Raytheon R20 - Rain Clutter

3.1.2 The controls
<D POWER I ST-BY/OFFI, IX-MIT/OFF I KEYS
In the "OFF" state no power applied to the Radar system.
Upon pressing the I ST-BY/OFF I key, power is supplied to the scan-
ner and Display Unit, and the sign "R20" is displayed in the middle of
screen during the warm-up condition. Approximately 90 seconds af-
ter the initial switching to ST-BY, the sign "R20" will disappear from
the screen and the sign "READY"· will be displayed on the screen.
The radar is now ready and available for operation.
Pressing the
IX-MIT/OFF I key, (with the sign "READY" displayed)
puts the radar
to transmit and echoes from targets will be received,
amplified, and displayed on your screen.
By pressing the I ST-BY/OFF I key, the radar returns to "Standby"
condition with the transmitter "OFF" and "STANDBY" appears in the
CRT center.
By pressing the I ST-BY /OFF! and IX-MIT/OFF I keys simultaneously,
the radar
will turn "OFF" and all Alpha-Numeric information will ex-
tinguish.
@ RANGE C....,.I R....,.AN~G-=·1~~ I 'V, !J.)
By holding the I RANGE I key depressed until the buzzer sounds, the
"R" character or RANGE indication located on the lert bottom corner
or display will be displayed as reversed character. [[)
By pressing the 'V or 6 key, the desired RANGE scale can be
selected. At the initial turn-on, the radar will be on the 2 nm range.
Upon pressing the key 6, the range increments by one step, con-
versly the range decrements by the key 'V. If the 'V or 6 key is
held depressed, the range will continue stepping successively in the
desired direction.
The selected range automatically determines the proper number and
distance betwteen the range rings.
TABLE 3-1 RELATION OF RANGE, RINGS AND PULSE LENGTH
Range Rings
Distance
Between
0.25 nm
2
0.125 nm
0.5 nm 2
0.25 nm
l nm 4
0.25 nm
2 nm
4
0.5 nm
4 nm
4 l
nm
8
nm
4
2 nm
16
nm
4
4
nm
3 - 2
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@ TUNE CITUNE I 'V, /J.)
By holding the fTITiiIBl key depressed until the buzzer sounds, the
"T" character of TUNE indication located on the lert bottom corner
of display will be displayed as reversed character. II]
By pressing the 'V or 6 key, the TUNE control will maximize the
target echoes.
If land targets are not within the radar's range, adjust
the control for maximize sea clutter return. An on-screen bar indi-
cates the "TUNE" position in its range.
© GAIN c[fillli] 'V, !J.)
By holding the I GAIN I key depressed until the buzzer sounds, the
"G"; character or GAIN indication will be displayed as reversed char-
acter. [ill
By pressing the 'V or 6 key, the GAIN control is varied and thus
controls the strength
or echo returns on the radar screen. An on-
screen bar indicates the Gain level selected for display.
® SEA CLUTTER Cl SEA CL I 'V, !J.)
By holding the I SEA CLUTTER I key depressed until the buzzer
sounds, the "S" character or SEA CLUTTER will be displayed as re-
versed character. [fil
By pressing the 'V or 6 key, the SEA CLUTTER level varies the
near-by gain on short ranges. The echo returns from sea surface.
Clutter
can be reduced when the STC Gain is increased. There is an
on screen bar indication of the STC level in use.
@ RAIN CLUTTER cl RAIN CL I 'V, !J.)
By holding the I RAIN CL I key depressed until the buzzer sounds, the
"R" character or RAIN CLUTTER will be displayed as reversed char-
acter.[[]
By pressing the 'V, or 6 key, the RAIN CLUTTER control can
break up the returns from rain or snow thus allowing weaker targets
to become visible. As you pu'sh the '6. key, the echoes will become
narrow and the returns from rain or snow will be reduced. An on-
screen bar indicates the selected rain clutter level.
0 VRM <CTEMJ 'V, /J.)
By holding the VRM key depressed until the buzzer sounds, the
"VRM" characters will be displayed as reversed character. I VRM I
By pressing the 'V or 6 key, the VRM position is changed. U the
VRM key is depressed for a short time, the VRM can be turned
"OFF". The VRM distance is displayed on the CRT arter the VRM
characters in "nautical miles."
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