US-12628084-B2 - Adaptive, power-efficient transmitter control for battery-powered wireless sensors

Abstract

The disclosure provides an apparatus and method that conserves battery power in a battery-operated wireless sensor. A first sample and at least a subsequent second sample is obtained of an analog signal whose magnitude varies over time in accordance with variations over time in a process parameter. The magnitude of the first sample is mapped to a first digital value, and the magnitude of the subsequent second sample is mapped to a second digital value in accordance with an ADC quantization scheme. The first digital value to mapped to a first level, and the second digital value is mapped to a second level in accordance with a digital quantization scheme. The second digital value is transmitted only when the second level differs from the first level.

Inventors

• Obieda M.A.K. Ghazal

Assignees

• Oryx Holdings

Dates

Publication Date

20260512

Application Date

20240123

Claims (19)

1. 1 . An apparatus comprising: a sensor configured to provide an analog signal having a magnitude that varies in accordance with variations in a sensed process parameter; an analog to digital converter (ADC) configured to map a first sample of the analog signal to a first digital value, and a second sample of the analog signal to a second digital value according to an ADC quantization scheme; a digital quantizer configured to map the first digital value to a first level and the second digital value to a second level according to a digital quantization scheme; and a radio frequency (RF) transmitter configured to activate to transmit the second digital value in response to receiving a signal indicating the second level differs from the first level.
2. 2 . The apparatus of claim 1 wherein the sensor comprises a load cell and the magnitude of the analog signal varies in accordance with variations in a force exerted on the load cell by a fluid-bearing container.
3. 3 . The apparatus of claim 2 further comprising a unit converter configured to convert the first digital value to a first weight of the fluid-bearing container and the second digital value to a second weight of the fluid-bearing container, wherein the RF transmitter is activated to transmit the second weight in response to receiving a signal indicating the second level differs from the first level.
4. 4 . The apparatus of claim 3 wherein the digital quantization scheme configures the apparatus to adapt an activation rate of the RF transmitter in accordance with changes in relative magnitudes of the analog signal from sample to sample.
5. 5 . The apparatus of claim 4 wherein the digital quantization scheme configures the apparatus to control the RF transmitter to have a relatively low activation rate when the magnitude of the analog signal varies little from sample to sample, and a relatively high activation rate when the magnitude of the analog signal varies greatly from sample to sample thereby operating the transmitter in a power-efficient manner without limiting transmission range of the transmitter.
6. 6 . The apparatus of claim 5 wherein the transmitter has an activation rate that varies in accordance with variations in a rate of consumption of fluid in the fluid-bearing container.
7. 7 . The apparatus of claim 6 wherein the transmitter has an activation rate determined at least in part by a magnitude of a difference between the second weight and the first weight.
8. 8 . The apparatus of claim 7 wherein the sensor, the ADC, the digital quantizer and the transmitter are configured to receive operating power from a battery.
9. 9 . The apparatus of claim 8 including a battery sensor coupled to the battery and configured to provide a battery parameter value to the transmitter, wherein the transmitter is configured to transmit the second digital value and the battery parameter value in response to detecting the second level different from the first level.
10. 10 . The apparatus of claim 9 wherein the transmitter is configured to transmit the second digital value and the battery parameter value in response to detecting the battery parameter value below a threshold value.
11. 11 . The apparatus of claim 10 wherein the sensor, the ADC, the digital quantizer and the transmitter comprise a processor and the apparatus further comprises a memory storing processor-executable instructions that configure the processor to: compare the battery parameter value to a threshold value; and detect one of: the battery parameter value at or above the threshold value, and the battery parameter value below the threshold value.
12. 12 . The apparatus of claim 11 wherein the processor is further configured to: in response to the battery parameter value at or above the threshold value, activate the transmitter to transmit the battery parameter value in response to detecting the second level differs from the first level; and in response to the battery parameter value below the threshold value, transmit the battery parameter value.
13. 13 . The apparatus of claim 12 further comprising a detector circuit including: a first register configured to store the first level; a second register configured to store the second level; and a comparator configured to compare the first register to the second register and provide a comparator output indicating one of: the second level differs from the first level, and the second level equal to the first level.
14. 14 . The apparatus of claim 13 wherein the RF transmitter changes from an active state to an inactive state in response to the detector circuit detecting the second level equal to the first level.
15. 15 . The apparatus of claim 14 wherein the digital quantization scheme is defined by a number of levels, and the activation rate of the transmitter is determined at least in part by the number of levels and at least in part by the rate of consumption.
16. 16 . A method comprising: obtaining a first sample and at least a second sample of an analog signal whose magnitude varies over time in accordance with variations over time in a process parameter; mapping the magnitude of the first sample to a first digital value, and the magnitude of the second sample to a second digital value in accordance with an ADC quantization scheme; mapping the first digital value to a first level, and the second digital value to a second level in accordance with a digital quantization scheme; and activating a transmitter to transmit the second digital value in response to detecting the second level different from the first level.
17. 17 . The method of claim 16 further comprising: storing the first level in a first register; storing the second level in a second register; comparing the first register to the second register to detect one of: the second level not equal to the first level, and the second level equal to the first level; in response to detecting the second level not equal to the first level, enabling the transmitter to transmit the second digital value; and in response to detecting the second level equal to the first level, maintaining the transmitter in an idle state.
18. 18 . The method of claim 17 further comprising: mapping the magnitude of the first sample to the first digital value and the magnitude of the second sample to the second digital value in accordance with an ADC quantization scheme; and mapping the first digital value to the first level and the second digital value to the second level in accordance with a digital quantization scheme.
19. 19 . A method of operating a transmitter of a battery-powered wireless sensor apparatus comprising: placing the transmitter in an idle state; sampling an analog signal provided by a sensor to provide at least first and second respective measurements of a magnitude of the analog signal; mapping the first and second respective measurements to corresponding, respective first and second digital values; mapping the respective first and second digital values to corresponding respective first and second quantization levels; in response to detecting the second quantization level different from the first quantization level: activating the transmitter; transmitting the second digital value; returning the transmitter to the idle state; and in response to detecting the second quantization level the same as the first quantization level, maintaining the transmitter in the idle state.

Description

TECHNICAL FIELD The disclosure relates in general to wireless sensors, and more particularly to battery-powered wireless sensors employing radio frequency (RF) transmitters to communicate sensor data. BACKGROUND Wireless sensors include radio frequency (RF) transmitters to communicate sensor data via an air medium. RF transmitters include power amplifiers to boost the RF signal conveying the sensor data to a power level sufficient for effective transmission through the air medium. Power amplifiers consume considerable power in their active states. Wireless sensors may be battery powered. Battery-powered wireless sensors are portable, simple to install and cost effective. They can be deployed in remote or mobile environments that lack constant access to an external power source. However, meeting the power demands of RF transmitters with the limited energy storage capacity of batteries without sacrificing operational capability of the sensor poses a significant technical challenge. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments are illustrated by way of example and not limitation in the features of the accompanying drawings in which like numerals indicate like elements. FIG. 1 is a block diagram of an example adaptive, energy-efficient wireless sensor apparatus; FIG. 2 is a flowchart of an example adaptive, energy-efficient method for controlling a transmitter of a wireless sensor apparatus; FIG. 3 is a schematic diagram of an example sensor component of the adaptive, energy-efficient wireless sensor apparatus shown in FIG. 1; FIG. 4 is a schematic diagram of the sensor component shown in FIG. 3 including a load cell implementing the sensor element; FIG. 5 is a block diagram of an example implementation of an adaptive, energy-efficient battery-operated wireless sensor including a battery sensor; FIG. 6 is a flowchart of an example adaptive, energy-efficient method for conserving battery life in a battery-operated wireless sensor; FIG. 7 is a schematic diagram of an example implementation of the sensor component of the adaptive, energy-efficient wireless sensor shown in FIG. 2; FIG. 8 is a block diagram of an example implementation of an adaptive, energy-efficient wireless sensor apparatus; and FIG. 9 is a flowchart of an example adaptive, energy-efficient method for controlling a transmitter in a wireless sensor apparatus. DETAILED DESCRIPTION OF THE DRAWINGS FIG. 1 FIG. 1 is a block diagram of an example wireless sensor apparatus 100. Apparatus 100 is shown to comprise a sensor 140, an analog to digital converter (ADC) 150, a digital quantizer 160, a detector circuit 172 and a radio frequency (RF) transmitter 190 including an antenna 199. In the example implementation of FIG. 1, ADC 150, digital quantizer 160 and detector circuit 172 are integrated, i.e., implemented using one or more integrated circuits (IC) comprising a processor 400. Sensor 140, processor 400 and RF transmitter 190 are configured to cooperate to transmit sample data provided by sensor data 140 through antenna 199 and into an air medium to a compatible RF receiver (not shown). In a processor implementation, the components and circuits shown in FIG. 1 may be implemented by lower-level structural components and circuits comprising processor 400. Examples of lower-level components include counters, registers, memory cells and other storage elements, as well as logic gates, logic circuits, clocks and other digital circuitry. In those implementations, memory 450 stores processor-executable instructions by which processor 400 manipulates the lower-level components to perform the functions described herein in terms of the higher-level components shown in the block diagrams. As shown in FIG. 1, sensor 140, processor 400 and RF transmitter 190 can be supplied with operating power by a power source 555. In battery-powered implementations of apparatus 100, power source 555 may comprise one or more batteries. In mains-powered implementations, power source 555 may be component such as an AC/DC converter supplying DC power derived from a mains power source. In one example implementation, processor 400 comprises a system on a chip (SoC). In that implementation, RF transmitter 190 is provided on the SoC in a cooperative arrangement with a micro control unit (MCU) also provided on the SoC. An example of a suitable, commercially available SoC is the ESP32 Series SoC made by Espressif Systems of Shanghai, China and available from amazon, eBay, AliExpress and other online retailers as well as from many local electronics stores. In general, Sensor 140 is configured to sense a parameter P of a process 20 and to provide an analog signal 141 whose magnitude varies over time in accordance with variations in parameter P over time. Examples of analog sensors within the scope of the disclosure include, but are not limited to temperature sensors, load sensors, force sensors, charge sensors and the like. Sensor 140 provides analog signal 141 to ADC 150. ADC 150 is confi