Method and apparatus for communicating control and other information over a power bus

Abstract

An information signal to be communicated to a roof-mounted light bar or other electrical or electronic device travels over the vehicle's or other environment's power bus or other power conductor. In one exemplary illustrative non-limiting implementation, a modulated current load draws power supply current in an amount that is instantaneously responsive to at least some characteristic of the information signal to be communicated. This modulated current loading induces the vehicular or other power supply (e.g., DC battery) to modulate its output voltage in a manner that is responsive to the modulated current loading. A voltage sensor and demodulator also connected to the power bus senses the resulting voltage fluctuations and demodulates those fluctuations to recover or regenerate the original information signal. The recovered information signal may be used for any purpose including but not limited to controlling aspects of the operation of an emergency vehicle light bar or other audible and/or visual warning system or other device. The data sender and data receiver can be co-located to provide a full duplex or half duplex powerline communicated transceiver.

1 . A vehicular based system for providing controllable audible and/or visible warning indications that a law enforcement and/or rescue emergency exists, said system comprising: 
 a current modulator;    a battery coupled to said current modulator, said battery providing an output voltage that is at least in part responsive to said current modulator; and    a voltage demodulator coupled to said battery, said voltage demodulator demodulating said battery output voltage and outputting responsive control signals, and    a light display unit responsive to said control signals, said light display unit comprising a light and sound bar mounted to the exterior roof of said vehicle.    
   
   
       2 . A communications kit for controlling a vehicular based system for providing controllable audible and/or visible warning indications that a law enforcement and/or rescue emergency exists, said system including a battery and a light display unit comprising a light and sound bar mounted to the exterior roof of said vehicle, said kit comprising: 
 a current modulator adapted for coupling to said battery, said current modulator, in use, causing said battery to generate an output voltage that is at least in part responsive to said current modulator; and    a voltage demodulator coupled to said battery, said voltage demodulator demodulating said battery output voltage and outputting responsive control signals to control said light display unit.    
   
   
       3 . The kit as in  claim 2  wherein said current modulator and voltage demodulator are disposed within a common housing.  
   
   
       4 . The kit of  claim 2  wherein said current modulator includes a FET in enhancement mode.  
   
   
       5 . The kit of  claim 2  wherein said current modulator provides pulse width modulation.  
   
   
       6 . The kit of  claim 2  wherein said voltage demodulator is adapted to be installed within said light display unit.  
   
   
       7 . The kit of  claim 6  wherein said light display unit comprises a roof-mounted light bar.  
   
   
       8 . A system for using a power source connected to a power line to communicate information to a device coupled to said power line, said system comprising: 
 a modulated current load coupled to said power line, said modulated current load drawing a current from said power line that is at least in part responsive to an information signal, said drawn current inducing voltage fluctuations at said power source that are in response to said information signal; and    a device coupled to said power line, said device capturing said voltage fluctuations on said power line and demodulating said captured voltage fluctuations to recover said information signal.    
   
   
       9 . The system of  claim 8  wherein said power source comprises a finite power source.  
   
   
       10 . The system of  claim 8  wherein said power source comprises a direct current batter.  
   
   
       11 . The system of  claim 8  further including a noise interrupter coupled to said power line, said noise interrupter temporarily disconnecting a noisy load from said power line during capture of said voltage fluctuations by said device.  
   
   
       12 . A system for communicating information over a power line, comprising: 
 means responsive to an information signal and coupled to said power line for drawing a current from said power line that is at least in part substantially instantaneously responsive to said information signal, said drawn current inducing voltage fluctuations on said power line that are at least in part instantaneously responsive to said drawn current; and    means coupled to said power line for capturing and demodulating said voltage fluctuations to extract at least a portion of said information signal.    
   
   
       13 . A system for using a power source connected to a power line to communicate information to a device coupled to said power line, said system comprising: 
 a data transmitter that induces fluctuations on said power line in response to said information signal;    a data receiver coupled to said power line, said data receiver capturing said fluctuations on said power line and performing at least action in response thereto; and    a load interrupter coupled to said data receiver, said load interrupter temporarily decouples at least one load from said power line during said capturing of fluctuations.    
   
   
       14 . The system of  claim 13  further including a charge storing element coupled to said load interrupter, said charge storing element supplying power to said at least one load while said load interrupter temporarily decouples said at least one load from said power line.  
   
   
       15 . The system of  claim 14  wherein said charge storing element comprises at least one capacitor.  
   
   
       16 . On a vehicle based system for providing controllable audible and/or visible warning indications that a law enforcement and/or rescue emergency exists, said system comprising: 
 a data transmitter connected to said powerline, said data transmitter inserting a control signal onto said powerline;    a data receiver connected to said powerline, said data receiver obtaining said control signal from said powerline; and    a light bar control unit coupled to said data receiver, said light bar control unit controlling light and sound emanating from the exterior roof of said vehicle at least in part in response to said obtained control signal.    
   
   
       17 . A light bar of the type for mounting on the exterior roof of a law enforcement and/or rescue vehicle, said light bar comprising: 
 a power connector;    at least one rotator;    a data receiver coupled to said power connector, said data receiver receiving control signals from said power connector; and    a controller that selectively applies power to said rotator at least in part in response to said received control signals, said controller momentarily interrupting power to said rotator during control signal reception by said data receiver.