6 Interference

The PULSE STAR II has been developed to eliminate a lot of the electromagnetic interference. Land cables, railroad tracks, electric motors, water pumps etc. produce strong magnetic fields that can interfere with the PULSE STAR II. In this case you will notice unusual rhythmic audio signals being emitted from your PULSE STAR II.

Magnetic soil (iron oxides, for example) can also cause disturbances. This type of soil is noticeable when lowering the search coil. The tick-rate significantly increases even when there is no metal object below the surface. As long as the disturbing ground is level, you can hold the coil at the same distance from the ground and maintain a constant tick-rate. The PULSE STAR II can be tuned by positioning the coil at the correct searching height from the ground, and then pushing the MODE switch to RETUNE. Tuning adjustment to different areas (regardless of ground conditions) will not reduce the sensitivity.

If reduced sensitivity to iron objects and other smaller objects is acceptable, an increased SAMPLING DELAY will also reduce ground effects. Holding the coil higher helps to reduce ground effects as well.

Strong electromagnetic disturbances are the worst kind of interferences. Reducing the sensitivity will help greatly. For this, an OFFSET is stored within the PULSE STAR II.

To correct disturbances:

  1. Adjust the PULSE STAR II by switching to RETUNE mode with the search coil at the correct height.
  2. Next, hold a metal object near the coil so that the meter will show "2" (or a higher number if sensitivity needs to be reduced further). While holding the object at this particular distance, push the MODE switch momentarily to RETUNE again.
  3. Take the metal object away from the coil. This should give a negative meter reading and cause the tick-rate to be lowered.
  4. Next, increase the tick-rate to a few ticks per second with the AUDIO TUNE knob. Now the PULSE STAR II is less sensitive. An object must cause the same indication that you previously simulated with the metal object in order to be detected (the offset has to be overcome). You can go on searching now with reduced sensitivity.

To recall the highest sensitivity again, use RETUNE and re-adjust the ticking-noise down to a few clicks per second.

Another possibility to reduce the sensitivity is to turn AUDIO TUNE all the way to the left. Now the "dead area" up to the start of the ticking-noise has to be passed. However, this method does not affect the meter and the LEDs for the metal discrimination.

Using the Universal Search-Loop as a compensated coil (see chapter 8 Accessories) helps to overcome interference as well.

IMPORTANT: At times when strong interference occurs due to ground effects or electro-magnetic fields, the LEDs might turn on. A reliable metal distinction can only be made if sensitivity is reduced as per the first method (storing an offset).

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