correct Nyquist interval. These phase corrections are stored in a lookup table in the signal processor memory. Averaging the phases associated with each PRT improves the velocity estimate. The phase corrections for the first nine intervals are given in Table 1. Once the absolute phase is determined the unfolded velocity can be calculated as follows:

where l is the average wavelength of the transmitted chips. As the frequency separation on ELDORA is around 10 MHz, this has a negligible effect on the accuracy of the velocity estimate.

Region

D =(K_{2}-K_{1})f_{ 1}-f_{ 2}

Correction

-5p < f_{ 2£} -3(K_{2}/K_{1})p

p

-2p (1+K_{2}/K_{1})

-3(K_{2}/K_{1})p < f_{ 2£} -3p

-3p /2

-p (2+K_{2}/K_{1})

-3p < f_{ 2£} -(K_{2}/K_{1})p

p /2

-p (1+K_{2}/K_{1})

-(K_{2}/K_{1})p < f_{ 2£} -p

-2p

-p

-p < f_{ 2£ p}

0

0

p < f_{ 2£} (K_{2}/K_{1})p

2p

p

(K_{2}/K_{1})p < f_{ 2£} 3p

-p /2

p (1+K_{2}/K_{1})

3p < f_{ 2£} 3(K_{2}/K_{1})p

3p /2

p (2+K_{2}/K_{1})

3(K_{2}/K_{1})p < f_{ 2£} 5p

-p

2p (1+K_{2}/K_{1})

Table 1 Phase Corrections for First 9 Intervals

Estimates for the mean velocities associated with T_{2} and T_{1} are given by the following: