USER’S MANUAL__________________________________________________________________
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There are two broad categories of time series signal processing:
- Time Domain Processing using the I and Q samples directly to
calculate "autocorrelations" and then using the autocorrelations to
compute the moments. This is used by many systems since the
algorithms are very efficient requiring minimal storage and
computational power. However, time domain algorithms are
generally not adaptive or very flexible.
- Frequency Domain Processing using the I and Q samples to calculate
a Doppler power spectrum and then applying algorithms, such as
clutter filtering or second trip echo filtering/extraction, in the
frequency domain. The Doppler spectrum is then inverted to obtain
the autocorrelation functions and these are used to calculate the
moments. The frequency domain is well suited to more complex
adaptive algorithms, that is, where the processing algorithm is
optimized for the data.
The RVP900 supports the concept of "major modes" or processing modes
to process the time series. Currently the following major modes are
supported:
- DFT/FFT Mode is a frequency domain approach which is used for
most operational processing applications. There are a variety of
clutter filtering options, including the Gaussian Model Adaptive
Processing (GMAP) algorithms.
- Pulse Pair Processing or PPP Mode is a time domain approach that is
used primarily for dual polarization applications.
- Random Phase Mode or RPHASE is a frequency domain approach
similar to the DFT/FFT, except that filtering and extraction of both the
first and second trip echoes is supported.
- Batch Mode during which a small batch of low PRF pulses is
transmitted (for example, for 0.1 degree of scanning) followed by a
large batch of higher PRF pulses (for example, for 0.9 degrees of
scanning) to determine which ranges are likely contaminated by
second trip echo. This was developed to support a particular US
WSR88D legacy requirement.
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