User manual: Installation and Operation of Direction Finder System RHOTHETA RT-600 / SAR-DF 517
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2.2.3
Special Options in COSPAS-SARSAT Bearing mode
Especially for the use together with beacons transmitting a data signal according to COSPAS-SARSAT
specifications in the 406-MHz-Band, special functionalities and pages are being provided.
After selection of a COSPAS/SARSAT Frequency (Refer to the chapter “Frequency selection Page”), the bearing
page provides additional information and operating options.
Operational Elements and Display in COSPAS-SARSAT Bearing Mode
(1)
>Auto Squelch< indication, indicating that the squelch level is set automatically to be close to the noise
floor. It is recommended to always use the Auto Squelch during COSPAS-SARSAT operation. This can be
achieved by manually selecting 0 % (lowest possible value) or 60 % (highest possible value) as squelch
level. During COSPAS-SARSAT-Operation, this will force the automatic setting of the level.
(2)
>Decode< menu option, allows to open the COSPAS/SARSAT Decode sub-page by shortly pushing the
F1 push-button above the menu option.
(3)
>>121.500< menu option. The COSPAS-SARSAT signal in the 406 MHz band is transmitted only every 50
seconds in form of a short data burst of 440 or 520 ms. Approaching the transmitter, it will be received
earlier than the 121.500 MHz continuous signal due to its high transmitter power. However, in a lower
distance to a transmitter, bearing on 121.500 MHz is faster thanks to the continuous or rapidly intermittent
signal. The 121.500 MHz menu option allows a direct switch-over to 121.500 MHz. Direct return back from
121.500 to the COSPAS-SARSAT band is possible from the 121.500 MHz bearing Window in COSPAS-
SARSAT mode. Please refer to the chapter “121.500 MHz bearing Window in COSPAS-SARSAT mode”
for details.
(4)
>Frequency range< indication. COSPAS-SARSAT is using a channel spacing of 3 kHz for its beacons.
Due to the internal architecture of the direction finder, it is possible to receive more than one channel in
the same time. Thus, frequency steps of the direction finder are 8.33 kHz instead of 3 kHz. The receive
frequency covered by the current receive frequency setting is shown in the display line above the receive
frequency indication.
Important:
If the exact frequency of the COSPAS-SARSAT beacon is unknown, it is strongly recommended to use
the COSPAS-SARSAT scanning functionality for detecting the correct frequency (Refer to the chapter
“Frequency selection Page” & “COSPAS-SARSAT Scan Mode”)
