# US 12,216,086 B2 · Multiplexing readout circuit and method for electromagnetic inspection array probe > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,216,086 B2 - Document ID: US12216086B2 - Status: Granted - Kind: B2 - Application number: 18/076,540 - Filed: 2022-12-07 - Published: 2023-06-08 - Granted: 2025-02-04 - Earliest claimed: 2021-12-08 - Assignees: Eddyfi Canada Inc. - Applicants: Eddyfi Canada Inc. - Inventors: Francis Jeanson; Florian Hardy - Web page: https://patentgrep.com/patent/US12216086B2 ## CPC - G01N 27/9006: {Details, e.g. in the structure or functioning of sensors} - G01N 27/9046: {by analysing electrical signals} - G01N 27/904: with two or more sensors - H04Q 9/00: Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom - H04Q 2209/40: using a wireless architecture - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - H04Q: SELECTING (switches, relays, selectors H01H; wireless communication networks H04W) ## Abstract A readout circuit for an electromagnetic inspection system for nondestructive testing of a test object is disclosed. The inspection system includes a plurality of sensors for sensing an electromagnetic response from the test object and generating therefrom a plurality of response signals. The readout circuit can include a plurality of anti-aliasing filters, each configured to receive the response signal from one of the sensors and bandlimit the response signal to produce one of a plurality of bandlimited signals. The readout circuit can also include a time-division multiplexer configured to multiplex the bandlimited signals into a time-division multiplexed (TDM) signal including a sequence of frames outputted at a TDM frame rate, each frame including a plurality of time slots, each time slot assigned to one of the bandlimited signals, wherein the anti-aliasing filters are configured to operate based on the TDM frame rate to attenuate aliasing artifacts in the TDM signal. ## Claims ### Claim 1 A readout circuit for an electromagnetic inspection system for nondestructive testing of a test object, the electromagnetic inspection system comprising a plurality of sensors configured to sense an electromagnetic response from the test object and generate a respective plurality of response signals from the sensed electromagnetic response, the readout circuit comprising: a plurality of anti-aliasing filters, each anti-aliasing filter being configured to receive the response signal from a respective one of the sensors and to bandlimit the respective response signal to produce a respective one of a plurality of bandlimited signals; and a time-division multiplexer coupled to the plurality of anti-aliasing filters and configured to multiplex the plurality of bandlimited signals into a time-division multiplexed (TDM) signal, the TDM signal comprising a sequence of frames outputted at a TDM frame rate, each frame comprising a plurality of time slots, each time slot being assigned to a respective one of the plurality of bandlimited signals, wherein the plurality of anti-aliasing filters is configured to operate based on the TDM frame rate to attenuate aliasing artifacts in the TDM signal. ### Claim 2 (depends on 1) The readout circuit of claim 1, wherein each response signal has a main signal component at an excitation frequency, and wherein each anti-aliasing filter is configured to attenuate the respective response signal at frequencies above an attenuating frequency equal to the TDM frame rate minus the excitation frequency. ### Claim 3 (depends on 2) The readout circuit of claim 2, wherein the excitation frequency ranges from about 2 Hz to about 20 kHz, and wherein the TDM frame rate ranges between about 10 kHz and about 500 kHz. ### Claim 4 (depends on 2) The readout circuit of claim 2, wherein each anti-aliasing filter is configured to attenuate a magnitude of the respective response signal by at least 75% at the attenuating frequency and by at most 5% at the excitation frequency. ### Claim 5 (depends on 1) The readout circuit of claim 1, wherein each response signal has a main signal component at an excitation frequency, wherein each anti-aliasing filter is configured to attenuate the respective response signal at frequencies above an attenuating frequency, and wherein the attenuating frequency is equal to or less than half the TDM frame rate and is higher than the excitation frequency. ### Claim 6 (depends on 1) The readout circuit of claim 1, wherein at least one of the plurality of anti-aliasing filters is a low-pass filter. ### Claim 7 (depends on 1) The readout circuit of claim 1, wherein at least one of the plurality of anti-aliasing filters is a band-pass filter. ### Claim 8 (depends on 1) The readout circuit of claim 1, wherein the number of anti-aliasing filters ranges between 8 and 128. ### Claim 9 (depends on 1) The readout circuit of claim 1, wherein the readout circuit further comprises a plurality of amplifiers, wherein each amplifier is coupled between a respective one of the plurality of sensors and a respective one of the plurality of anti-aliasing filters, and wherein each amplifier is configured to amplify the respective response signal prior to the respective response signal reaching the respective anti-aliasing filter. ### Claim 10 A readout method for an electromagnetic inspection system for nondestructive testing of a test object, the electromagnetic inspection system comprising a plurality of sensors configured to generate a respective plurality of response signals indicative of an electromagnetic response induced from the test object, the readout method comprising: receiving the plurality of response signals from the plurality of sensors; performing a bandlimiting operation on the plurality of response signals to produce a plurality of bandlimited signals; and performing a time-division multiplexing operation on the plurality of bandlimited signals to produce a time-division multiplexed (TDM) signal comprising a sequence of frames outputted at a TDM frame rate, each frame comprising a plurality of time slots, each time slot being assigned to a respective one of the plurality of bandlimited signals, wherein the bandlimiting operation is carried out based on the TDM frame rate to attenuate aliasing artifacts in the TDM signal. ### Claim 11 (depends on 10) The readout method of claim 10, further comprising, with the plurality of sensors: sensing the electromagnetic response induced from the test object; and generating the plurality of response signals from the sensed electromagnetic response. ### Claim 12 (depends on 10) The readout method of claim 10, wherein each response signal has a main signal component at an excitation frequency, and wherein the bandlimiting operation comprises attenuating each response signal at frequencies above an attenuating frequency equal to the TDM frame rate minus the excitation frequency. ### Claim 13 (depends on 10) The readout method of claim 10, further comprising amplifying each response signal prior to performing the bandlimiting operation. ### Claim 14 (depends on 10) The readout method of claim 10, further comprising: digitizing the TDM signal into a digital TDM signal; and processing the digital TDM signal to determine therefrom information conveying a characteristic associated with test object. ### Claim 15 An electromagnetic inspection system for nondestructive testing of a test object, the electromagnetic inspection system comprising: an emitter unit configured to generate an excitation signal to induce an electromagnetic response from the test object; a receiver unit comprising a plurality of sensors configured to sense the electromagnetic response induced from the test object and generate a respective plurality of response signals from the sensed electromagnetic response; and a readout circuit comprising: a plurality of anti-aliasing filters, each anti-aliasing filter being configured to receive the response signal from a respective one of the sensors and to bandlimit the respective response signal to produce a respective one of a plurality of bandlimited signals; and a time-division multiplexer coupled to the plurality of anti-aliasing filters and configured to multiplex the plurality of bandlimited signals into a time-division multiplexed (TDM) signal, the TDM signal comprising a sequence of frames outputted at a TDM frame rate, each frame comprising a plurality of time slots, each time slot being assigned to a respective one of the plurality of bandlimited signals, wherein the plurality of anti-aliasing filters is configured to operate based on the TDM frame rate to attenuate aliasing artifacts in the TDM signal. ### Claim 16 (depends on 15) The electromagnetic inspection system of claim 15, wherein the excitation signal generated by the emitter unit is a time-varying magnetic field, the electromagnetic response induced from the test object comprises magnetic fields produced by eddy currents induced within the test object by the time-varying magnetic field generated by the emitter unit, and the plurality of response signals generated by the plurality of sensors conveys information about the eddy currents induced within the test object. ### Claim 17 (depends on 15) The electromagnetic inspection system of claim 15, wherein the emitter unit comprises a least one emitter coil, and wherein the plurality of sensors comprises a plurality of receiver coils. ### Claim 18 (depends on 15) The electromagnetic inspection system of claim 15, wherein the electromagnetic inspection system is implemented as an eddy-current array probe, a remote-field array probe, a near-field array probe, or a combination thereof. ### Claim 19 (depends on 15) The electromagnetic inspection system of claim 15, further comprising: an analog-to-digital converter implemented in or connected to the readout circuit, the analog-to-digital converter being configured to digitize the TDM signal into a digital TDM signal; and a processor configured to process the digital TDM signal to determine therefrom information conveying a characteristic of the test object. ### Claim 20 (depends on 19) The electromagnetic inspection system of claim 19, wherein the characteristic of the test object relates to a flaw, a dimensional parameter, a material property, or any combination thereof.