
Intellivox DDC Installation Manual Appendix | EN 20 |
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Notes for type
•Both ends of the
•The +9 V (pin 9) at the
•RTS and CTS are internally connected, DTR and DSR are also internally connected.
3.4 LBC 3262/00 Ambient SPL and
temperature sensor.
Description.
The Intellivox electronics module is equipped with an external terminal (labeled ambient noise / temp) to connect a sensor for the ambient SPL and temperature measurement. Although the unit is able to operate normally without the sensor, it is needed when the auto gain function or the frost protection is used.
The temperature is measured by a NTC resistor. By means of a software correction table the
Location of the sensor.
Both NTC and microphone are mounted in a single compact enclosure which can be located at a certain distance from the column. In most situations the best location is determined by the microphone (see also chapter 2.2). The auto gain will only work correctly if the diffuse ambient noise level is used as a reference. This means that the microphone should be kept away from direct sound sources such as talking people, outlets of the air conditioning system or other loudspeakers.
The implemented software protocol freezes the volume setting when an audio signal is present in order to prevent ‘hunting’ of the column’s gain setting caused by its own radiated acoustical energy.
•Although the circuit of the combined sensor is not complex, the specific characteristics are very important for a correct interpretation of the measured values. For this reason it is strongly advised to use the appropriate factory tested sensor (see chapter 3.1 for order codes).
Wiring.
For reasons of RFI immunity and optimum noise characteristics two different ground terminals are implemented. The terminal labeled GND is connected directly to the chassis, while the terminals labeled AGND are reference ground terminals.
•GND and AGND should be kept apart under all circumstances!
For correct wiring an asymmetrical shielded 2 way cable with overall shield is advised. Alternatively the twin twisted cable, which is also optionally in use for the
Fig 16 Wiring configuration using asymmetrical cable type
Bosch Security Systems July 2003