Sweep frequency control apparatus and method

• US 3,883,868 A
• Filed: 07/23/1973
• Issued: 05/13/1975
• Est. Priority Date: 07/23/1973
• Status: Expired due to Term

• Current Assignee: Ronald S. Palmer
• Original Assignee: Ronald S. Palmer
• Inventors: Palmer, Ronald S.
• Primary Examiner(s): Pitts, Harold I.
• Application Number:
  US05/381,837
• Time in Patent Office: 659 Days
• Field of Search: 340/408,409,222,152T,151,163,207
• US Class Current: 307/117
• CPC Class Codes: G08B 26/002 only replying the state of the sensor
• CPC Class Codes: H04N 2007/17372 the upstream transmission being initiated or timed by a signal from upstream of the user terminal
• CPC Class Codes: H04N 7/173 with two-way working, e.g. subscriber sending a programme selection signal
• CPC Class Codes: H04Q 9/08 Calling by using continuous ac

Abstract

Apparatus and method for sensing flux disturbances at a number of different, operative locations remote from a central controller. A sweep frequency generator applies an output signal to the sensors at the various operative locations and a flux disturbance at a particular location is represented by a resonant condition at a characteristic frequency responsive to the generator output signal. The sensed information is directed to the controller which determines if the frequency at which resonance occurs is the proper frequency for the particular location and, if so, the controller sends a control signal to an actuable mechanism corresponding to the particular operative location. In one embodiment, the apparatus has a plurality of control modules at respective operative locations, the modules being coupled by a pair of coaxial cables to the controller and the sweep generator, respectively. The outer conductors of the cables interconnect a d.c. power source to the electronic components of each module, respectively. A flux disturbance at an operative location occurs when an enabling device capable of resonating at a characteristic frequency is brought into proximity to the module. Each mechanism is operated by the controller when the resonant frequency corresponds to that which is programmed in the controller for the particular operative location. In another embodiment, the apparatus has a single control module inductively coupled to a plurality of tuned circuits, each having a characteristic frequency and sensitive to a predetermined change. The sensed information can represent acquired data useful to operate certain mechanisms through the controller. In a third embodiment, a single control module uses a notch filter adapted to receive an analog signal which can be represented digitally and used to actuate the controller and thereby an operable mechanism corresponding thereto.

Claims

1. Apparatus for controlling the operation of a plurality of spaced, independent, actuatable mechanisms comprising:

a control module for each mechanism, respectively, each module having first means permitting an enabling device capable of resonanting at a predetermined frequency to be inductively coupled thereto;

a sweep generator operable to provide an output signal whose frequency varies successively over a range of frequencies;

first conductor means common to the modules for coupling the sweep generator thereto to permit said output signal to be applied simultaneously to the modules, each module having second means thereon responsive to said output signal when the module is inductively coupled to an enabling device and when the output signal has the frequency at which the corresponding enabling device resonates for generating a first signal indicating the inductive coupling between the module and the enabling device and indicating the resonant condition of the last-mentioned enabling device, each module having third means responsive to a second signal for actuating the corresponding mechanism;

a central controller; and

second conductor means common to said modules for connecting said controller thereto to permit said controller to receive a first signal from a module, said controller being operable to successively address the modules and to generate a second signal after a first signal has issued from a module, said second conductor means being operable to direct the second signal to the third means of a module to actuate the corresponding mechanism.

2. Apparatus as set forth in claim 1, wherein each of said first conductor means and said second conductor means includes a coaxial cable.

3. Apparatus as set forth in claim 2, wherein each module has a number of components responsive to d.c. electrical power, and wherein is included a d.c. power supply having a positive terminal and a negative terminal coupled to the outer conductors of respective cables, and means interconnecting said outer conductors and said components of each module, respectively.

4. Apparatus as set forth in claim 1, wherein said controller has means for generating a control code representing a plurality of addresses for respective modules, and means for directing the code serially onto said second conductor means to successively address said modules as said output signal is applied to said first conductor means.

5. Apparatus as set forth in claim 4, wherein said second signal comprises a portion of the address for a module whose second means has generated a first signal.

6. Apparatus as set forth in claim 1, wherein the lengths of the first conductor means and the second conductor means are substantially the same.

7. Apparatus as set forth in claim 1, wherein is included means coupled with the second conductor means for determining the frequency of each first signal, said controller having a memory adapted to receive and store information corresponding to the resonant frequencies of the enabling devices capable of enabling respective modules, said determining means being coupled to said controller for actuating the latter to cause it to generate said second signal when the frequency of the first signal is compared with and is substantially the same as the corresponding frequency value stored in said memory.

8. A method of coNtrolling a plurality of operable mechanisms at respective first loccations spaced from each other comprising:

providing a sweep signal source at a second location remote from the first locations with the sweep signals having a frequency which varies successively over a range of frequencies, each first location having a respective frequency of said sweep signal assigned thereto and each mechanism being operable when a control signal is sent from the second location to the corresponding first location;

providing first and second signal paths between the second location and the first locations, each path being common to all of the first locations, directing said sweep signal along the first path so that the sweep signal is simultaneously applied to said first locations;

successively addressing said first locations by applying respective address signals one after another along said second path to the first locations, changing a characteristic of the sweep signal during a first sweep of the sweep signal if an operative condition exists at a first location;

generating a second signal responsive to the change of said characteristic;

directing the second signal along the second path to the second location, repeating the addressing of the first locations until the first location at which an operative condition exists is re-addressed;

interrutping the address of the first locations when the first location at which the operative condition exists is re-addressed;

sending the sweep signal and the second signal simultaneously along the first and second paths, respectively, to the second location when the last-mentioned first location is re-addressed;

determining the frequency of the sweep signal corresponding to said change with the frequency determination being made at the second location in response to the reception of the sweep and second signals at said second location;

comparing the determined frequency with the frequency assigned to said last-mentioned first location; and

directing a control signal from the second location to said last-mentioned first location to cause actuation of the mechanism thereof if the frequency determined at the second location has a value assigned to that of the first location.

9. A method as set forth in claim 8, wherein said determining step includes comparing the frequency of the sweep signal with a predetermined reference at the second location.

10. A method as set forth in claim 8, wherein said determining step includes measuring the time of at least a single cycle of the sweep signal at the second location.