Fast frequency switching for RFID applications
AssigneeImpinj, Inc.
InventorsMichael H. Thomas, Omer Onen, Joe Tarantino, Christopher J. Diorio
Life of this patent
Estimating the term…
Abstract
RFID readers may be configured to supply power to tags during frequency hops. When a reader is supplying power to a passive RFID tag via a first RF waveform having a first radio frequency and determines that it is to frequency-hop, the reader may determine whether the tag requires power during the hop. If so, the reader begins (or continues) to synthesize a second RF waveform with a second radio frequency while also synthesizing the first RF waveform, and frequency-hops by transitioning from transmitting the first RF waveform to transmitting the second RF waveform such that the power transmitted during the transition is sufficient for the tag to operate.
Claims20
A method for a radio frequency identification (RFID) reader that transmits commands to an RFID tag using amplitude modulation (AM) of a radio frequency (RF) waveform to avoid powering-down the RFID tag when changing a frequency of the RF waveform, the method comprising:
- transmitting an RF waveform at a first frequency with a command modulated onto a portion of the RF waveform;
- modulating the RF waveform with a low-amplitude AM pulse;
- switching the frequency of the RF waveform to a second frequency different from the first frequency during the low-amplitude pulse;
- and
- at the end of the low-amplitude pulse, transmitting the RF waveform at the second frequency, wherein an average power of the portion of the RF waveform is sufficient for the tag to receive the command.
A radio frequency identification (RFID) reader that transmits commands to an RFID tag using amplitude modulation (AM) of a radio frequency (RF) waveform and is configured to avoid powering-down the RFID tag when changing a frequency of the RF waveform, the reader comprising:
- a transceiver configured to transmit RF waveforms;
- and
- a processor coupled to the transceiver and configured to:
- amplitude-modulate a portion of the RF waveform with a command, wherein the modulation includes a low-amplitude pulse;
- cause the transceiver to transmit the modulated RF waveform at a first frequency;
- during the low-amplitude pulse, cause the frequency of the RF waveform to be switched from the first frequency to a second frequency different from the first frequency;
- and
- at the end of the pulse, cause the transceiver to transmit the RF waveform at the second frequency, wherein an average power of the portion of the RF waveform is sufficient for the tag to receive the command.
A radio frequency identification (RFID) reader that transmits commands to an RFID tag using amplitude modulation (AM) of a radio frequency (RF) waveform and is configured to avoid powering-down the RFID tag when changing a frequency of the RF waveform, the reader comprising:
- a transceiver configured to transmit RF waveforms;
- and
- a processor coupled to the transceiver and configured to:
- cause the transceiver to transmit the RF waveform at a first frequency, wherein a portion of the RF waveform is amplitude-modulated with a command;
- identify a modulated portion of the RF waveform whose amplitude and duration are suitable for frequency switching;
- during the identified modulated portion, cause the frequency of the RF waveform to be switched to a second frequency different from the first frequency;
- and
- cause the transceiver to transmit the RF waveform at the second frequency, wherein an average power of the portion of the RF waveform is sufficient for the tag to receive the command.
Dependencies are inferred from the claim text.