RF dynamic power control and radio protection in metering devices

Techniques for dynamic power control of a radio of a utility data collection device (e.g., utility meter configured for wireless communications) are described that utilize a detection scheme applied to a Front End Module (FEM) in the utility data collection device. A utility data collection device measures a Voltage Standing Wave Ratio (VSWR) presented to the FEM during transmission. The result of this measurement allows the utility data collection device to dynamically control the input power to a FEM transmit portion. Utilizing these techniques, the utility data collection device can adjust to environmental changes and conditions experienced in the field.

BACKGROUND

Utility service providers employ numerous radio frequency (RF) utility meters, smart meters, sensors, and/or control devices (collectively “utility data collection devices”) as part of advanced metering infrastructures (AMIs) and/or automated meter reading (AMR) environments. These utility data collection devices are generally equipped with front-end modules (FEMs) that facilitate one- or two-way RF wireless communications.

To facilitate wireless communications, a utility data collection device has one or more antennas that interface to the FEM, such that each antenna is “impedance matched” to the FEM to minimize mismatch loss. Regarding transmission from a power amplifier, mismatch loss in transmission line theory is the amount of power generally expressed in decibels (dB) that will not be available on the output (e.g., a transmit antenna) due to impedance mismatches and signal reflections. A FEM that is properly terminated with the same impedance as that of the characteristic impedance of the antenna will have no reflections and therefore no mismatch loss.

In a factory setting, antennas are substantially impedance matched to their corresponding FEMs. However, after utility data collection devices are deployed in the field, numerous external influences can result is impedance mismatches between the FEM and the antenna of a utility data collection device. As an example, a utility data collection device may be located in a “non-friendly” RF enclosure, such as inside an all metal enclosure, covered with metal foil (e.g., intentional or unintentional tampering by a user), or the like. These externally induced impedance mismatches can give rise to reflections of a transmitted signal that may be strong enough to damage a power amplifier of an FEM, or cause a transmitted signal to become non-linear, degrading the signal-to-noise ratio (SNR) of a transmitted signal and increasing the difficulty of a receiver to receive the transmitted signal. Thus, these externally induced impedance mismatches can damage the FEM of a utility data collection device and/or degrade the signal transmitted by the utility data collection device.

DETAILED DESCRIPTION

Overview

A utility meter, smart meter, sensor, and/or control device (collectively “utility data collection device” (UDCD)) that is, for example, part of an advanced metering infrastructure (AMI) and/or an automated meter reading (AMR) environment, generally contains a front-end module (FEM) used to transmit and receive radio frequency (RF) signals via one or more antennas. A transmit portion of the FEM should ideally be linear, such that the gain of the transmit amplifier/antenna combination is essentially constant for any combination of input and output signal. A linear system will respond at that same frequency with a certain magnitude and a certain phase angle of an output signal relative to an applied input signal. If the system is not linear, the output signal will be distorted. When a transmit antenna connected to a transmit interface of a FEM of a utility data collection device is subjected to externally (or internally) induced factors that cause an impedance mismatch between the transmit interface of the FEM and the antenna, the transmitted signal becomes distorted. A portion of the transmitted power is generally reflected back to the transmit amplifier, which can damage or destroy the transmit amplifier, or distort the transmitted signal.

This application describes techniques for dynamic power control of a radio of a utility data collection device by introducing a detection scheme using the FEM. In an embodiment, both the forward travelling wave and the reflected wave are accurately measured by a processing unit of the utility data collection device to determine a Voltage Standing Wave Ratio (VSWR) presented to the FEM during transmission. The result of this measurement allows the utility data collection device to dynamically control the input power to a FEM transmit portion. As an example, the input power to the FEM transmit portion is controlled to compensate for antenna load conditions, such as externally (or internally) induced factors that may have caused an impedance mismatch between an antenna and the FEM.

In an embodiment, a processing unit of a utility data collection device measures the forward traveling wave in the FEM by utilizing a directional coupler in the FEM to couple some of the forward traveling wave to a power detector that provides an output voltage proportional to the transmitter's output power. The reflected wave is also measured in the FEM by utilizing a directional coupler to couple some of the reflected traveling wave to a power detector that provides an output voltage proportional to the reflected power. The output of the two separate detectors is then sampled by an analog-to-digital (A/D) converter, and compared to determine a true VSWR measurement. As a result, the processing unit dynamically adjusts the transmitter output power to simultaneously provide a more linear output along with protecting the transmitter from incurring damage due to a bad load (e.g., impedance mismatch) at the antenna.

This application also describes techniques for calibrating a power level transmitted by the FEM using a switch located inside the FEM. In an embodiment, a processing unit of a utility data collection device will direct a switch (e.g., double-pole-double-throw (DPDT) switch) to switch a transmit signal in the FEM to a calibrated known load so that detectors of the processing unit are accurately calibrated in both manufacturing and in the field as an on-the-fly check. As an example, in manufacturing, the detected outputs are calibrated and a lookup table is used to provide appropriate power settings relative to detected power. As another example, the processing unit can activate the switch to apply a known load to verify specific power settings and adjust the calibration of the detectors in the field as a means to account for various environmental changes to which the utility data collection device may be subjected. In an embodiment, the processing unit of a utility data collection device uses a lookup table that is tailored to characteristics of the FEM transmitter to dynamically control the transmit power level of the FEM transmitter.

This application also describes techniques for protection of a transmitter of the FEM that involve monitoring a current of the FEM transmitter. In an embodiment, a current monitor inside the FEM toggles a voltage output that provides the processing unit of the utility data collection device with a way of detecting if an over-current condition has occurred in the FEM transmitter. The processing unit can then shut the FEM transmitter down and proceed through a series of steps to determine the cause of the over-current condition.

The utility data collection devices described herein may operate in the example context of a wireless utility network (e.g., mesh, star, mobile/handheld, etc.) including a plurality of utility data collection devices, such as utility meters that measure, store and transmit utility consumption data. Utility data collection devices may include, for example, low-power digital radios, smart utility meters (e.g., electric, gas, and/or water meters), sensors (e.g., temperature sensors, weather stations, frequency sensors, etc.), control devices, transformers, relays, switches, valves, and other network devices. As such, these utility data collection devices may be part of low power and lossy networks (LLNs), and operate using protocols (e.g., ZigBee, IEEE 802.15.4 and its variants, or the like) suitable for low-rate wireless personal area networks (WPANs), home area networks (HANs), neighborhood area networks (NANs), or the like. As such, in other implementations, a utility data collection device may include any device coupled to a communication network and capable of sending and/or receiving data. In an embodiment, a utility data collection device is a device (e.g., utility meter) that directly collects or concentrates utility consumption data (e.g., consumption of gas, water, electricity), and is configured to wirelessly transmit that data to one or more receiving entities.

Example implementations and embodiments are described below. In a first section, an “Example Architecture” discusses an example environment of utility data collection devices. A second section, “Example Utility Data Collection Device,” discusses various examples of a utility data collection device. A further section, “Example Methods of Utility Data Collection Device Operation,” discusses example methods of operation of a utility data collection device. Finally, the application concludes with a brief “Conclusion.” This Overview and the following sections, including the section headings, are merely illustrative implementations and embodiments and should not be construed to limit the scope of the claims.

Example Architecture

FIG. 1is a schematic diagram of example architecture100of a utility data collection environment. The architecture100includes a plurality of utility data collection devices (UDCDs)102(1)-102(N) (collectively referred to as utility data collection devices or UDCDs102) communicatively coupled to one or more of collection systems104, utility central office106, or to each other via direct communication paths or “links.” Network108represents one or more wired or wireless networks used to facilitate communications between at least a subset of utility data collection devices, collection system(s)104and the utility central office106. One or more of collection system(s)104may be collocated with utility central office106and one or more of collection system(s)104may be distributed throughout environment100in wired or wireless communication with utility central office106via network108. In one example, utility data collection devices102may be part of a low power and lossy network (LLN). As an example, network108has one or more wireless nodes (not shown) for communicating with wireless devices, such as utility data collection devices102. One or more collection system(s)104and/or the utility central office106may include wireless interfaces for communicating with wireless devices, such as utility data collection devices102.

As an example, utility data collection device102(1) provides collected utility data wirelessly to a collection system104. Collection system104may process collection data received from one or more of utility data collection device102, and provide the processed utility data to the utility central office106for validation, storage, analytics, or other purposes. As illustrated inFIG. 1, utility data collection device102(1) has a wireless “link” to utility data collection device102(2), such that utility data collection device102(1) may receive data collected by utility data collection device102(2), and pass that data upstream to the collection system(s)104and/or the central office106.

Utility data collection device102(3) is shown inFIG. 1as having a wireless link to network108for wirelessly providing collected utility data to collection system(s)104and/or utility central office106. Utility data collection devices102(1)-102(3) represent any number of utility data collection devices that are part of an advanced metering infrastructure (AMI).

Utility data collection device102(N) is shown inFIG. 1as having a wireless link to one of various types of mobile collection system(s)110. Utility data collection device102(N) is configured to wirelessly transmit collected utility data to mobile collection system(s)110. As an example, utility data collection device102(N) represents one of any number of utility data collection devices that are part of an automated metering (AMR) environment. Mobile collection system(s)110may be configured to collect utility data, process the collected utility data, wirelessly communicate collected utility data to networks108, wirelessly communicate collected utility data to utility central office106, or manually provide collected utility data to collection system(s)104and/or utility central office106as one or more data files.

Utility data collection device102(2) is representative of utility data collection devices102and includes a radio112. Radio112includes one or more antennas114, a front-end module116for transmitting and receiving RF signals, a transceiver118to transceive RF signals associated with one or more RF communication technologies (e.g., frequency shift keying (FSK), offset quadrature phase shift keying (OQPSK), orthogonal frequency-division multiplexing (OFDM), code division multiple access (CDMA), etc.) associated with one or more communication protocols (e.g., ZigBee, IEEE 802.15.4 and its variants, etc.), power line communications and at least one processing unit120.

Front-end module116may include one or more transmit amplifiers (e.g., power amplifier, transmit amplifier stages, etc.), receive amplifiers (e.g., low-noise amplifier (LNA)), switches (e.g., double-pole-double-throw (DPDT) switch), couplers (e.g., directional coupler) and control logic. Front-end module116may also include one or more antenna interfaces configured to be impedance matched with antenna(s)114to minimize mismatch loss. As an example, a transmitter interface of front-end module116is configured to have essentially the same characteristic impedance as an interface of transmit antenna114, to minimize, or essentially eliminate, reflection of power transmitted by front-end module116. When a transmit antenna114and a transmitter interface of front-end module116do not have matching impedances, some of the electrical energy cannot be transferred from the transmit amplifier of front-end module116to transmit antenna114. Energy not transferred through antenna114may be reflected back towards the transmit amplifier of front-end module116. It is the interaction of these reflected waves with forward waves which causes standing wave patterns. Reflected power has three main implications in radio transmitters: Radio Frequency (RF) energy losses increase, distortion occurs at the transmitter due to reflected power from the mismatched antenna load and damage to the transmitter can occur.

Processing unit120includes one or more processors122communicatively coupled to memory124. Memory124stores one or more software or firmware modules, which are executable on or by the one or more processors122to implement various functionality. While the modules are described herein as being software or firmware executable on a processor, in other embodiments, any or all of the modules may be implemented in whole or in part by hardware (e.g., as an application specific integrated circuit (ASIC), a gate array, a specialized processing unit, etc.).

In the embodiment ofFIG. 1, memory124includes a FEM monitoring module126to monitor FEM116, an FEM control module128for controlling FEM116, and various other modules130to facilitate the collection, management, processing and distribution of collected utility data, as well as other functions required for operation of a utility data collection device102. In the embodiment ofFIG. 1, utility data collection device102includes one or more analog-to-digital (A/D) converters132to facilitate conversion of analog signals, such as analog signals detected from FEM116, into digital signals for processing by processing unit120. Utility data collection device102may also include one or more digital-to-analog (D/A) converters (not shown) to convert, for example, digital signals from processing unit120into analog signals for FEM116. In the embodiment ofFIG. 1, utility data collection device102also includes detectors134(1-N). As an example, detectors134(1-N) may include power detectors that convert detected power to voltage signals associated with the detected power.

Memory124is an example of computer-readable media and may take the form of volatile memory, such as random access memory (RAM) and/or non-volatile memory, such as read only memory (ROM) or flash RAM. Computer-readable media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules, or other data for execution by one or more processors of a computing device. Examples of computer-readable media include, but are not limited to, phase change memory (PRAM), static random-access memory (SRAM), dynamic random-access memory (DRAM), other types of random-access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information for access by a computing device. As defined herein, computer-readable media does not include communication media, such as modulated data signals and carrier waves.

Example Utility Data Collection Device

FIG. 2is a schematic diagram of example environment200showing an example of a utility data collection device102ofFIG. 1. Numerous other configurations of utility data collection devices are possible, thusFIG. 2illustrates but one example environment of an example utility data collection device102. Furthermore, example environment200focuses on embodiments of transmitter monitoring and control, associated with a transmitter portion of FEM116and a transmit antenna114. However, other embodiments are also possible.

FIG. 2illustrates various exemplary interfaces (e.g., connections, connection points, etc.) between processing unit120and FEM116including current flag202, transmitted power204, reflected power206, transmit power control208, switch control210, and/or other interfaces212. In various embodiments, other interfaces212may provide for communication of analog and/or digital signals between processing unit120and FEM116, and may contain one or more A/D and/or D/A converters (not shown). As an example, other interface(s)212provides for control of components of FEM116by processing unit120, detection of signals (e.g., measurements) from FEM116by processing unit120and/or communications between FEM116and processing unit120.

FIG. 2shows FEM116further including FEM transmitter214for transmitting RF signals from transceiver118. By way of example, FEM transmitter214may include, but is not limited to, transmit amplifier(s)216(e.g., power amplifier, transmit amplifier stages, etc.) for transmitting signals containing data, such as utility consumption data, a forward wave coupler218for obtaining measurements accessible at interface transmitted power204associated with a transmitted power level in FEM214, a reverse wave coupler220for obtaining measurements accessible at interface reflected power206associated with a reflected power level in FEM214, one or more switches222for switching signals being transmitted within FEM transmitter214to different transmission paths, a current monitor224to drive interface current flag202, a load226(e.g., a calibration load) and control logic228to facilitate and control various operations of FEM116. Load226is shown within FEM transmitter214in the example embodiment ofFIG. 2. However, in other embodiments, load226may be external to FEM transmitter214as well as external to FEM116within UDCD102, or may be omitted entirely. In an embodiment, load226is connected to a switch222, such that processing unit120, via switch control210, can instruct switch222to switch a transmit path between interface230and load226. As an example, processing unit120instructs switch222to switch a transmission path to load226for calibration purposes. In an embodiment, processing unit120receives a signal (e.g., wireless signal) to instruct switch222to switch a transmission path to load226. As an example, processing unit120may be configured to report measurements of transmitted and reflected power when the transmission path is connected to antenna114and/or load226to a reporting entity (e.g., utility central office106.) Such measurements may allow a reporting entity to detect a potential impedance mismatch between antenna114and FEM116, or other related issues. In another embodiment, processing unit120may determine to control switch222to compare measurements of transmitted and reflected power when the transmission path is connected to antenna114and load226. Processing unit120may report results of the comparison to a reporting entity, for example, when there are differences between transmitted and reflected power between antenna114and load226above a threshold.

FIG. 2shows FEM116interfacing with antenna(s)114via interface230. Interface230may include any interface between FEM116and antenna(s)114, such as a connector (e.g., coax connector, direct connection), a filter, an impedance matching network, and/or the like. As an example, in manufacturing UDCD102, interface230includes a substantially impedance matched connection between FEM116and antenna(s)114. Interface230may include multiple interfaces for multiple antenna(s)114, one or more unused interfaces, multiple interfaces for a single antenna114or a single interface for a single antenna114.

For purposes of simplicity,FIG. 2shows A/D converter132as a single A/D converter that receives a signal from detector134(1) associated with a measurement level on interface transmitted power204and a signal from detector134(2) associated with a measurement level on interface reflected power206. However, as an example, A/D converter132may include multiple A/D converters, such as, one for each of detectors134(1) and134(2). As another example, detectors134(1) and134(2) may each include an A/D converter132. As another example, processing unit120may control a switch (not shown) that selects when one of detectors134(1) and134(2) are directed to A/D converter132. Other configurations are within the scope of the disclosure. In various embodiments, A/D converter132is configured to receive an analog signal from detector134(1) associated with a measurement level on interface transmitted power204and receive an analog signal from detector134(2) associated with a measurement level on interface reflected power206, convert these analog signals to digital signals, and provide the digital signals to processing unit120for processing by FEM monitoring module126. Based at least in part on the processing performed by FEM monitoring module126, in an embodiment, FEM monitoring module126is configured to work in conjunction with FEM control module128to adjust a power level transmitted by transceiver118to FEM transmitter214via interface transmit power control208. In an alternate embodiment, FEM control module128may direct FEM116to adjust a power level transmitted by FEM transmitter214, such as, via other interface(s)212. Additionally, in an embodiment, FEM control module128may be configured to control one or more of switch(es)222in FEM transmitter214via interface switch control210.

FEM monitoring module126may also be configured to receive a signal from FEM116via interface current flag202, and work in conjunction with FEM control module128to adjust a power level transmitted by transceiver118to FEM transmitter212via interface transmit power control208, adjust a power level transmitted by FEM transmitter214via other interface(s)212and/or control one or more of switch(es)220in FEM transmitter212via switch control202. In an embodiment, FEM116is configured to provide a signal on interface current flag202that indicates an over-current condition in FEM transmitter214, such that processing unit120takes action to shut down transceiver118and/or FEM transmitter214.

As described herein, processing unit120implements a dynamic power control of power transmitted in radio112by using a detection scheme with FEM116. As an example, processing unit120accurately measures both the forward travelling wave and the reflected wave in a transmission path of FEM transmitter214during transmission to determine the Voltage Standing Wave Ratio (VSWR) presented to FEM116.

In an embodiment, forward wave coupler218measures at least a portion of the forward travelling wave (e.g., a signal transmitted by one or more of transmit amplifiers216), and provides the measurement of the forward travelling wave to power detector134(1) via transmitted power204connection. Then, detector134(1) provides an output voltage proportional to the transmitted power to A/D converter132which provides a digital conversion of the output voltage to processing unit120. In an embodiment, forward wave coupler218is a connection in the transmit path of FEM transmitter214, such as a connection between amplifier stages of transmit amplifiers216. As such, a measurement of the forward travelling wave may be substantially isolated from influence by the reflected wave via isolation provided by a downstream amplifier stage in a cascade of transmit amplifier stages. In an alternate embodiment, forward wave coupler218is a directional coupler in the transmit path of FEM transmitter214such that forward wave coupler218couples at least a portion of the forward traveling wave provided to detector134(1) via connection transmitted power204.

Reverse wave coupler220measures at least a portion of a reflected wave (e.g., a reflected portion of the forward traveling wave) in the transmit path of FEM transmitter214(e.g., measured at a last amplifier stage of a cascade of transmit amplifiers216), and provides the measurement of the reflected wave to power detector134(2) via reflected power206connection. Then, detector134(2) provides an output voltage proportional to the reflected power to A/D converter132which provides a digital conversion of the output voltage proportional to the reflected power to processing unit120. In an embodiment, reverse wave coupler220is a directional coupler in the transmit path of FEM transmitter214that couples at least a portion of the reflected wave provided to detector134(2) via connection reflected power206.

In an embodiment, FEM monitoring module126compares the measurements of the transmitted power and the reflected power (e.g., A/D converted voltages from detectors134(1) and134(2), respectively), to determine a true VSWR measurement. Knowing the VSWR measurement allows FEM control module128to dynamically control a transmit power level of FEM transmitter214. In an embodiment, FEM control module128uses lookup table232stored in memory124to dynamically control a transmit power level of FEM transmitter214. As an example, lookup table232associates VSWR measurements and/or measurements of the transmitted power and the reflected power with appropriate transmit power levels of FEM transmitter214. As another example, lookup table232contains predetermined thresholds (e.g., thresholds for VSWR, transmitted power and/or reflected power) indicating whether FEM control module128should increase a transmitted power level, decrease a transmitted power level, or maintain a current transmitted power level. As another example, lookup table232contains a plurality of associations between VSWR measurements, measurements of transmitted power and/or measurements of reflected power associated with various appropriate transmit power levels for FEM transmitter214.

As an example, after UDCD102is deployed to the field, externally (or internally) induced factors may cause an impedance mismatch between FEM116and antenna(s)114. FEM monitoring module126may detect this change in antenna load as an increased VSWR measurement, such that FEM control module128may incrementally lower the transmitted power until FEM monitoring module126determines that the VSWR measurement is within an acceptable range. FEM monitoring module126may use lookup table232to facilitate the determination that the VSWR measurement is within an acceptable range. As another example, FEM monitoring module126may detect the change in antenna load due to the externally (or internally) induced factors as an increased VSWR measurement, such that FEM control module128adjusts the transmitted power to a level as indicated in lookup table232.

Thus, FEM monitoring module126and FEM control module128work in conjunction to dynamically adjust the transmitter output power to simultaneously provide a more linear transmitted signal, along with protecting the transmitter (i.e., FEM transmitter214) from incurring damage due to a bad load (e.g., impedance mismatch) at antenna114. In an embodiment, based on environmental or other changes that require altered power level settings, processing unit120may adjust lookup table232with one or more updated associations and/or values that reflect the altered power level settings.

For example, a VSWR measurement of 1.2:1 denotes a maximum standing wave amplitude that is 1.2 times greater than the minimum standing wave value. A VSWR measurement of 1:1 indicates, for example, that the characteristic impedance of FEM116at interface230matches the characteristic impedance of antenna114, such that substantially no reflected power is measured at detector134(2). High levels of reflected power can distort, damage or destroy components of FEM transmitter214. Some FEM transmitters are designed to withstand relatively large levels of reflected power (e.g., VSWR=8:1) without damage and/or high levels of reflected power within a VSWR stability and load mismatch susceptibility level (e.g., VSWR=4:1). These design constraints increase the cost of FEM transmitters. Thus, the techniques described herein allow for dynamically adjusting the transmitter output power to simultaneously provide a more linear output along with protecting the transmitter from incurring damage due to a bad load (e.g., impedance mismatch) at the antenna, such that the transmitter is not required to endure high levels of reflected power, thereby reducing the cost of the FEM transmitter.

In another embodiment, processing unit120is configured to control switch222in FEM116to switch to known calibration load226to facilitate calibration of radio112in manufacturing, or on the fly after UDCD102has been installed in the field. As an example, processing unit120instructs switch222, via interface switch control210, to switch the transmit path of FEM transmitter214from, for example, interface230, to load226. Since load226is a known calibration load, detectors134(1) and134(2) can be calibrated. In manufacturing, the detected outputs (i.e., outputs of detectors134(1) and134(2)) are calibrated such that lookup table232provides power settings relative to detected output values of detected power. In the field, processing unit120dynamically adjusts power levels up and/or down to verify specific power settings and adjusts the calibration of detectors134(1) and134(2) as a means to account for environmental changes. In an embodiment, load226includes multiple known loads, and processing unit120is configured to select any of the known loads of load226as part of a calibration process. In an embodiment, switch222is a double-pole-double-throw (DPDT) switch.

In yet another embodiment, processing unit120is configured to monitor interface current flag202from FEM116to facilitate an additional protection of FEM transmitter214. As an example, a current monitor inside FEM116will toggle a voltage output on current flag202to notify processing unit120if an over-current condition has occurred. In the event that an over-current condition has occurred, processing unit120can then shut down FEM transmitter214and proceed through a series of steps to determine the cause of the over-current condition. In an embodiment, if an over-voltage condition is indicated on current flag202, FEM control module128is configured to instruct transceiver118to stop transmitting to FEM116by sending transceiver118a shut-down command or signal via transmit power control208. In another embodiment, FEM control module128is configured to send a shut-down command or signal to FEM116via other interfaces212.

Example Methods of Utility Data Collection Device Operation

FIG. 3illustrates an example method300of implementing a detection scheme to a FEM. The method300is described with reference to the example architecture200ofFIG. 2for convenience. However, the method300is not limited to use with the example architecture200ofFIG. 2and may be implemented using other architectures and devices.

At operation302, a UDCD determines a VSWR in a transmission path of a front end module (FEM) in the UDCD. As an example, processing unit120compares a transmitted power level and a reflected power level provided by detectors134(1) and134(2), respectively, to determine the VSWR. Detector134(1) is a transmitted power detector that is interfaced to forward wave coupler218in FEM116and detector134(2) is a reflected power detector that is interfaced to reverse wave coupler220in FEM116. At operation304, processing unit120dynamically controls an input power to the transmission path of the FEM based at least in part on the measured VSWR. As an example, processing unit120controls the power output level of transceiver118over interface transmit power control208to adjust the input power level presented to FEM transmitter214.

In operation, processing unit120may detect a current flag signal via interface current flag202indicating an over-current condition. Processing unit120may then direct transceiver118to stop transmitting in the transmission path, and then take steps to determine a cause of the over-current condition.

In manufacturing or in the field, processing unit120may direct switch222to switch the transmission path to known calibrated load226, determine a VSWR in the transmission path associated with the known calibrated load and calibrate detectors134(1) and134(2) based at least in part on the determined VSWR in the transmission path associated with the known calibrated load. Processing unit120may use lookup table232for dynamically controlling the input power to the transmission path of FEM transmitter214based at least in part on the measured VSWR.

FIG. 4illustrates an example method400of implementing a detection scheme to a FEM. The method400is described with reference to the example architecture200ofFIG. 2for convenience. However, the method400is not limited to use with the example architecture200ofFIG. 2and may be implemented using other architectures and devices.

At operation402, processing unit120detects a measurement indicating a transmitted power level in a transmission path of FEM transmitter214from detector134(1) via A/D converter132. At operation404, processing unit120detects a measurement indicating a reflected power level in the transmission path of FEM transmitter214from detector134(2) via A/D converter132. At operation406, processing unit120determines a relationship between the measurement indicating a transmitted power level and the measurement indicating a reflected power level. At operation408, processing unit120dynamically controls an input power level to the transmission path based at least in part on the determined relationship.

CONCLUSION