Vaisala RVP900 User Manual

USER’S MANUAL__________________________________________________________________
68 __________________________________________________________________ M211322EN-D
3.2.6 IFDR Input A/D Saturation Levels
There are two analog signals that must be supplied to the IFDR:
- IF receiver signal
- IF Tx Sample (Burst Pulse) for magnetron, or COHO reference for
klystron
Both of these inputs are on SMA connectors. The IF signal should be
driven by the front-end mixer/LNA/IF-Amp. components, similar to the
way a LOG receiver would normally be installed. The magnetron burst
pulse, or klystron COHO reference, is also derived in the same manner as
a traditional analog receiver.
The A/D input saturation level for both the IF-Input and Burst-Input is
+8 dBm. In almost all installations, an external, anti-alias filter is installed
on both of these inputs. These filters (if supplied by Vaisala) are mounted
externally on one side of the IFDR, and have an insertion loss of 0.5 dB to
1.0 dB. Thus, the input saturation level is +8.5 dBm to +9.0 dBm,
measured at the filter inputs.
For the burst pulse, or COHO reference, it is important not to exceed the
A/D saturation level. This reference signal should be strong enough, so that
most of the bits in the A/D converter are used effectively, but it should also
allow a few deciBels below the saturation level for safety. The
recommended power level is in the range -10 dBm to +4 dBm, measured
as described in Section C.15 Burst Pulse Alignment on page 374. This is
important for making a precise phase measurement on each pulse.
Table 4 IFDR LED Indicators
Red (Uplink) Green (Ready) Meaning
Blink Blink Reset sequence (power-up or from
uplink)
On On
Normal Operation (two
-way
communication with IFDR and
computer are both okay)
NOTE
Even for fully coherent Klystron and TWT systems, Vaisala recommends
the use of an actual IF Tx sample. If this is not possible, then the COHO
may be used instead. If there is phase modulation, then the phase-shifted
COHO should be input.

Vaisala RVP900 Specifications

General

Brand	Vaisala
Model	RVP900
Category	Receiver
Language	English