Method and device for phase calibration with active load modulation
A method for operating an RFID device is disclosed. In the embodiment, the method involves establishing a radio-frequency link, receiving signal samples of the radio-frequency link, determining the offset of an initial phase of the link by filtering noise from the signal samples, windowing the filtered signal samples, and calculating an offset value from phase differences between the windows of signal samples, and modifying a configuration profile based on the offset value. During data transmission the configuration profile can be used to configure the transmitter in order to maintain the constant phase during transmission.
1. A method for operating a radio-frequency identification (RFID) device, the method comprising:
establishing a radio-frequency link;
receiving signal samples of the radio-frequency link;
determining an offset of an initial phase of the radio-frequency link by:
filtering noise from the signal samples;
windowing the filtered signal samples; and
calculating an offset value from phase differences between a plurality of windows of the signal samples; and
modifying a configuration profile based on the offset value.
2. The method of claim 1 , wherein the method further comprises configuring an analog transponder to convert a message to an analog signal according to the configuration profile by trimming a clock offset.
3. The method of claim 1 , wherein signal samples are received by generating clock signals from the radio-frequency link.
4. The method of claim 1 , wherein the steps of receiving the signal samples, determining the offset, and modifying the configuration profile are repeated before each transmission by the RFID device.
5. The method of claim 1 , wherein the RFID device is calibrated without resonance tuning.
6. The method of claim 1 , wherein the RFID device is configured with a fixed resonance.
7. A method for operating an RFID device, the method comprising:
establishing a radio-frequency link with an RFID device;
receiving a configuration profile at the RFID device; and
trimming a clock offset of the RFID device with a dynamic transmission configuration circuit based on the configuration profile.
8. The method of claim 7 , wherein the method further comprises:
receiving signal samples of the radio-frequency link;
transmitting the signal samples to an external calibration device;
generating the configuration profile with the external calibration device by:
filtering noise from the signal samples;
windowing the signal samples; and
calculating an offset value from the phase difference between the signal samples; and
transmitting the configuration profile to the RFID device.
9. The method of claim 7 , wherein the method further comprises configuring an analog transponder to convert a message to an analog signal according to the configuration profile by trimming a clock offset.
10. The method of claim 7 , wherein the configuration profile is generated based on signal samples received by another RFID device having similar components.
11. The method of claim 7 , wherein the configuration profile is generated without resonance turning.
12. The method of claim 8 , wherein the steps of receiving the signal samples, transmitting the signal samples, generating the configuration profile, and transmitting the configuration profile are repeated before each transmission by the RFID device.