Vaisala RVP900, User Manual

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Output
IF transmit waveforms are synthesized by the IFDR and can be output over two SMA
connectors.
The IF transmit waveforms are programmable in phase, frequency, and amplitude. In the
simplest case, it might supply the Coherent Local Oscillator (COHO), which is mixed with the
STALO to generate the transmit radio frequency for Klystron or TWT systems.
Other applications include pulse compression and frequency agility scanning.
Timing
The sampling clock in the IFDR is selected for stability. The sample clock serves a similar
function to the COHO on a traditional Klystron system, it is the master time keeper. The
RVP901 IFDR sample clock is used to phase lock the entire RVP900: the Rx, Tx,
miscellaneous I/O are phase-locked to the IFDR sample clock. It is programmable over a
wide range of frequencies.
3.1.2 RVP901 IFDR IF to I and Q Processing
RVP901 IFDR performs parallel FIR filtering, simultaneously on each channel. This allows
frequency agility receiving functions within the bandwidth of the analog receiver, which
unifies the transmit frequency agility to provide advanced signal processing.
The IFDR performs the initial processing of the IF digital data stream and outputs
I and Q
data values to the host computer through the CAT5e Ethernet. The frequency, phase, and
amplitude of the burst pulse are also measured.
In sum, the processor performs the following functions:
• Band pass filters the IF signal using configurable digital FIR filter matched to the pulse
width. This also includes:
• Range gating and optional coherent averaging
• Calculating
I and Q quadrature values
• Calculates transmit burst sample frequency, phase, and amplitude
• Corrects
I and Q phase and amplitude based on transmit burst sample
• Runs the interference rejection algorithm
• Calculates the AFC frequency error with output to IFDR for digital control of STALO (for
magnetron systems)
The digital approach allows the software algorithms for these functions to be easily
changed. Configuration information (for example, processor major mode, PRF, pulse width,
gate spacing, and so on) is supplied from the host computer.
More Information
‣
Digital IF Band Pass Design Tool (page 27)
‣
IF Signal Processing (page 172)
3.1.3 Digital Receiver Function
A digital receiver can perform the following functions:
Chapter 3 – Functional Description
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