磁棒线圈：
Magnetic coil
电磁接收头：
Electromagnetic Accept end
电缆：
Cable
磁力线：
Magnetic field lines
● In general, the peak method has a strong signal and wide peaks, which will not
be easily subject to interference from adjacent cables. even disturbed, it is always
easy to distinguish. So crest method applies perfectly when just beginning to
discover cable.
The crest method has a weak signal and narrow crest, which is good for
delicate location. But it is susceptible to crosstalk from adjacent cables, so it
applies perfectly for the final precise positioning.
2. test of burial depth of cable
Test principle as shown:
From top to bottom:
声音最小：
Smallest sound
声音最小：
Smallest sound
