User's Manual Part 2

Operator Manual
Raytheon Marine GmbH
Germany
R
NSC 18
RADAR
3−9
3748DOC020102Edition: 14.JAN.2005
3.2.1.4 Second trace false echo
The second trace false echo appears when the signal is received at the next
pulse repetition period after it was reflected by a high mountain or similar object
in long distance. Therefore, the position in which it appears is identified by sub-
tracting distance corresponding to the pulse repetition interval from the actual
distance. Assuming the pulse period is 1000 µs and the range scale is adjusted
tor 12 NM, the pulse reflected from a target 80 NM away returns after 1000 µs.
Targets lying at a distance of beyond (80 NM + 12 NM=) 92 NM, therefore, can
generate second trace false echoes.
A target in 83 NM distance may generates an echo on the radar display at 3NM
(see Figure: 3−6).
Transmit pulse
1
Transmit pulse
2
Echo from
transmit pulse 1
Range
scale 3NM
Pulse period
1/pulse repetition frequency
with 1000/s approx. 80 NM
Second trace false echo
Range
scale 12 NM
Figure: 3−6 Second Trace False Echo Effect