METHOD AND APPARATUS FOR SENSING AN ENVIRONMENTAL CONDITION DURING FREQUENCY HOPPING

• US 20170331460A1
• Filed: 07/31/2017
• Published: 11/16/2017
• Est. Priority Date: 11/18/2006
• Status: Active Grant

• Current Assignee: Rfmicron, Inc.
• Original Assignee: Rfmicron, Inc.
• Inventors: Rokhsaz, Shahriar, Pitner, Greg
• Granted Patent: US 10,224,903 B2
• Time in Patent Office: Days
• CPC Class Codes: G06K 19/0717 the sensor being capable of sensing environmental conditions such as temperature history or pressure
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 7/10148 the step consisting of dynamically tuning the resonant circuit of the interrogation device that is emitting the interrogation signal, e.g. for impedance matching inside of the interrogation device for tuning related to loop aerials in general H01Q7/00
• CPC Class Codes: G06K 7/10336 the antenna being of the near field type, inductive coil
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• CPC Class Codes: H01Q 1/36 Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewithH01Q1/08, H01Q1/14 take precedence
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 13/106 Microstrip slot antennas patch antenna elements H01Q9/0407
• CPC Class Codes: H01Q 7/005 with variable reactance for tuning the antenna
• CPC Class Codes: H01Q 9/0407 Substantially flat resonant element parallel to ground plane, e.g. patch antenna dipole H01Q9/285; monopole H01Q9/40
• CPC Class Codes: H01Q 9/285 Planar dipole H01Q9/065 takes precedence; patch antenna H01Q9/0407
• CPC Class Codes: H03H 7/40 Automatic matching of load impedance to source impedance
• CPC Class Codes: H03J 2200/10 Tuning of a resonator by means of digitally controlled capacitor bank
• CPC Class Codes: H03J 3/20 of single resonant circuit by varying inductance only or capacitance only
• CPC Class Codes: H03J 3/22 of single resonant circuit by varying inductance and capacitance simultaneously
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04B 5/77 for interrogation
• CPC Class Codes: H04W 4/38 for collecting sensor information
• CPC Class Codes: H04W 4/70 Services for machine-to-machine communication [M2M] or machine type communication [MTC]
• CPC Class Codes: H04W 4/80 Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication

Abstract

A method includes receiving a series of radio frequency (RF) signals, where, from RF signal to RF signal of the series of RF signals, a carrier frequency is changed in accordance with a frequency hopping pattern. The method further includes, while receiving the series of RF signals, sensing an environmental condition by, for a frequency hop of at least some frequency hops of the frequency hopping pattern, adjusting a characteristic of a wireless sensor to maintain proximal alignment of a resonant frequency of the wireless sensor with the carrier frequency corresponding to a present frequency of the at least some frequency hops and generating a value to represent the adjustment of the characteristic, where a set of values is generated for the at least some frequency hops and where the set of values is used to determine a sensed value of the environmental condition.

Claims

1. A method for execution by a wireless sensor, the method comprises:

receiving a series of radio frequency (RF) signals, wherein, from RF signal to RF signal of the series of RF signals, a carrier frequency is changed in accordance with a frequency hopping pattern; and

while receiving the series of RF signals, sensing an environmental condition by;

for a frequency hop of at least some frequency hops of the frequency hopping pattern;

adjusting a characteristic of the wireless sensor to maintain proximal alignment of a resonant frequency of the wireless sensor with the carrier frequency corresponding to a present frequency of the at least some frequency hops; and

generating a value to represent the adjustment of the characteristic, wherein a set of values is generated for the at least some frequency hops, wherein the set of values is used to determine a sensed value of the environmental condition.

2. The method of claim 1, wherein the frequency hopping pattern comprises:

a periodic, a non-sequential, and random pattern to switch from one carrier frequency of a plurality of carrier frequencies to another carrier frequency of the plurality of carrier frequencies.

3. The method of claim 1, wherein the adjusting the characteristic comprises:

adjusting capacitance of a tank circuit coupled to an antenna that receives the series of RF signals, wherein the wireless sensor includes the tank circuit and the antenna.

4. The method of claim 1, wherein the adjusting the characteristic comprises one of:

adjusting impedance of an antenna of the wireless sensor to affect the resonant frequency;

adjusting capacitance of a capacitor of the wireless sensor to affect the resonant frequency, wherein the capacitor includes one or more of a varactor and a selectable capacitor bank; and

adjusting inductance of an inductor of the wireless sensor to affect the resonant frequency.

5. The method of claim 1 further comprises at least one of:

sending, by the wireless sensor, the set of values for the at least some frequency hops to a sensor computing device, wherein the sensor computing device normalizes the set of values to produce a normalized value that represents the sensed value of the environmental condition; and

normalizing, by the wireless sensor, the set of values to produce the normalized value and sending, by the wireless sensor, the normalized value to the sensor computing device.

6. The method of claim 5, wherein the normalizing the set of values comprises:

identifying a subset of the values of the set of values corresponding to a subset of carrier frequencies of a plurality of frequencies of the series of RF signals; and

normalizing the subset of values based on frequency differences between the subset of carrier frequencies and differences between values of the subset of values.

7. A wireless sensor comprises:

a radio frequency (RF) receiving circuit operable to receive a series of radio frequency (RF) signals, wherein, from RF signal to RF signal of the series of RF signals, a carrier frequency is changed in accordance with a frequency hopping pattern; and

a processing module operably coupled to the RF receiving circuit, wherein the processing module is operable to sense an environmental condition by;

for a frequency hop of at least some frequency hops of the frequency hopping pattern;

adjusting a characteristic of the wireless sensor to maintain proximal alignment of a resonant frequency of the wireless sensor with the carrier frequency corresponding to a present frequency of the at least some frequency hops; and

generating a value to represent the adjustment of the characteristic, wherein a set of values is generated for the at least some frequency hops, wherein the set of values is used to determine a sensed value of the environmental condition.

8. The wireless sensor of claim 7, wherein the frequency hopping pattern comprises:

a periodic, a non-sequential, and random pattern to switch from one carrier frequency of a plurality of carrier frequencies to another carrier frequency of the plurality of carrier frequencies.

9. The wireless sensor of claim 7, wherein the processing module is operable to adjust the characteristic by:

adjusting capacitance of a tank circuit coupled to an antenna that receives the series of RF signals, wherein the wireless sensor includes the tank circuit and the antenna.

10. The wireless sensor of claim 7, wherein the processing module is operable to adjust the characteristic by one of:

adjusting impedance of an antenna of the wireless sensor to affect the resonant frequency;

adjusting capacitance of a capacitor of the wireless sensor to affect the resonant frequency, wherein the capacitor includes one or more of a varactor and a selectable capacitor bank; and

adjusting inductance of an inductor of the wireless sensor to affect the resonant frequency.

11. The wireless sensor of claim 7 further comprises at least one of:

an RF transmitting circuit operable to transmit the set of values to a sensor computing device, wherein the sensing computing device is operable to normalize the set of values to produce a normalized value that represents a sensed value of the environmental condition; and

the processing module operable to normalize the set of values to produce the normalized value and the RF transmitting circuit operable to send the normalized value to the sensor computing device.

12. The wireless sensor of claim 11, wherein the set of values is normalized by:

identifying a subset of the values of the set of values corresponding to a subset of carrier frequencies of a plurality of frequencies of the series of RF signals; and

normalizing the subset of values based on frequency differences between the subset of carrier frequencies and differences between values of the subset of values.