Locator transmitter having an automatically tuned antenna
First Claim
1. A locator transmitter for transmitting a signal of a predetermimed AC frequency suitable for tracing underground lines, said locator transmitter comprising:
- a generator for generating a selected one of a plurality of different available frequencies, said generator providing a first output signal for use in transmitting to an underground line, and a second output signal for tuning a filter;
a tunable filter receiving the selected frequency defined by said first output signal of the generator and for filtering the first output signal, and for receiving the second output signal for tuning the filter to provide a precise AC signal having a frequency defined by the frequency of the first output signal;
an antenna for radiating said precise AC signal;
processor means coupled to said generator for controlling said generator to generate said first and second output signals; and
automatic tuning means coupled to said antenna and to said processor means for automatically tuning said antenna in response to a selection of one of said different available frequencies to tune the resonant frequency of the antenna in order to maximize the power of the signal radiated from the antenna, thereby increasing the distance at which said lines may be traced.
2 Assignments
0 Petitions
Accused Products
Abstract
The present invention generally relates to a system for use in determining the location and orientation of concealed underground objects and, more particularly, to an improved locator system having a unique and improved interface with an operator. In accordance with one embodiment of the invention, a magnetic field detector for locating concealed underground objects is provided. The magnetic field detector includes a housing having an upper housing portion and a lower housing portion. A receiver is disposed within said housing for receiving magnetic field signals from the concealed underground objects. A swivel joint couples the upper housing portion and the lower housing portion to permit relative rotational motion.
184 Citations
18 Claims
-
1. A locator transmitter for transmitting a signal of a predetermimed AC frequency suitable for tracing underground lines, said locator transmitter comprising:
-
a generator for generating a selected one of a plurality of different available frequencies, said generator providing a first output signal for use in transmitting to an underground line, and a second output signal for tuning a filter; a tunable filter receiving the selected frequency defined by said first output signal of the generator and for filtering the first output signal, and for receiving the second output signal for tuning the filter to provide a precise AC signal having a frequency defined by the frequency of the first output signal; an antenna for radiating said precise AC signal; processor means coupled to said generator for controlling said generator to generate said first and second output signals; and automatic tuning means coupled to said antenna and to said processor means for automatically tuning said antenna in response to a selection of one of said different available frequencies to tune the resonant frequency of the antenna in order to maximize the power of the signal radiated from the antenna, thereby increasing the distance at which said lines may be traced. - View Dependent Claims (2, 3, 4, 5)
-
-
6. A method of tuning an antenna for use in a locator transmitter of the type that outputs a signal of a precision frequency suitable for tracing an underground line, comprising the steps of:
-
receiving by said locator transmitter a user selected frequency and in response thereto programming a multi-frequency generator to generate the user selected frequency; coupling the selected frequency to a low pass filter having a narrow bandpass of about 20 Hz or less and tuning the low pass filter to produce a filtered signal of the selected frequency to avoid power line frequencies and harmonics thereof from interfering with the selected and filtered frequency; and tuning said antenna so that the resonant frequency of the antenna is tuned so as to maximize the power of a signal of said selected and filtered frequency when said selected and filtered frequency is radiated from said antenna, whereby a precision frequency and narrow bandwidth signal is transmitted to the underground line. - View Dependent Claims (7, 8, 9, 10, 11, 12)
-
-
13. A locator transmitter for transmitting a signal of a predetermined frequency suitable for tracing an underground line, said locator transmitter comprising:
-
a digital frequency synthesizer for generating one of a plurality of available digital signal frequencies; a processor responsive to an input for programming the digital frequency synthesizer to generate a selected digital signal frequency; a filter for converting the selected digital signal frequency to a corresponding AC signal frequency; said filter being tunable for changing center frequency characteristics thereof based on a frequency programmed by said processor to be generated by said digital frequency synthesizer; an antenna for radiating said AC signal frequency produced by said filter; and tuning means programmable by said processor and coupled to said antenna for automatically tuning said antenna based on a frequency of the selected digital signal frequency so that the resonant frequency of the antenna is tuned in order to maximize the power of the signal radiated from the antenna, thereby increasing the distance at which said underground line may be traced. - View Dependent Claims (14, 15, 16)
-
-
17. A locator transmitter for transmitting a signal of a predetermined frequency suitable for tracing underground lines, said locator transmitter comprising:
-
a console having a first control for inputting a frequency for transmitting and a second control for inputting a power setting for such transmission; a digital frequency synthesizer for generating one of a plurality of available digital signal frequencies; a processor responsive to an operator input via the console first control for programming the digital frequency synthesizer to generate a selected digital signal frequency, and responsive to the console second control to establish a transmitter power corresponding to an operator input via the console; a filter for converting the selected digital signal frequency to a corresponding AC signal frequency; said filter being tunable by a signal from said digital frequency synthesizer for changing center frequency characteristics thereof based on a selection of a frequency to be generated by said digital frequency synthesizer; a tunable antenna for radiating said selected AC signal frequency at the selected power; a connector for connecting thereto an accessory cable for radiating the selected AC signal frequency; tuning means programmable by said processor and coupled to said antenna for automatically tuning said antenna to said AC signal frequency so that the resonant frequency of the antenna is tuned in order to maximize the power of the signal radiated from the antenna, thereby increasing the distance at which said lines may be traced; and a detector for detecting connection of the accessory cable to said connector, and said processor is responsive to the detection by said detector for coupling the AC frequency signal to the accessory cable rather than the antenna. - View Dependent Claims (18)
-
Specification