INTRODUCTION TO ELECTRONIC IDENTIFICATION (EID)
How Does it Work?
A few simple steps enable EID devices to transmit a signal to an EID Reader System, which then decodes the signal that can be sent to a weigh scale indicator or computer. The steps are:
1. The EID Reader System generates a radio frequency (RF) magnetic field.
2. An EID device placed inside the RF field is energised.
3. The energised EID device transmits a signal containing a unique number to the EID Reader System.
4. The EID Reader System decodes the signal into a unique sixteen-digit number. (This number is commonly referred to as the ISO (International Standards Organisation) number)
5. The ISO number is sent to a weigh scale or computer where it is stored and/or displayed on the screen.
6. The number can now be referenced against other important farm information.
The following illustration shows the steps involved in information being transmitted between an EID device and an EID Reader System.
Important Points
- All NLIS approved EID devices are passive and only transmit a signal when energised in an appropriate RF field.
- The International Standards Organisation (ISO) has reserved a frequency of 134.2 kHz and set the communications protocols for animal use. This is partly because higher frequencies are obstructed by organic and animal tissue.
- EID devices can be inside the animals or covered in mud and they will still be read by an EID Reader System. Therefore, no direct line of sight is required.
- Each animal should be identified with only one EID device.
- To guarantee traceability only one device, i.e. only one animal, should be in the read area at any one time and animal flow must be carefully controlled.
- Steel plate obstructs the RF field and steel structures can greatly affect the performance of many readers.
- The maximum distance a passive device can be read is generally limited to a maximum of 1.5m depending on EID Reader System output and the ability of the device to return a signal.
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