Isolated receiver powered by transmitter

A fire protection system includes a first transceiver communicatively coupled with a first end of a communication link; a second transceiver communicatively coupled with a second end of the communication link and configured for communicating a signal with the first transceiver via the communication link; a first coupling/decoupling circuit configured to provide overlayed power by overlaying power from a first power source onto the signal at the first end of the communication link; and a second coupling/decoupling circuit configured to provide separated power by separating the signal from the overlayed power at the second end of the communication link, wherein the separated power is configured to power the second transceiver.

FIELD

The present disclosure relates generally to fire protection systems, and more particularly, to providing power in fire protection systems.

SUMMARY

In an aspect, a fire protection system includes a first transceiver communicatively coupled with a first end of a communication link. The fire protection system further includes a second transceiver communicatively coupled with a second end of the communication link and configured for communicating a signal with the first transceiver via the communication link. The fire protection system further includes a first coupling/decoupling circuit configured to provide overlayed power by overlaying power from a first power source onto the signal at the first end of the communication link. The fire protection system further includes a second coupling/decoupling circuit configured to provide separated power by separating the signal from the overlayed power at the second end of the communication link, wherein the separated power is configured to power the second transceiver.

In a further aspect, an apparatus in a fire protection system includes a first transceiver communicatively coupled with a first end of a communication link and configured to communicate a signal with a second transceiver coupled with a second end of the communication link. The apparatus further includes a coupling/decoupling circuit configured to provide overlayed power by overlaying power from a first power source onto the signal at the first end of the communication link, wherein the overlayed power is configured to power the second transceiver at the second end of the communication link.

In another aspect, an apparatus in a fire protection system includes a first transceiver communicatively coupled with a first end of a communication link and configured to communicate a signal with a second transceiver communicatively coupled with a second end of the communication link. The apparatus further includes a coupling/decoupling circuit configured to provide separated power by separating the signal from power overlayed onto the communication link, wherein the separated power is configured to power the first transceiver.

DETAILED DESCRIPTION

Aspects of the present disclosure provide a fire protection system in which a first transceiver provides power to a second isolated transceiver by overlaying power onto a communication link that is used to communicate signals between the first transceiver and the second transceiver. By isolating the second transceiver and powering the second transceiver with the overlayed power, the present aspects protect the communicated signals against interference and/or ground voltage mismatch, without requiring an isolated direct current (DC)-to-DC converter for powering the second transceiver.

Turning now to the figures, example aspects are depicted with reference to one or more components described herein, where components in dashed lines may be optional.

Referring toFIG.1, in some non-limiting example aspects, building automation equipment, such as a first fire protection equipment box110and a second fire protection equipment box112, may be installed throughout a building100(or other structure). The first fire protection equipment box110and the second fire protection equipment box112may be adjacent to each other within the building100, or may be distanced/separated across the building100. Each one of the first fire protection equipment box110and the second fire protection equipment box112may be a fire alarm control panel. The first fire protection equipment box110may include a first user interface (UI)102communicatively coupled with a first processor104. Similarly, the second fire protection equipment box112may include a second UI118communicatively coupled with a second processor121.

In some aspects, the first fire protection equipment box110and the second fire protection equipment box112may communicate with each other via a wired communication link120. Specifically, for example, a first transceiver106in the first fire protection equipment box110may be communicatively coupled with the first processor104, and a second transceiver114in the second fire protection equipment box112may be communicatively coupled with the second processor121. Further, the first transceiver106and the second transceiver114are communicatively coupled via the communication link120and thereby provide a communication path between the first processor104and the second processor121.

In some cases, challenges may arise from the differences between the connected systems, namely, the first fire protection equipment box110and the second fire protection equipment box112. Specifically, regarding the voltage of “Earth” which is taken as the 0V reference, there may be factors that produce a difference between two points of “Earth” across the scale of the building100. For example, an electric motor130in the building100, such as a large heating, ventilation, and air conditioning (HVAC) motor, an industrial electric motor, etc., may induce electricity onto surrounding metal and cause undesirable interference onto the signals communicated between the first fire protection equipment box110and the second fire protection equipment box112via the communication link120.

These issues are exacerbated when the operating frequency/bandwidth of the signals communicated between the first fire protection equipment box110and the second fire protection equipment box112via the communication link120is high (e.g., greater than 1 Mbps), for example, in case of digital audio communication via the communication link120. In particular, for example, as compared to communicating lower frequency signals (e.g., less than 10 kbps) via the communication link120, communicating higher frequency signals via the communication link120is more sensitive to disruption/electromagnetic interference even when the first fire protection equipment box110and the second fire protection equipment box112are close to each other. The higher the data speed in a communication link, the more sensitive the communication link120is to interference at short distances.

For example, the electric motor130may emit electromagnetic noise160, and may induce a difference in ground potential associated with the first fire protection equipment box110and the second fire protection equipment box112. This difference in ground potential may be modeled as a battery140in between a first earth potential150of the first fire protection equipment box110and a second earth potential155of the second fire protection equipment box112.

Some systems mitigate these challenges by isolating the signal along the communication link120using isolation and differential signaling. Isolation interrupts the interference caused by differences in power supplies or by radiofrequency (RF) noise (e.g., electromagnetic noise160) induced in long wires. Differential signaling is a method of encoding digital information on a single pair of wires such that each wire takes turns being of opposite voltage values around a central voltage point/potential. Cycling the voltage values around the central voltage point/potential and detecting the voltage value crossings may make the wires more immune to interference and may also reduce the impact of wiring losses. The RS-485 standard is one example standard that utilizes this technique.

The aforementioned interference and ground potential mismatch challenges are compounded in fire protection systems due to a regulation requirement to detect wiring faults between a circuit and “Earth.” Earth in this context is the ground potential, and represents the voltage of surrounding building steel, metal conduit, steel enclosures, metal junction boxes, etc. When fire alarm wiring becomes damaged or is installed improperly, the wiring may come into contact with these structural metals, and the fire protection system is required to be able to detect these single point faults and notify the technician/building owner of a potential issue. Because of this requirement to be able to sense wiring faults, fire alarm wiring cannot be completely isolated.

Additionally, high speed isolators (such as, for example, ISO721D from Texas Instruments) require power on both sides of the isolation barrier, which may require a dedicated power converter at each isolator that is large and expensive. For example, referring toFIG.2, some fire protection systems provide isolation by including a first DC-to-DC converter206and a first isolator204at the first fire protection equipment box110to isolate the first transceiver106, and similarly including a second DC-to-DC converter210and a second isolator208at the second fire protection equipment box112to isolate the second transceiver114. However, such DC-to-DC converters may be large and expensive.

Some aspects of the present disclosure provide a lower cost solution to the aforementioned interference and ground potential mismatch issues by sending power across the data lines while also providing the required fire alarm wiring fault detection. In some aspects, for example, by implementing Power-over-Data-Lines (PoDL) techniques, one side of a building interconnection (e.g., the first fire protection equipment box110) may perform the earth fault detection as well as provide the power to run an isolator on the other side (e.g., the second fire protection equipment box112). The isolator may include, for example, a transformer with feedback and regulation. PoDL is a technique that biases a differential signal with a DC offset that carries power.

In some cases, implementing PoDL techniques may require very large components to decouple the power from the high-speed data (and the components may get larger with more power demand). Further, the data is required to be balanced (e.g., the data cannot have too many 1's or 0's in a row), and the power drawn is required to be very constant so as to not distort the data. However, in the present aspects, the requirements of PoDL are mitigated and PoDL is leveraged for providing a path for earth fault detection.

Referring toFIG.3, in some non-limiting example aspects, the first fire protection equipment box110and the second fire protection equipment box112may include a first differential signaling transceiver215and a second differential signaling transceiver280, respectively, in order to implement differential signaling (according to, for example, the RS-485 standard) as the basic communication layer for communicating a signal217over field wiring250that connects the first fire protection equipment box110with the second fire protection equipment box112.

In some non-limiting example aspects, each one of the first differential signaling transceiver215and the second differential signaling transceiver280may include an RS-485 transceiver. The RS-485 is a differential signaling encoding system. In some non-limiting example aspects, the output pins of an RS-485 transceiver (such as, for example, LTC 485 from Linear Technology) may flip between two states, such as but not limited to +2.5V and −2.5V.

InFIG.3, the first differential signaling transceiver215and the second differential signaling transceiver280are in bidirectional signal communication with each other over the field wiring250. Also, additional components (225,220,270,275, as described in further detail below) are implemented in the first fire protection equipment box110and the second fire protection equipment box112such that the field wiring250delivers power from a DC power supply222in the first fire protection equipment box110to the second differential signaling transceiver280in the second fire protection equipment box112. Accordingly, in terms of power delivery, the first fire protection equipment box110is a “source” and the second fire protection equipment box112is a “destination,” while the signal217which is communicated over the field wiring250may flow in the same direction, or counter to, the direction of power delivery.

In some non-limiting example aspects, the first fire protection equipment box110includes an earth fault detection circuit230. In some non-limiting example aspects, Earth fault detection is accomplished by weakly forcing the “Earth” reference potential to an intermediate voltage (e.g., via resistors302inFIG.4). In some non-limiting aspects, for example, the intermediate voltage may be 10 VDC. When a wiring fault shorts the field wiring250to earth (e.g., when a stray wire strand of the field wiring250comes into contact with an earthed conduit), this new earth fault short overrides the weak intermediate voltage. The earth fault detection circuit230senses this change in the Earth voltage (e.g., via an earth bias detection circuit304which may be implemented using, for example, one or more comparators) and provides a notification indicating that there is an issue.

In some non-limiting example aspects, the second fire protection equipment box112includes an isolator290that provides a signal and power isolation barrier300between the second RS 485 transceiver280and other components in the second fire protection equipment box112. The isolator290is powered by the power overlayed onto the field wiring250. Accordingly, in these aspects, there is no need for a DC-to-DC power converter at the second fire protection equipment box112for providing power to the isolator290.

In some non-limiting example aspects, in the first fire protection equipment box110, the first differential signaling transceiver215is capacitively coupled via capacitors225to the field wiring250. In some non-limiting example aspects, the field wiring250may be a copper wiring pair which is twisted to mitigate common interference that applies to both wires. Each of the capacitors225may be, for example, 1 micro Farad. The conductors in the field wiring250are also connected to +24 VDC and OVDC through inductors220. Each of the inductors220may be, for example, 1 milli Henry. This capacitively-coupled data and inductively-coupled power is thus provided by a first PoDL circuit227comprising the capacitors225and the inductors220.

In some non-limiting example aspects, in the second fire protection equipment box112, capacitors275and inductors270similarly provide a second PoDL circuit277and may have the same or similar values as respective ones of the capacitors225and the inductors220at the first fire protection equipment box110. Accordingly, the capacitors275and the inductors270comprising the second PoDL circuit277separate the DC power on the field wiring250from the differentially-signaled data on the field wiring250. This separated DC power may then be filtered and regulated to smooth out changes in load, and powers the second Differential signaling transceiver280and an isolator290that establishes a signal and power isolation barrier300to isolate the signal217in the second fire protection equipment box112.

In some non-limiting example aspects, at the data layer, the raw data in the signal217is encoded so as to have balanced DC polarity. This may be accomplished, for example, using Manchester encoding or more advanced algorithms such as 8b/10b encoding. This ensures that there are not too many sequential 1's or 0's that interact with the PoDL components to cause errors.

By implementing the first PoDL circuit227, the second PoDL circuit277, and balanced data encoding, the present aspects utilize PoDL to replace the second DC-to-DC converter210inFIG.2. The coupling/decoupling components in the second PoDL circuit277in the second fire protection equipment box112inFIG.3are smaller and lower cost than the second DC-to-DC converter210that provided the same functionality inFIG.2.

Referring toFIG.5, in some alternative non-limiting example aspects, the power overlayed onto the field wiring250may be used at the second fire protection equipment box112to source power to the second processor121as well as one or more additional devices306controlled by the second processor121in the second fire protection equipment box112. For example, in some non-limiting example aspects, the capacitors275and the inductors270at the second fire protection equipment box112separate the DC power on the field wiring250from the differentially-signaled data on the field wiring250. This separated DC power may then be filtered and regulated to smooth out changes in load, and powers the second differential signaling transceiver280, the second processor121, and the devices306that are controlled by the second processor121.

In some non-limiting example aspects, the devices306may include one or more initiating devices and/or one or more notification devices, such as, but not limited to, a strobe, a self-amplified speaker, an emergency signage, a smoke detector, a sounder, etc. Accordingly, there is no need for a power source at the second fire protection equipment box112to provide power to the processor121and the devices306.

Some further aspects are provided below.

1. A fire protection system comprising:a first transceiver communicatively coupled with a first end of a communication link;a second transceiver communicatively coupled with a second end of the communication link and configured for communicating a signal with the first transceiver via the communication link;a first coupling/decoupling circuit configured to provide overlayed power by overlaying power from a first power source onto the signal at the first end of the communication link; anda second coupling/decoupling circuit configured to provide separated power by separating the signal from the overlayed power at the second end of the communication link,wherein the separated power is configured to power the second transceiver.

2. The fire protection system of clause 1,wherein the first coupling/decoupling circuit is configured to capacitively couple a signal port of the first transceiver to the communication link, andwherein the first coupling/decoupling circuit is configured to inductively couple the first power source to the communication link.

3. The fire protection system of clause 1 or 2,wherein the second coupling/decoupling circuit is configured to capacitively decouple a signal port of the second transceiver from the communication link, andwherein the second coupling/decoupling circuit is configured to inductively decouple the separated power from the communication link.

4. The fire protection system of any one of the above clauses, further comprising an isolator communicatively coupled with the second transceiver and configured for communicating the signal with the second transceiver.

5. The fire protection system of clause 4,wherein the isolator comprises a first side and a second side, andwherein the isolator is configured to provide an isolation barrier between the first side and the second side.

6. The fire protection system of clause 5,wherein the first side of the isolator is communicatively coupled with the second transceiver, andwherein the second side of the isolator is communicatively coupled with a processor.

7. The fire protection system of clause 5 or 6, wherein the separated power is configured to power the first side of the isolator.

8. The fire protection system of clause 6 or 7, wherein a second power source is configured to power the processor and the second side of the isolator.

9. The fire protection system of any one of clauses 1 to 3,wherein the second transceiver is communicatively coupled with a processor, andwherein the separated power is further configured to power the processor.

10. The fire protection system of clause 9, wherein the separated power is further configured to power one or more devices that are controlled by the processor.

11. The fire protection system of clause 10, wherein the one or more devices comprise one or more fire protection devices.

12. The fire protection system of clause 11, wherein the one or more fire protection devices comprise an initiating device or a notification device.

13. The fire protection system of clauses 11 or 12, wherein the one or more fire protection devices comprise a strobe, a self-amplified speaker, an emergency signage, a smoke detector, or a sounder.

14. The fire protection system of any one of the above clauses, wherein the second transceiver is located distant from the first transceiver.

15. The fire protection system of any one of the above clauses, further comprising a ground fault detection circuit configured to detect a ground fault using the power from the first power source.

16. The fire protection system of clause 15, wherein the ground fault detection circuit is collocated with the first transceiver.

17. The fire protection system of any one of the above clauses, wherein the communication link comprises a twisted pair of wires.

17-1. The fire protection system of any one of the above clauses, wherein the isolator comprises a transformer.

18. The fire protection system of any one of the above clauses, wherein each one of the first transceiver and the second transceiver comprises a differential signaling transceiver.

19. An apparatus in a fire protection system, comprising:a first transceiver communicatively coupled with a first end of a communication link and configured to communicate a signal with a second transceiver coupled with a second end of the communication link; anda coupling/decoupling circuit configured to provide overlayed power by overlaying power from a first power source onto the signal at the first end of the communication link,wherein the overlayed power is configured to power the second transceiver at the second end of the communication link.

20. An apparatus in a fire protection system, comprising:a first transceiver communicatively coupled with a first end of a communication link and configured to communicate a signal with a second transceiver communicatively coupled with a second end of the communication link; anda coupling/decoupling circuit configured to provide separated power by separating the signal from power overlayed onto the communication link,wherein the separated power is configured to power the first transceiver.

Referring toFIG.6, a computing device700may implement all or a portion of the functionality described inFIGS.1-5above. For example, the computing device700may be or may include at least a portion of the first fire protection equipment box110, the second fire protection equipment box112, the first UI102, the second UI118, the first processor104, the second processor121, or any other component described herein with reference toFIGS.1-5above. The computing device700includes a processor702which may be configured to execute or implement software, hardware, and/or firmware modules that perform any functionality described herein with reference toFIGS.1-6above. For example, the processor702may be configured to execute or implement software, hardware, and/or firmware modules that performs any functionality described herein with reference to the first fire protection equipment box110, the second fire protection equipment box112, the first UI102, the second UI118, the first processor104, the second processor121, or any other component/system/device described herein with reference toFIGS.1-5above.

The processor702may be a micro-controller, an application-specific integrated circuit (ASIC), or a field-programmable gate array (FPGA), and/or may include a single or multiple set of processors or multi-core processors. Moreover, the processor702may be implemented as an integrated processing system and/or a distributed processing system. The computing device700may further include a memory704, such as for storing local versions of applications being executed by the processor702, related instructions, parameters, etc. The memory704may include a type of memory usable by a computer, such as random access memory (RAM), read only memory (ROM), tapes, magnetic discs, optical discs, volatile memory, non-volatile memory, and any combination thereof. Additionally, the processor702and the memory704may include and execute an operating system executing on the processor702, one or more applications, display drivers, etc., and/or other components of the computing device700.

Further, the computing device700may include a communications component706that provides for establishing and maintaining communications with one or more other devices, parties, entities, etc., utilizing hardware, software, and services. The communications component706may carry communications between components on the computing device700, as well as between the computing device700and external devices, such as devices located across a communications network and/or devices serially or locally coupled with the computing device700. In an aspect, for example, the communications component706may include one or more buses, and may further include transmit chain components and receive chain components associated with a wireless or wired transmitter and receiver, respectively, operable for interfacing with external devices.

Additionally, the computing device700may include a data store708, which can be any suitable combination of hardware and/or software, that provides for mass storage of information, databases, and programs. For example, the data store708may be or may include a data repository for applications and/or related parameters not currently being executed by processor702. In addition, the data store708may be a data repository for an operating system, application, display driver, etc., executing on the processor702, and/or one or more other components of the computing device700.

The computing device700may also include a user interface component710operable to receive inputs from a user of the computing device700and further operable to generate outputs for presentation to the user (e.g., via a display interface to a display device). The user interface component710may include one or more input devices, including but not limited to a keyboard, a number pad, a mouse, a touch-sensitive display, a navigation key, a function key, a microphone, a voice recognition component, or any other mechanism capable of receiving an input from a user, or any combination thereof. Further, the user interface component710may include one or more output devices, including but not limited to a display interface, a speaker, a haptic feedback mechanism, a printer, any other mechanism capable of presenting an output to a user, or any combination thereof.