USER’S MANUAL__________________________________________________________________
28 __________________________________________________________________ M211322EN-D
All communication to the main RVP902 server chassis goes over a special
CAT5e type cable. The major volume of data is the I and Q samples and
some status indicators.
The RVP900 provides comprehensive AFC support for tuning the STALO
of a magnetron system. Alternatively, the magnetron itself can be tuned by
a motorized tuning circuit controlled by the RVP900. A digital interface
(10 V) is supported.
2.6.1 Digital Receiver Function
The RVP901 receives the analog receive waveforms and digitizes IF
samples. The advantage of this design is that the receiver electronics
(LNA, RF mixer, IF preamp, and IFDR) can be located as far as 25 m away
from the RVP902 server chassis. This makes it possible to choose optimum
locations for both the IFDR and the RVP902, for example, the IFDR could
be mounted on the antenna, and the processor box is in a nearby equipment
room.
A remarkable amount of computing power is resident on the IFDR, in the
form of an FPGA that can execute 38.4 billion multiply/accumulate cycles
per second. This allows the use of multiple FIR filter arrays to run
simultaneously. The FPGA serve as the first stage of processing of the raw
IF data samples. Its job is to perform the down-conversion, band pass, and
deconvolution steps that are required to produce (I,Q) time series. The time
series data are then transferred over a Gigabit Ethernet connection to the
RVP902 server for final processing.
The FIR filter array can buffer as much as 80 microseconds of 100 MHz IF
samples, and then compute a pair of 2880-point dot products on those data
every 0.83 microseconds. This could be used to produce over-sampled
(I,Q) time series having a range resolution of 125 m and a bandwidth as
narrow as 30 Khz. The same computation can also yield independent
125 m time series data from an 80 microseconds compressed pulse, whose
transmit bandwidth was approximately 1 MHz.
Finer range resolutions are also possible, down to a minimum of 25 m. A
special feature of the RVP900 is that the bin spacing of the (I,Q) data can
be set to any desired value between 25 m and 2000 m. Range bins are
placed accurately to within +2.2 m of any selected grid, which does not
have to be an integer multiple of the sampling clock. However, when an
integer multiple (N x 8.333 m) is selected, the error in bin placement
effectively drops to zero.
Dual-polarization radars that are capable of simultaneous reception for
both horizontal and vertical channels are interfaced to the same piece of
hardware. Being the sampling time is highly coherent, ZDR biases do not
To Next Page
Loading...
Need help?
General