CD reset

Follow Avatar Anthony Caplin
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About CD reset

When you trace a signal on very long target lines, the transmitter signal gradually bleeds into the ground by capacitance. This means the phase angle of the remaining signal gradually changes. A CD Reset can be used to re-establish correct CD operation. 

To perform a CD reset, press and hold the frequency key.png key.

This is referred to as phase-shift and can occur whenever an alternating current signal is flowing in a system of conductors that have a significant capacitance or inductance. The relative phase angle between the two frequencies will alter, but only over extended distances.

 

CD reset

 

The illustration above 'CD Reset' represents a buried line with significant capacitance to ground. It illustrates the gradual phase-shift that occurs along the line. The diagram shows a reference point on each waveform. At first, the reference point occurs right on the Peak of a positive half cycle (A). It gradually moves towards the zero crossing point (D) and ends up on the Peak of a negative half cycle (F). The direction has shifted from forwards to backwards. At the intermediate point (D) the current flow cannot be determined. At this point the CD arrows on the RD8200 locator will flash on and off. In the example shown in the illustration, by returning to (C) which is the last point at which a CD reading was achieved, and performing a CD reset, the response at (C) will be equivalent to that of (A).

In most cases the phase angle shift does not occur until many kilometers from the transmitter and in some cases a CD reset may only be required every 20 kilometers (15 miles).

Performing a CD reset

To perform a CD reset:

While using any CD frequency,

  1. Press and hold theantenna key.png key.

Alternatively

  1. Press the power key.pngkey to enter the menu.
  2. Scroll to the CDR menu using the up arrow.png or down arrow.png keys.
  3. Press the antenna key.png key to enter the CDR menu.
  4. Select YES.
  5. Press the frequency key.png key to reset CD and exit to the main menu.