Installation Instructions

Hardware Installation

RVP8 User’s Manual

September 2005

2–19

being used as the RF source, then you may want to lock your RVP8 to the STALO’s own

reference clock (generally 10MHz). For dual-pol magnetron systems you must lock the

RVP8 in this manner to measure differential phase.

S For klystron and other synchronous radars there will always be some kind of reference

clock in the system. In the simplest case of a single-pol radar in which the RVP8 fires

the transmitter directly, you may be able to get away with using free-running clocks.

However, in virtually all cases it is best to lock the RVP8 to (one of) the radar’s existing

timing reference(s).

The following table lists the different clock modes for the RVP8/Rx, RVP8/Tx, and IFD. The

frequency of the required crystal oscillator is given, along with the type that is required. The

VF155 oscillators are general purpose units, VFAC170 is low-jitter free-running, and VF940 is

low-jitter Voltage Controlled Crystal Oscillator (VCXO).

Table 2–8: Clock Locking Component Options

Lock Mode RVP8/Rx RVP8/Tx IFD

U16: 26.983 (VF155) U9 : 80.944 (VF940) 35.975 (VFAC170)

Free-Running

The IFD is free-running, and the Rx and Tx cards lock to it. Use this mode for simple

magnetron radars in which there is no system reference clock.

U16: 26.983 (VF155) U9 : 81.000 (VF940) 36.000 (VF940)

N-MHz External

Reference

A reference clock at some integer N-MHz is applied to both the IFD and Tx inputs, both

of which lock directly to it. This is the recommended hookup for klystron radars or

magnetron radars that use a synthesized STALO derived from, e.g., 10MHz.

57 5491 MHz

U16: 26.983 (VF155) U9 : 80.928 (VF940) 35.968 (VF940)

5491

WSR88D COHO

For NEXRAD systems, the COHO is fed directly into both the IFD and Tx inputs. The

IFD sampling rate is 5/8 of the COHO frequency, and the Tx rate is 45/32.

31 0703 MHz

U16: 27.186 (VF155) N/A 36.248 (VF940)

0703

ASR-9 COHO

These special frequencies are used for the ASR-9 surveillance radars. The IFD locks to

7/6 times the COHO frequency of the radar.