The 16th Symposium of Meteorological Observations and Instrumentation
92nd AMS Annual Meeting, New Orleans, USA, 22–26 January 2012
Weather Radar Virtual Signal Generator as Test Bench for Algorithm Development
Jinming Ge, Alan Siggia
Louisville, CO 80027, USA
Weather radar receiver data is needed to simulate or test digital signal processing (DSP) algorithms. But actual signal may be either difficult to obtain, or with different or uncontrollable characteristics from what expected. A virtual radar signal generator with controllable strength, center frequency, bandwidth and relative phase delay (for multiple channels) is presented in this paper.
A zero-mean uniformly distributed (white) noise passes through a very narrow bandwidth (nBw) band-pass FIR filter centered at frequency (nFc) to generate a band-limited base signal in time domain:
BaseSig(nBw, nFc) = WhiteNoise * FIR A signal with controllable bandwidth and center frequency can be generated from the BaseSig(Bw) by down-sampling it with a factor (Hp). The re-sampled signal will have a bandwidth Bw:
Sig(Bw, Fc) = BaseSig(nBw, nFc) * Sample(Hp)
When multiple channel signals are needed, their relative phase delay (Dp) can also be controlled via delayed sampling:
Sig(Bw, Fc, Dp) = BaseSig(nBw, nFc) * Sample(Hp+Dp)
If the relative strength of the multiple channel signals needs to be modeled, an extra parameter (Am) can be introduced to the generator as:
Sig(Bw, Fc, Dp, Am)=Am * BaseSig(nBw, nFc) * Sample(Hp+Dp)
The optimal configuration of the parameters (nBw, nFc) and the number of samples of BaseSig is related to the range and resolution of the parameters of the simulated virtual signal Sig.
Fig.1 shows the similar envelopes of the virtual weather radar signal and the signal from large number of raindrops, as a validation of the modeling used in the generator.