Long range multiple point wireless control and monitoring system

• US 4,968,978 A
• Filed: 09/02/1988
• Issued: 11/06/1990
• Est. Priority Date: 09/02/1988
• Status: Expired due to Term

• Current Assignee: International Bank
• Original Assignee: Stolar Incorporated
• Inventors: Stolarczyk, Larry G.
• Primary Examiner(s): Jordan, Charles T.
• Assistant Examiner(s): ELDRED, JOHN W
• Application Number:
  US07/239,771
• Time in Patent Office: 795 Days
• Field of Search: 340/854, 340/855, 340/856, 340/857, 175/40, 175/50
• US Class Current: 340/854.6
• CPC Class Codes: E21C 35/24 Remote control specially adapted for machines for slitting or completely freeing the mineral control in general G05
• CPC Class Codes: E21D 23/12 Control, e.g. using remote control E21D23/16 takes precedence
• CPC Class Codes: E21D 23/148 Wireless transmission of signals or commands
• CPC Class Codes: E21F 17/18 Special adaptations of signalling or alarm devices for mine lifts B66B; gas-sensitive devices per se G01N
• CPC Class Codes: G08C 15/00 Arrangements characterised by the use of multiplexing for the transmission of a plurality of signals over a common path
• CPC Class Codes: G08C 17/04 using magnetically coupled devices
• CPC Class Codes: G08C 2201/40 Remote control systems using repeaters, converters, gateways
• CPC Class Codes: G08C 2201/51 Remote controlling of devices based on replies, status thereof
• CPC Class Codes: G08C 23/00 Non-electrical signal transmission systems, e.g. optical systems

Abstract

A method for remotely monitoring conditions such as carbon monoxide for methane gas concentration, longwall roof support pressure, machine parameters or uncut coal, trona or potash layer thickness in a natural resource mining system such as a longwall or continuous mine system. The method utilizes a plurality of sensors connected to low magnetic moment transmitters, e.g. 0.1 ATM², or high magnetic moment transmitters, e.g. 2.5 ATM², that transmit collected data during multiple short burst transmission periods. Prior to transmission, the data is converted to a digital word format. An algorithm in the transmitter microcomputer ensures that random time intervals exist between data transmission bursts thus preventing a data transmission clash at the central receiver. A microcomputer algorithm in the central receiver protects against data contention caused by simultaneous transmission from several sensors. The data is transmitted to the central receiver either through a natural waveguide pathway or through a utility conductor that is magnetically coupled to the transmitter and central receiver by properly oriented electrically short magnetic dipole antennas. The method can be used, for example, to automatically control the positioning of a plurality of longwall roof supports or to transmit data from a longwall drillhead, along the drill rod, to the central receiver. Data can be communicated between a remote location and a surface area by utilizing a system of repeaters inductively coupled to a utility conductor. Use of the repeater system permits operation of mining machines from a surface computer.

Claims

1. A method for remotely monitoring conditions in a natural resource deposit which comprises:

placing a sensor near an area to be monitored;

inductively coupling a sensor transmitter to a conductor using an electrically short magnetic dipole antenna;

periodically supplying power to the sensor transmitter and to the sensor during a power-on period;

monitoring conditions in said area to be monitored by collecting data with the sensor during said power-on period;

converting said data collected by the sensor to a digital format;

activating the sensor transmitter for a time interval sufficient to transmit a transmitted digital word, comprised of at least some of said data collected by the sensor during said power-on period, to a central receiver;

forming a first narrow-band frequency modulated signal by using said first digital word to frequency modulate a carrier signal; and

transmitting said first modulation signal during said power-on period, from the sensor transmitter, through said conductor, to said central receiver.

2. The method of claim 1 wherein said conductor comprises a utility conductor.

3. The method of claim 1 wherein, said conductor comprises a natural waveguide.

4. The method of claim 1 further including the steps of:

deactivating said sensor transmitter after transmitting said first modulated signal; and

reactivating said sensor transmitter at a random time interval and retransmitting said first modulated signal as a second modulated signal identical to said first modulated signal.

5. The method of claim 4 further including the step of:

receiving said first modulated signal and said second modulated signal at said central receiver;

demodulating said first modulated signal after it is received and demodulating said second modulated signal after it is received to yield a first received digital word and a second received digital word, respectively; and

ensuring the validity of said first received digital word by comparing said first received digital word to said second received digital word.

6. The method of claim 5 further comprising:

verifying that a first received digital word is contains a predetermined number of bits; and

verifying that the parity of said first received digital word is identical to the parity of said transmitted digital word.

7. The method of claim 1 wherein said carrier frequency is in the range of 30 kHz to 3 MHz.

8. The method of claim 1 wherein said first modulated signal is formed by utilizing a two-frequency modulation signal to modulate said carrier signal.

9. The method of claim 1 wherein said electrically short magnetic dipole antenna is a tuned loop antenna.

10. A method for remotely monitoring conditions in a natural resource deposit which comprises:

placing a sensor near an area to be monitored;

periodically supplying power to a sensor transmitter and to the sensor;

monitoring conditions in said area to be monitored by collecting data with the sensor;

converting said data collected by the sensor to a digital word;

activating the sensor transmitter for a time interval sufficient to transmit said digital word;

transmitting said digital word from the sensor transmitter over an electrical conductor to a central receiver using an electrically short magnetic dipole antenna to couple the sensor transmitter to said electrical conductor;

deactivating the sensor transmitter after transmitting said digital word; and

reactivating the sensor transmitter at a random time interval and retransmitting said digital word.