DANPHONE Futronic GMDSS-AIS-SART, Руководство пользователя, Страница: 9 / 42

9
SELF TEST
In the SELFTEST mode it's possible to check the function of some of the circuits in the test box.
This should be used to check the test box before it is used for inspection of a GMDSS
installation. The following self-test functions can be performed:
PLL-TEST
: This mode performs an automatic test to assure that the frequency synthesizer
controlled oscillator goes into "lock" at all the applied synthesis frequencies. The frequency
synthesizer controlled oscillator is programmed to each frequency in turn and then the "lock
detect" output is watched for about 1 sec. to check for a correct lock. In case of a lock failure,
the test is stopped and the LCD display indicates the frequency out of lock. The test continues
when one of the push buttons are activated.
FRQ TEST : This mode is used for test of the MARK/SPACE frequencies in the MF/HF range by
means of the internal frequency counter.
To check the generation and measurement of MF/HF mark/space frequencies, connect a coax
cable from RF IN to RF OUT, choose the MF/HF frequency to be checked and select MARK or
SPACE:
FRQ TEST gives the possibility for control of MF/HF MARK/SPACE frequencies as well as the
frequency counter as the chosen MARK/SPACE frequency is available at the RF OUT socket
and can be measured via RF IN. The result is shown on the LCD display. The SPACE
frequency should be 85 Hz higher than the centre frequency. The MARK frequency should be
85 Hz lower than the centre frequency.