Bittner Audio - Application Handbook
Page 51
The following illustration shows the principal lay-out. The diagram shows an uninterrupted
monitoring of the audio path in compliance with the EN-60489:
The paging system is responsible for the monitoring from microphone capsule to its own inputs,
whereas the SXL monitors the rest of the audio chain. Every 90 seconds, relay 4 switches a 20kHz
pilot tone for 10 seconds to the transmission chain. During the 10 seconds, the SXL measures the
impedance of the amplifier channels of interest (parameter
LoadSigChk
). In the case that the
measured value is not within the impedance window, an error will be displayed.
To ensure a reliable measurement, a sufficiently high output level is required. This level averages
at about 1 to 2 Watts, depending on the amplifier model. Therefore, the line length and its
corresponding losses are important.
At very low levels (close to the lower limit), the measurement taken during the first few minutes
after turning on the amplifier may yield inaccurate results. To avoid misunderstandings, the
system offers the parameter
LoadSig start after
to delay the first measurement. A value of 600 s
(= 10 minutes) has proven to be adequate.
3.7.9.4.
Error Acknowledgment
A possible amplifier problem will be indicated by a blinking AMPLIFIER LINK STATUS LED (refer to
3.7.6. LED Indicators Seite 36) on the front panel and by a short description on the LCD (refer to
3.7.12. Error Codes Seite 59). In addition, the error is recorded to the logbook (refer to 3.7.8.2.7.
Logbook Seite 48).
To meet the safety requirements of today’s installations, a detected error needs to be confirmed
after its clearance. The confirmation results in two events:
˜
The SXL tests whether the error has really been removed or still exists
˜
If the test has been successful, the verification will be recorded to the logbook
