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TB12N-WR WIFI Best Practices

Article ID: 49
Last updated: 05 Jul, 2013
Revision: 14
PC-TB12N-WR Best Practices
 
BATTERY-LIFE CONSIDERATIONS
There are a number of factors that may affect the battery life of the PC-TB12N-WR sensors. The following best practices will improve battery life:
 
1.       Set the sensor to a static IP address rather than using a dynamic (DHCP) IP address. The radio must remain on for a longer period of time to request and receive a dynamic address from the DHCP server.
 
2.       Set the wireless access point to a specific channel and program the sensor to connect on that particular channel. If Auto-Channel must be used, then limit the channels to 1, 6, and 11. Set the sensor to only search those three channels. The more channels that the sensor must scan the faster the batteries will be depleted.
 
3.       If your location has more than one wireless access point that use the same SSID set each access point to a specific channel and program the sensor to connect only to the channel of the closest access point. If multiple access points have the same SSID and are using auto-channel the sensor may bounce between multiple access points causing the radio to remain on for a longer period of time depleting the batteries.
 
4.       TB12-Series sensors should not be used for near-real-time data collection. Use the longest possible transmit period. Although the sensor is able to transmit data at intervals as small as two minutes, it is best to use a 4 hour (or longer) transmit interval to conserve battery power. (Keep in mind that logging is independent of the transmit interval. For example: log data every 15 minutes and transmit it every 4 hours.)
  
5.       Verify that you have adequate signal strength using the WiFi Setup Utility. The sensors may have difficulty connecting to the access point with signal strengths below -63 DbM.
 
6.       Verify that sensors are aligned and in the proper firing and power modes (front/side beacons and high/low power modes) for the application. If the RX unit has difficulty ‘seeing’ the beam from the TX unit it will try to re-synchronize which requires more power from the batteries.
 
7.       Verify that the following settings are DISABLED in the Advanced Options of the Wi-Fi Setup Utility:
a.       DHCP Caching
b.       ARP Caching
c.       DNS Caching
d.      Allow Channels 12 and 13 (If possible)
 
8.       When performing a change of batteries. After swapping the batteries press and hold the service button next to the USB port for approximately 10 seconds,or until the message NEW BATT is displayed on the LCD counter. Release the service button and tap the service button once more to force a new data transmission and service signal from the sensors. (Use 3.6 Volt Lithium Batteries Only)
 
ACCURACY CONSIDERATIONS
 
1.       Mounting Height – To avoid receiving multiple counts caused by swinging arms and legs it is recommended that the sensors be mounted at a height between 48 and 54 inches. If the sensors must be lowered to count children the arms and/or legs of adults may cause false counts.
 
2.       Couples and Groups – Break beam sensors are most accurate when traffic is single-file, and going in one direction at a time. If multiple people break the beam at the same time, the sensor will only count one. All though these sensors are capable of spanning distances of up to 30 ft., it is important to remember that as you increase the distance and allow larger crowds to pass through at the same time, you decrease accuracy.
 
3.      TB12-Series sensors are nondirectional sensors; so be sure you are using scale factor in your reports. Note: If you are using Vea View your spread sheets and graphs can be scaled, set scale factor to .5.

4.       IR Interference – Sunlight, automatic door sensors, night-vision security cameras, and other sources of infrared light near the sensor may cause false or missed counts. Avoid mounting sensors within close proximity to a source of infrared light. If sensors will be used in an area that receives full sun, the sensors should be tested in the desired mounting location, in full sun, prior to permanently mounting them on the walls or door frames.  Keep the rubber lens grommets on, they are designed to block sunlight and external sources of Infra-red.

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