Short range communication system

#The invention relates to short-range data communication.

#Radio frequency identification (RFID) systems, for example, typically include a reader or interrogator, a transponder and a data processor. The reader may include an internal microcontroller, a transmitter, a receiver, and an antenna. The transponder is usually a passive device (having no power source) embedded in a card or key tag, and may include an antenna and a RFID application specific integrated circuit (ASIC). The interrogator transmits an electromagnetic wave defining a surveillance zone. When a transponder enters the zone, the electromagnetic energy from the interrogator begins to energize the ASIC in the transponder, which initializes and then broadcasts an identity signal.

#A RFID system may use a low-energy, back-scattering technology that selectively reflects or back-scatters the electromagnetic energy from the transponder back to the interrogator. Receiving circuitry in the interrogator senses and decodes the back-scattered signal to determine the identity of the transponder. Such a system may be used to identify, track and/or locate people or objects.

#FIG. 1 is an implementation of a low-power, short-range communication system according to the invention.

#FIGS. 2A and 2B are simplified block diagrams of transponders of a type that may be used in the system of FIG. 1.

#FIGS. 3A, 3B and 3C are flowcharts illustrating interrogator status reporting mode, location mode and position mode implementations according to the invention.

#FIG. 1 shows an implementation of a low-power, short-range communication system 10 for communicating with one or more transponders. The communication system 10 includes a wireless interrogator 12, communication lines 14a to 14n, which may be pairs of conductive wires or conductive fibers, and coupling ports 16a to 16n. The coupling ports may be circular loops (coils) and operate as antennas to transmit the interrogation signals wirelessly. In particular, each coupling coil may be designed to behave like an inductor. Thus, each of the coils may have a number of turns and produce a magnetic field that varies with the interrogation signal generated by the interrogator.

#The interrogator 12 includes a microcontroller 2 connected to a frequency modulator 4 and to a receiver/transmitter 6. The receiver/transmitter module may include a form of suitable modulation and demodulation circuitry to condition/modulate the interrogation signals with the correct amount of power and security and within a certain bandwidth around a particular center frequency for transmission over the media, and to receive using demodulation techniques the transponder response signals with an acceptable level of signal accuracy and integrity. In addition, error correction features may be used. A power source 7 may be connected to each of the other circuit elements and to a switch 5 that may be utilized by a user to activate the interrogator 12. The interrogator may also include or be connected to an output device 8 that may be used to indicate information to the user, such as the presence of transponders or to store data received from a particular transponder for later analysis, or to process the data. The output device may also be a means for providing Internet access to the interrogator so that data may be transmitted via e-mail, for example, to enable e-commerce. In addition, the output device may enable the interrogator 12 to transmit data or information via a cell phone using transmission protocols such as GSM or CDMA, Bluetooth, Home RF, or any current or future wireless protocols, for example, 3G (3rd Generation wireless cellular standards), or to transmit data via standard line telephones or via other communication devices. The interrogator 12 may also include, or be connected to, a data input device 9 that may be used to enter data or information to the interrogator, or to send data or information to a transponder, or both. Thus, the input device may be used for various purposes, such as updating information, or loading a new version of software or for data transmission and/or to request data retrieval.

#Some of the communication lines, such as line 14b, may terminate in a socket 15 or other connector for direct connection to a transponder or may be directly wired to a transponder or actuator or other types of electronic devices. In addition, the system may include one or more coupling connectors 11a and 11b. The coupling connector 11a includes a coupling port 16d for wireless connection to the interrogator 12, a communication line 14e, and a coupling port 16e for establishing communication with a transponder 18c or with another coupling connector 11b. The coupling connector 11b includes a coupling port 16f, a communication line 14f and a coupling port 16g. Thus, coupling connectors may wirelessly connect to each other, to an interrogator or to one or more transponders.