EID Tag Reading Problems
Reading EID Tags with a static panel reader is not difficult or new. The
technology is based on some very basic laws of physics and has been around
since the 1970's. Hand held readers tend to appear to read better, simply
because although they are effected by the same factors that effect static panel
reader, the read range is less important. When affected
by electronic noise or poor tags the user simply compensates by moving the reader
nearer to the tag.
When a static panel reader fails to read the tag the result is of course very
frustrating with no obvoius cause. The main problem being that a number of
factors can effect the performance of an antenna but with only one
result: Read failure!
To start with a brief overview of how the reader works is useful. This applies to
both hdx and fdx tags
1. The EID reader energises the tag by producing an electro magnetic field, which
charges the tag with power as the tag enters the field.
2. The tag, when energised transmits its electronic code
3. The reader receives this electronic code and outputs the code to the connected
computer, weigh head etc.
HDX and FDX tags - Half Duplex and Full Duplex
Although the two tag types operate in a slightly different way, they have one
fundamental difference which effects their read quality or at least the EID
Readers ability to receive the transmitted code.
FDX tags are based on AM (amplitude modulation) radio technology
HDX tags are based on FM (frequency modulation) radio technology
In effect this is like you listening to Radio 4 on long wave as opposed to FM.
Electronic Noise
Electronic noise is like the weeds in your field, we can define a weed as
anything we actually don't want to be there. Electronic noise is similar in that
we can define it as any electronic signals which we don't want.
The world has a level of background noise, the strength of the signal compaired
to the noise is refered to as the Signal to Noise Ratio (level). If your
signal level falls below the level of the noise then you simply cannot hear the
signal and things fail. FDX tags are effected by noise more than HDX tags.
There are two basic sources of electronic noise.
1. 240 volt mains interferance
The first is noise generated by power supplies, or 12 volt mains adapters. If you
are running either mains powered equipment or equipment running from cheap 240v
AC to 12V DC adapters in the local vaccinity to the reader you are likely to get
interferance. If you do intend to run the equipment or even the EID reader
itself from a mains adapter you need to buy one that filters the mains 'hum' out
of the 12 V DC. Other sources include lights, mains leads, electric
fencing systems.
2. Radio inteference
The second type of interference is radio interference, this may well include
unsupressed vehicles, RF transmitters etc. This type of interference is less
likely unless a race is connected to your weigh crate as the race acts as a big
antenna and literally pick up the noise and raise the noise level in the weigh
crate.
Reducing Noise and Interference
1. Run your EID reader, Tru-Test XR3000 and Drafting controller off a smooth 12
volt supply, i.e Battery or very smooth power supply.
2. Ensure any 240 volt power leads are as far away as possible.
3. Isolate the weigh crate from the race.
4. Switch off quad bikes and vehicles
EID Pops up in some very strange places
1. Dogs - your weigh crate will quite happily read the chips in your dog! Ensure
the dog is not asleep round the back.
2. Car Keys - Ford for one have used EID tags in car keys as a security feature.
Your weigh crate will continue to read your keys in your pocket. (not all car
keys do this)
3. Check your pockets for extra tags!