WO2017053635A1

WO2017053635A1 - Increased sampling in non-uniform sampling analog-to-digital converters

Info

Publication number: WO2017053635A1
Application number: PCT/US2016/053207
Authority: WO
Inventors: Mark Rich; Michael Peter Mack; Brian Kaczynski
Original assignee: Google Inc.
Priority date: 2015-09-25
Filing date: 2016-09-22
Publication date: 2017-03-30
Also published as: CN107710624A; EP3353895A1

Abstract

Analog-to-digital conversion is performed on a received an analog input signal. A supplemental analog signal is generated. The supplemental analog signal is characterized by an amplitude sufficient to trigger each voltage threshold in a non-uniform sampling analog- to-digital converter. The received analog input signal and the generated supplemental signal are mixed. The non-uniform sampling analog-to-digital converter converts the mixed analog signal, producing a series of {amplitude, time} tuples representative of the mixed signal. The series of {amplitude, time} tuples are interpolated to form a series of samples periodic in time representative of the mixed signal. The supplemental signal is removed from the interpolated series.

Description

INCREASED SAMPLING IN NON-UNIFORM SAMPLING ANALOG-TO-DIGITAL

CONVERTERS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62/233,241, filed September 25, 2015, entitled "Increased Sampling In Non-Uniform Sampling Analog-To-Digital Converters," the entire contents of the above-identified priority application are hereby fully incorporated herein by reference.

TECHNICAL FIELD

[0002] The technology disclosed herein relates to systems, methods, and computer program products for non-uniform sampling (NUS) analog-to-digital converters (ADC). Example embodiments relate to increasing the number of amplitude crossings in an NUS ADC of a digital radio frequency (RF) receiver.

BACKGROUND

[0003] FIG. 1 presents a simplified block diagram of a conventional digital heterodyne RF receiver 100. The wireless communications signal 90 to be received by such a receiver 100 may be characterized as comprising three components: the signal of interest 92 (referred to in FIG. 1 as the "desired signal"), interference 94, and noise 96. The signal of interest 92 typically includes information that has been encoded, modulated, and up-converted to a carrier signal in the RF band by a transmitter (not shown).

[0004] Conventionally, a carrier signal is a waveform at a much higher frequency than the baseband modulated encoded information that can be mixed with the baseband modulated encoded information to transmit the information through space as an electromagnetic wave, or to allow several carrier signals at different frequencies to share a common physical transmission medium by frequency division multiplexing. Some types of RF communication, for example, spread spectrum and orthogonal frequency division multiplexing (OFDM), do not use a conventional sinusoidal carrier wave.

[0005] The interference 94 may be from one or more man made RF sources. Broadly stated, narrowband interference typically is from intended transmissions such as radio, television, and mobile phone systems; while broadband interference typically is unintentional, and emanates from sources such as electrical power transmission lines that are not intended to be transmitters.

[0006] Noise 96 refers to all other RF components of energy in the signal 90, of which noise of the receiver itself in the RF range (for example, from a noisy power supply coupled to the RF path) may be a principal component.

[0007] In such a receiver 100, the signal 90 can be received by an antenna system 110. Typically, the antenna system 110 is configured to be more responsive to a wide band of frequencies around the carrier frequency, for example, the entire commercial Frequency Modulation (FM) broadcast band comprising many separate FM channels, than to frequencies outside the range of the signal of interest 92.

[0008] A signal conditioning subsystem 120 typically is used to limit noise and interference first by applying an RF Filter 122 to reduce received noise 96 and interference 94 outside the frequency band of the signal of interest 92. Then, the filtered signal may be amplified, for example, by using a low noise amplifier/variable gain amplifier (LNA/VGA) 124.

[0009] After reducing noise and interference in the signal conditioning subsystem 120, the conventional heterodyne receiver 100 will remove the carrier, effectively bringing the modulated encoded signal from the RF range, in which it is much easier to transmit the signal over distance, down to baseband. In the case of a simple sinusoidal carrier signal, a mixer mixes the output of the signal conditioning subsystem 120 with a local oscillator (LO) 130 matched to the carrier signal using a mixer 140 to remove the carrier signal.

[0010] In a digital receiver, such as conventional heterodyne receiver 100, the output of the mixer 140 remains an analog signal. Analog-to-digital converter (ADC) 150 can be used to convert the analog signal from mixer 140 to a digital signal. Conventional ADCs sample a generally continuous analog input signal; in the case of the conventional heterodyne receiver 100, it is the baseband version of the conditioned signal 90 plus any noise that signal 90 has picked up along the way. A conventional ADC samples the analog signal uniformly in time, resulting in replicas of the signal energy at each integer multiple of the sampling frequency.

SUMMARY

[0011] Embodiments of the technology disclosed herein provide systems, methods, and computer program products for analog-to-digital conversion. In such methods, an embodiment can receive an analog input signal and generate a supplemental analog signal. The supplemental analog signal can be characterized by amplitude sufficient to trigger each voltage threshold in a non-uniform sampling (NUS) analog-to-digital converter (ADC). A mixer can mix the received analog input signal and the generated supplemental analog signal. The NUS ADC can convert the mixed analog signal, producing a series of {amplitude, time} tuples representative of the mixed signal. The embodiment can interpolate the series of {amplitude, time} tuples to form a series of samples periodic in time representative of the mixed signal. The embodiment can remove the supplemental signal from the interpolated series, leaving a digital representation of the input signal.

[0012] These and other aspects, objects, features, and advantages of the example embodiments will become apparent to those having ordinary skill in the art upon consideration of the following detailed description of illustrated example embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a block diagram depicting a conventional heterodyne RF receiver.

[0014] FIG. 2 is a block diagram depicting a non-uniform sampling (NUS) ADC.

[0015] FIG. 3 presents a time domain plot and a frequency domain plot of a simple received signal sampled by an NUS ADC.

[0016] FIG. 4 is a block diagram depicting an NUS ADC using a supplemental signal to increase the number of samples obtained by the ADC, in accordance with certain example embodiments.

[0017] FIG. 5 is a block flow diagram depicting example methods for increasing the number of samples in an NUS ADC, in accordance with certain example embodiments.

[0018] FIG. 6 is a plot of relative power spectral density of a 1 MHz-centered converted signal using 1) no supplemental signal, 2) a 700 mVp supplemental signal centered at 2 MHz, and 3) a 700 mVp supplemental signal centered at 32 MHz, in accordance with certain example embodiments.

[0019] FIG. 7 is a block diagram depicting a computing machine and a module, in accordance with certain example embodiments. DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

Overview

[0020] A non-uniform sampling (NUS) ADC measures the time at which the input signal crosses certain amplitude thresholds - thereby sampling the analog signal uniformly in amplitude. The use of an NUS ADC as converter 150 can improve the dynamic range of a communication receiver. The accuracy of the conversion process is a function of the uncertainty in the measurement in time and amplitude. A conventional ADC measures amplitude at a specific time. A non-uniform ADC samples amplitude and measures time and can allow separate control of the uncertainty of the measurement. Also, measuring time results in an irregular sequence of measurements. The lack of regularity reduces the indirect mixing of noise into the signal otherwise known as aliasing.

[0021] Referring to FIG. 2, a notional NUS ADC 200 is illustrated. In the NUS ADC of FIG. 2, the analog input 210 corresponds to the output of mixer 140. The anticipated range of input voltages is 0 VDC to greater than V14. Evenly spaced reference voltages, V0 - VI 4, are established by using resistors R. As the input voltage 210 varies between 0 VDC and a voltage greater than V14, the collected output of the comparators 220 will indicate the voltage. Each time a comparator 220 changes state, a transition trigger block 230 can prompt an encode transition block 240 to record which comparator outputs indicate that the analog input voltage 210 exceeds the reference voltage for that comparator 220. At the same time, the transition trigger block 230 can prompt a time to digital converter block 250 to record the time of the transition, typically to an accuracy of 10 ps or less. Together, each amplitude 260 and time 270 tuple {amplitude, time} represents one of a series of samples. The series of samples can be interpolated to produce an interpolated series of samples that then can be processed by digital signal processor 160 to demodulate the converted signal and decode the information from the demodulated signal.

[0022] NUS ADCs suffer when input signal amplitude is low (resulting in less amplitude information), or when the signal changes slowly between amplitude thresholds (resulting in long periods of time without amplitude information). Referring to FIG. 3, an example 300 of non-uniform sampling of a pure tone signal 302 at frequency fl is illustrated. Frequency domain plot 320 shows signal 302 at frequency fl. In the time domain plot 310, in the region of the maximum amplitude 312, the time between samples is tl-tO. In the region of the minimum amplitude 314, the time between samples is t3-t2. It can be seen that t3-t2 and tl- tO are not the same, and that each is greater than the average interval between samples. This non-uniformity results in reduced information content in the sampled signal.

[0023] In example embodiments described herein, a known, locally generated supplemental signal is introduced into the NUS ADC along with the signal of interest. This locally generated supplemental signal can be structured to control both the amplitude range and the rate of amplitude threshold crossings. Since the supplemental signal is locally generated, the supplemental signal can be removed from the digital signal following the sampling process. The use of a locally generated supplemental signal increases the complexity of the sampling system less than other methods used to improve sampling system performance, such as two-step converters.

[0024] In the two-step approach, a second stage NUS ADC is turned on whenever too long an interval exists between sample events. This condition occurs when either insufficient signal amplitude exists or a rate of change of signal is too slow. For example, if signal 302 were modified such that the peak to peak amplitude was less than two amplitude intervals, the NUS would only measure two zero crossings (events) per cycle - corresponding to the "insufficient amplitude." If the signal were stretched horizontally, the same number of samples as is shown would result, but the average time between points would be reduced (too slow a rate of change). The two-step NUS ADC approach more than doubles the complexity of the single stage converter but is shown to improve performance. Both the supplemental signal and two-step approaches rely upon an underlying non-uniform sampling process and can be used together.

[0025] In example embodiments, devices and any other computing machines associated with the technology presented herein may be any type of computing machine such as, but not limited to, those discussed in more detail with respect to FIG. 7. Furthermore, any functions, applications, or modules associated with any of these computing machines, such as those described herein or any others (for example, scripts, web content, software, firmware, or hardware) associated with the technology presented herein may by any of the modules discussed in more detail with respect to Figure 7. The computing machines discussed herein may communicate with one another as well as other computer machines or communication systems over one or more networks. The network may include any type of data or communications network, including any of the network technology discussed with respect to Figure 7. [0026] Turning now to the remaining drawings, in which like numerals indicate like (but not necessarily identical) elements throughout the figures, example embodiments are described in detail.

Example System Architectures

[0027] Referring to FIG. 4, and continuing to refer to prior figures for context, a block diagram depicting an NUS ADC assembly 400 using a supplemental signal to increase the number of samples obtained, in accordance with certain example embodiments, is shown. In the example of FIG. 4, the analog input signal 420 is a complex signal comprising both an in phase component / 422 (also referred to as the "real" component of the complex signal) and a quadrature component Q 424 (also referred to as the "imaginary" component of the complex signal). Analog input signal 420 corresponds to the baseband modulated signal output by mixer 140 of the heterodyne RF receiver 100 of FIG. 1.

[0028] Each processing channel, the / channel (top) and the Q channel (middle), includes a signal conditioning block, RX IFILTER 432 for the / channel and RX QFILTER 434 for the Q channel. Each of the RX IFILTER 432 and the RX QFILTER 434 performs signal conditioning to reduce noise and interference of an input signal 420, in the fashion of the RF filter 122 and LNA/VGA 124 of the conventional heterodyne receiver 100 of FIG. 1. This stage is optional.

[0029] Each processing channel, the / channel and the Q channel, includes an NUS digital-to-analog convenor (DAC) 460, INUS ADC 442 and QNUS ADC 444 that produce a series of {amplitude, time} tuples as described in conjunction with the NUS ADC 200 of FIG. 2. Each component of the analog input signal to be sampled and digitally processed includes components representing the signal of interest 92, a supplemental signal, interference signal(s) 94, and noise 96, where the aggregate power level can vary by 70 dB.

[0030] The role of Supplemental Signal Control 450, NUS DAC 460, mixers 472 and 474, and interpolation and supplemental signal removal 482 and 484, is described in conjunction with the block flow diagram of FIG. 5.

Example Processes

[0031] Referring to FIG. 5, and continuing to refer to prior figures for context, a block flow diagram depicting example methods for increased samples in NUS ADCs, in accordance with certain example embodiments, is shown. In such methods an analog input signal can be received - Block 510. Consider, as a continuing example, a radio frequency (RF) receiver similar to the receiver 100 depicted in FIG. 1, and including an NUS ADC assembly 400 of FIG. 4. The receiver 100 receives signal 90 comprising noise 96, a 1 MHz center frequency (baseband) signal of interest 92, and interference 94. The receiver 100 conditions the signal 90 to reduce noise and interference power, and down converts the conditioned signal to baseband, resulting in analog input 420. While the RF receiver 100 of FIG. 1 is used herein as a continuing example, not all embodiments of the present technology require use in an RF receiver.

[0032] The technology can generate a supplemental analog signal characterized by amplitude sufficient to trigger each voltage threshold in a non-uniform sampling analog-to- digital converter - Block 520. In the continuing example, the supplemental signal control 450 of NUS ADC 400 generates a digital version of a 700 mVp tone at 2 MHz, and the NUS digital-to-analog converter (DAC) 460 converts the digital supplemental signal to a complex supplemental analog signal having / and Q components. In the continuing example, the 700 mVp amplitude of the supplemental analog signal is selected to trigger the comparators in each of the INUS ADC 442 and the QNUS ADC 444, meaning that all of the comparators in each ADC would be triggered in each cycle of the supplemental analog signal. The time between trigger events can be selected to sample as much information about the signal of interest 92 as possible. The structure of the supplemental analog signal waveform (e.g., pure tone, swept, triangle) is selected to simplify extraction in the interpolator.

[0033] Selecting the supplemental signal to be about the frequency of interest can allow simple filtering for removal. The fact that the signal is locally generated, and hence known, can allow it to be subtracted. Using a triangle wave supplemental signal can allow each comparator's response to be calibrated.

[0034] The technology can mix the received analog input signal and the generated supplemental analog signal - Block 530. In the continuing example, mixers 472 and 474 mix the / and Q components of the analog input signal 420, respectively.

[0035] The non-uniform sampling analog-to-digital converter can convert the mixed analog signal, producing a series of {amplitude, time} tuples representative of the mixed analog signal - Block 540. In the continuing example, each INUS ADC 442 and QNUS ADC 444 convert the / and Q components of the mixed signal, respectively, to produce / and Q {amplitude, time} tuples representative of the / and Q components of the analog input signal 420, respectively.

[0036] The technology can remove the supplemental signal from the / and Q components of the periodic-in-time signal, respectively, to produce an in phase and quadrature series of samples that are periodic in time and representative of the / and Q components of the signal of interest 92 - Block 550. Removal can be by filtering or subtraction based on the structure, amplitude, and frequency of the supplemental signal. An anti-aliasing filter also can be employed in each Interpolation and Supplemental Signal Removal block 482, 484. Each Interpolation and Supplemental Signal Removal block 482, 484 can then interpolate the series of {amplitude, time} tuples to form a series of samples periodic in time representative of the mixed signal and can remove the supplemental signal from the interpolated series - Block 560. In the continuing example, each Interpolation and Supplemental Signal Removal block 482, 484 interpolates the / and Q {amplitude, time} tuples, respectively, to produce an in phase and quadrature series of samples that are periodic in time and representative of the mixed signal, respectively. The technology can output the interpolated series with supplemental signal removed as a digital conversion of the analog input signal - Block 570.

[0037] Referring to FIG. 6, and continuing to refer to prior figures for context, a plot of relative power spectral density of a 1 MHz-centered converted signal using 1) no supplemental signal, 2) a 700 mVp supplemental signal centered at 2 MHz, and 3) a 700 mVp supplemental signal centered at 32 MHz, in accordance with certain example embodiments is shown. In FIG. 6, the solid line represents the "no supplemental signal" case. The signal-to-noise ratio (S R) for the "no supplemental signal" case is approximately 35 dB/Hz. Where a 700 mVp supplemental signal centered at 2 MHz is added to 1 MHz- centered converted signal, the SNR improves to approximately 60 dB/Hz with a signal-to- spur ratio of approximately 50 dB/Hz. In the third case, the supplemental signal centered at 32 MHz gives the best SNR (approximately 70 dB/Hz) and signal to spur ratio (approximately 55 dB/Hz), while also producing the best frequency separation between the supplemental signal and the signal of interest.

Other Example Embodiments

[0038] Figure 7 depicts a computing machine 2000 and a module 2050 in accordance with certain example embodiments. The computing machine 2000 may correspond to any of the various computers, servers, mobile devices, embedded systems, or computing systems presented herein. The module 2050 may comprise one or more hardware or software elements configured to facilitate the computing machine 2000 in performing the various methods and processing functions presented herein. The computing machine 2000 may include various internal or attached components such as a processor 2010, system bus 2020, system memory 2030, storage media 2040, input/output interface 2060, and a network interface 2070 for communicating with a network 2080.

[0039] The computing machine 2000 may be implemented as a conventional computer system, an embedded controller, a laptop, a server, a mobile device, a smartphone, a set-top box, a kiosk, a vehicular information system, one more processors associated with a television, a customized machine, any other hardware platform, or any combination or multiplicity thereof. The computing machine 2000 may be a distributed system configured to function using multiple computing machines interconnected via a data network or bus system.

[0040] The processor 2010 may be configured to execute code or instructions to perform the operations and functionality described herein, manage request flow and address mappings, and to perform calculations and generate commands. The processor 2010 may be configured to monitor and control the operation of the components in the computing machine 2000. The processor 2010 may be a general purpose processor, a processor core, a multiprocessor, a reconfigurable processor, a microcontroller, a digital signal processor ("DSP"), an application specific integrated circuit ("ASIC"), a graphics processing unit ("GPU"), a field programmable gate array ("FPGA"), a programmable logic device ("PLD"), a controller, a state machine, gated logic, discrete hardware components, any other processing unit, or any combination or multiplicity thereof. The processor 2010 may be a single processing unit, multiple processing units, a single processing core, multiple processing cores, special purpose processing cores, co-processors, or any combination thereof. According to certain embodiments, the processor 2010 along with other components of the computing machine 2000 may be a virtualized computing machine executing within one or more other computing machines.

[0041] The system memory 2030 may include non-volatile memories such as read-only memory ("ROM"), programmable read-only memory ("PROM"), erasable programmable read-only memory ("EPROM"), flash memory, or any other device capable of storing program instructions or data with or without applied power. The system memory 2030 may also include volatile memories such as random access memory ("RAM"), static random access memory ("SRAM"), dynamic random access memory ("DRAM"), and synchronous dynamic random access memory ("SDRAM"). Other types of RAM also may be used to implement the system memory 2030. The system memory 2030 may be implemented using a single memory module or multiple memory modules. While the system memory 2030 is depicted as being part of the computing machine 2000, one skilled in the art will recognize that the system memory 2030 may be separate from the computing machine 2000 without departing from the scope of the subject technology. It should also be appreciated that the system memory 2030 may include, or operate in conjunction with, a non-volatile storage device such as the storage media 2040.

[0042] The storage media 2040 may include a hard disk, a floppy disk, a compact disc read only memory ("CD-ROM"), a digital versatile disc ("DVD"), a Blu-ray disc, a magnetic tape, a flash memory, other non-volatile memory device, a solid state drive ("SSD"), any magnetic storage device, any optical storage device, any electrical storage device, any semiconductor storage device, any physical-based storage device, any other data storage device, or any combination or multiplicity thereof. The storage media 2040 may store one or more operating systems, application programs and program modules such as module 2050, data, or any other information. The storage media 2040 may be part of, or connected to, the computing machine 2000. The storage media 2040 may also be part of one or more other computing machines that are in communication with the computing machine 2000 such as servers, database servers, cloud storage, network attached storage, and so forth.

[0043] The module 2050 may comprise one or more hardware or software elements configured to facilitate the computing machine 2000 with performing the various methods and processing functions presented herein. The module 2050 may include one or more sequences of instructions stored as software or firmware in association with the system memory 2030, the storage media 2040, or both. The storage media 2040 may therefore represent examples of machine or computer readable media on which instructions or code may be stored for execution by the processor 2010. Machine or computer readable media may generally refer to any medium or media used to provide instructions to the processor 2010. Such machine or computer readable media associated with the module 2050 may comprise a computer software product. It should be appreciated that a computer software product comprising the module 2050 may also be associated with one or more processes or methods for delivering the module 2050 to the computing machine 2000 via the network 2080, any signal-bearing medium, or any other communication or delivery technology. The module 2050 may also comprise hardware circuits or information for configuring hardware circuits such as microcode or configuration information for an FPGA or other PLD.

[0044] The input/output ("I/O") interface 2060 may be configured to couple to one or more external devices, to receive data from the one or more external devices, and to send data to the one or more external devices. Such external devices along with the various internal devices may also be known as peripheral devices. The I/O interface 2060 may include both electrical and physical connections for operably coupling the various peripheral devices to the computing machine 2000 or the processor 2010. The I/O interface 2060 may be configured to communicate data, addresses, and control signals between the peripheral devices, the computing machine 2000, or the processor 2010. The I/O interface 2060 may be configured to implement any standard interface, such as small computer system interface ("SCSI"), serial-attached SCSI ("SAS"), fiber channel, peripheral component interconnect ("PCI"), PCI express (PCIe), serial bus, parallel bus, advanced technology attached ("ATA"), serial ATA ("SAT A"), universal serial bus ("USB"), Thunderbolt, Fire Wire, various video buses, and the like. The I/O interface 2060 may be configured to implement only one interface or bus technology. Alternatively, the I/O interface 2060 may be configured to implement multiple interfaces or bus technologies. The I/O interface 2060 may be configured as part of, all of, or to operate in conjunction with, the system bus 2020. The I/O interface 2060 may include one or more buffers for buffering transmissions between one or more external devices, internal devices, the computing machine 2000, or the processor 2010.

[0045] The I/O interface 2060 may couple the computing machine 2000 to various input devices including mice, touch-screens, scanners, electronic digitizers, sensors, receivers, touchpads, trackballs, cameras, microphones, keyboards, any other pointing devices, or any combinations thereof. The I/O interface 2060 may couple the computing machine 2000 to various output devices including video displays, speakers, printers, projectors, tactile feedback devices, automation control, robotic components, actuators, motors, fans, solenoids, valves, pumps, transmitters, signal emitters, lights, and so forth.

[0046] The computing machine 2000 may operate in a networked environment using logical connections through the network interface 2070 to one or more other systems or computing machines across the network 2080. The network 2080 may include wide area networks (WAN), local area networks (LAN), intranets, the Internet, wireless access networks, wired networks, mobile networks, telephone networks, optical networks, or combinations thereof. The network 2080 may be packet switched, circuit switched, of any topology, and may use any communication protocol. Communication links within the network 2080 may involve various digital or an analog communication media such as fiber optic cables, free-space optics, waveguides, electrical conductors, wireless links, antennas, radio-frequency communications, and so forth.

[0047] The processor 2010 may be connected to the other elements of the computing machine 2000 or the various peripherals discussed herein through the system bus 2020. It should be appreciated that the system bus 2020 may be within the processor 2010, outside the processor 2010, or both. According to some embodiments, any of the processor 2010, the other elements of the computing machine 2000, or the various peripherals discussed herein may be integrated into a single device such as a system on chip ("SOC"), system on package ("SOP"), or ASIC device.

[0048] In situations in which the systems discussed here collect personal information about users, or may make use of personal information, the users may be provided with a opportunity or option to control whether programs or features collect user information (e.g., information about a user's social network, social actions or activities, profession, a user's preferences, or a user's current location), or to control whether and/or how to receive content from the content server that may be more relevant to the user. In addition, certain data may be treated in one or more ways before it is stored or used, so that personally identifiable information is removed. For example, a user's identity may be treated so that no personally identifiable information can be determined for the user, or a user's geographic location may be generalized where location information is obtained (such as to a city, ZIP code, or state level), so that a particular location of a user cannot be determined. Thus, the user may have control over how information is collected about the user and used by a content server.

[0049] Embodiments may comprise a computer program that embodies the functions described and illustrated herein, wherein the computer program is implemented in a computer system that comprises instructions stored in a machine-readable medium and a processor that executes the instructions. However, it should be apparent that there could be many different ways of implementing embodiments in computer programming, and the embodiments should not be construed as limited to any one set of computer program instructions. Further, a skilled programmer would be able to write such a computer program to implement an embodiment of the disclosed embodiments based on the appended flow charts and associated description in the application text. Therefore, disclosure of a particular set of program code instructions is not considered necessary for an adequate understanding of how to make and use embodiments. Further, those skilled in the art will appreciate that one or more aspects of embodiments described herein may be performed by hardware, software, or a combination thereof, as may be embodied in one or more computing systems. Moreover, any reference to an act being performed by a computer should not be construed as being performed by a single computer as more than one computer may perform the act.

[0050] The example embodiments described herein can be used with computer hardware and software that perform the methods and processing functions described previously. The systems, methods, and procedures described herein can be embodied in a programmable computer, computer-executable software, or digital circuitry. The software can be stored on computer-readable media. For example, computer-readable media can include a floppy disk, RAM, ROM, hard disk, removable media, flash memory, memory stick, optical media, magneto-optical media, CD-ROM, etc. Digital circuitry can include integrated circuits, gate arrays, building block logic, field programmable gate arrays (FPGA), etc.

[0051] The example systems, methods, and acts described in the embodiments presented previously are illustrative, and, in alternative embodiments, certain acts can be performed in a different order, in parallel with one another, omitted entirely, and/or combined between different example embodiments, and/or certain additional acts can be performed, without departing from the scope and spirit of various embodiments. Accordingly, such alternative embodiments are included in the scope of the following claims, which are to be accorded the broadest interpretation so as to encompass such alternate embodiments.

[0052] Although specific embodiments have been described above in detail, the description is merely for purposes of illustration. It should be appreciated, therefore, that many aspects described above are not intended as required or essential elements unless explicitly stated otherwise. Modifications of, and equivalent components or acts corresponding to, the disclosed aspects of the example embodiments, in addition to those described above, can be made by a person of ordinary skill in the art, having the benefit of the present disclosure, without departing from the spirit and scope of embodiments defined in the following claims, the scope of which is to be accorded the broadest interpretation so as to encompass such modifications and equivalent structures.

Claims

CLAIMS What is claimed is:

1. A computer-implemented method for analog-to-digital signal conversion, comprising:

receiving an analog input signal;

generating a supplemental analog signal, the supplemental analog signal characterized by an amplitude sufficient to trigger at least one voltage threshold in a non-uniform sampling analog-to-digital converter;

mixing the received analog input signal and the generated supplemental analog signal; converting, by the non-uniform sampling analog-to-digital converter, the mixed analog signal, producing a series of {amplitude, time} tuples representative of the mixed signal;

removing, by the one or more computing devices, the supplemental signal from the series of {amplitude, time} tuples;

interpolating, by one or more computing devices, the series of {amplitude, time} tuples with the supplemental signal removed to form a series of samples periodic in time representative of the mixed signal;

outputting, by the one or more computing devices, the interpolated series with supplemental signal removed as a digital conversion of the analog input signal.

2. The method of claim 1, wherein the supplemental analog signal is one of a pure tone signal, a triangle tone signal, and a swept tone signal.

3. The method of claim 1 or 2, wherein:

the analog input signal is a complex analog input signal, and

mixing, converting, and interpolating are conducted in parallel channels for each of the in phase and quadrature components of the complex analog input signal.

4. The method of any of claims 1 to 3, wherein generating the supplemental analog signal comprises:

generating a supplemental digital signal; and

converting the supplemental digital signal to a supplemental analog signal.

5. The method of claim 4, wherein removing the supplemental signal comprises removing the supplemental signal by filtering or subtraction processing.

6. The method of any of claims 1 to 5, wherein the supplemental analog signal is characterized by an amplitude sufficient to trigger each voltage threshold in a non-uniform sampling analog-to-digital converter.

7. A radio frequency receiver, comprising:

an antenna subsystem, operative to receive an analog signal of interest via a communication channel, the analog signal of interest comprising modulated encoded information;

a supplemental analog signal generator operative to generate a supplemental analog signal, the supplemental analog signal characterized by an amplitude sufficient to trigger at least one voltage threshold in a non-uniform sampling analog-to-digital converter;

a mixer operative to mix the received analog signal of interest and the supplemental analog signal;

a non-uniform sampling analog-to-digital converter operative to:

receive the mixed signal,

produce a series of non-uniformly sampled {amplitude, time} tuples representing the mixed signal;

remove, by the one or more computing devices, the supplemental signal from the series of {amplitude, time} tuples;

interpolate, by one or more computing devices, the series of {amplitude, time} tuples with the supplemental signal removed to form a series of samples periodic in time representative of the mixed signal; and

a digital signal processor (DSP), operative to demodulate interpolated series and decode the digital information from the demodulated series.

8. The radio frequency receiver of claim 7, wherein the supplemental analog signal is one of a pure tone signal, a triangle tone signal, and a swept tone signal.

9. The radio frequency receiver of claim 7 or 8, wherein:

the analog input signal is a complex analog input signal; and

mixing, converting, and interpolating, are conducted in parallel channels for each of the in phase and quadrature components of the complex analog input signal.

10. The radio frequency receiver of any of claims 7 to 9, wherein generating the supplemental analog signal comprises:

generating a supplemental digital signal, and

converting the supplemental digital signal to a supplemental analog signal.

11. The radio frequency receiver of claim 10, wherein removing the supplemental signal comprises removing the supplemental signal from the interpolated series of {amplitude, time} tuples by filtering or subtraction processing.

12. The radio frequency receiver of any of claims 7 to 11, wherein the supplemental analog signal is characterized by an amplitude sufficient to trigger each voltage threshold in a non-uniform sampling analog-to-digital converter.

13. A computer program product, comprising:

a non-transitory computer-readable storage device having computer-executable program instructions embodied thereon that when executed by a computer cause the computer to perform analog-to-digital signal conversion, the computer-executable program instructions comprising:

computer-executable program instructions to receive an analog input signal; computer-executable program instructions to generate a supplemental analog signal, the supplemental analog signal characterized by an amplitude sufficient to trigger at least one voltage threshold in a non-uniform sampling analog-to-digital converter;

computer-executable program instructions to mix the received analog input signal and the generated supplemental analog signal;

computer-executable program instructions to convert, in the non-uniform sampling analog-to-digital converter, the mixed analog signal, producing a series of {amplitude, time} tuples representative of the mixed signal;

computer-executable program instructions to interpolate the series of {amplitude, time} tuples to form a series of samples periodic in time representative of the mixed signal; and

computer-executable program instructions to remove the supplemental signal from the interpolated series.

14. The computer program product of claim 13, wherein the supplemental analog signal is one of a pure tone signal, a triangle tone signal, and a swept tone signal.

15. The computer program product of claim 13 or 14, wherein:

the analog input signal is a complex analog input signal; and

16. The computer program product of any of claims 13 to 15, wherein generating the supplemental analog signal comprises:

generating a supplemental digital signal, and

converting the supplemental digital signal to a supplemental analog signal.

17. The computer program product of claim 16, wherein removing the supplemental signal comprises removing the supplemental signal from the interpolated series of {amplitude, time} tuples by filtering or subtraction processing.

18. The computer program product of any of claims 13 to 17, wherein the supplemental analog signal is characterized by an amplitude sufficient to trigger each voltage threshold in a non-uniform sampling analog-to-digital converter.

19. A system to perform analog-to-digital conversion, comprising: a storage device; and

a processor communicatively coupled to the storage device, wherein the processor executes application code instructions that are stored in the storage device to cause the system to:

receive an analog input signal;

generate a supplemental analog signal, the supplemental analog signal characterized by an amplitude sufficient to trigger at least one voltage threshold in a nonuniform sampling analog-to-digital converter;

mix the received analog input signal and the generated supplemental analog signal;

convert, in the non-uniform sampling analog-to-digital converter, the mixed analog signal, producing a series of {amplitude, time} tuples representative of the mixed signal;

interpolate the series of {amplitude, time} tuples to form a series of samples periodic in time representative of the mixed signal; and

remove the supplemental signal from the interpolated series.

20. The system of claim 19, wherein the supplemental analog signal is one of a pure tone signal, a triangle tone signal, and a swept tone signal.

21. The system of claim 19 or 20, wherein:

the analog input signal is a complex analog input signal; and

22. The system of any of claims 19 to 21, wherein generating the supplemental analog signal comprises:

generating a supplemental digital signal, and

converting the supplemental digital signal to a supplemental analog signal.

23. The system of claim 22, wherein removing the supplemental signal comprises removing the supplemental signal from the interpolated series of {amplitude, time} tuples by filtering or subtraction processing.

24. The system of any of claims 19 to 23, wherein the supplemental analog signal is characterized by an amplitude sufficient to trigger each voltage threshold in a non-uniform sampling analog-to-digital converter.