Choice of Frequency
- 512 kHz
- This low frequency is most useful for line tracing and identification over long distances. It does not couple easily to unwanted lines.
but - It is too low for induction, and it falls within the band of power frequency harmonic interference.
- This low frequency is most useful for line tracing and identification over long distances. It does not couple easily to unwanted lines.
- 8 kHz
- This medium frequency is the most useful general-purpose signal, high enough for induction, outside the power frequency interference band, and with limited coupling to wanted lines.
but - It may not be high enough to impose a strong signal on small diameter line like telecom cables.
- This medium frequency is the most useful general-purpose signal, high enough for induction, outside the power frequency interference band, and with limited coupling to wanted lines.
- 33 kHz
- This higher frequency is easily applied by induction to most lines, so is very useful for initial search. It travels on small diameter lines.
but
- This higher frequency is easily applied by induction to most lines, so is very useful for initial search. It travels on small diameter lines.
- It couples more easily to unwanted lines and loses its strength over shorter distances than lower frequencies.
- 100+ kHz
- This very high frequency range deals with the difficult cases – induction onto small diameter lines in dry sandy soil, and short lengths of cable. It is very easy to apply by induction
but
- This very high frequency range deals with the difficult cases – induction onto small diameter lines in dry sandy soil, and short lengths of cable. It is very easy to apply by induction
- It couples very easily to unwanted lines and does not travel far.
- It couples very easily to unwanted lines and does not travel far.