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Using the antenna, the antenna is used to identify the individual parts of the animal individually. As livestock passes by, the antenna recognizes the individual animal tag.

The antenna frequency uses transmit (128 kHz) and receive (80 kHz).

But I suspect that there is a situation where we are not receiving interference from anywhere. because we do not perceive about 10 to 20 %. Only this farm has this problem.

Is there any interference in that frequency band?

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    \$\begingroup\$ (1st guess) 100kHz is a fairly common switching frequency for switch mode power supplies. (wild guess) Loran radio navigation system uses 100kHz band. Loran transmits pulses with power levels on the order of a megawatt. If the farm happens to be close to a Loran tower, a coil can pick up Loran. (There are equivalent systems outside US under different names, and they use the 100kHz band as well.) \$\endgroup\$ Jul 21, 2017 at 0:51
  • \$\begingroup\$ Loran C (100 KHz) was shut off several years ago in the US and Canada. There may still be chains operating elsewhere... \$\endgroup\$ Jul 21, 2017 at 1:13
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    \$\begingroup\$ electric fences can generate broadband noise in this band+when moist and/or dirty insulators. Use a CB or AM radio on a quiet channel to verify. It might sound like ticking up to the line rate. \$\endgroup\$ Jul 21, 2017 at 3:01
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    \$\begingroup\$ Build yourself an RF Sniffer for 90kHz - (a simple RC tuned circuit with a diode detector should do) and find the source(s) see davidbridgen.com/rfdet.htm \$\endgroup\$ Jul 21, 2017 at 9:26

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Fluorescent under-shelf lights, such as used in office cubicles or as lights just to hang on the milking-barn walls, operate at 80 kHz.

I found this interference, while developing circuits for IRDA at 115 kHz at 1 meter and 2 meter ranges in sunlight.

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