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Figure 33 Frequency, Phase and Amplitude of a Compressed Tx Pulse
The figure shows that the waveform consists of a linear FM chirp that occupies about 87% of
the central pulse duration. The frequency remains nearly constant in the leading and trailing
edges, hence the label
Non-Linear FM .
The central chirp is contained within a larger amplitude modulation envelope that applies
full scale power within the middle 82% of the pulse, and also provides bandlimited shaping
of the leading and trailing edges.
This waveform was designed using the
$
automatic search-and-optimize command in the
Pa menu. For a given pulse length and bandwidth of the Tx waveform, this command allows
you to try thousands of combinations of FM shape and amplitude shape, searching for the
combination that minimizes the sum of PSL and ISL (in dB). This gives the best overall
waveform for weather radar observations in which both the PSL and ISL are important.
6.8.2 Available Subcommands In Pa
Pa
subcommands change the bandwidth, pulse width, and shaping parameters of the
transmit waveform, and alter the format of the display:
Available Subcommands within 'Pa':
S/s & L/l Pulse Length Shorter/Longer
N/n & W/w Bandwidth Narrower/Wider
1/2/3 Select Tuning Parameter to Change
D/d & U/u Selected Tuning parameter Down/Up
V/v Doppler Frequency Shift Up/Down
Z/z Amplitude Zoom
$ Search for Optimal Waveform
RVP900 User Guide M211322EN-J
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