User's Manual

RVP8 User’s Manual
October 2005
TTY Nonvolatile Setups
3–22
Bandwidth of transmit pulse: 3.25 MHz
Pulselength of transmit pulse: 15.00 usec
These questions select the bandwidth and pulse length of the Tx waveform. The
bandwidth value represents the true spectrum width of the complete waveform, i.e.,
including all the effects of whatever frequency modulation and amplitude modulation
the waveform happens to use. Thus, a spectrum analyzer (or the RVP8’s Ps plot)
would show an overall spectrum width equal to this desired value.
Likewise, the pulse length value represents the entire time duration of the waveform,
including whatever amplitude modulations may be included at the tails.
Zero offset of transmit pulse: 0.00 usec
The Tx waveform is normally synthesized with its center lined up with range zero. If
the radar’s high-power amplifier had zero delay, this would serve to define the middle
of the transmit pulse as range zero, which is the usual RVP8 convention. This offset
question is provided so that the RVP8/Tx output waveform can be shifted in time to
compensate for whatever delays are present in the radar’s IF/RF electronics.
Note: This transmit pulse timing offset is typically checked via the Pb plot by making
sure that the Tx burst is centered within the FIR data window.
TxWave MIN tuning params: 0.0000, 0.0000, 0.0000
TxWave MAX tuning params: 1.0000, 1.0000, 1.0000
TxWave tuning parameters: 0.9500, 1.0000, 0.0490
The RVP8 uses three real-valued tuning parameters to make the synthesis of complex
waveforms more flexible. Each waveform class can be altered and fine tuned with up
to three degrees of freedom, making it possible for a single class (e.g., the non-linear
FM class) to generate a huge variety of actual waveforms. These adjustable constants
also form the basis of the automatic waveform optimization procedure described for
the Pa command in Section 4.6.2.
Each of the three parameters has a minimum value, a maximum value, and a current
value, all of which can be changed from this menu. The Min/Max limits are used
within the Pa command to maintain sensible bounds as the parameters are adjusted.
In general, the Min/Max values will be entered from the Mt<n> menu, but the actual
values will be tuned using either manual or automatic procedures found in the Pa
command.
The CWPulse class of waveforms do not use any of the tuning parameters because
the Tx waveform is completely determined by the desired bandwidth and pulsewidth,
i.e., there are no remaining degrees of freedom to adjust. Thus, these three questions
do not appear in the CWPulse case.
The linear FM class is also entirely specified by just the bandwidth and pulsewidth
values, and does not reference any of the tuning parameters. However, the non-linear
FM class is the most flexible of all, and references all three tuning parameters as
follows:
S Parameters #1 and #2 are the (X,Y) location of the non-linear “breakpoint” for
the FM curve. Referring to the white plot line in Figure 4–9, the Time/Frequency
behavior of the pulse can be drawn in a coordinate system whose abscissa ranges