Locating

®

 

7.Repeat steps 2 through 6 until the “+/–” signs flip from one to the other over a very small area. This is either the FNLP or the RNLP. To find the other locate point, walk in the assumed direction of drilling. If the signal strength increases you are at the RNLP; if it decreases you are at the FNLP.

8.To confirm you are over the FNLP or RNLP (as opposed to being over the transmitter), rotate the receiver (with the trigger held in) 360° at the FNLP or RNLP. The signal strength should remain con- stant during the entire rotation. If the signal strength changes significantly, you are not directly above the FNLP or the RNLP.

Calculating Depth Based on Distance Between FNLP & RNLP

It is possible to estimate the transmitter’s depth should the information displayed in the depth/distance window become unreliable. This is only possible if the pitch and negative locate points are reliable and the ground surface is level.

To estimate the transmitter’s depth, first measure the distance between the FNLP and the RNLP. The pitch of the transmitter must also be reliably known. Using the Depth Estimation Table below, find the divider that most closely corresponds to the transmitter’s pitch. Then use the following formula to esti- mate the depth:

Depth = Distance between FNLP and RNLP

Divider

For example, if the transmitter’s pitch is 34% then the corresponding divider value (from the table) is 1.50. In this example, the distance between the FNLP and the RNLP is 11.5 ft (3.5 m). The depth would be:

 

Depth

=

11.5 ft

= 7.66 ft or approximately 7.7 ft (2.35 m)

 

 

 

 

1.50

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Depth Estimation Table

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Pitch

Divider

 

 

Pitch

Divider

 

Pitch

 

Divider

 

 

Pitch

Divider

0

1.41

 

 

 

26

1.47

 

52

 

1.62

 

 

78

1.84

2

1.41

 

 

 

28

1.48

 

54

 

1.63

 

 

80

1.85

4

1.42

 

 

 

30

1.48

 

56

 

1.64

 

 

82

1.87

6

1.42

 

 

 

32

1.49

 

58

 

1.66

 

 

84

1.89

8

1.42

 

 

 

34

1.50

 

60

 

1.68

 

 

86

1.91

10

1.42

 

 

 

36

1.51

 

62

 

1.69

 

 

88

1.93

12

1.43

 

 

 

38

1.52

 

64

 

1.71

 

 

90

1.96

14

1.43

 

 

 

40

1.54

 

66

 

1.73

 

 

92

1.98

16

1.43

 

 

 

42

1.55

 

68

 

1.74

 

 

94

2.00

18

1.44

 

 

 

44

1.56

 

70

 

1.76

 

 

96

2.02

20

1.45

 

 

 

46

1.57

 

72

 

1.78

 

 

98

2.04

22

1.45

 

 

 

48

1.59

 

74

 

1.80

 

 

100

2.06

24

1.46

 

 

 

50

1.60

 

76

 

1.82

 

 

 

 

52

DigiTrak® Mark III Operator’s Manual

Page 60
Image 60
Digitrex 3-3000-00a-F manual Calculating Depth Based on Distance Between Fnlp & Rnlp, Pitch Divider