Patent Publication Number: US-2021168913-A1

Title: Remote power delivery for distributed lighting with integrated data transmission

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority to U.S. Provisional Application No. 62/942,692, entitled “Remote Power Delivery for Distributed Lighting with Integrated Data Transmission,” filed Dec. 2, 2019, which is expressly incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     In various situations, it may be desirable to locate devices with low-power electrical loads remotely from their power source. Placed remotely such as in an outdoor environment, the devices could be made to be more resilient, lower in cost, smaller in size, and more flexible in usage. Simultaneously, a DC power supply driving the devices via electrical cabling may be located in a protected location. The protected environment may ensure safety for the power supply and make maintenance or repair of the power supply convenient. Although examples for this arrangement are plenty, one is the use of light emitting diodes (LEDs) as distributed lighting to illuminate an area. 
     LEDs are semiconductor-based radiative elements that provide efficient options for distributed lighting. LEDs are often arranged in groups or banks with the radiative element or load being called the LED head. They are typically driven by DC power from a power source, which may be located with the LED head but also could be positioned at a remote location. 
     In many situations involving LEDs for area illumination, it is beneficial or required to locate the LED head remotely from the power unit. These situations may include installations where repair and replacement of the light fixture may be difficult, such as undercabinet lighting and outdoor architectural lighting. Reasons for separating the power units from the LED heads include consolidation of power and control at the same location, reliability and ease of repair in a reachable location possibly with lower environmental requirements, system cost, or packaging. Another reason for separation may be to provide a more flexible installation where multiple small lighting endpoints are driven from a single power box. 
     Challenges can arise for communicating between power sources and remotely located loads such as LEDs. In a given installation, the LED heads may have different configurations and capabilities that can impact the source power. Specific market requirements may even require individual addressing of LED loads. Communications from the power unit may include group or individual dimming levels for the LEDs, white or color operating points for the LEDs, and instructions on how to respond to locally connected sensors. These requirements mean that at least a one-way communication as a form of control from the power unit to the lighting heads is needed. Furthermore, this method allows for wired communications which in some cases provides added reliability over wireless-type implementations. 
     Moreover, transmissions from the lighting heads to the power unit may be needed. The lighting heads may be close to or incorporate other features such as sensors or actuators. The feedback from these accessories may be useful for centralized control of a remote lighting solution. Other feedback useful for an installation may include maximum power draw to allow the central unit to dim all units to avoid overload, communication of supported functions such as ability to support white point control, minimum input voltage to allow the central unit to optimize its operating point, etc. Therefore, two-way communication between the power unit and the lighting heads may also be needed. 
     While sophisticated electronic options may satisfy these needs, the lighting industry is extremely cost driven. All features must be supplied at a low cost for each unit and for the system, while maintaining a solution that provides user protections such as low voltage and fast disconnect response times, among many others. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description is described with reference to the accompanying figures. The same reference numbers in different figures indicate similar or identical items. 
         FIG. 1  is a general block diagram of a system for remote power delivery with integrated data transmission consistent with examples of the disclosure. 
         FIG. 2A  is a functional block diagram of a power source with integrated data transmission within the system of  FIG. 1  consistent with an example of the disclosure. 
         FIG. 2B  is a functional block diagram of an endpoint within the system of  FIG. 1  consistent with an example of the disclosure. 
         FIG. 3  is an exemplary schematic diagram for one-way communications in a system for remote power delivery consistent with an example of the disclosure. 
         FIG. 4  is an exemplary schematic diagram for two-way communications in a system for remote power delivery consistent with an example of the disclosure. 
         FIG. 5  is a system level block diagram of remote power delivery with integrated data transmission having redundant sources and loads consistent with an example of the disclosure. 
         FIG. 6  is a schematic diagram of a circuit used for simulating data communication integrated with power delivery consistent with an example of the disclosure. 
         FIG. 7  are timing diagrams of a simulation on the circuit of  FIG. 6  consistent with an example of the disclosure. 
     
    
    
     DESCRIPTION 
     The following detailed description is generally directed to technologies for integrating data communication with power and delivering both at least from a power source to a remote electrical load. Among various implementations, the remote electrical load may be LED heads or endpoints positioned apart from power supplies that drive them. 
     To effectuate communication from a power supply to an affiliated LED endpoint, a power source includes a modulator that modulates control data onto a carrier frequency and transmits the modulated signal to the remote endpoint along with power. At the endpoint, the modulated signal is demodulated to extract the control data while the power is provided to drive the LED. In response to the received control data, the endpoint may affect operation of the LED. A selection of inductors and capacitors forms two filter types in the system. A low-pass filter for the power supply and the load enables the power to pass between them, and a high-pass filter for the modulator and demodulator enables the integrated data communication to pass between them. A similar arrangement may provide bidirectional communication from the endpoint back to the power source. Technical benefits other than those specifically identified herein can also be realized through an implementation of the disclosed technologies. 
     Utilizing the technologies described herein, various embodiments and examples in this disclosure may include a system having a source for delivering power integrated with control data, a conductor communicating the power and a first modulation signal from the source, and an endpoint positioned remotely from the source for receiving the power and the first modulation signal. In some implementations, the technologies described herein may be applied only to a source for delivering power integrated with control data or only to an endpoint for receiving power integrated with control data. 
     In various embodiments of the present disclosure, the source may include a power supply with a source low-pass filter coupled to a supply output and configured to provide power to the supply output. In some examples, the power supply may be an AC-DC converter configured to convert mains AC power to DC power. The source low-pass filter may be a supply capacitor in parallel with the power supply and a supply inductor in series between the power supply and the supply output. The supply capacitor and supply inductor may be selected with values to provide a low-pass filter sufficient to pass the power to a supply output while preventing higher frequencies from interfering with the power supply. 
     As also exemplified in the disclosure, a source microcontroller or similar digital decoding or control device may receive an external input relating to control data for an electrical load and provide a first information signal that includes the control data at a data frequency. The external input may indicate through the control data, for example, a dimming value for an LED at a remote load. Programming within the source microcontroller provides a conversion of the received control data into the first information signal. 
     In another example, the system and specifically the source for delivering power integrated with control data may include a source modulator coupled to the source microcontroller. The source modulator may have circuitry configured to generate a first modulation signal. In some options, the modulation circuitry is an AND gate with a first input coupled to receive the first information signal and a second input coupled to an oscillator to receive a first carrier frequency. In certain examples, the first carrier frequency is greater than the data frequency, preferably by a multiple or more. in some embodiments, the first carrier frequency may be at least 10 times the data frequency to help minimize system noise. For instance, the first carrier frequency may be greater than 20 KHz. As well, the first carrier frequency may be chosen to avoid the AM range and, for instance, could be less than 525 KHz. 
     The source modulator may be further configured to pass the first modulation signal through a source high-pass filter to the supply output. In some examples, the high-pass filter may be an injection capacitor in series between the modulator and the supply output. The value of the injection capacitor may be selected to permit the passage of the first modulation signal from the source modulator onto the supply output while preventing interference from lower frequency signals at the supply output. 
     In further examples as disclosed herein, a conductor may be connected to the supply output to communicate the power to an endpoint remotely located from the source. The conductor may be part of a two-wire cable suitable for conveying both the power and the first modulation signal across a distance between the source and the endpoint. 
     In additional examples, the system may further include the endpoint positioned remotely from the source for receiving the power and the first modulation signal. The endpoint may include an endpoint input coupled to the conductor to receive the power, a load with an endpoint low-pass filter coupled to the endpoint input, an endpoint demodulator, and an endpoint microcontroller. In some examples, the low-pass filter may be a load capacitor in parallel with the load and a load inductor in series between the endpoint input and the load. Values for the load inductor and the load capacitor may be chosen so that the low-pass filter sufficiently blocks high-frequency signals on the conductor at the endpoint input while passing the power to the load. 
     Further, the endpoint demodulator may include an endpoint high-pass filter coupled to the endpoint input and include demodulation circuitry. The high-pass filter may be a demodulator capacitor positioned in series with the endpoint input and the endpoint demodulator with a capacitance value selected to permit passage of the first modulation signal but to prevent interference by lower frequency voltages at the endpoint input. The demodulation circuitry of the endpoint demodulator may be configured to demodulate the first modulation signal received with the power at the endpoint input. 
     In yet further examples, the endpoint may include a microcontroller or similar electronics configured to receive the control data from the endpoint demodulator and to provide signals for controlling operation of the load based at least in part on the control data. For instance, the control data may specify a particular dimming level for an LED as the load. The endpoint microcontroller may process the control data to effectuate a change in dimming level for an LED arranged as the load in the system. 
     In some implementations, the system for delivering and receiving power integrated with control data may include circuitry to permit transmission of data from the endpoint to the source. Specifically, the endpoint microcontroller may be arranged to receive feedback data local to the load. The feedback data may include, for instance, a desired white point control setting for an LED acting as the load or any other response from a sensor relative to the operation of the LED. 
     The endpoint may additionally include an endpoint modulator coupled to the endpoint microcontroller and having modulation circuitry. The modulation circuitry may generate a second modulation signal comprising a second carrier frequency modulated with a second information signal that includes the feedback data. In some arrangements, the modulation circuitry of the endpoint modulator may be an AND gate with a first input receiving the second information signal from the endpoint microcontroller and a second input receiving the second carrier frequency from an oscillator. In certain implementations, the second carrier frequency is the same as the first carrier frequency to create a half-duplex communication system. Potential contention between the first modulated signal and the second modulated signal may be managed, for example, by time slots or similar coordination. In other options, the second carrier frequency is different from the first carrier signal to create a full-duplex communication system. The endpoint modulator provides the second modulation signal to the endpoint input for transmission along the conductor to the source. 
     In other examples, the source may further include a source demodulator coupled between the supply output and the source microcontroller. The source demodulator may receive the second modulation signal at the supply output that was transmitted by the endpoint modulator. The source demodulator may include circuitry to demodulate the second information signal from the second carrier frequency and to provide the second information signal to the source microcontroller. As a result, the feedback data generated at the endpoint may be transmitted back to the source and may be processed by the source microcontroller to further control operation of the load. 
     In other variations, the system as disclosed may include additional sources connected in parallel with the source. The additional sources may each have an additional power supply and an additional source modulator to provide redundancy for the source. 
     As well, in other embodiments, the system may include additional endpoints connected in parallel to the endpoint. The additional endpoints may each have an additional load and an additional endpoint demodulator. Each additional endpoint may be addressed separately by the source through the modulated signal to communicate control data specific to the specific load within the additional endpoint. 
     As a combination of reliability and cost, examples of the system can decrease use of electronic components on the load. This decrease can help make the whole system more reliable and less susceptible to electrical transients, temperature changes, and many of the other potential disturbances outdoor items are exposed to. The coupling and decoupling into the power line and extracting of the transmitted data may connect remote LED endpoints while eliminating the downsides of the main power system being in close proximity. As well, the arrangement can maintain features such as dimming, which would traditionally not be feasible over long remote applications such as using phase-cut dimming or other power control techniques. 
     As described in the context of the figures, the disclosed system takes advantage of the remote heads not having large instantaneous load changes as seen by the central power unit. This is accomplished either with bulk capacitance limiting the load change as seen by the central power unit and/or limiting the speed of load changes via hardware or firmware. As the instantaneous load changes are slow, the required bandwidth of the delivered power can also be low. This allows the power cable to be decoupled from the central power source and the endpoints via low-cost inductors, and for digital data to be injected onto the power cable using low-cost capacitors and capacitive coupling as long as the modulation frequency is sufficiently higher than the required bandwidth of the power delivery. 
     By reducing the bandwidth required for power delivery, low-cost circuitry can be used for signal injection and detection on the power delivery cable. As the digital data is modulated and demodulated, significant noise rejection over simple voltage level signaling is achieved. Alternate systems that pulse-width modulate the power delivery to accomplish dimming require large power bandwidths to enable dimming to low levels, especially with modern flicker requirements. These large switching transients can generate significant electromagnetic interference (EMI) limiting cable length and/or requiring more expensive cabling schemes to ensure EMI compliance. 
     While this disclosure refers to LED endpoints, substantially the same implementation could be used for any low-power endpoint, such as area sensors. In these other implementations as well, the total cost of the solution or the implementation of the solution would benefit from having the primary unit powering one or multiple endpoints in a different and remote location from the power source according to the examples of this disclosure. 
     While the embodiments disclosed herein are presented primarily in the context of delivering DC power integrated with data from a power source to one or more LED heads located remotely, the technologies disclosed herein can be utilized to deliver DC power and other types of data configurations to endpoints other than LEDs. Additional details regarding the configuration and operation of the various components and processes described briefly above will be presented below with regard to  FIGS. 1-7 . 
     In the following detailed description, references are made to the accompanying drawings that form a part hereof, and that show, by way of illustration, specific embodiments or examples. The drawings herein are not drawn to scale. Like numerals represent like elements throughout the several figures (which might be referred to herein as a “FIG.” or “FIGS.”). 
     As generally described herein,  FIG. 1  is a general block diagram of a system for remote power delivery with integrated data transmission. The block diagram of  FIG. 1  illustrates at a high level the overall layout and context for a power-delivery system  100  described in more detail in various embodiments that follow. 
     As illustrated in  FIG. 1 , a system  100  for remote power delivery with integrated data transmission may generally include a power unit  110  providing electrical power by way of a conductor  120  to an electrical load  130  positioned at a remote location. Power unit  110  includes a power source  200 , although in at least one implementation as shown in  FIG. 1 , power unit  110  may have a plurality of power sources such as power source  200 A to power source  200 N. Power sources  200 A- 200 N may be connected in parallel to provide known advantages for the distribution of electrical power as needed, as well as to provide redundancy in case a single power source  200  becomes inoperable. 
     In techniques described in further detail in this disclosure, generic power source  200  may deliver low-voltage DC power for use by electrical load  130 . As well, power source  200  generates a modulated information signal for communicating data to remote load  130  together with the delivered power. 
     Conductor  120  may be a standard two-wire cable readily known in the industry for distributing low voltage power to a load. Alternatives for the cable to include additional conductors, whether for delivering power or separately providing other data communications, are possible and would not detract from the principles of the present disclosure. 
     Remote load  130  receives electrical power delivered from power unit  110  via conductor  120  and may include any type of low-power electrical load commonly positioned remotely from its power source. In the present disclosure, remote load  130  is generally one or more banks of LEDs configured for distributed lighting to illuminate an area, such as overhead lighting in a room or security lighting outside a building. Other examples would be well understood, including various ambient sensors, cameras, small motors, and similar devices. 
     Remote load  130  includes an electrical load or endpoint  250 , although in at least one implementation as shown in  FIG. 1 , remote load  130  may have a plurality of electrical loads  250  such as endpoint  250 A to endpoint  250 N. Endpoint  250  receives low-voltage power from conductor  120  as provided by power source  200  and uses that power for its operation. In addition, endpoint  250  includes electronics sufficient to receive and demodulate the information signal provided by power source  200 . Endpoint  250  may then process control data within the information signal to affect operation of its device, e.g. a bank of LEDs. 
     In particular implementations addressed further below, system  100  may also include functionality for endpoint  250  to communicate feedback to power source  200 . For example, sensors in the vicinity of endpoint  250  may collect information about the operation of the electrical load, and endpoint  250  may send a separate modulated signal across conductor  120  to be received and processed by power source  200 . 
       FIG. 2A  is a functional block diagram of a power source  200  with related circuitry according to certain examples for the present disclosure. Power source  200  provides power to a remote load integrated with data and may generally entail a power portion  202  and a data portion  204 . Power source  200  may output the electrical power together with data to a conductor  120 , preferably as a cable of a conventional two-wire conductor. 
     In the example of  FIG. 2A , power portion  202  provides a relatively constant output of DC voltage, such as 12 VDC, to conductor  120 . Power supply  208  receives an AC input from mains power  206 , such as 120 VAC, and converts the AC power to a DC voltage for delivery to conductor  120 . While  FIG. 2A  depicts a conversion from AC mains power to constant DC power, other variations for providing electrical power to a remote load do not detract from the principles of the present disclosure. For instance, power source  200  may derive its initial electrical power other than from AC mains power. DC power could be provided as an origin to power source  200 , wherein AC-DC converter  208  may function, for example, to step down the voltage of the received DC power rather than to convert AC to DC. AC-DC converter as part of power supply  208  may include various filters for its voltage output consistent with the techniques described further below. 
     Data portion  204  of power source  200  may include an endpoint control module  210 . Having electrical components in known configurations, endpoint control module  210  may consolidate input from one or more sources in the form of control data for a remote endpoint  250 . As examples in  FIG. 2A , for an endpoint  250  that includes an LED for area illumination, an analog dimming module  212  may provide control data relevant to adjusting a dimming level for the LED. The input from analog dimming module  212  could be provided in various ways, including by a simple resistive element to provide an analog voltage to endpoint control module  210 . Other mechanisms and techniques for generating and conveying control data to and from endpoint control  210  will be readily apparent to those of ordinary skill in the art. 
     An RF control input  214  may serve as an additional or alternative source for providing control data to endpoint control module  210 . In this manner, a user may remotely provide input to system  100  for setting parameters for a load  250  positioned remotely, such as in a hard-to-service location. RF control input  214  could include components and functionality well known to those skilled in the art. RF control input  214  may receive by RF or other technologies the desired parameters for a remote load  250 . RF control input  214  may convert or otherwise alter its input to provide information as control data to endpoint control module  210 . 
     As illustrated in  FIG. 2A , the AC power input  206  itself may provide information relative to the setting of parameters and determining control data for a remote load  250 . For instance, in implementations where load  250  includes one or more LEDs, the AC power input  206  may include phase-cut dimming to communicate a dimming level desired for the LEDs. Rather than communicate the phase-cut dimming to the LEDs across conductor  120 , which may prove ineffective depending on the distance of conductor  120 , system  100  includes endpoint control module  210  within power source  200 . Endpoint control  210  may have electrical components in known configurations sufficient to detect the values for phase-cut dimming received in the AC voltage from AC power input  206 . 
     Data portion  204  of power source  200  may include a data processing module  216  to receive the control data from endpoint control module  210 . As described in additional detail below, data processing module  216  includes electrical components sufficient to convert the received control data into an information signal in the form of a serial transmission of data at predetermined data rate. For instance, the information signal may be a series of digital bits at a sequence of 2400 bits per second. 
     Further, data processing module  216  may include modulation circuitry to modulate the information signal onto a carrier signal of a select frequency to form a modulated signal. The form of modulation may be of any desired type, such as amplitude modulation, pulse-width modulation, or pulse-density modulation. The signal that is coupled onto the power delivery conductors may communicate information via encoding of data, or via timing information, such as a modulated PWM signal. In one example described more fully herein, the modulation is amplitude modulation, and carrier frequency greater than the data rate of the information signal by at least a multiple to ensure minimum attenuation of the modulated signal. In some examples, the carrier frequency exceeds the data rate by at least 10 times. The resultant modulated signal may use an encoding scheme, such as Manchester encoding, to ensure that the average DC signal level is near 0. 
     Data processing module  216  passes the modulated signal containing the control data to an injection/detection module  218 . Injection/detection module  218  includes electrical components sufficient to allow the modulated signal to travel along conductor  120  to endpoint  250 . Injection/detection module  218  enables the higher frequency of the modulation signal join the DC voltage output from AC-DC converter  208  without allowing the DC voltage to interfere with signals from microcontroller  216 . 
     As a result, and as generally depicted in  FIG. 2A , conductor  120  receives a combination of DC power and a modulated signal containing control data for transmission from power source  200  to endpoint  250 . 
       FIG. 2B  is a functional block diagram of endpoint  250  with related circuitry according to certain examples for the present disclosure. As with power source  200 , endpoint  250  may generally entail a power portion  252  and a data portion  254 . Endpoint  250  may receive electrical power together with control data from conductor  120 . 
     Endpoint  250  receives, in the example of  FIG. 2B , a relatively constant output of DC power from power source  200  via conductor  120 , and applies that DC power to drive a load  258 , specifically one or more LEDs. Endpoint  250  includes load driver  256 , which may have circuitry capable of providing, for example, a constant DC current for driving a bank of LEDs  258 . In one example, load driver  256  may include a DC-DC constant current driver known to those skilled in the art for powering LEDs  258 . 
     In some embodiments, power portion  252  of endpoint  250  may include an accessory driver  260  for providing a source of electrical power for external accessories  262 . External accessories  262  may include devices such as sensors that detect performance or surrounding conditions for LEDs  258 . For example, sensors  262  may detect the color balance or luminance provided by LEDs  258 , among many other parameters. Accessory driver  260  may include circuitry capable of providing, for example, a constant DC voltage output required for operating the accessories  262  in a known fashion. 
     Data portion  254  of endpoint  250  may include a detection/injection module  264 . Detection/injection module  264  may have electrical components sufficient to allow the modulated signal received on conductor  120  with a higher frequency to pass while essentially blocking the relatively constant DC voltage. 
     In addition, data portion  254  includes a data processing module  266  coupled to detection/injection module  264 . In some examples, data processing module  266  receives the modulated signal from detection/injection module  264  and includes electrical components sufficient to extract the information signal from the modulated signal. For instance, data processing module  266  may contain circuitry that demodulates the modulated signal to recover the information signal. Moreover, data processing module  266  may obtain the control data from the information signal and may generate signaling to apply the control data to LED load  258 . For example, if the control data relates to a dimming level to be applied, data processing module  266  conveys that control data to change the dimming of LED load  258 . Similar responses will be apparent for other parameters for LED load  258 , as for different types of load  258 . 
     While system  100  has been described with respect to one-directional communication from power source  200  to endpoint  250 , in some embodiments system  100  may include the capability for communication from endpoint  250  to power source  200  as well. Specifically, sensors or other accessories  262  may capture feedback data to be shared with power source  200 . For instance, a color balance or luminance value for a bank of LEDs  258  may be detected by one or more sensors  262  and provided as feedback data to data processing module  266 . Data processing module  266  may, in some examples, include circuitry for generating a second information signal based on the feedback data and modulating a second carrier frequency with the second information signal to create a second modulated signal. Detection/injection module  264  may include electrical filters to pass the second modulated signal onto conductor  120  for passage to power source  200 . 
     In this bidirectional option, referring to  FIG. 2A , injection/detection module  218  within power source  200  may additionally include electrical filters selected to allow passage of the second modulated signal to data processing module  216 . Data processing module  216  within power source  200  may include circuitry that demodulates the second modulated signal received from endpoint  250  and extracts the second information signal and/or the feedback data. Data processing module  216  may, in some examples, provide the feedback data for user consideration or apply the data to determine through various algorithms additional control data to be sent to endpoint  250 . 
     In some examples, data processing unit  216  in power source  200  and/or data processing unit  266  in endpoint  250  may include algorithms to control and manage the delivery of data signals between the remote units. These algorithms may aim to avoid or compensate for potential collisions in the delivery of data such as by handling contentions on conductor  120  similar to a data bus. These contentions may arise, for example, when two power source  200  and endpoint  250  attempt to communicate at the same time over conductor  120 . Alternatively, or additionally, when a power unit  110  or a remote load  130  contains more than one power source or endpoint, respectively, as illustrated in  FIG. 1 , multiple ones of these units may communicate simultaneously. The algorithms will ensure the integrity of data transmission. Basic examples of such algorithms may include delays in transmissions, timing intervals, and other techniques within the knowledge of those of ordinary skill in the art. Moreover, the system may include address information in the signal such that communication sources can communicate with one communication load at a time or communicate with all communication loads at once. 
       FIG. 3  is a generalized schematic diagram for one-way communications in an example for a system  300  for remote power delivery consistent with high-level system  100 . As generally depicted in  FIG. 3 , source  200  may include a voltage supply  302  of AC or DC constant voltage. In one example, voltage supply  302  is a power source providing DC power. Coupled to voltage supply  302  is a low-pass filter that permits the passage of the DC power, while preventing interference from higher frequency signals on cable  120 . In one example of  FIG. 3 , the low-pass filter is formed by a capacitor  304  in parallel with voltage supply  302  and an inductor  306  in series between voltage supply  302  and an output of source  200  where conductor  120  is coupled. The values for capacitor  304  and inductor  306  may depend on the frequencies selected for operating system  300 , as discussed further below. 
     Similarly for endpoint  250 , a low-pass filter permits the passage of the DC power to load  258 , while filtering out higher frequencies. In particular, as shown in  FIG. 3 , low-pass filter may be formed by a capacitor  308  in parallel with load  258  and an inductor  310  in series between conductor  120  and load  258 . The values for capacitor  308  and inductor  310  may depend on the particular frequencies selected for operating system  300 , as discussed further below. 
     Data processing module  216  in  FIG. 2A  and data processing module  266  in  FIG. 2B  may be implemented, in part, by microcontroller  311  and microcontroller  313 , respectively. While the preferred implementations of this disclosure involve few and simple devices to provide low-cost solutions, the functionality of either microcontroller  311  or  313  may also be embodied in various forms, including one or more processors and one or more computer readable media that stores various modules, applications, programs, or other data. The computer-readable media may include instructions that, when executed by the microcontroller or one or more processors, cause the processors to perform the operations described herein. In some implementations, microcontroller may include a central processing unit, microprocessor, a digital signal processor or other processing units or components known in the art. Alternatively, or in addition, the functionally described herein can be performed, at least in part, by one or more hardware logic components. Additionally, microcontroller  311  or  313  may possess its own local memory, which also may store program modules, program data, and/or one or more operating systems. 
     Microcontroller  311  may be configured to receive control data from endpoint control module  210 . As discussed above, the control data from module  210  contains values, settings, changes, instructions, or other information intended to affect the operation of an endpoint  250  located remotely. Microcontroller  311  may be coded to function in a manner that receives the control data and outputs an information signal at a suitable data rate, such as 2400 bits per second, that includes the control data. 
     Data processing module  216  may also include, in the example of  FIG. 3 , a modulator  312 . Modulator  312  receives the information signal from microcontroller  311  and generates the modulated signal to send to endpoint  250 . As shown in  FIG. 3 , modulator  312  in a simple and low-cost implementation may include a digital AND gate  314  that receives at one input the information signal from microcontroller  311  and at a second input a carrier frequency generated by an oscillator  316 . In addition, modulator  312  may have a driver  318  and a capacitor  320  coupled in series to an output of source  200 . Capacitor  320  can provide the function of a high-pass filter, enabling the modulated signal to pass onto conductor  120 , and suitable values for capacitor  320  are within the knowledge of those skilled in the art. Other implementations are possible for modulator  312 , with the implementation in  FIG. 3  providing a low-cost alternative with few components. 
     Data processing module  266  in  FIG. 2B  may be partially implemented with a demodulator  330 , which functions to demodulate the received modulated signal. In a simple embodiment shown in  FIG. 3 , demodulator  330  may entail capacitor  332 , receiver  334 , capacitor  336 , and resistive element  338 . Capacitor  332  is configured in series with receiver  334  and conductor  120  and provides a high-pass filtering function similar to capacitor  320 . Capacitor  336  and resistive element  338  are tuned components with values selected to help demodulate the information signal from the carrier signal on the received demodulated signal. 
     Data processing module  266  in  FIG. 2B , as mentioned, may also be partially implemented with microcontroller  313 . Microcontroller  313 , as with microcontroller  311 , is controlled to perform operations according to stored instructions. Microcontroller  313  may receive the information signal from demodulator  330  after demodulation has occurred. As noted previously, microcontroller  313  may process the information signal to determine the control data sent from source  200  and may perform operations to change settings or performance of load  258 , which may be one or more LEDs or other electronic components. 
     As illustrated in  FIG. 3 , supply  200  may include an inductor  306  coupled with a capacitor  304 , and the load  258  may include an inductor  310  coupled with a capacitor  308 . Inductor  306  coupled with capacitor  304  and inductor  310  coupled with capacitor  308  form filter networks. These filter networks allow inductor  306  and inductor  310  to decouple the high-frequency signals associated with the modulated signal injected on the cable from modulator  312  via capacitor  320  and received on cable  120  via capacitor  332  by demodulator  330 . 
     Ignoring parasitics, the minimum cutoff frequency of the decoupling will be approximately defined as: 
     
       
         
           
             
               Decoupling 
               
                 3 
                  
                 db 
               
             
             = 
             
               Maximum 
                
               
                 ( 
                 
                   
                     1 
                     
                       1 
                       * 
                       π 
                       * 
                       
                         
                           Lsupply 
                           * 
                           Csupply 
                         
                       
                     
                   
                   , 
                   
                     1 
                     
                       1 
                       * 
                       π 
                       * 
                       
                         
                           Lload 
                           * 
                           Cload 
                         
                       
                     
                   
                 
                 ) 
               
             
           
         
       
     
     where Lsupply is inductor  306 , Csupply is capacitor  304 , Lload is inductor  310 , and Cload is capacitor  308 . Therefore, one of ordinary skill in the art may select capacitor and inductor values for the arrangement as exemplified in  FIG. 3  to balance a frequency to be injected onto cable  120  by modulator  312 . To ensure minimum attenuation of the modulated signal, the modulation or carrier frequency generated by the oscillator, such as oscillator  316 , should be greater than about 10 times the decoupling frequency. 
     In certain implementations consistent with this disclosure, the system  300  may operate with a carrier frequency that is greater than the data rate of the information signal. Nominally, the carrier frequency may be at least a multiple of the data rate, and in some examples, at least 10 times the data rate. Therefore, if the data rate for the information signal from microprocessor  311  is 2400 bits per second, the carrier frequency from oscillator  316  for modulation would preferably be at least, but not limited to, 24,000 Hz. This difference may advantageously reduce any ripple at the output of the demodulator  330  and help enable low-cost and accurate detection of the transmitted data. As well, in other examples, the carrier frequency for modulation rate could be greater than 20 KHz to avoid any potential for acoustic noise but be less than 525 KHz to 1.705 MHz to avoid interference with the AM radio band. 
     Consequently, data communication on system  300  in some embodiments may be configured to operate at much lower frequencies than typical communication standards, such as between 20 KHz-525 KHz. These lower frequencies may significantly reduce system cost and electromagnetic interference. In addition, units operating according to these examples may require less power to remain in an off state. Minimum dissipated power is a function of the capacitors used for coupling to the power, the signaling voltage level, and the modulation frequency. Lowering the modulation frequency has an approximately linear relationship to minimum dissipated power. The minimum modulation frequency is influenced by the value of the decoupling inductors and the size of the power supply and load capacitance. 
       FIG. 4  is a generalized schematic diagram for two-way communications in an example system  400  for remote power delivery. System  400  depicts having the same circuitry for one-way communication from source  200  to endpoint  250  as shown in  FIG. 3 . In addition, to accommodate bidirectional communications, system  400  may include an endpoint modulator  410  coupled between microcontroller  313  and cable  120  and a source demodulator  420  coupled between cable  120  and microcontroller  311 . 
     In the example of  FIG. 4 , endpoint modulator  410  may have circuitry similar to modulator  312  in  FIG. 3 . Specifically, endpoint modulator  410  may include a digital AND gate  412  with one input connected to an output of microcontroller  313  and a second input connected to an oscillator  414 . The output of the microcontroller  313  may provide a second information signal at a data rate, such as 2400 bits per second. The second information signal may contain in substance feedback data to be passed to source  200 . Without limitation, the feedback data may relate to detections by sensors or other accessories  262 , operational status levels for load  258  such as white point settings for one or more LEDs, and the like. Oscillator  414  provides a second carrier frequency for modulating the second information signal. In some examples, the second carrier frequency is the same as the first carrier frequency. The second carrier frequency may also be different from the first carrier frequency, as desired. The AND gate  412  produces a second modulated signal from the second carrier frequency and the second information signal. 
     A second portion of endpoint modulator  410  may include a driver  416  and a capacitor  418 . This second portion may function as a high-pass filter and include a value for capacitor  418  to permit passage of the frequencies for the second modulated signal while blocking lower frequency signals. Selection of the appropriate capacitance for a given design will be within the knowledge of one of ordinary skill in the art. 
     Source demodulator  420  in  FIG. 4  may have circuitry similar to demodulator  330  in  FIG. 3 . Specifically, source demodulator  420  may in some examples have a high-pass filter at its input resembling the output of endpoint modulator  410 , i.e. with capacitor  422  in series with driver  424 . This arrangement may have values selected to permit the passage of the second modulated signal received from cable  120 . Following driver  424 , a tuned capacitor  426  and resistive element  428  in parallel are selected with values to filter the second carrier frequency from the second information signal on the received second modulated signal in a manner resembling demodulator  330  in endpoint  250 . As a result, source demodulator  410  may provide to an input of microcontroller  311  the second information signal. In turn, microcontroller  311  using programmed instructions may process the second information signal to determine the feedback data. Microcontroller  311  may act on the feedback data, for example, through programmed instructions by sending new control data to endpoint  250  to alter behavior of remote load  258  or by providing the feedback data to a user, perhaps via a graphical user interface. 
     Accordingly, system  400  enables bidirectional communication of data between source  200  and endpoint  250  simply and at low cost. A minimal number of inexpensive components are provided for both source  200  and endpoint  250 , which can lead to units and an overall system that are affordable and avoid technical complexity. While other components may be added or chosen in various implementations that could increase cost or complexity, the embodiments of  FIGS. 3 and 4  represent a simple approach that alone may achieve a desired objective for delivering power with integrated data transmission for a remote load such as one or more LEDs. 
       FIG. 5  is a block diagram indicating a possible arrangement with multiple power sources  200  and multiple endpoints  250 . In some examples, each source  200 A and  200 B may provide electrical power to conductor  120  from a supply  208  through low-pass filters  510 . The outputs of sources  200 A and  200 B may be ganged together in parallel for redundancy. Each endpoint  250 A and  250 B in turn may receive the delivered power from conductor  120  through low-pass filters  510  for driving loads  258 . The inputs of endpoints  250 A and  250 B may be ganged together in parallel. 
     In certain implementations such as shown in  FIG. 5 , each source  200 A and  200 B may receive external input from endpoint control  210 . The external input for the power unit may include signaling from a variety of origins, as discussed above for  FIG. 2A , to indicate desired performance or settings for a load  258  at one or both of endpoints  250 A and  250 B. 
     Likewise, each endpoint  250 A and  250 B may receive external input from a local sensor or accessory  262 A or  262 B. The external input for the remote load may include signaling from a variety of origins, as discussed above for  FIG. 2B , to feed data back to the power unit relating to settings or operation for a load  258  at one or both of endpoints  250 A and  250 B. 
     In some examples, circuitry  510  may provide functionality as a modulator and/or a demodulator within one or more of the sources  200 A and  200 B. As discussed above for other implementations, circuitry  510  can collectively send and receive modulated data communications between power sources  200  and endpoints  250  in a bidirectional manner. Load control  260  within endpoint  250 A and  250 B may implement the control data sent by a source  200 A or  200 B with respect to a load  258 . 
       FIG. 6  is a schematic diagram of a circuit  600  for simulating data communication integrated with power delivery for an arrangement similar to  FIG. 3 . As an example, circuit  600  contains a central power unit  602  and three remote loads  604 ,  606 , and  608 . A noise source  608  was added in series with power unit  602  to simulate noise that would naturally be present from a typical switching power supply. Power unit  602  was fixed at a constant 56V. Noise source  608  was set as a 1V pk-pk square wave signal at 100 KHz. The loads  604 ,  606 , and  608  were implemented as resistors designed to provide a load of approximately 10 W. In one example, the resistances were 313.6 Ohms. 
     Circuit  600  includes capacitor  610  and resistor  612  as typical simulated capacitance for power supply  602  at the operating conditions. In one example, capacitor  610  is 1200 uF. Resistor  612  improves the simulation of capacitor  610  and are set at 0.2 Ohms. Similarly, capacitors  614 ,  616 , and  618  represent typical bulk capacitance affiliated with the loads and are selected at 100 uF. 
     Inductors  620 ,  622 ,  624 , and  626  represent the decoupling inductance that would be incorporated into the central power unit  602  and the remote loads  602 ,  604 , and  606 . They have values of 100 u. Resistors  628 ,  630 ,  632 , and  634  represent the typical parasitic resistances of these inductors, respectively, and are set at 0.1 Ohms. 
     In certain examples, parasitic resistance may also be added to the cable to simulate poor connections and losses likely in the signal and ground conductors. Resistors  636 ,  638 , and  640  may represent a potentially lossy 1 Ohm cable resistance for the positive wire, while resistors  642 ,  644 , and  648  may represent 1 Ohm lossy connections to ground. Finally, resistor  648  represents a 0.1 Ohm source impedance from source  602  to maximize noise. 
       FIG. 7  illustrates results of a simulated transmission of a modulated signal across simulation circuit  600  of  FIG. 6  in the form of timing diagrams. Top waveform  710  depicts is the signal to be encoded, which may represent the information signal discussed above exiting microcontroller  311  within power source  200  in  FIG. 3 . Waveform  720  illustrates a carrier frequency to be used for modulation, such as the frequency generated by oscillator  316 . Note that the relative high frequency of the waveform  720  makes it appear to be a solid form. Waveform  730  illustrates this carrier frequency when zoomed in at a smaller scale to show its oscillation. The fourth waveform  740  is an exemplary modulated signal that could appear on cable  120  that connects the power unit  200  and the endpoint unit  250 . Finally, the last waveform  750  depicts the simulated signal that would be generated after demodulation, such as at the input to microcontroller  313  within endpoint  250  in  FIG. 3 . Note that a logical zero (low level) for the signal to be encoded in waveform  710  represents a logical active level. Hence, the modulated signal on the cable in waveform  740  is visible and the output of the demodulator in waveform  750  is a logical high when the signal to be encoded is near a zero voltage level (logical low). 
     Sequences for exchanging control data, feedback data, and instructions between power sources  200  and endpoints  250  may vary widely and are within the knowledge of those skilled in the art. Without limitation, some examples include, upon system power-up, or at a time as initiated by one of the connected units, the endpoints  250  first communicating their operational requirements to the power sources  200 . Power sources  200 , based on the operational requirements of the loads, will modify the operating parameters of the power sources  200  to optimize system performance (i.e., the sources may reduce their output voltage to optimize the efficiency of the connected loads or they may enter a power-saving state). 
     In some examples, upon system power up, power source  200  will query all connected endpoints  250  to determine maximum power draw. If the maximum power draw exceeds the capability of the power source  200 , source  200  will not enable power output onto the loads and may trigger a warning signal, visual, sonic, or via a communications interface. Alternately, for LED loads, power source  200  may calculate a maximum light output (dimming level) that prevents it from being overloaded and will ensure this value is not violated. 
     Although this subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as illustrative forms of implementing the claims. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure. Various modifications and changes can be made to the subject matter described herein without following the example configurations and applications illustrated and described, and without departing from the true spirit and scope of the present invention, which is set forth in the following claims.