Patent ID: 12210115

DETAILED DESCRIPTION

FIG.1is a conceptual diagram illustrating an example device that includes transmit elements that are orthogonal to the elements of the receive array. Device100, in the example ofFIG.1, includes transmit array104, receive array110and an isolation area106. In some examples device100may be configured to transmit and receive frequency modulated continuous wave (FMCW) radar signals, but the techniques of this disclosure may apply to other types of transmitted and received signals such as communication signals, wireless power transfer, and similar signals.

In the example ofFIG.1, transmit antenna104includes a plurality of transmit antenna elements102aligned in an array of a single column aligned along a first axis122of device100. In other examples, not shown inFIG.1, transmit antenna104may include two or more columns, also aligned along axis, or plane122. Each transmit element102of the plurality of transmit elements of may be polarized in a selected direction. For example, each of transmit elements102may be polarized to align with axis122or each of transmit elements102may be polarized to align with axis120. In other examples each of transmit elements102may be polarized to align with some other angle, e.g., relative to axis122, such as at forty-five degrees, twenty degrees or some other angle (not shown inFIG.1).

In some examples, transmit antenna104may be configured to output a high-aspect ratio transmit beam that covers an area of interest (AOI), also referred to as a field of regard. The high-aspect ratio transmit beam may have a long axis aligned with axis120and a short axis aligned with axis122. In some examples the transmit beam may be a fixed transmit beam. In other examples, transmit electronics of device100may include circuitry (not shown inFIG.1) to scan the transmit beam, e.g., along the short axis.

Receive array antenna110, in the example ofFIG.1, is separate from transmit antenna104, and includes an array of receive elements112. In some examples, receive elements112may be subdivided into quadrants or other arrangements. In the example of a radar device, receive array antenna110may be configured to receive reflected signals, e.g., FMCW radar signals reflected from a target. The reflected FMCW radar signals in the example of device100may have been transmitted by transmit antenna104.

Each element of the plurality of receive elements112may be polarized in a second direction orthogonal to the direction of transmit elements102of transmit antenna104. In the example in which transmit elements102are polarized to align with axis122, then receive elements112are polarized to align with axis120and vice versa. Similarly, for transmit antenna elements102polarized at some angle to, e.g., 45° axis120, then receive elements112are polarized orthogonal to that angle, e.g., 135° to axis120.

To ensure that transmit antenna104and receive array antenna110operate with co-polarized signals, device100also includes a vertical to horizontal polarizer (or vice versa) located between the device100and the target (not shown inFIG.1). The polarizer may be a low insertion loss device (e.g., less than 0.5 dB or even 0.25 dB) configured to receive radar signals and output the received radar signals converted to an orthogonal polarization direction. The output orthogonal polarization direction is the same as either one of the polarization direction of the transmit elements102or the direction of the receive elements112. The polarizer may be located either between the transmit antenna104and the target or between the target and the receive array antenna110. In this manner, the transmit elements102and receive elements112are co-polarized with respect to the target, but the surface waves between transmit antenna104and receive array antenna110are cross polarized.

The cross-polarized antenna elements between transmit antenna104and receive antenna110may surface waves to be attenuated, for example by approximately 20-25 dB in some examples. Isolation area106, which in some examples may be implemented as an electronic band gap (EBG) isolation area, is configured to isolate and prevent interference between the higher power transmit signals from transmit antenna104and the lower power reflected signals received at receive array antenna110. The techniques of this disclosure, that include cross polarization at the surface, e.g., in the plane defined by axis120and122, with a polarizer to co-polarize the signals with respect to the target, may provide several advantages when compared to other similar antenna devices. For example, the size108of isolation area106may be reduced, yet maintain isolation to prevent interference between transmitted and received signals, which may reduce the overall size of the antenna. In some examples, a smaller antenna may allow device100to be used on a smaller vehicles, such as unmanned aerial vehicles (UAV). Other advantages may include that the improved isolation may be applied to increase the array size or transmit power of transmit array104without increasing the overall size of the radar and thereby achieve additional range from the radar.

FIG.2is a conceptual diagram illustrating an example antenna with horizontally polarized transmit elements and vertically polarized receive elements. In this disclosure, “horizontal” and “vertical” will be used with respect to the figure orientation, e.g., horizontal may be aligned with axis120and vertical may be aligned with axis122depicted above inFIG.1. However, “horizontal” and “vertical” may depend on the orientation of the antenna with respect to the horizon as well on the mounting and application for the device.FIG.2depicts transmit antenna204, isolation area206, e.g., EBG206and receive array antenna210.

In the example ofFIG.2, transmit elements102are patch elements. Transmit elements202may connect to the transmit electronics in the horizontal direction. In other words, connection230, e.g., microstrip230, may connect to transmit elements202from the transmit electronics along the right edge of each transmit element202, as shown in the figure. The patch elements, e.g.,202and212in the example ofFIG.2. are shown as square elements. However, in other examples, the transmit or receive elements of this disclosure may be any shape, such as round, oval, octagonal or other shapes.

Receive elements212, in the example ofFIG.2, connect to the receive electronics in pairs. In other examples, each individual receive element212may connect to the receive electronics (not shown inFIG.2). Connection232, which may also be a microstrip, may connect from each of receive elements212to the receive electronics (not shown inFIG.2) along the top edge of each receive element212, as shown in the figure. In other examples, for the same connection orientation of connections230and transmit elements202, each of receive elements212may connect to connection232from the bottom edge of each receive element212.

FIG.3is a conceptual diagram illustrating an example antenna with vertically polarized transmit elements and horizontally polarized receive elements.FIG.3depicts transmit antenna304, isolation area306and receive array antenna310.

In the example ofFIG.3, transmit elements302are patch elements. Transmit elements302may connect to the transmit electronics in the vertical direction. In other words, connection330, which may be a microstrip in some examples, may connect to transmit elements302from the transmit electronics along the top edge of each transmit element302, as shown in the figure. In other examples of vertical polarization, connection330may also connect to the bottom edge of elements302, as shown inFIG.3.

Receive elements312, in the example ofFIG.3, connect to the receive electronics in pairs. As described above in relation toFIG.2, in other examples, each individual receive element312may connect to the receive electronics (not shown inFIG.3). Connection332, which may also be a microstrip, may connect from each of receive elements312to the receive electronics (not shown inFIG.3) along the right edge of each receive element312, as shown in the figure. In other examples, for the same connection orientation of connections330and transmit elements302, each of receive elements312may connect to connection332from the left edge of each receive element312.

FIGS.4A and4Bare conceptual diagrams illustrating an example antenna with transmit elements and horizontally receive elements polarized at an angle. In the example ofFIG.4A, receive elements412may be polarized at angle422relative to an axis420that approximately bisects transmit array404and receive array410. Transmit elements402are polarized orthogonal to angle422. The connections432to the receive electronics from receive elements412may coincide with angle422. As described above in relation toFIG.1, angle422may be any angle, such as 60°, 45°, 30° or some other angle. The connections430to the transmit electronics may be perpendicular to connections432to receive elements412.

Similarly, in the example ofFIG.4B, transmit elements402may be polarized at angle422relative to an axis420that approximately bisects transmit array404and receive array410. Receive elements412are polarized orthogonal to angle422in the example ofFIG.4B. The connections452to the receive electronics from receive elements412may be perpendicular to angle422. The connections450to the transmit electronics may align with angle422.

FIG.5Ais a conceptual diagram illustrating an example cross-polarized antenna with an orthogonal polarizer located at the receive array and including an air gap. As described above in relation toFIGS.1-4B, the cross-polarized antenna may include transmit antenna504, band gap506, receive array antenna508and polarizer510A. Transmit antenna504, band gap506, receive array antenna508are examples of the transmit antennae, received array antennae and isolation area106described above in relation toFIG.1, as well as inFIGS.2-4Bin which the surface waves between transmit and receive antennas, which may cause interference, are cross polarized.

Transmit antenna504, band gap506, receive array antenna508may be part of an electromagnetic energy transmission and receive device520that includes additional printed circuit boards (PCB) and/or PCB layers518with other electronics, including power supply circuitry, signal processing circuitry and so on. In some examples, the other circuitry may be on PCBs separate from the PCB including transmit antenna504, band gap506, receive array antenna508. In other examples, transmit antenna504, band gap506, receive array antenna508may be one or more layers of a multi-layer circuitry board that includes the transmit electronics, receive electronics and other signal processing circuitry. In some examples, the electromagnetic energy transmission and receive device may be an FMCW radar device.

In the example ofFIG.5A, polarizer510A may be located between receive array antenna508and target512and has an air gap502. In some examples polarizer510A may be a separate PCB from receive array508, and may still be mechanically and/or electrically connected to device520.

In operation, transmit antenna504may output radar signals, e.g., in the high aspect ratio transmit beam514A described above in relation toFIG.1, which may reflect off target512. The reflected radar signals516A from target512may arrive at polarizer510A and be polarized in the same direction as transmitted from transmit antenna504. Polarizer510A may be configured to receive reflected radar signals516A from target512and output the received radar signals to receive array antenna508converted to an orthogonal polarization direction from the radar signals516A received from target512. In this manner, receive array antenna508may receive reflected radar signals516A in the same polarization as the receive elements for receive array antenna508.

FIG.5Bis a conceptual diagram illustrating an example cross-polarized antenna with an orthogonal polarizer located at the transmit array and including an air gap. As described above in relation toFIGS.1-5A, the cross-polarized antenna may include transmit antenna504, band gap506, receive array antenna508and polarizer510B. Transmit antenna504, band gap506, receive array antenna508and PCB layers518have the same functions and characteristics as described above in relation toFIG.5A.

In the example ofFIG.5B, polarizer510B may be located between transmit antenna504and target512and has an air gap503. In some examples polarizer510B may be a separate PCB from transmit antenna504, and may still be mechanically and/or electrically connected to device520.

In operation, transmit antenna504may output radar signals. Polarizer510B may be configured to receive the radar signals from antenna504and output transmit beam (Tx beam)514B, but converted to an orthogonal polarization to the transmission antenna elements of transmit antenna504.

Receive array antenna508may receive reflected radar signals516A from target512, which are polarized in the same direction as the receive elements. In this manner, receive array antenna508may receive reflected radar signals516B in the same polarization as the receive elements for receive array antenna508.

FIG.5Cis a conceptual diagram illustrating an example cross-polarized antenna with an orthogonal polarizer located at the receive array.FIG.5Dis a conceptual diagram illustrating an example cross-polarized antenna with an orthogonal polarizer located at the transmit array.FIGS.5C and5Dare, respectively, examples ofFIGS.5A and5B, but do not include an air gap between the polarizer and the antenna. In some examples polarizer510C and510D may be implemented as a circuit board layer located between the respective antenna and target512.

FIGS.5C and5Dmay have the same or similar functions and characteristics, respectively, as described above in relation toFIGS.5A and5B. In the example ofFIG.5C, transmit antenna504may output radar signals514C which may reflect off target512. The reflected radar signals516C from target512may arrive at polarizer510C and be polarized in the same direction as transmitted from transmit antenna504. Polarizer510C may be configured to receive reflected radar signals516C from target512and output the received radar signals to receive array antenna508converted to an orthogonal polarization direction from the radar signals516C received from target512. In the example ofFIG.5D, transmit antenna504may output radar signals, as described above. Polarizer510D may be configured to receive the radar signals from antenna504and output transmit beam (Tx beam)514D, but converted to an orthogonal polarization to the transmission antenna elements of transmit antenna504. Receive array antenna508may receive reflected radar signals516D from target512, which are polarized in the same direction as the receive elements.

FIG.6is a conceptual diagram illustrating an example cross-polarized antenna with a circular polarization converter placed over the transmit antenna and a switchable left hand circular polarization (LHCP) and right hand circular polarization (RHCP) converter placed over the receive array antenna. In some examples the polarizer may be implemented using switchable components, such as pin diodes. The polarizer using pin diodes can turn on and off, which may create a short or open circuit for a specific signal path. A specific set of pin diodes turned on and other set turned off may provide one type of circular polarization, e.g., LHCP, while reversing the configuration may provide another type of polarization e.g., RHCP.

Transmit antenna504, band gap506, receive array antenna508and PCB layers518have the same functions and characteristics as described above in relation toFIG.5A. In some examples, device620may include an air gap602between polarizers610and611and the respective antenna. In other examples, polarizers610and611may be implemented over transmit antenna504and receive array antenna508with no air gap.

In operation, transmit antenna504may output radar signals. In some examples, polarizer611may be configured to receive the radar signals from antenna504and output Tx beam614, but converted to an LHCP polarization. In other examples, polarizer611may be configured to receive the radar signals from antenna504and output Tx beam614, but converted to an RHCP polarization. The reflected radar signals616from target512may arrive at polarizer610, which is a switchable LHCP/RHCP converter, with an axial ratio of less than 3 dB. Polarizer610may be configured to receive reflected radar signals616from target512and output the received radar signals to receive array antenna508converted to the same polarization as the receive elements for receive array antenna508.

FIG.7is a conceptual diagram illustrating an exploded view of an example integrated radar system including a multi-layer circuit board in accordance with one or more techniques of this disclosure. In the example ofFIG.7, integrated radar system700is implemented as a multi-layer printed circuit board (PCB)701that may include antenna layer702and one or more circuit layers703.FIG.7illustrates an example radar system which may include antenna such as device100described above in relation to FIG.1. Similarly, in some examples, antenna layer702may be configured as any of the antennae described above in relation toFIGS.2-6. In some examples, circuit layers703may be an example of PCB layers518described above in relation toFIG.5A.

Antenna layer702may include a radiation layer and feed network layer705(not visible inFIG.7). As described above in relation toFIGS.1-6, antenna layer702may include band gap722, receive array antenna726, and transmit antenna728with transmit elements724. In the example ofFIG.7, transmit antenna728includes two columns of transmit elements724. In other examples, e.g., as described above in relation toFIG.1, transmit antenna728may include a single column of transmit elements. In the example ofFIG.7, polarizer720is located over receive array antenna726, e.g., between receive array antenna726and a target (not shown inFIG.7). However, in other examples, polarizer720may be located over transmit antenna728, or over both transmit antenna728and receive array antenna726, in the example of a RHCP and/or LHCP polarization configuration, described above in relation toFIG.6.

Circuit layers703may include signal processing circuitry comprising transmit electronics and receiver electronics. For example, receiver electronics may include receiver circuitry, such as receiver circuits708A-708D, analog-to-digital (A/D) converters706A-706D as well as other circuit elements. An analog-to-digital converter may also be called an “ADC.” Though shown as a single PCB in the example ofFIG.7, system700may include two or more PCBs (not shown inFIG.7) such as a power supply board, communications board, and other circuit boards operatively coupled together to form system700.

Multi-layer PCB701may include circuits and components that implement radar transmitter electronics, radar receiver electronics, one or more processors710, communication electronics, power conditioning and distribution, clock/timers and other circuitry and components. The one or more processors710may be configured to control the radar transmitter electronics and radar receiver electronics as well as process and identify radar targets and send notifications and information to users using the communication electronics. A processor may include, any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a system on chip (SoC) or equivalent discrete or integrated logic circuitry. A processor may be integrated circuitry, i.e., integrated processing circuitry, and that the integrated processing circuitry may be realized as fixed hardware processing circuitry, programmable processing circuitry and/or a combination of both fixed and programmable processing circuitry.

Antenna layer702may be electrically connected to circuit paths and components on one or more circuit layers703via transmitter and receiver feed networks, such as connections230and232described above in relation toFIG.2. In some examples, plated vias may provide connections between one or more circuit layers703, as well as to antenna layer702. A via may be a plated or un-plated hole that may be drilled, etched, or otherwise formed between layers of multi-layer PCB701. A plated via may be plated with a conductive material to electrically connect layers. Some examples of conductive material may include copper, solder, conductive epoxy, or other materials.

Protective shield704may cover and provide structural support for example integrated radar system700. Protective shield704may be a molded plastic, stamped or formed sheet metal or other suitable material. Protective shield704may include a conductive coating in one or more areas to provide shielding for electromagnetic interference (EMI). Protective shield704may include penetrations for power, communication or other connections as well as be configured to securely mount integrated radar system700. Though depicted as rectangular in the example ofFIG.7, the multi-layer circuit board, and protective shield704, may be any shape, including round, oval, octagonal, and so on.

FIG.8is a flow chart illustrating an example mode of operation of a cross-polarized antenna of this disclosure. As seen in the example ofFIG.8, transmitter electronics of a radar system, such as circuitry on circuit layer703of radar system700shown inFIG.7or electromagnetic energy transmission and receive device520shown inFIG.5Amay generate a frequency modulated continuous wave radar signal (800).

The radar system may transmit, e.g., by transmit antenna504operatively coupled to transmitter electronics, the FMCW radar signal. As described above in relation toFIGS.1-6, the transmit antenna may include a plurality of transmit antenna elements with each element of the plurality of transmit elements is polarized in a first direction (802).

The receive array antenna, e.g., receive array antenna508, may receive reflected FMCW signals transmitted by the transmit antenna from target512, as shown inFIGS.5A-5D(804). As described above forFIGS.1-6, each element of the of receive elements may be polarized in a second direction orthogonal to the first direction. Therefore, a polarizer, such as polarizer510A,510B,510C or510D located between the radar system and target512may convert radar signals received by the polarizer to an orthogonal polarization direction (806) and output the received radar signals (808).

The techniques of this disclosure may also be described in the following examples.

Example 1: A frequency modulated continuous wave (FMCW) radar device comprising: a transmit antenna comprising: a plurality of transmit antenna elements aligned in a single column, wherein each element of the plurality of transmit elements is polarized in a first direction; a receive array antenna separate from the transmit antenna, comprising an array of receive elements, wherein the receive array antenna is configured to receive reflected FMCW signals transmitted by the transmit antenna from a target, wherein each element of the plurality of receive elements is polarized in a second direction orthogonal to the first direction; and a polarizer, located between the FMCW radar device and the target; electrically and mechanically connected to the FMCW radar device; and the polarizer configured to receive radar signals and output the received radar signals converted to an orthogonal polarization direction, wherein the orthogonal polarization direction is the same as one of the first direction or the second direction.

Example 2: The device of example 1, further comprising an air gap between the polarizer and the FMCW radar device.

Example 3: The device of any of examples 1 and 2, wherein the polarizer is located between the transmit antenna and the target; and wherein the polarizer is configured to receive radar signals from the transmit antenna and output the received radar signals to the target converted to an orthogonal polarization direction from the radar signals received from the transmit antenna.

Example 4: The device of any of examples 1 through 3, wherein the polarizer is located between the receive array antenna and the target; and wherein the polarizer is configured to receive radar signals from the target and output the received radar signals to the receive array antenna converted to an orthogonal polarization direction from the radar signals received from the target.

Example 5: The device of any of examples 1 through 4, wherein the polarizer is configured with an insertion loss of less than 1.0 dB.

Example 6: The device of any of examples 1 through 5, wherein the polarizer is implemented as a circuit board, separate from the transmit antenna and the receive antenna.

Example 7: The device of any of examples 1 through 6, wherein the polarizer is implemented as a circuit board layer.

Example 8: A system comprising: signal processing circuitry comprising: a transmit antenna comprising: a plurality of transmit antenna elements aligned in a single column, wherein each element of the plurality of transmit elements is polarized in a first direction; a receive array antenna separate from the transmit antenna, comprising an array of receive elements, wherein the receive array antenna is configured to receive reflected FMCW signals transmitted by the transmit antenna from a target, wherein each element of the plurality of receive elements is polarized in a second direction orthogonal to the first direction; and a polarizer, located between the FMCW radar device and the target; electrically and mechanically connected to the FMCW radar device; and the polarizer configured to receive radar signals and output the received radar signals converted to an orthogonal polarization direction, wherein the orthogonal polarization direction is the same as one of the first direction or the second direction.

Example 9: The system of example 8, further comprising an air gap between the polarizer and the FMCW radar device.

Example 10: The system of any of examples 8 and 9, wherein the polarizer is located between the transmit antenna and the target; and wherein the polarizer is configured to receive radar signals from the transmit antenna and output the received radar signals to the target converted to an orthogonal polarization direction from the radar signals received from the transmit antenna.

Example 11: The system of any of examples 8 through 10, wherein the polarizer is located between the receive array antenna and the target; and wherein the polarizer is configured to receive radar signals from the target and output the received radar signals to the receive array antenna converted to an orthogonal polarization direction from the radar signals received from the target.

Example 12: The system of any of examples 8 through 11, wherein the polarizer is configured with an insertion loss of less than 1.0 dB.

Example 13: The system of any of examples 8 through 12, wherein the polarizer is implemented as a circuit board, separate from the transmit antenna and the receive antenna.

Example 14: The system of any of examples 8 through 13, wherein the polarizer is implemented as a circuit board layer.

Example 15: A method comprising: generating, by transmitter electronics, a frequency modulated continuous wave (FMCW) radar signal; transmitting, by a transmit antenna operatively coupled to transmitter electronics, the FMCW radar signal, wherein the transmit antenna comprises a plurality of transmit antenna elements aligned in a single column, wherein each element of the plurality of transmit elements is polarized in a first direction; receiving, by a receive array antenna, reflected FMCW signals from a target, wherein the reflected FMCW signals were transmitted to the target by the transmit antenna, wherein the receive array antenna comprises a plurality of receive elements arranged in an array of receive elements, and wherein each element of the plurality of receive elements is polarized in a second direction orthogonal to the first direction; converting, by a polarizer, radar signals received by the polarizer to an orthogonal polarization direction; and outputting, by the polarizer, the received radar signals, wherein the orthogonal polarization direction is the same as one of the first direction or the second direction, and wherein the polarizer located between the FMCW radar device and the target.

Example 16: The method of example 15, wherein the polarizer is located between the transmit antenna and the target; and wherein the polarizer is configured to receive radar signals from the transmit antenna and output the received radar signals to the target converted to an orthogonal polarization direction from the radar signals received from the transmit antenna.

Example 17: The method of any of examples 15 and 16, wherein the polarizer is located between the receive array antenna and the target; and wherein the polarizer is configured to receive radar signals from the target and output the received radar signals to the receive array antenna converted to an orthogonal polarization direction from the radar signals received from the target.

Example 18: The method of any of examples 15 through 17, wherein the polarizer is configured with an insertion loss of less than 1.0 dB.

Example 19: The method of any of examples 15 through 18, wherein the polarizer is implemented as a circuit board, separate from the transmit antenna and the receive antenna.

In one or more examples, the functions described above may be implemented in hardware, software, firmware, or any combination thereof. For example, the various components ofFIGS.1-7, such as the circuitry on layer703ofFIG.7and on the PCB layers518may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over, as one or more instructions or code, a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media, which corresponds to a tangible medium such as data storage media, or communication media including any medium that facilitates transfer of a computer program from one place to another, e.g., according to a communication protocol. In this manner, computer-readable media generally may correspond to (1) tangible computer-readable storage media which is non-transitory or (2) a communication medium such as a signal or carrier wave. Data storage media may be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, code and/or data structures for implementation of the techniques described in this disclosure. A computer program product may include a computer-readable medium.

The term “non-transitory” may indicate that the storage medium is not embodied in a carrier wave or a propagated signal. In certain examples, a non-transitory storage medium may store data that can, over time, change (e.g., in RAM or cache). By way of example, and not limitation, such computer-readable storage media, may include random access memory (RAM), read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), electronically erasable programmable read only memory (EEPROM), flash memory, a hard disk, a compact disc ROM (CD-ROM), a floppy disk, a cassette, magnetic media, optical media, or other computer readable media. In some examples, an article of manufacture may include one or more computer-readable storage media.

Also, any connection is properly termed a computer-readable medium. For example, if instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. It should be understood, however, that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transient media, but are instead directed to non-transient, tangible storage media. Combinations of the above should also be included within the scope of computer-readable media.

Instructions may be executed by one or more processors, such as one or more DSPs, general purpose microprocessors, ASICs, FPGAs, or other equivalent integrated or discrete logic circuitry. Accordingly, the term “processor” and “processing circuitry,” as used herein may refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein. Also, the techniques could be fully implemented in one or more circuits or logic elements.

The techniques of this disclosure may be implemented in a wide variety of devices or apparatuses, including, an integrated circuit (IC) or a set of ICs (e.g., a chip set). Various components, modules, or units are described in this disclosure to emphasize functional aspects of devices configured to perform the disclosed techniques, but do not necessarily require realization by different hardware units. Rather, as described above, various units may be combined in a hardware unit or provided by a collection of interoperative hardware units, including one or more processors as described above, in conjunction with suitable software and/or firmware.

Various examples of the disclosure have been described. These and other examples are within the scope of the following claims.