Zenitel Ambient Noise Sensor (ANS)

An Ambient Noise Sensor (ANS) is a sample and hold device that monitors ambient noise continuously as a broadcast is made. The measured ambient noise level at that point in time is used to determine a reduction in broadcast level from a commissioned maximum value. In quiet conditions, the system allows greater volume attenuation to avoid unnecessary loudness. As ambient noise increases, the ANS progressively limits the amount of volume reduction, ensuring announcements remain clear and intelligible. In effect, the ANS acts as a volume attenuator, reducing how much the volume can be turned down while maintaining adequate speech intelligibility.

Operation

The operation of the ANS depends entirely on what it's mode is set to:

Enabled: the router audio output level will be adjusted to compensate for worst case ambient noise level.
None: Ignore the Ambient noise adjustment and broadcast at normal levels - normally used for Emergency messages and Microphones
Tolerant: This function allows the system to continue sampling ambient noise levels while the input is routed. This is useful for low level background music but must be used with care. It is important the audio levels of the background music does not exceed the minimum ANS level, otherwise the background music could directly drive the perceived ambient noise levels.

Key Points

Each router output can be controlled by up to 4 x ANS sensors. All ANS's for a zone must be connected either the Vipedia-12 on board GPIO or an external BMB.
ANS noise thresholds are configured in the VIPEDIA-12 SCT.
High and Low range settings define the maximum and minimum ranges of the ANS which can be set.
The ANS hardware has a switch to adjust its sensitivity for maximum and minimal operational ranges (Please note these must match the Noise Control settings in the SCT configuration):
- Hi setting = 65 dBA - 95 dBA
- Lo setting = 55dBA - 85dBA
Please note: ANS internal switches are set to the Hi position by default when shipped

Configuration Example

In this example, we will configure an ANS of the low range:

Target Maximum SPL Broadcast is measured at 95dB.
Minimum SPL Broadcast is measured at 65dB.
Background ANL (Ambient Noise Level) is measured at 55dB.
Signal to noise ratio required which is usually 10dB.

1. Calculate the Maximum ANS Threshold by subtracting the required signal-to-noise ratio (10 dB) from the maximum required SPL (90 dB):

95 dB − 10 dB = 85 dB

2. Configure the Maximum ANS Threshold by entering 85 dB as the Max Level in the SCT Noise Controls.

This means that once the ambient noise reaches 85 dB, the system will output at maximum the predefined maximum SPL of 95 dB.

3. Configure the Minimum ANS Threshold by entering 55 dB as the Min Level in the SCT Noise Controls.

This is the ambient noise level at which the ANS will begin adjusting the broadcast volume.

4. As the min ANS threshold is 55db you need to ensure that the ANS switch is set to the Lo and the corresponding setting in the Noise Control of the SCT matches.

The Low LED on the front panel of the ANS should illuminate verifying the switch is in the correct position.

Connections

ANS Connections

The 240ohm resistor is fitted at the rack terminals

Troubleshooting

Fault Finding

Operational Fault Symptom	Fault Description	Fault Code(s) Reported and Logged at the Router	Suggested Action
Loss of functionality of a single ANS	Remote I/O unit analogue channel fault (open or short)	REMXX/AINYY ANALOGUE I/P XX=Remote I/O Unit Address YY=Analogue Input Channel	Check wiring of the ANS on the specified analogue input channel. Check the ANS on the specified analogue input channel, and replace it if necessary. The ANS external and internal LEDs provide additional indication. Replace the BMB02 Remote I/O Unit.

ANS Front Panel LEDs’ Fault Reporting

HIGH and LOW LED Indication

Operational Fault Symptom	External LED Indication	Suggested Action
Total loss of functionality of an ANS Sensor	HIGH: OFF (ANS Range N/A) LOW: OFF (ANS Range N/A)	Check power supply to the ANS. Check wiring between the ANS and the BMB02 analogue input Check connection of sense resistor at BMB02 Check BMB01 unit. If faulty, replace BMB02
Incorrect ANS operation (too loud or too quiet).	High: ON (High Range 65dBA - 95dBA) Low: OFF (High Range 65dBA - 95dBA) High: OFF (Low Range 55dBA - 85dBA) Low: ON (Low Range 55dBA - 85dBA)	Confirm that the LEDs indicate the expected ANS range set-up. Check the brightness of the LED that is turned on. If the LED brightness decreases with increase in the ambient noise, then the ANS sensor is operating correctly. You may need to re-configure the ANS sensor to the required ANS range. Check the ANS range set at the Router/VIPA unit. If both the Router and the ANS Sensor have not been set to the same ANS range, then set either the Router/VIPA unit to the required ANS range.

ANS Internal LED's Fault Finding

Operational Fault Symptom	Internal LED Indication	Suggested Action
Total loss of functionality of an ANS Sensor	PWR LED (green) is OFF: Power is not present	Check power supply to the ANS. Check wiring between the ANS and the BMB02 analogue input. Check connection of sense resistor at BMB02. Check BMB02 unit. If faulty, replace BMB02.
Total loss of functionality of an ANS Sensor, though the ANS Sensor still appears to be functional	MIC FAULT LED (amber) is ON: Microphone capsule open or short circuit fault.	Check continuity of microphone capsule and associated wiring. If faulty, replace ANS sensor.

You can also monitor the Router input thresholds using a multimeter:

ANS Router Input Thresholds Diagram

ANS power supply comes from the Vipedia-12's "Onboard GPIO" or from a BMB01/BMB02.

Obsolete Variants

ANS04E
ANS03
ANS02
ANS01

Related Information

Additional documentation on Zenitel.com