Issue 11, March 2010

S64K: Ensuring Sensor Tag Detections Belong to Your Animals

In 2007, VEMCO introduced a new tag coding technique referred to as S64K. Tags programmed with S64K, alternate between a sensor tag ID (A69-1105) with sensor data, and a Pinger ID (A69-1303). This is illustrated below:

S64K was introduced to expand the use of sensor tags that had been previously restricted due to the limited number of unique IDs. Sensor tag ID allocation was previously managed using geographic separation - e.g. VEMCO working with the customer would ensure that duplicate tag IDs would not be deployed in nearby locations. By 2007, with the growing demand for sensor tags, this method was no longer practical.

Actual sensor tag IDs - A69-1105 - with only 256 unique IDs available, are now highly duplicated the world over, so it is imperative that you validate your sensor detections before assuming that they belong to your animals. In other words, another user may have the same sensor ID but with a different unique pinger ID. To validate your data, look through your detection data to ensure that the associated pinger ID (A69-1303) is present as well as the sensor ID and that the pinger and sensor IDs are alternating as expected based on the tag delay settings. A typical dataset in VUE might look as follows:

While a few detections are missing - it is still quite obvious that these two IDs go hand in hand and the user can be confident that the sensor tag detections are those associated with the unique pinger ID.

While this is not a perfect system, it has provided a stop gap allowing VEMCO to continue to provide sensor tags for a growing number of studies. In 2009, VEMCO announced the development of a new tag coding technique referred to as Global Sensors. With this new system, we are able to provide tens of thousands of unique sensor tag IDs. This eliminates the need for alternating pinger IDs making data analysis easier and increasing the sensor data update rate. Global Sensor tags are available now and can be detected by any VEMCO receiver upgraded to MAP-112. For more details or to order new Global Sensor tags, contact your VEMCO sales representative.