LF/MF
  Seemingly some cables are being layed through
out some parts of the UK for GAS es  OIL exploration. These cables will
will carry a signal to penetrate the earth and detect if gas/oil is
below. There will also be some small explosive charges at times in the
earth and these will be detected also by the cable and fed to a master
station.
  Does anyone know what frequency is
transmitted down these cables or mode of transmission PULSE etc
  This could be a source of QRM for the LF/MF
radio amateur and most people do not know it is taking place and
wondering where the QRM is coming from.
  There will be a network of cables for
hundreds of miles lying on fields and ditches etc while the exploration
is going on
   
   
  de mal/g3kev