A multi-protocol RFID interrogating system employs a synchronization technique (step-lock) for a backscatter RFID system that allows simultaneous operation of closely spaced interrogators. The multi-protocol RFID interrogating system can communicate with backscatter transponders having different output protocols and with active transponders including: Title 21 compliant RFID backscatter transponders; IT2000 RFID backscatter transponders that provide an extended mode capability beyond Title 21; EGO RFID backscatter transponders, SEGO RFID backscatter transponders; ATA, ISO, ANSI AAR compliant RFID backscatter transponders; and IAG compliant active technology transponders. The system implements a step-lock operation, whereby adjacent interrogators are synchronized to ensure that all downlinks operate within the same time frame and all uplinks operate within the same time frame, to eliminate downlink on uplink interference.

Systems and methods for operating a tag system. The methods comprise performing the following operations by a tag having an antenna: emitting a signal at a first frequency spectrum, if the tag is not proximate to a tag modulation marker; and emitting a signal at a second frequency spectrum, if the tag is proximate to the tag modulation marker.

An incontinence detection system monitors an area for moisture events and wirelessly transmits moisture-related information to one or more notification devices. The system has a pad that includes a substrate and one or more sensors supported by the substrate. The sensor(s) emit wireless signals indicative of the moisture-related information. A sensor event communication system forwards the sensor signals to another device, such as a notification device. Portions of the system are included in a patient support apparatus, such as a bed.

A radio frequency identification (RFID) system includes an RFID interrogator configured for generating an RFID signal, wherein a channel frequency of the RFID signal changes over time; at least one single feed patch antenna; and at least one single feed line configured for feeding the signal to the corresponding at least one single feed patch antenna. The single feed patch antenna is configured to transmit an electromagnetic wave in response to and at the channel frequency of the RFID signal such that the electromagnetic wave exhibits (1) a polarization tilt angle that varies depending on the channel frequency of the signal, (2) a substantially linear polarization at all channel frequencies of the signal within the given operational bandwidth, and (3) a range of polarization tilt angles across the given operational bandwidth that spans at least 70 degrees within a single quadrant. A method for frequency multiplexing includes similar components.

A multi-protocol RFID interrogating system employs a synchronization technique (step-lock) for a backscatter RFID system that allows simultaneous operation of closely spaced interrogators. The multi-protocol RFID interrogating system can communicate with backscatter transponders having different output protocols and with active transponders including: Title 21 compliant RFID backscatter transponders; IT2000 RFID backscatter transponders that provide an extended mode capability beyond Title 21; EGO RFID backscatter transponders, SEGO RFID backscatter transponders; ATA, ISO, ANSI AAR compliant RFID backscatter transponders; and IAG compliant active technology transponders. The system implements a step-lock operation, whereby adjacent interrogators are synchronized to ensure that all downlinks operate within the same time frame and all uplinks operate within the same time frame, to eliminate downlink on uplink interference.

A radio frequency identification (RFID) system for frequency multiplexing includes, in an exemplary embodiment, an RFID interrogator configured for generating an RFID signal, wherein a channel frequency of the RFID signal changes over time; at least one antenna or transmission line; and a diplexer coupling the RFID interrogator and the antennas or transmission lines and configured for distributing the RFID signal to each of the antennas or transmission lines, respectively, depending on the channel frequency of the RFID signal generated. The antennas or transmission lines are configured to transmit an electromagnetic wave in response to and at the channel frequency of the RFID signal distributed thereto. Other embodiments include RFID systems and methods including a frequency selective surface and both similar and different components and aspects for frequency multiplexing.

An information collection system includes a plurality of radio tags and a reading device. Each of the radio tags stores identification information and includes a sensor, an antenna that receives a carrier wave from the reading device, and a data transmission unit that sends measurement data including the identification information and information obtained by the sensor to the reading device after the carrier wave is received by the antenna. The plurality of radio tags send the identification information and the information obtained by the sensor with different natural periods from the data transmission units. The reading device transmits the carrier wave to each of the radio tags, receives data from each of the radio tags, and obtains the data.

An incontinence detection system monitors an area for moisture events and wirelessly transmits moisture-related information to one or more notification devices. The system has a pad that includes a substrate and one or more sensors supported by the substrate. The sensor(s) emit wireless signals indicative of the moisture-related information. A sensor event communication system forwards the sensor signals to another device, such as a notification device. Portions of the system are included in a patient support apparatus, such as a bed.

A multi-protocol RFID interrogating system employs a synchronization technique (step-lock) for a backscatter RFID system that allows simultaneous operation of closely spaced interrogators. The multi-protocol RFID interrogating system can communicate with backscatter transponders having different output protocols and with active transponders including: Title 21 compliant RFID backscatter transponders; IT2000 RFID backscatter transponders that provide an extended mode capability beyond Title 21; EGOTM RFID backscatter transponders, SEGOTM RFID backscatter transponders; ATA, ISO, ANSI AAR compliant RFID backscatter transponders; and IAG compliant active technology transponders. The system implements a step-lock operation, whereby adjacent interrogators are synchronized to ensure that all downlinks operate within the same time frame and all uplinks operate within the same time frame, to eliminate downlink on uplink interference.

Systems and methods for backscatter communications are provided that employ a backscatter reader to transmit a carrier signal to multiple backscatter tags having heterogeneous hardware and specifications. In response to receiving the carrier, the tags encode data into the received signal and, concurrently, transmit their respective backscattered signal to the reader. The concurrent signals are received by the reader as a combined signal. The reader detects edges in the received signal, based on the corresponding in-phase (I) and quadrature (Q) signals. The edges are then assigned to streams based on the offset or transmission rate of the tags. In some cases, the reader can detect edge collisions. These collisions can be resolved by causing the colliding signals to be retransmitted or by separating the colliding signals. The individual streams corresponding to each of the tags can then be decoded to identify the originally transmitted data from each tag.