So how much does an electric fence influence your ADSL link?
The normal voltage supplied by Telkom on a voice line is about 50VDC.
For ADSL, the DSL carrier is super-imposed on the voice line and
operates at a much higher frequency (300-600kHz in my tests). I built a
10:1 pre-scaler and fed the signal to an oscilloscope. Below, you can
see a normal DSL carrier signal.
Below is the exact same signal, but with my electric fence turned on. Notice the spike shown in the middle of the image:
And below is the section surrounding the spike taken with a higher
sampling frequency. As you can see, the spike is about 200µs wide.
When looking at the error counts reported by my ADSL modem (the excellent DLink 300T), it reports the following:
Total RX PDU's
Total RX error counts
Error rate (as a percentage)
So the error
rate is really extremely low. In addition, the spikes do not seem to
affect the efficiency of my link. I have a 512kbps line (512down/256up)
and I see the expected throughout of about 54kbytes/sec on a local
transfer. So, although an electric fence does introduce errors on the
line, it makes no real difference in practice.