Installation Instructions

Hardware Installation
RVP8 User’s Manual
September 2005
2–22
Depending on the installation, the jumpers on the I-O 62, Rx and Tx Cards may require
configuration. These are described in Appendix C.
2.3.4 External Pre-Trigger Input
Users may supply the RVP8 with their own CMOS-Level pre-trigger for installations in which
adequate trigger control already exists. The trigger input is provided directly on the Rx Card
(bottom BNC connector on the card panel labeled “TR-2 / In). See Appendix C for instructions
on how to set the Rx card jumpers to enable a pre–trigger input.
The trigger input uses CMOS levels (1.5V max low, 2.5V min high) for improved noise
immunity. The trigger input may also be driven as high as +100V or as low as –100V without
damage. This makes it easier to connect to existing high-voltage trigger distribution systems.
The rising or falling edge of this external “TRIGIN”signal is interpreted by the RVP8 as the
pretrigger point; the actual pulsewidth of the signal does not matter. The delay to range zero is
configured via the TTY Setups. The other trigger outputs are then synchronized to the input
trigger. The synchronization jitter between the user pretrigger and the other trigger outputs is
less than 0.014 microseconds.
Trigger jitter can be improved in the case of coherent systems, by phase locking the IFD to the
same reference clock used to generate the external triggers (typically the COHO). This provides
approximately 10 dB of additional phase stability.
The RVP8’s response to a missing external trigger is that the processor will insert fake (software)
”triggers” at a rate of 250Hz whenever the trigger input is missing for more than 0.100 seconds.
These fake triggers will keep the RVP8’s internal code and external outputs running in spite of
the missing input (the data values will all be zero, and the ”no trigger” bit will be set in GPARM
immediate status word #1). Normal operation automatically resumes as soon as the external
trigger is restored.
2.3.5 Connector Panel I/O Connections
Most of the connections between the radar and the RVP8 are made using the RVP8 Connector
Panel which connects to the I/O-62 by 1.8m (6 foot) cable. The panel is usually mounted on the
front or the back of the same 19” EIA rack that contains the RVP8 chassis. The I/O-62 cable
may be plugged into either the front or the back of the connector panel to optimize the cable run.
The Connector Panel uses a DC–DC converter to convert 12V unregulated input from the PCI
card into regulated +5V, +3.3V, and +/–12V to run the main electronics on the panel. The LEDs
on the panel are described below: