Inground transmitter with roll orientation pattern based frequency change
A transmitter for use in an inground tool transmits a locating signal for tracking an underground position of the inground tool. The locating signal is characterized by a transmission frequency which changes responsive to detecting a roll orientation pattern in which the transmitter is held stationary for a predetermined period of time.
1. A transmitter for use in an inground tool as part of a system in which the inground tool is moved underground in a region, said transmitter comprising:
a transmitter section for transmitting a locating signal from the inground tool for use in tracking an underground position of the inground tool in said region, the locating signal characterized by a transmission frequency;
a sensor for detecting a roll orientation of the transmitter; and
a processor coupled to the sensor to monitor the detected roll orientation to identify a roll orientation pattern including at least one roll orientation at which the transmitter is held stationary for a predetermined period of time and to change the transmission frequency responsive to detecting the roll orientation pattern.
2. The transmitter of claim 1 wherein said sensor is a three axis accelerometer.
3. The transmitter of claim 1 wherein the locating signal is a dipole signal.
4. The transmitter of claim 1 wherein the roll orientation pattern includes a sequence of roll position orientations.
5. The transmitter of claim 4 wherein the transmitter is held stationary at each one of the roll position orientations.