Method and apparatus for mitigating phase interference or cancellation by aligning the waveform to the third harmonic.

Abstract

Simply put, this is an embodiment of a system, method, and article for receiving an input audio signal. A baseline frequency may be determined. Crossover points may be determined for the drivers of a multiway speaker system, each crossover point containing a multiple of the third harmonic of the baseline frequency. A signal delay may be determined for the audio signal components to be transmitted to the driver. The audio signal components may be transmitted to the driver based on the determined signal delay. A synthesized audio signal containing the audio signal components may be generated by the driver.

Description

Technical Field

[0001] [Related Applications] This application claims priority to U.S. Provisional Application No. 63 / 420,929, filed on October 31, 2022, entitled "METHOD AND APPARATUS FOR MITIGATING PHASE INTERFERENCE OR CANCELLATION BY ALIGNING WAVEFORMS EMITTED FROM A SINGLE OR MULTIPLE TRANSDUCERS TO 3RD HARMONICS", the entire content of which is incorporated herein by reference in its entirety.

Background Art

[0002] To name just a few of many examples, there are various systems in which different portions of a signal are transmitted, such as audio systems, radar systems, cellular phone systems, or other types of radio frequency (RF) systems. In some of these systems, a wide range of signal frequencies can be transmitted. In some signal transmission systems, multiple transmitters or other transmission devices can be utilized to transmit different frequencies. The different frequencies can combine to form an output composite signal.

[0003] When multiple transmitters are utilized to transmit different frequencies, interference can occur between the output signals from each of the multiple transmitters. For example, in some instances, destructive interference can occur between the transmitted signals, such that a portion of the signal transmitted by one transmitter can effectively cancel out a portion of another signal transmitted by a different transmitter, resulting in a relatively weak composite signal and wasted resources.

Brief Description of the Drawings

[0004] The features and advantages of the exemplary embodiments, as well as the manner in which they are achieved, will become more readily apparent by referring to the following detailed description in conjunction with the accompanying drawings.

[0005] [Figure 1] This shows an embodiment of a chart plotting the frequency response of a multiway speaker system using a phase alignment method.

[0006] [Figure 2] An embodiment of a multiway speaker system is shown.

[0007] [Figure 3] An embodiment of a method for aligning the output from a driver to a multiple of the third harmonic of the baseline frequency is shown.

[0008] [Figure 4] An embodiment of a chart plotting the frequency response of a multiway speaker system using a third-harmonic alignment method is shown.

[0009] [Figure 5] An embodiment of a chart plotting the frequency response of a multiway speaker system according to an embodiment is shown.

[0010] [Figure 6] An embodiment of a chart plotting the frequency response of a multiway speaker system according to an embodiment is shown.

[0011] [Figure 7] A signal generation device according to an embodiment is shown.

[0012] [Figure 8] An embodiment of a method for aligning RF signal components for transmission is shown.

[0013] [Figure 9] This invention illustrates a system for RF communication between a cell tower and a mobile device according to an embodiment.

[0014] [Figure 10]An exemplary embodiment of an RF transmitter is shown.

[0015] Throughout the drawings and detailed descriptions, unless otherwise stated, the same drawing reference number is understood to refer to the same element, feature, and structure. The relative sizes and depictions of these elements may be exaggerated or adjusted for clarity, illustration, and / or convenience. [Modes for carrying out the invention]

[0016] In the following description, certain details are described in order to provide a complete understanding of the various forms of implementation. Various modifications to the embodiments will be readily apparent to those skilled in the art, and it should be understood that the general principles defined herein may be applied to other embodiments and uses without departing from the spirit and scope of this disclosure. Furthermore, many details are provided in the following description for illustrative purposes. However, those skilled in the art will readily understand that embodiments may be implemented without using these particular details. In other examples, well-known structures and processes are not shown or described in order to avoid obscuring the description with unnecessary details. Thus, this disclosure is not limited to the embodiments shown, and is considered to give a scope consistent with the principles and features disclosed herein.

[0017] According to one or more embodiments, a system and method are provided for determining the crossover point and equalization of a composite signal and for temporally aligning the outputs of one or more transducers. For example, the outputs of multiple transducers can be aligned to the third harmonic of a particular baseline frequency in order to reduce interference between the transducer outputs. According to one particular embodiment, the system may include a multiway speaker system having multiple drivers for outputting a particular range of frequencies, where the crossover point of the signals supplied to the drivers is aligned to a multiple of the third harmonic of the baseline frequency.

[0018] A speaker may be referred to herein as a “speaker” or “speaker driver,” and may include an electroacoustic transducer, for example, a device that converts an electrical audio signal into a corresponding audible sound. A speaker system may include one or more speaker drivers, an enclosure, and electrical connections. The terms “speaker,” “speaker driver,” and “driver” are used interchangeably herein. A driver may include a linear motor mounted on a diaphragm, the diaphragm which combines the movement of the linear motor with the movement of air to produce an audible sound. An audio signal from a microphone or recording device, for example, may be electronically amplified to a power level capable of driving the motor to reproduce the sound corresponding to the original unamplified electronic signal. In the audio industry, it is desirable to use multi-way speaker systems when creating audio works. As used herein, a “multi-way” speaker system refers to a speaker system including two or more drivers, each of which may be configured to emit an audio signal within a specific frequency range.

[0019] In a particular embodiment, a multi-way speaker system may include three different drivers, such as a high-frequency driver, a mid-frequency driver, and a low-frequency driver. Some high-frequency drivers can produce high frequencies up to about 100 kHz, but as used herein, “high-frequency driver” or “tweeter” refers to a driver designed to produce relatively high audio frequencies, such as about 2 kHz to 20 kHz. As used herein, “mid-frequency driver” or “mid-range woofer” refers to a driver that reproduces sounds in the mid-frequency range of about 200 Hz to about 2000 Hz. Some low-frequency drivers can provide frequencies up to about 4000 Hz, but as used herein, “low-frequency driver” or “woofer” refers to a driver designed to produce low-frequency sounds typically in the range of about 20 Hz to about 200 Hz.

[0020] In a particular embodiment, the multi-way speaker system can include a plurality of different drivers. Each driver can include a vibrating conical diaphragm or cone. For example, the cone of the low-frequency driver can have a diameter of about 10 inches to 18 inches, the cone of the mid-frequency driver can have a diameter of about 4 inches to 8 inches, and the cone of the high-frequency driver can have a diameter of about 1 inch to 3 inches.

[0021] A multiway speaker system, which includes multiple drivers, can selectively split an input audio signal into two or more frequency ranges so that different parts of the audio signal are sent to drivers designed to operate in different frequency ranges. As used herein, a “crossover point” refers to the frequency at which the input audio signal is split, where certain frequencies below the crossover point are provided to one driver, and certain frequencies above the crossover point are provided to another driver. In a multiway speaker system having three different drivers, such as a high-frequency driver, a mid-frequency driver, and a low-frequency driver, there may be two or more different crossover points. For example, one crossover point may be used to indicate which frequencies within a particular range are sent to the high-frequency driver and which to the mid-frequency driver, and a second crossover point may be used to indicate which frequencies within another frequency range are sent to the low-frequency driver and which to the mid-frequency driver. Some multiway speaker systems may have three or more different speaker drivers, and the total number of crossover points for such a multiway speaker system may be one less than the total number of speaker drivers. For example, there may be multiple drivers in each frequency band. If a particular multiway speaker system has 20 different speaker drivers, there may be a total of 19 different crossover points to indicate which speaker driver provides a particular frequency. Crossover points can be implemented using crossover filters. As used herein, “crossover filter” refers to an electronic filter circuit of the type that divides an audio signal into two or more frequency ranges. For example, the signal portions from the divided audio signal may be sent to speaker drivers designed to operate in different frequency ranges. The crossover filter may be, for example, either an active filter or a passive filter.

[0022] The purpose of selecting an appropriate crossover point is to split the audio signal sent to the drivers or speakers of a multi-way speaker system so that when the acoustic output of the driver combination reaches a person's ear, the person does not hear interference of the output frequencies near the frequency of the crossover point. Such a person can then hear the combination of the audio outputs from the multi-way speaker system as if it were from a single driver or speaker instead.

[0023] The selection of an appropriate crossover point can have a significant impact on the performance of a multi-way speaker system. For example, if the crossover point is selected at a non-ideal frequency, interference may occur between the outputs of two or more drivers. If the crossover point between the frequencies sent to the high-frequency driver and the mid-frequency driver is not selected at an appropriate frequency, interference may occur between the audio output by the high-frequency driver and the mid-frequency driver. If the amount of signal interference is relatively large, the audio sound output by the multi-way speaker system may, as a result, exhibit cancellation of specific frequencies across the audible spectrum. Furthermore, if such signal interference exists, the amount of power required to transmit the audio signal may be greater than the amount of power required when there is less interference.

[0024] Currently, the crossover point is selected based on the phase and frequency response of the speaker. For example, depending on the phase relationship of each frequency output by the speaker, different results may occur for the amplitude (sum or cancellation) of each frequency on-axis and off-axis. A common step when setting up a sound system is to phase-align at least one main speaker with a subwoofer. For example, the phase can be adjusted in time by introducing a delay in the generation of sound from a particular speaker in the system.

[0025] Acoustic engineers have several methods to address this problem and generate predictable responses at selected locations in a room. One method involves physical displacement; for example, measurements are taken at the desired location for a phase-aligned crossover, the frequency response of the reproduced test sound is measured, and the crossover point can be selectively moved to different frequencies by the acoustic engineer until the best results are obtained.

[0026] The crossover points in the embodiments described herein can be selected to be aligned to a multiple of the third harmonic of the baseline frequency in order to reduce signal interference between the outputs of different drivers. In certain embodiments, an input audio signal may be split into different audio signals that are received from a source and provided to dedicated drivers to produce audio outputs within a specific frequency range. For example, a portion of the input audio signal may be selectively sent to different drivers of a multiway speaker system to enable the multiway speaker system to produce a combined output audio sound with relatively little interference between the audio outputs from different drivers. To produce such a combined audio sound, an appropriate crossover point of the frequency to be split between different drivers can be selectively determined.

[0027] Figure 1 shows an embodiment 100 of a chart of frequency response plots for a multiway speaker system using a phase alignment method. Embodiment 100 shows output-to-input frequency response measurements taken at different locations of a multiway speaker system between approximately 1 Hz and approximately 20,000 Hz. For example, eight different plots are shown, plot 105 is a frequency response measurement at 0 degrees from the center. Plot 110 is a frequency response measurement at 10 degrees from the center. Plot 115 is a frequency response measurement at 20 degrees from the center. Plot 120 is a frequency response measurement at 30 degrees from the center. Plot 125 is a frequency response measurement at 40 degrees from the center. Plot 130 is a frequency response measurement at 50 degrees from the center. Plot 135 is a frequency response measurement at 60 degrees from the center. Plot 140 is a frequency response measurement at 70 degrees from the center. According to a particular embodiment, a human operator can use a protractor to determine the angle relative to the center of the multiway speaker system. When measuring a single box, the measurement can be performed on a flat surface between 1 meter and 10 feet.

[0028] In one example, pink noise can be provided as input to a microphone played by a multiway speaker system. The frequency response of the pink noise output by the multiway speaker system can be measured. As used herein, “pink noise” refers to an input composite signal containing each frequency of the input signal having the same amplitude. As used herein, “coherence” refers to a statistic that can be used to examine the relationship between two signals or datasets. For example, a coherence measurement can indicate the magnitude of an output signal reproduced at a particular frequency relative to the magnitude of a corresponding input signal at the same frequency. Coherence can indicate an estimate of the power transfer between the input and output of a multiway speaker system. In a speaker system that accurately reproduces the input signal, the coherence measurement is 100%, where the amount of audio output or reproduced at each observed frequency is equal to the amount of audio signal input at each observed frequency. In Embodiment 100 of Figure 1, the coherence for most observed frequencies between approximately 60 Hz and approximately 12 kHz is close to 100%. However, there is a drop in coherence between approximately 90Hz and 450Hz, where the plots are shifted relative to each other.

[0029] For example, plots 105-140 each show the effect of specific signal cancellation. For instance, a phase shift between signals can cause signal cancellation. The phase can vary based on the amplitude of the frequencies output by each driver. In other words, the audio output from different drivers in a multi-way speaker system can cancel the audio output from other drivers, resulting in various dropouts as shown in the plot of Embodiment 100. For example, the magnitude of Embodiment 100 shows dropouts at approximately 450Hz, 3500Hz, 6000Hz, and 9500Hz as a result of such phase interaction. Plots 105-140 show measurements taken at approximately the same volume at angles plotted on a horizontal plane. These plots show how the phase shifts, resulting in cancellation and changes in the frequency response as you move away from the center. The dropouts shown in plots 105-140 can be caused by phase interference along that plane.

[0030] According to embodiments of the present invention, interference between the audio outputs of different drivers in a multiway speaker system can be reduced compared to interference in existing speaker systems. To reduce such interference, the waveforms from each driver can be aligned using a baseline or center frequency (e.g., crossover frequency). For example, two or more transducers can be aligned based on the time of the third harmonic of a selected baseline frequency.

[0031] In one implementation, measurements can be taken from each driver without filtering to determine what each driver produces. The frequency response is a measurement of the magnitude and phase of the output of a device in response to an input stimulus. A device or system exhibiting a flat response reproduces the input more accurately through the output without enhancement in specific areas. In other words, a flat response means that what comes in goes out. The flatter the response, the more "pure" the audio is considered to be. A flat frequency response is important in devices such as loudspeakers, monitors, and microphones when audio accuracy is required.

[0032] In implementing a multi-way speaker system with a flat frequency response, the amplitudes of the frequencies emitted from each speaker in the multi-way speaker system can be approximately the same or within a 10% range of each other. For example, it may be desirable to have mid-range and high-frequency outputs from each driver that are approximately the same magnitude.

[0033] In a multi-way speaker system, an appropriate crossover point can be selected between different speaker drivers to produce a flat frequency response. The output of each speaker driver can be analyzed to determine the capabilities of each driver. If it is determined that a low-frequency driver can reproduce frequencies as low as, for example, 50 Hz, then 50 Hz can be considered the breakpoint or resonant frequency of the low-frequency driver. As used herein, the “cutoff frequency” or “resonant frequency” of a speaker refers to the frequency at which it becomes increasingly impossible for the speaker to produce a sound output for a given input signal. Speakers may be associated with different impedance measurements at different frequencies. Resonance can cause a significant increase in impedance, and at certain high frequencies, measuring the speaker’s audio inductance (or semi-inductance) may again increase the impedance. At resonance, the speaker’s impedance may be considered pure resistance.

[0034] After the cutoff or resonant frequency of a speaker driver is determined, it may be used as a baseline frequency to determine the crossover frequencies of other drivers. For example, the third harmonic of the baseline frequency may be determined. The third harmonic may include a frequency three times the baseline frequency. Therefore, if the baseline frequency of a low-frequency driver is determined to be 50 Hz, the third harmonic of the low-frequency driver may be 150 Hz. Alignment of the crossover point for a particular driver can be done using the third harmonic at the baseline or center frequency.

[0035] Figure 2 shows an embodiment 200 of a multiway speaker system. In embodiment 200, an input audio signal can be received by the multiway speaker system, which outputs the audio as audible sound. The input audio signal can be received by a processor 205. The processor 205 can communicate with different drivers, such as a low-frequency driver 210, a mid-frequency driver 215, and a high-frequency driver 220. The low-frequency driver 210 can generate a first output audio. The mid-frequency driver 215 can generate a second output audio. The high-frequency driver 220 can generate a third output audio. The combination of the first output audio, the second output audio, and the third output audio includes a composite audio output that can be heard by one or more people.

[0036] The processor 205 may have information regarding the characteristics of each driver, including the range of output frequencies that each driver can generate. For example, as described above, the cutoff frequency of the low-frequency driver 210 may be determined or known and may be used as the baseline frequency. In some embodiments, the processor 205 may retrieve the characteristics of each driver from memory or storage device where such information is stored. After determining the baseline frequency of the low-frequency driver, a value that is a multiple of the third harmonic of the baseline frequency may be determined. For example, if the baseline frequency is determined to be 50 Hz, a value that is a multiple of the third harmonic of the baseline frequency may be identified.

[0037] A harmonic is a wave or signal whose frequency is an integer multiple of the frequency of a reference signal or wave of the same frequency. As used herein, "third harmonic" refers to a wave or signal whose frequency is a multiple of 3 of the baseline frequency. For example, if the baseline frequency is 50 Hz, the first third harmonic may be a multiple of 3 of the baseline frequency, i.e., 150 Hz in this example. The sixth harmonic has twice the frequency of the third harmonic. In this example, the sixth harmonic is 300 Hz. By determining consecutive multiples of the third harmonic frequency, a value of the third harmonic that is close to the cutoff frequency of the mid-range driver may be selected as the crossover point between the low-frequency driver and the mid-frequency driver. For example, if the cutoff frequency of the mid-range driver is known to be approximately 275 Hz, the crossover point can be selected at 300 Hz, which is the sixth harmonic of the baseline frequency. In this example, the sixth harmonic is twice the frequency of the third harmonic. Similarly, if the cutoff frequency of the high-frequency driver is known to be approximately 2200Hz, the crossover point can be selected at 2250Hz, which is the 45th harmonic of the baseline frequency. In this example, the 45th harmonic is 15 times the third harmonic frequency. Table A shows the multiples of the third harmonic of the 50Hz baseline frequency and the length of time each frequency takes to complete a single cycle, as shown below. The selection of an appropriate crossover point corresponding to a multiple of the third harmonic of the baseline frequency can be done manually by a sound engineer, or automatically or dynamically, such as through an automated process in some implementations. For example, a processor may execute program code that automatically determines an appropriate crossover point corresponding to a third harmonic of the baseline frequency, according to some implementations. [Table 1]

[0038] By selecting the crossover point as a multiple of the third harmonic of the baseline frequency in this way, the combined output signal remains in phase and is less or no interference between the outputs of various drivers. When tuned to the third harmonic, the response of each frequency band remains nearly the same.

[0039] To ensure that the output signals from each driver are in phase, timing delays can be introduced to account for the delays introduced when transmitting signals to different drivers. For example, if the baseline frequency is 50 Hz, it can be decided that such a frequency generates 50 cycles per second. Thus, it takes 20 ms to complete one cycle at a 50 Hz baseline. Signals to the intermediate frequency driver and the high frequency driver can be delayed, respectively, taking into account the time difference of the baseline frequency and the fact that each of the selected third harmonic multiples completes a full cycle.

[0040] The signals supplied to the intermediate and high-frequency drivers can be delayed to ensure that the end times of the audio signals from each driver are approximately the same. For example, a signal delay can be introduced to ensure that the end times of one cycle of the 50Hz baseline frequency reproduced by the low-frequency driver, one cycle of the 300Hz sixth harmonic frequency reproduced by the intermediate-frequency driver, and one cycle of the 2250Hz forty-fifth harmonic frequency reproduced by the high-frequency driver are output at approximately the same time.

[0041] The reason for introducing these delays is that low-frequency drivers take time to reproduce the baseline frequency because it takes time for their frequency to exit the speaker enclosure. To align the drivers, delays can be introduced so that signals at each crossover point frequency are radiated by the drivers of a multi-way speaker system almost simultaneously. Thus, if a system has three drivers in a multi-way speaker system, and there is a first crossover point at 300 Hz, which is the sixth harmonic between the low-frequency driver and the mid-frequency driver, and a second crossover point at 2250 Hz, which is the 45th harmonic, then a time delay can be introduced to account for the two crossover points. For example, as shown in Table A, a 2250 Hz signal takes approximately 0.444 ms to complete one full cycle. The time it takes for a signal to complete one full cycle can be determined by dividing the number "1" by the frequency of the signal. Thus, in this example, a 2250 Hz signal takes 1 / 2250 seconds, or approximately 0.444 ms, to complete one full cycle. In this example, the first crossover point is located at 300Hz, and this signal takes approximately 3.333ms to complete one full cycle. Therefore, since 300Hz takes longer to complete one full cycle than a 2250Hz signal, a time delay can be introduced to delay the output of the high-frequency driver compared to the mid-frequency driver. Similarly, a baseline signal with a baseline of 50Hz takes longer to complete one cycle by the low-frequency driver. As mentioned above, a 50Hz baseline signal takes 20ms to complete one cycle.

[0042] Therefore, to ensure that the audio signal is played back by different drivers almost simultaneously, the audio signals sent to the mid-frequency driver and the high-frequency driver can be delayed. For example, the signal to the mid-frequency driver can be delayed by 16.667ms (e.g., 20ms - 3.333ms). Similarly, the signal provided to the high-frequency driver can be delayed by 19.556ms (e.g., 20ms - 0.444ms).

[0043] In this example, a time delay can be introduced to reduce or eliminate interference between output signals and to align the output to the third harmonic of the 50 Hz baseline frequency.

[0044] Figure 3 shows an embodiment 300 of a method for aligning the output from a driver to a multiple of the third harmonic of the baseline frequency. Such an embodiment 300 can be performed, for example, by a processor in combination with one or more drivers. Embodiments according to the claimed subject may include all, fewer, or more of blocks 305 to 330. Furthermore, the order of blocks 305 to 330 is merely illustrative.

[0045] In operation 305, the input audio signal can be received. In operation 310, the baseline frequency may be determined. As described above, the baseline frequency may be determined to be the cutoff frequency of a low-frequency driver according to one embodiment. In operation 320, the crossover points between drivers can be determined. For example, a crossover point aligned to a multiple of the third harmonic frequency of the baseline frequency can be selected. In operation 325, a signal delay can be determined for each driver so that the audio generated by each driver is temporally aligned. In operation 330, the input audio signal may be split at the crossover points, and the resulting audio signal components are sent to the drivers. In operation 330, each driver may process the received audio signal components and generate an audio output. The audio outputs of each driver may collectively include synthesized audio.

[0046] Figure 4 shows Embodiment 400 of a chart of frequency response plots for a multiway speaker system using the third harmonic alignment method described above with respect to Embodiment 300 in Figure 3. Embodiment 400 shows output vs. input frequency response measurements taken at different locations of the multiway speaker system between approximately 1 Hz and approximately 12,000 Hz. For example, six different plots are shown. Plot 405 is a measurement of the frequency response at a position 0 degrees from the center, plot 410 is a measurement of the frequency response at a position 15 degrees from the center, plot 415 is a measurement of the frequency response at a position 30 degrees from the center, and plot 420 is a measurement of the frequency response at a position 45 degrees from the center. Plot 425 is a measurement of the frequency response of the high-frequency driver only, and plot 430 is a measurement of the frequency response of the low-frequency driver only.

[0047] In one example, pink noise may be provided as input to a microphone played through a multiway speaker system, and the frequency response of the pink noise output by the multiway speaker system may be measured. This is shown in Embodiment 400 of Figure 4.

[0048] As shown, the plot of Embodiment 400 shown in Figure 4 shows improved coherence compared to the plot of Embodiment 100 shown in Figure 1. By aligning the signal to the third harmonic as shown in Embodiment 400, signal interference is reduced and signal coherence is improved at the same time.

[0049] In this embodiment, since there is little to no phase distortion, the size of the overall output is irrelevant. The advantage of this system is that there is less audio interference from different speakers, and therefore it is highly efficient.

[0050] By introducing a time delay to align the waveforms emitted by different drivers to the third harmonic of the center frequency between the two bands, various advantages can be realized. For example, phase interference between signals output by different drivers in a multi-way speaker system can be reduced or effectively eliminated in some cases. By reducing such phase interference, the system can operate more efficiently, and thus the input power to the speaker system can be reduced. Furthermore, the synthesized audio sound emitted by the speaker system can exhibit improved acoustic parameters. For example, the sound may be more pleasing to the human listener and exhibit less audio distortion.

[0051] Figure 5 shows Embodiment 500, a chart of a frequency response plot for a multiway speaker system according to one embodiment. For example, the multiway speaker system of this exemplary embodiment may include a low-frequency driver, a mid-frequency driver, and a high-frequency driver, with a configuration similar to that shown in Embodiment 200 of Figure 2. The frequency response of Embodiment 500 corresponds to a three-way speaker cabinet, and the speaker manufacturer's specifications regarding the horizontal pattern are off-axis by only 0 to 80 degrees or 40 degrees. In Embodiment 500, the vertical axis represents decibels (dB), and the horizontal axis represents the frequency of the output signal. For example, the chart of Embodiment 500 shows a plot of the volume in dB generated for each frequency according to different multiway speaker settings.

[0052] Embodiment 500 shows three different plots of frequency response. Plot 515 is a plot of the frequency response of a multiway speaker system when the system's factory setting is used at 0 degrees on axis. In other words, plot 515 shows the frequency response of the multiway speaker system when the crossover point is not changed or adjusted by the end user from the initial factor setting. The measured dB at frequencies between approximately 180 Hz and 13,800 Hz in plot 515 tends to be low between approximately 180 Hz and 1,200 Hz and high between approximately 1,200 Hz and 13,800 Hz. As shown in the figure, the dB decreases from approximately 0 dB at approximately 180 Hz to approximately -6 dB at approximately 180 Hz and increases to approximately 3 dB at approximately 13,800 Hz.

[0053] Plot 510 shows the frequency response of a multiway speaker system when the system's factory settings are used with the speakers 30 degrees away from the axis. As shown in the figure, plot 510 has a peak at approximately 250 Hz, and the measured dB at frequencies between approximately 250 Hz and approximately 13,000 Hz in plot 510 is relatively constant, indicating a relatively flat response.

[0054] Plot 505 shows the frequency response of a multi-way speaker system at 0 degrees on axis when the crossover points between the low-frequency driver and the mid-frequency driver, and between the mid-frequency driver and the high-frequency driver, are selected to be multiples of the third harmonic of the baseline frequency. In plot 510, dB increases between the cutoff frequency of the multi-way speaker system at approximately 50 Hz and the peak measurement of approximately 12 dB slightly above 1,600 Hz. dB decreases from the peak measurement at approximately 1,600 Hz to the maximum measurement frequency in plot 505 at approximately 18,000 Hz. Thus, as described above with respect to Embodiment 300 in Figure 4, by selecting the crossover frequencies in this example, which are multiples of the third harmonic of the baseline frequency, and introducing a corresponding signal delay, interference between signals radiated by the different drivers of the multi-way speaker system can be reduced, resulting in larger mid-range dB values ​​measured at the mid-range frequency in the chart shown in Embodiment 500.

[0055] Figure 6 shows Embodiment 600 of a chart plotting the frequency response of a multiway speaker system according to one embodiment. For example, the multiway speaker system in this exemplary embodiment may include a low-frequency driver, a mid-frequency driver, and a high-frequency driver, with a configuration similar to that shown in Embodiment 200 of Figure 2, and similar to the configuration described above with respect to the chart shown in Embodiment 500 of Figure 5. The frequency response of Embodiment 600 corresponds to a three-way speaker cabinet, and the speaker manufacturer's specifications for the horizontal pattern are off-axis by 0 to 80 degrees or 40 degrees. In Embodiment 500, the vertical axis represents decibels (dB), and the horizontal axis represents the frequency of the output signal. For example, the chart of Embodiment 600 shows a plot of the volume in dB generated for each frequency according to different multiway speaker settings.

[0056] Plot 605 shows the frequency response of a multi-way speaker system at 0 degrees on-axis when the crossover points between the low-frequency driver and the mid-frequency driver, and between the mid-frequency driver and the high-frequency driver, are selected to be multiples of the third harmonic of the baseline frequency, and an equalizer is applied to produce a relatively flat response. The equalizer can boost or cut (e.g., make louder or softer) certain frequency ranges to improve sound quality.

[0057] Plot 610 shows the frequency response of a multi-way speaker system at 30 degrees from the axis, where the crossover points between the low-frequency driver and the mid-frequency driver, and between the mid-frequency driver and the high-frequency driver, are selected to be multiples of the third harmonic of the baseline frequency, and an equalizer is applied to produce a relatively flat response.

[0058] As shown in the diagram, when a crossover point that is a multiple of the third harmonic of the baseline frequency is selected, and an equalizer is also used, a relatively flat response can be achieved for the output audio signal.

[0059] Figure 7 shows a signal generator 700 according to one embodiment. The signal generator 700 may include a processor 705. An amplifier 710 can boost or amplify the transmitted signal. The processor can receive a user input, for example, which includes the values ​​of one or more crossover points for an output signal. The processor 705 can be used to process the user input to determine how to split the input signal into two or more drivers or transducers, such as a first transducer 715 and a second transducer 720. For example, the first transducer 715 may include a low-frequency transducer, and the second transducer may include a high-frequency transducer. The processor 705 can execute computer executable code stored in memory 725. The processor 705 can cause the first transducer 715 and the second transducer 720 to convert the input signal into an output signal, and the sum of the output signals from the first transducer 715 and the second transducer 720 includes a combined output signal. For example, an input signal can be provided to an amplifier 710. The amplifier 710 may include a two-channel amplifier in which the output of the first channel is provided to the first transducer 715 and the output of the second channel is provided to the second transducer 720. As described above, the crossover point between the first transducer 715 and the second transducer 720 can be selected based on the user input, for example, such that the crossover point is a multiple of the third harmonic of the baseline frequency, and can be selected, for example, to reduce destructive interference between the signal outputs of the first transducer 715 and the second transducer 720. Although only two transducers are shown in Figure 7, it should be understood that in some embodiments, two or more transducers can be used. It should be understood that when a total of N transducers are used, the amplifier 710 can include N output channels. In some embodiments, multiple amplifiers can be used, such as when there are a relatively large number of transducers.Furthermore, in some embodiments, the control unit can be used in combination with the processor 705 or in place of the processor 705.

[0060] Although embodiments have been described above in relation to speaker systems, it should be understood that the above teachings are equally applicable to other embodiments, including signal processing and / or signal reproduction. For example, there are various radio frequency (RF) embodiments that can be improved by tuning the center frequencies of various output RF signals to the third harmonic frequency.

[0061] According to one embodiment, if there are three different RF signals transmitted at different frequencies, for example, to reduce interference between the transmissions of each RF signal, the transmission of the higher frequency RF signal may be delayed relative to the transmission of the lower frequency RF signal. For example, if the RF signals are transmitted at frequencies of 1000 Hz, 2000 Hz, and 10000 Hz, the center frequency between each consecutive RF signal and the next lowest frequency RF signal may be determined and used to determine how much to delay the transmission of each consecutive RF signal. In this example, the lowest frequency RF signal at 1000 Hz may be transmitted at time t0. The next highest RF signal has a frequency of 2000 Hz. The center frequency between the 1000 Hz signal and the 2000 Hz signal may be determined. In this case, it is 1500 Hz. The transmission of the 2000 Hz signal may be delayed relative to the transmission of the 1000 Hz signal by the reciprocal of the determined center frequency, for example, 1 / (1500 Hz) or 0.666 ms. The next highest RF signal, 10000Hz, can be similarly delayed relative to the transmission of the 2000Hz signal, based on the center frequency between these RF signals. For example, the center frequency between the 2000Hz and 10000Hz signals is 6000Hz. Therefore, the transmission of the 10000Hz signal can be delayed by 1 / (60000Hz) or 0.166ms relative to the transmission of the 2000Hz signal. Thus, in the above example, the 1000Hz signal may be transmitted at time t0, the 2000Hz signal at a delay of time t0 + 0.666ms, and the 10000Hz signal at a delay of time t0 + 0.833ms (0.666ms + 0.166ms).

[0062] Such teachings may be applied within the domain of transmitting RF signals for telecommunications. For example, such teachings may be applied to communications between a mobile phone and one or more cell towers. For example, a cell tower may transmit signals having multiple different frequencies via its antenna, and / or the mobile phone itself may transmit signals having multiple different frequencies from its antenna.

[0063] Figure 8 shows an embodiment 800 of a method for aligning RF signal components for transmission. Such an embodiment 800 may be performed by a processor in combination with, for example, one or more transducers. Embodiments according to the claimed subject may include all, fewer, or more of blocks 805 to 830. Furthermore, the order of blocks 805 to 830 is merely illustrative.

[0064] In operation 805, the transmitted input RF signal may be received and / or determined. In operation 810, the input RF signal may be filtered into multiple RF signal components of different frequency ranges. For example, there may be multiple signal filters that filter the input RF signal into multiple different RF signal components, each having a different frequency. To give just a few examples of many, for instance, one RF signal component may have a frequency of about 100 Hz, another RF signal component may have a frequency of 1000 Hz, and yet another RF signal component may have a frequency of about 10000 Hz.

[0065] In operation 815, the center frequency may be determined between each consecutive RF signal component. For example, if one RF signal component has a frequency of 10 Hz and the next consecutive RF signal component has a frequency of 100 Hz, the center frequency between these two RF signal components may be, for example, 55 Hz, which is half the distance (in terms of frequency) between each RF signal component.

[0066] In operation 820, the timing delay may be determined between the transmissions of each RF signal component, and the timing delay is based on the center frequency between each consecutive RF signal component and the next smallest RF signal component being transmitted. In operation 825, multiple RF signal components may be transmitted through one or more transducers based on the timing delay determined in operation 820. Multiple RF signal components may be received by an RF receiver, demodulated, and combined into a received RF combined signal.

[0067] By delaying the transmission of RF signal components based on the center frequency between consecutive RF signal components and the next smallest RF signal component, and then transmitting these RF signal components, phase interference and intermodulation of the transmitted RF signals can be reduced.

[0068] Figure 9 shows a system 900 for RF communication between a cell tower 905 and a mobile device 910 according to one embodiment. To name just a few of the many possible components, the cell tower 905 may include various components such as a processor 915, a receiver 920, a memory 925, an amplifier 930, and a transducer 935. The transducer 935 can be considered, for example, an antenna that converts electric current to electromagnetic waves, or vice versa. It should be understood that in some embodiments, the cell tower 905 may include multiple transducers. The receiver 920 can receive one or more signals transmitted by the mobile device 910.

[0069] As described above with respect to Embodiment 800 in Figure 8, the transmitted RF signal may be filtered into multiple RF signal components of different frequencies. For example, the processor 915 may include a filtering function, or it may control one or more other components that can perform this signal filtering. In one embodiment, the RF input signal may be amplified by the amplifier 930 and then filtered. The center frequency between a successive RF signal component (e.g., continuous in terms of signal frequency) and the next lowest frequency RF signal component may be determined and then adjusted so that the adjusted center frequency is a multiple of the third harmonic of the baseline RF signal. By aligning the center frequency adjusted based on a multiple of the third harmonic of the baseline RF signal in this manner, disruptive interference between the signal outputs of the first transducer 935 and the second transducer 940 can be reduced, for example. In some embodiments, the adjusted center frequency may be dynamically selected by the processor 915. For example, if the baseline frequency is known or can be determined with respect to the input RF signal, the tuned center frequency that constitutes the optimal third harmonic of the baseline frequency may be selected or determined by the processor 915.

[0070] The mobile device 910 may include, for example, a mobile phone. The mobile device 910 may include a receiver 940 for receiving one or more signals transmitted by the cell tower 905 and / or for receiving a user input indicating the crossover point of the signals transmitted by the mobile device 910. The mobile device 910 may include various components such as a processor 950, memory 955, memory 960, amplifier 965, and transducer 970, but these components are just examples of many possible components. It should be understood that in some implementations, the mobile device 910 may include multiple transducers. As described above, the center frequency between the RF signal components may be selected, for example, to reduce destructive interference between the RF signal components during transmission, such as a baseline RF signal or a multiple of the third harmonic of the frequency. The received RF signal components can be demodulated and converted into an RF combined signal.

[0071] While a transmission between a cell tower 905 and a mobile device 910 is shown in Embodiment 900 of Figure 9, it should be understood that these teachings also apply to other RF applications. For example, RF signal transmission between a microphone and a headset can implement these teachings, as can RF communication or transmission between other types of devices that transmit RF signals.

[0072] Figure 10 shows an exemplary embodiment 1000 of an RF transmitter. For example, data may be received by a modulator 1005. The modulator 1005 can superimpose a low-frequency (e.g., data or other information) signal onto a high-frequency (carrier) signal for radio transmission. The output of the modulator 1005 can be fed to an intermediate frequency (IF) filter 1010, which can compensate for the complex response of higher-order filter shapes. The output of the IF filter 1010 can be fed to a mixer 1020, which mixes the output of the IF filter 1010 with an input frequency signal 1015. The output of the mixer 1020 can be fed to both a high-pass filter 1025 and a low-pass filter 1030. The high-pass filter 1025 can filter frequencies other than specific high frequencies. The low-pass filter 1030 can filter frequencies other than specific low frequencies. It should be understood that in some embodiments, more than two (or fewer) signal filters may be utilized. The output of the high-pass filter 1025 can be provided to the first power amplifier 1035. The output of the low-pass filter 1030 can be provided to the second power amplifier 1040. The first power amplifier 1035 and the second power amplifier 1040 can amplify the signal strength so that their respective output amplified signals are transmitted through the antenna 1045.

[0073] The teachings described herein can also be applied within Wi-Fi networks where multiple signals are combined into a single signal by one or more routers or access points. For example, such teachings can be applied to systems that transmit or otherwise process waveforms to cancel out phase interference. In one exemplary embodiment, a system in which multiple frequencies are transmitted from the same antenna can benefit from aligning different frequencies radiated from the same antenna to the third harmonic of the center frequency between each of the frequencies being used. Such teachings can further be applied to the field of radar.

[0074] While the embodiments described above relate to digital signal processing, it should be understood that such teachings are also applicable to analog systems. For example, instead of using a signal processor to introduce a time delay to align the signal output by a driver to the third harmonic of the fundamental frequency, the drivers can be physically positioned in a precise manner so that the outputs of different drivers located at different positions effectively introduce a time delay.

[0075] As understood in accordance with the preceding specification, one or more embodiments of the above-described embodiments of the present disclosure can be implemented using computer programming or engineering techniques, including computer software, firmware, hardware, or any combination or subset thereof. The resulting programs, having computer-readable code, can be embodied or provided in one or more non-temporary computer-readable media, thereby enabling the manufacture of computer program products, i.e., products, according to the embodiments discussed in the present disclosure. For example, non-temporary computer-readable media may be, but are not limited to, fixed drives, diskettes, optical discs, magnetic tapes, semiconductor memory such as flash memory and read-only memory (ROM), and / or any transmitting / receiving media such as the Internet, cloud storage, the Internet of Things, or other communication networks or links. Products containing computer code can be manufactured and / or used by executing the code directly from one medium, by copying the code from one medium to another, or by transmitting the code over a network.

[0076] A computer program (also called a program, software, software application, "app," or code) may contain machine instructions for a programmable processor and may be implemented in advanced procedural and / or object-oriented programming languages ​​and / or assembly / machine languages. As used herein, the terms “machine-readable medium” and “computer-readable medium” refer to any computer program product, device, cloud storage, Internet of Things, and / or apparatus (e.g., magnetic disks, optical disks, memory, programmable logic devices (PLDs)) used to provide machine instructions and / or data to a programmable processor, including machine-readable medium that receives machine instructions as machine-readable signals. However, “machine-readable medium” and “computer-readable medium” do not include transient signals. The term “machine-readable signal” refers to any signal used to provide machine instructions and / or any other type of data to a programmable processor.

[0077] The terms “and,” “or,” “and / or,” and “and / or” as used herein include a variety of meanings, which are also expected to depend at least partially on the specific context in which such terms are used. Typically, when used to relate a list such as A, B, or C, “or” is intended to mean A, B, and C, as used here in an inclusive sense, as well as A, B, or C, as used here in an exclusive sense. Furthermore, the terms “one or more” and / or similar are used to describe any single feature, structure, and / or characteristic, and also to describe multiple and / or several other combinations of features, structures, and / or characteristics. Of course, for all of the foregoing, the specific context of the explanation and / or use provides useful guidance on the inferences to be drawn. It should be noted that the following explanations merely provide one or more exemplary examples, and the subject matter claimed is not limited to these one or more exemplary examples. However, again, the specific context of the explanation and / or use provides useful guidance on the inferences to be drawn.

[0078] While several exemplary techniques have been described and demonstrated herein using various methods and systems, it should be understood by those skilled in the art that various other modifications may be made and equivalents may be substituted without departing from the claimed subject matter. Furthermore, many modifications may be made to adapt specific situations to the teachings of the claimed subject matter without departing from the central concepts described herein. Thus, the claimed subject matter is not limited to the specific embodiments disclosed, but such claimed subject matter may also include all implementations within the scope of the appended claims and their equivalents.

Claims

1. The steps include receiving the input audio signal, The steps include determining the baseline frequency and A step of determining crossover points for a driver of a multiway speaker system, wherein each crossover point includes a multiple of the third harmonic of the baseline frequency, The steps include determining the signal delay of the audio signal component to be transmitted to the driver, The steps include transmitting the audio signal component to the driver based on the determined signal delay, The steps include: generating a synthesized audio signal including the audio signal components using the driver; A method that includes this.

2. The method according to claim 1, wherein the baseline frequency is determined at least in part on one cutoff frequency of the driver.

3. The method according to claim 1, wherein the signal delay is determined at least in part on the selected crossover point in order to align the signal output from the driver.

4. The method according to claim 1, wherein the step of determining the crossover point is performed manually.

5. The method according to claim 1, wherein the step of determining the crossover point is performed automatically.

6. One or more drivers of a multiway speaker system that generate the audio signal components of a synthesized audio signal, Processor and The processor includes, Receives input audio signal, Determine the baseline frequency, Determine the crossover points of one or more drivers, where each crossover point includes a multiple of the third harmonic of the baseline frequency. Determine the signal delay of the audio signal component to be transmitted to the aforementioned driver. Based on the determined signal delay, the audio signal component is transmitted to the driver. system.

7. The system according to claim 6, wherein the processor determines the baseline frequency at least in part based on one cutoff frequency of the driver.

8. The system according to claim 6, wherein the processor determines the signal delay at least partially based on the selected crossover point in order to align the signal output from the driver.

9. The system according to claim 6, wherein the processor determines the crossover point based on user input.

10. The system according to claim 6, wherein the processor automatically determines the crossover point.

11. The steps include receiving an input radio frequency (RF) signal, The steps include filtering the input RF signal into a plurality of RF signal components, The steps include determining the center frequency of each of the consecutive RF signal components of the RF signal component, The steps include determining a timing delay for the transmission of one or more of the RF signal components based on the respective center frequencies determined, The steps include transmitting the RF signal component through one or more transducers based on the determined timing delay, A method that includes this.

12. The method according to claim 11, wherein the RF signal component includes a portion of the radar signal.

13. The method according to claim 11, further comprising the step of transmitting the RF signal component by one or more transducers of the cell tower.

14. The method according to claim 11, further comprising the step of transmitting the RF signal component by one or more transducers of the mobile device.

15. The method according to claim 11, wherein a specific timing delay for a specific RF signal component having a specific frequency includes the reciprocal of the respective center frequencies between the specific RF signal component and another RF signal component having a lower frequency than the specific RF signal component.

16. The method according to claim 11, wherein the timing delay is determined automatically.

17. The method according to claim 11, wherein the timing delay is determined manually.

Images