Apparatus and method for decoding data from a wireless signal

Abstract

Embodiments of the present disclosure relate to devices and methods for decoding data from a wireless signal. An electronic device receives a wireless signal encoded with data in an amplitude shift keying format. The electronic device passes the wireless signal through a low pass filter. The low pass filter has a cutoff frequency between a first frequency associated with a first type of data value and a second frequency associated with a second type of data value. The low pass filter has an effect of changing the wireless signal from the amplitude shift keying format to an on-off keying format without losing data. The electronic device decodes the data from the wireless signal in the on-off keying format.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of wireless communication. The present disclosure more specifically relates to wireless communication between two nearby devices. BACKGROUND

[0002] Wireless communication signals are transmitted from a transmitting device to a receiving device. In many cases, the transmitting device transmits a carrier signal. One broad class of modulation schemes is amplitude shift keying (ASK). In ASK modulation schemes, information is transmitted by modulating the amplitude of the carrier signal. A low amplitude can represent a binary value of 0. A high amplitude can represent a binary value of 1.

[0003] Within the class of ASK modulation schemes, there are various sub-classes. In some schemes, information is not transmitted by the amplitude level but by a transition in the carrier signal amplitude (Manchester coding). The advantage is that the transition supports the recovery of the clock, and for this reason, these schemes are also referred to as self-clocking. For example, a binary 0 can be encoded as binary 01, which corresponds to a low-to-high transition. A binary 1 can be encoded as binary 10, which corresponds to a high-to-low transition. The transition occurs in the middle of the bit interval to support clock recovery. There can also be a transition at the bit boundary to set the carrier amplitude at the correct level. In another case, information is encoded based on the presence or absence of a transition in the middle of the bit interval (differential Manchester coding). For example, a binary 0 can be encoded as binary 00 or 11 (no transition in the middle of the bit interval). A binary 1 can be encoded as binary 01 or 10 (a transition occurs in the middle of the bit interval). The encoding pattern is chosen to guarantee a transition at the bit boundary to support clock recovery.

[0004] One problem that arises in certain ASK modulation schemes is that depending on the type of data, the modulated carrier can have a large bandwidth. For example, in some ASK modulation schemes, a stream of binary 1s can be encoded as 10101010…, a stream of binary 0s can be encoded as 01010101…, and alternating 1s and 0s can be encoded as 01100110011…. The latter stream has half the bandwidth relative to the first two streams.

[0005] In some ASK modulation schemes, a stream of binary 1s is encoded as 10101010…, and a stream of binary 0s is encoded as 00110011…. Again, the bandwidth of the latter stream is half that of the former. The effect is that at the receiving end, a filter with a larger bandwidth is utilized, and a higher sampling frequency can be required to decode one type of binary value stream (e.g., all 0s or all 1s) relative to the other type of binary value stream. This can degrade performance and increase the cost and complexity of the receiving device. SUMMARY

[0006] Embodiments of the present disclosure provide a receiving electronic device of a wireless communication system that utilizes a receive bandwidth corresponding to a lower of two frequencies present in a modulated carrier signal received by the receiving device to decode data. In particular, the receiving device utilizes a low pass filter that filters out signal characteristics corresponding to a larger bandwidth. The electronic device accomplishes this without losing data corresponding to the larger bandwidth.

[0007] The receiving electronic device can receive a self-clocking ASK modulated signal and convert the self-clocking ASK modulated signal to an on-off keying (OOK) signal by passing the ASK signal through a low pass filter. The higher frequency is completely suppressed by the low pass filter, resulting in zero amplitude for bits having a larger modulation bandwidth and non-zero amplitude for bits having a smaller modulation bandwidth. The bits having the larger modulation bandwidth can be recovered based on the duration between non-zero amplitude events.

[0008] This provides several benefits. A lower frequency clock can be used in the receiving device without losing bits associated with a larger bandwidth in the received signal. Because the passband of the receive side filter is narrow, out-of-band noise is more effectively suppressed. For the same reason, very close interferers can also be rejected. Thus, a receiving device according to the principles of the present disclosure has higher power efficiency and is more tolerant of noise.

[0009] The bit rate and corresponding bandwidth can be too large for the communication channel, or the bandwidth provided by the communication channel can be too narrow to pass bits having a larger modulation bandwidth without distortion. A receiving device according to the principles of the present disclosure will still be able to receive and decode the data stream without error. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a block diagram of a wireless communication system according to one embodiment.

[0011] Figure 2 is a plurality of graphs illustrating a carrier signal and ASK and OOK transmission modulation schemes.

[0012] Figure 3 includes a plurality of graphs illustrating various data patterns with differential Manchester encoding according to one embodiment.

[0013] Figure 4A is a plurality of graphs illustrating various signals modulated according to a differential Manchester ASK modulation scheme.

[0014] Figure 4B is a plurality of graphs illustrating ASK by a receiving device according to one embodiment. Figure 4A of a signal.

[0015] Figure 4Cis a plurality of graphs showing signals processed by a receiving device according to one embodiment. Figure 4A

[0016] Figure 5A - 5C is a plurality of graphs showing signals after noise is introduced into the signals of Figure 4A - 4C according to one embodiment.

[0017] Figure 6 is a block diagram of a wireless communication system 600 according to one embodiment.

[0018] Figure 7 is a flowchart of a method for operating a wireless communication system according to one embodiment. DETAILED DESCRIPTION

[0019] Figure 1 is a block diagram of a wireless communication system 100 according to one embodiment. The wireless communication system 100 includes a receiving electronic device 102 and a transmitting electronic device 104. The transmitting electronic device 104 and the receiving electronic device 102 communicate with each other using wireless communication technology.

[0020] The receiving electronic device 102 includes a receiving circuit 106. The receiving circuit 106 receives wireless signals from the transmitting electronic device. The receiving circuit 106 can include one or more antenna coils, one or more receive clocks, one or more controllers, and one or more memories. The receiving circuit 106 enables the receiving electronic device 102 to receive wireless signals from the transmitting electronic device 104 and read data encoded into the wireless signals.

[0021] The receiving circuit 106 of the receiving electronic device 102 includes a filter 108. As will be set forth in greater detail below, the filter 108 enables the receiving circuit 106 to receive wireless signals from the transmitting electronic device 104 that include both large bandwidth data values and small bandwidth data values, and filter out characteristics of the large bandwidth data values without losing data associated with the large bandwidth data values.

[0022] Figure 2 includes a graph 204 showing a carrier signal. With reference to Figure 1 and Figure 2 , the graph 204 corresponds to a carrier signal output from the transmitting electronic device 104. The carrier signal is a radio frequency signal that facilitates wireless communication. The carrier signal can include a substantially sinusoidal waveform, a square wave, or other type of waveform.

[0023] Data can be encoded into the carrier signal by the transmitting electronic device 104. The data can be encoded into the carrier signal by modulating the carrier signal. Various modulation schemes can be utilized to encode data into the carrier signal.

[0024] ​One type of modulation scheme is an ASK modulation scheme. Figure 2 Graph 206 in FIG. 2A illustrates a basic ASK modulation scheme. In an ASK modulation scheme, data is encoded into a carrier signal by modulating the amplitude of the carrier signal. Figure 2 Graph 202 illustrates a series of data values. Graph 206 illustrates the amplitude of a carrier signal during each of these data values. A binary 0 is encoded into the carrier signal by reducing the amplitude of the carrier signal. A binary 1 is encoded into the carrier signal by increasing the amplitude of the carrier signal or by leaving the carrier signal at a standard amplitude. As can be seen from graphs 206 and 202, when the encoded value is a binary zero, the carrier signal in graph 206 has a low amplitude. When the encoded value is a binary 1, the carrier signal of graph 206 has a high amplitude, or substantially equal to the amplitude of the unmodulated carrier signal. Alternatively, a binary 1 can be encoded with a low amplitude, and a binary 0 can be encoded with a high amplitude. As will be set forth in greater detail below, there are various types of modulation schemes that fit into the ASK modulation scheme category.

[0025] Another type of modulation scheme is an OOK modulation scheme. Figure 2 Graph 208 in FIG. 2A illustrates the basic concept of an OOK modulation scheme. In an OOK modulation scheme, data is encoded into a carrier signal by turning the carrier signal on and off. A data value of 0 can be encoded into the carrier signal by turning the carrier signal completely off or reducing the amplitude of the carrier signal to substantially zero. A data value of 1 can be encoded into the carrier signal by turning the carrier signal on. Thus, when a 0 is encoded into the carrier signal, the amplitude of the carrier signal is reduced to zero. When a 1 is encoded into the carrier signal, the amplitude of the carrier signal is maintained at a standard level. Alternatively, a 1 can be encoded by turning the carrier signal off, and a 0 can be encoded by turning the carrier signal on.

[0026] In some cases, the level of the carrier signal is not sufficient to enable the receiving electronics 102 to decode the data encoded into the carrier signal. A sampling clock, i.e., the bit boundaries and intervals in which data is encoded into the carrier signal, is known so that the receiving electronics 102 can sample and decode the data from the carrier signal. The clock signal can be sent separately from the carrier signal in order to maintain synchronization and avoid bit slippage. The clock signal can also be sent with the data by using a particular type of encoding.

[0027] One example of a self-clocking ASK scheme is Manchester encoding. In Manchester encoding, information is sent through a transition in the amplitude of the signal carrier. In particular, the direction of the transition determines the bit. For example, a 0 is encoded as 01, which corresponds to a low-to-high transition, and a 1 is encoded as "10", which corresponds to a high-to-low transition. There is always a transition in the middle of the bit interval. A clock signal can be extracted from the transitions. A transition can also occur at the bit boundary to set the carrier at the correct level.

[0028] Another example of a self-clocking ASK encoding scheme is differential Manchester encoding. In differential Manchester encoding, information is again sent through a transition in the amplitude of the carrier signal, but in this case the presence or absence of a transition in the middle of the bit interval determines the bit. For example, a 0 is encoded as 00 or 11, with no transition in the middle. A 1 is encoded as 01 or 1, with one transition in the middle. The encoding pattern is chosen to guarantee a transition at the bit boundary. For this reason, a clock signal can be extracted from the presence of a transition at the bit boundary.

[0029] Figure 3 A plurality of graphs showing various data patterns with differential Manchester encoding according to one embodiment are included. Graph 302 shows a series of all Os encoded into a carrier signal with differential Manchester encoding. Graph 304 shows a series of all Is encoded into a carrier signal with differential Manchester encoding. Graph 306 includes a mix of Os and Is.

[0030] As can be seen from graphs 302 and 304, in differential Manchester encoding a series of all Is utilizes twice the bandwidth of a series of all Os. The pulse width of a 1 is half the pulse width of a 0. Thus, the frequency associated with a binary 1 in differential Manchester encoding is effectively twice the frequency associated with a binary 0 in differential Manchester encoding.

[0031] Reference Figure 1 and Figure 3 If the transmitting electronics 104 transmits data by encoding a carrier signal with a differential Manchester encoding scheme, it can be desirable for the receiving electronics 102 to utilize a receive clock or sampling rate associated with the higher frequency of a binary 1. However, in some cases it can not be possible for the receiving electronics to utilize a higher frequency or sampling, or it can be too power intensive. In addition, in some cases the transmission channel can not provide the large bandwidth typically utilized by high frequencies in a modulated carrier, so the received waveform is severely distorted.

[0032] The receiving electronics 102 overcomes these drawbacks by utilizing filter 108. Specifically, in the differential Manchester coding scheme, the receiving electronics 102 utilizes filter 108 to filter out all frequencies higher than those associated with binary 0. Therefore, the low-pass filter 108 is a low-pass filter having a cutoff frequency between the lower frequencies associated with binary 0 and the higher frequencies associated with binary 1.

[0033] Electronic device 102 effectively converts the ASK modulated wireless signal received from transmitting electronic device 104 into an OOK modulated signal. Specifically, because signal characteristics associated with 1 are filtered out by filter 108, the signal becomes an OOK signal, where 1 has zero amplitude and 0 has non-zero amplitude. The 0s have non-zero amplitude because they have frequencies lower than the cutoff frequency of the low-pass filter 108.

[0034] Because the receiving electronics 102 converts the ASK modulated signal into an OOK modulated signal in which only 0s have amplitude, the receiving electronics 102 does not require a sampling rate associated with the higher frequencies of 1s in the differential Manchester ASK signal received from the transmitting electronics 104. The receiving electronics 102 can extract 1s from the OOK signal in essentially the same way as extracting 0s from a conventional OOK signal. In particular, the gaps between non-zero amplitude features, or the gaps between the falling and rising edges of the OOK signal, indicate the presence of one or more binary 1s. The duration or length of the gaps between non-zero amplitudes or high amplitudes indicates the number of 1s present.

[0035] Figure 4A This diagram includes a plurality of wireless signals received and initially demodulated by receiving electronics 102 from transmitting electronics 104 according to one embodiment. Prior to demodulation, the signals are received in a differential Manchester ASK coding scheme. Figure 4A The signal is shown in Figure 402, which shows a stream of all 1s. Figure 404 shows a mixed stream of 1s and 0s, where there are more 1s than 0s. Curve 406 shows a mixed stream of 1s and 0s, where the number of 1s and 0s is approximately equal. Figure 408 shows a mixed stream of 1s and 0s, where there are more 0s than 1s. Figure 410 shows a stream of all 0s. Curves 402–410 show the frequency differences associated with 0s and 1s in the Differential Manchester coding scheme. In particular, the frequency associated with 1s is approximately twice the frequency associated with 0s.

[0036] Figure 4B Including, according to one embodiment, corresponding to Figure 4Aof the signal after passing through the edge detector. Graph 412 corresponds to graph 402 after passing through the edge detector. Graph 414 corresponds to graph 404 after passing through the edge detector. Graph 416 corresponds to graph 406 after passing through the edge detector. Graph 418 corresponds to graph 408 after passing through the edge detector. Graph 420 corresponds to graph 410 after passing through the edge detector. The edge detector can be Figure 1 of the receiving circuit 104 of the receiving electronics 102.

[0037] According to one embodiment, Figure 4C includes a signal corresponding to Figure 4B of the signal after passing through Figure 1 of the low pass filter 108 of the receiving electronics 102. Graph 422 corresponds to graph 412 after passing through the low pass filter 108. Graph 424 corresponds to graph 414 after passing through the low pass filter 108. Graph 426 corresponds to graph 416 after passing through the low pass filter 108. Graph 428 corresponds to graph 418 after passing through the low pass filter 108. Graph 430 corresponds to graph 420 after passing through the low pass filter 108.

[0038] Figure 4C The higher frequency features associated with the digit 1 are shown to be completely absent after being passed to the low pass filter 108. Graph 422 shows that a stream of all 1s results in a signal with no amplitude. Graph 430 shows that a stream of all 0s produces a signal with a frequency associated with the lower frequency of 0s in the differential Manchester encoding scheme. In each of the signals 422-430, the higher frequency features associated with 1s in the differential Manchester encoding scheme are removed.

[0039] Figure 4C The graph of the signal corresponds to an OOK modulated signal. In Figure 4C In the OOK signal, a 1 is represented by a duration of substantially no amplitude. In Figure 4C In the OOK signal, a 0 is represented by a duration of non-zero amplitude. As previously described, a 1 can be extracted from the OOK signal by determining the duration of the substantially zero amplitude period between non-zero amplitude periods. In practice, other signal processing or conditioning can be performed on the signal prior to decoding or retrieving data from the OOK signal. For example, the signal processing or conditioning can transform the sharp features of graphs 422-430 into substantially square wave-like features. Various other types of signal processing or conditioning can be performed without departing from the scope of the disclosure. Figure 4C

[0040] ​While embodiments have been described of converting a differential Manchester encoded signal into an OOK signal in which 1 has no amplitude and 0 has a non-zero amplitude, other types of encoding schemes can be utilized without departing from the scope of the present disclosure. For example, other types of ASK encoded signals can be converted into other types of OOK signals.

[0041] One benefit of the narrower bandwidth associated with filter 108 is that more out-of-band noise is suppressed. Another benefit is that very close interferers can be rejected. Interferers at bit rate frequencies can also be rejected. These interferers can be generated by non-linearities in the transmission channel or in the analog receive and demodulation circuitry (mixers and filters). Interferers generated by non-linearities are difficult to remove by linear processing techniques such as adaptive equalization filters. Adaptive filters can not converge to the correct solution, and even when they do converge, the linear compensation for the non-linearity can not be sufficient. The application of filter 108 makes the receive electronics 102 more tolerant to noise and robust to adjacent interferers, especially those generated by non-linearities. The implementation is non-adaptive and eliminates the probabilistic behavior of adaptive filters that can fail at runtime. This results in smaller circuit area, lower power consumption, and lower bit error rate.

[0042] Another benefit is that when the bandwidth of the communication channel is less than the bandwidth required by a larger frequency, the receiver according to the present disclosure becomes insensitive to distortions associated with the larger frequency. If everything else remains equal, the receiver according to the present disclosure will support successful decoding of a higher communication bit rate (twice the rate allowed by a conventional ASK receiver).

[0043] In one example, the received signal is sampled and demodulated to have 24 samples per bit interval. Differential Manchester encoding is used. Low pass filter 108 is configured with a cutoff frequency = Fbit(12 sample moving average) and a cutoff frequency = Fbit / 2 (24 sample moving average). The edge detector is a correlator of a step function with 24 samples per bit interval (12 low, 12 high).

[0044] After differential Manchester encoding, there is always a transition at the bit boundary. When a 0 is transmitted, there is no other transition, and the output of the edge detector will have two local maxima or minima separated by a full bit interval. When a 1 is transmitted, there is also a transition in the middle of the bit interval, and the output of the edge detector will have three local maxima or minima separated by half a bit interval. When the signal is transformed into OOK, a 1 will flatten the output, while a 0 will have the output with only one local maximum or minimum. To avoid bit slippage and ensure synchronization, long sequences of 1 can be avoided. This can be obtained by bit stuffing techniques or by proper encoding, such as adding an even parity bit every N bits, where N is even.

[0045] Figure 5A - 5C is a graph showing signals associated with 4C according to one embodiment, where an interferer is added to the signals. More specifically, Figure 4A - 5C is a graph showing signals associated with 4C according to one embodiment, where an interferer is added to the signals. More specifically, Figure 5A The graphs 502-510 correspond to the graphs 402-410 of Figure 4A The graphs 502-510 correspond to the graphs 402-410 of Figure 4B The graphs 522-530 correspond to the graphs 422-430 of Figure 5A The graphs 522-530 correspond to the graphs 422-430 of It is noted that the graphs 522-530 show that the low pass filter significantly reduces the impact of the interferer, as the graphs 522-530 strongly match the graphs 422-430, but with a small amount of noise. Such a small amount of noise would not accurately prevent the coating of data from the signal.

[0046] Returning to Figure 1 In one embodiment, the transmitting electronic device 104 is a wireless charging device. In this case, the carrier signal is configured to provide energy to the receiving electronic device 102. For example, the transmitting electronic device 104 outputs the carrier signal when the receiving electronic device 102 is placed adjacent to the transmitting electronic device 104. The receiving electronic device 102 includes an energy harvesting circuit that harvests energy from the carrier signal. In this case, the carrier signal can also be referred to as a wireless charging signal. The receiving electronic device 102 can generate a charging current from the carrier signal.

[0047] In one embodiment, the wireless charging circuit operates according to the Qi wireless charging standard. The Qi wireless charging circuit outputs a charging field in the range between 100 kHz and 500 kHz, although other frequencies can be used as a tuning standard or as different application requirements for other frequencies outside of this range. Data can be encoded into the charging field at a lower frequency than the frequency of the charging field. When the encoded data is from the charging field, a low pass filter will effectively filter out the impact of the higher frequency charging field. Other wireless charging standards can be utilized without departing from the scope of the present disclosure.

[0048] In one embodiment, the transmitting electronic device 104 and the receiving electronic device 102 are near field communication (NFC) devices. Specifically, the transmitting electronic device 104 outputs an NFC carrier signal having interrogation data encoded into the carrier signal. The receiving electronic device 102 receives the carrier signal and decodes the carrier signal using a low pass filter as previously described. The receiving electronic device and the transmitting electronic device 104 can communicate with each other using NFC protocols. In one example, the NFC carrier signal has a frequency of 13.56 MHz. However, other frequencies of the carrier signal can be utilized without departing from the scope of the present disclosure. The data is encoded into the carrier signal at a lower frequency than the frequency of the carrier signal. Thus, when the data is encoded from the NFC carrier signal, the low pass filter can effectively suppress the influence of the higher frequency NFC carrier signal. The receiving electronic device 102 can include an active NFC device or a passive NFC device.

[0049] While Figure 1 The transmitting electronic device 104 and the receiving electronic device 102 are shown, however, in practice, the receiving electronic device can also transmit data to the transmitting electronic device 104. Thus, the transmitting electronic device 104 and the receiving electronic device can each transmit and receive data from each other. Thus, the transmitting electronic device 104 and the receiving electronic device 102 can be referred to as first and second electronic devices.

[0050] Figure 6 is a block diagram of a wireless communication system 600 in accordance with one embodiment. The wireless communication system 100 includes an electronic device 122 and a wireless charging device 124. The wireless charging device is Figure 1 an example of the transmitting electronic device 104. The electronic device 122 is Figure 1 an example of the receiving electronic device 102.

[0051] The transmitting electronic device 104 includes a transceiver 121, a control system 123, a power source 125, and a charging port 126. The control system 123 includes control logic 127. The components of the transmitting electronic device 104 cooperate together to provide wireless communication and separate wireless charging.

[0052] The transceiver 121 enables the wireless charging device 124 to transmit signals and receive signals. The transceiver 121 can include one or more antennas for transmitting NFC signals and for receiving NFC signals. The transceiver 121 can include additional circuitry for enabling the transceiver 121 to transmit signals including interrogation signals, carrier signals, and other types of signals. The transceiver 121 can include additional circuitry for enabling the transceiver 121 to receive and process signals including interrogation signals and other types of signals from the electronic device 122.

[0053] The control system 123 includes control circuitry for controlling the functions of the wireless charging device 124. The control system 123 controls the operation of the transceiver 121. The control system 123 controls the transmission of signals by the transceiver 121. The control system 123 also controls the reception of signals by the transceiver 121. The control system 123 can include processing resources, memory resources, and data transmission resources.

[0054] The control system 123 includes control logic 127. The control logic 127 can include instructions for controlling the operation of the control system 123. The control logic 127 can include instruction protocols for performing operations, processes, and methods performed by the wireless charging device 124, including those described herein. The control logic 127 can correspond to software instructions stored in memory of the wireless charging device 124.

[0055] The power source 125 provides power to the wireless charging device 124. The power source 125 can include one or more of an internal battery, a wired power connection to an external power source, a wireless power connection to an external power source.

[0056] The transceiver 121 selectively provides a wireless charging field to the electronic device 122. The transceiver 121 includes one or more antennas. In one embodiment, the transceiver 121 operates according to the Qi wireless charging standard. The Qi wireless charging circuit outputs a charging field with a range between 87 kHz and 205 kHz. The transceiver 121 can also operate according to charging protocols or standards other than Qi without departing from the scope of the present disclosure.

[0057] The transceiver 121 of the wireless charging device 124 can be controlled by the control logic 127 of the control system 123. The RF transceiver selectively outputs a wireless charging field based on the type of NFC device detected by the control system 123.

[0058] The charging dock 126 includes a physical area on which the electronic device 122 can be positioned to receive a wireless charging signal from the wireless charging device 124. When the electronic device 122 is positioned on the charging dock 126, the wireless charging device 124 detects the electronic device 122 and causes the transceiver 121 to begin outputting a wireless charging field.

[0059] The electronic device 122 includes an antenna coil 130, a controller 132, an energy harvesting circuit 136, and a memory 134. The antenna coil 130 includes one or more antennas and other circuitry for receiving signals from and providing signals to the wireless charging device 124. Thus, the antenna coil 130 can be part of a transceiver of the electronic device 122.

[0060] The controller 132 controls operation of the antenna coil 130. The controller 132 controls the modulated signal output from the antenna coil 130 in response to the interrogation signal received from the wireless charging device 124. The controller 132 can control the modulation of the impedance of the antenna coil 130. The memory 134 stores identification data related to the electronic device 122.

[0061] The energy harvesting circuit 136 harvests energy from the signal when the antenna coil 130 receives the signal from the wireless charging device 124. If the electronic device 122 is an active electronic device, the electronic device 122 can use the energy harvested from the wireless charging signal to provide a charging current to a battery of the electronic device 122. If the electronic device 122 is a passive electronic device, the energy harvested from the wireless charging signal can be used to power other components of the electronic device 122.

[0062] In one embodiment, when the antenna coil 130 receives the wireless charging signal, the wireless charging signal is passed to both the energy harvesting circuit 136 and the low pass filter 108 in parallel with each other. The low pass filter 108 filters out higher frequency signals associated with higher bit rate or bandwidth data values encoded into the wireless charging signal, such as binary 1 in the case of differential Manchester encoding. Thus, the low pass filter 108 effectively converts the ASK modulated wireless charging signal to an OOK modulated wireless charging signal. Then, as previously described, a controller or other receiving circuit can decode the data from the OOK signal. Other circuits can be included by the electronic device 122 without departing from the scope of the disclosure.

[0063] Figure 7 is a flowchart of a method 700 for operating an electronic device according to one embodiment. The method 700 can utilize components, systems, and processes described with respect to Figure 1 -6. At 702, the method 700 includes receiving, with a first electronic device, a carrier signal transmitted from a second electronic device, the carrier signal including data encoded with a phase shift keying scheme. At 704, the method 700 includes generating, from the carrier signal of the first electronic device, an on-off keying signal by passing the carrier signal through a low pass filter. At 706, the method 700 includes decoding, with the first electronic device, the data from the on-off keying signal.

[0064] In one embodiment, a method includes receiving, with an electronic device, a carrier signal encoded with data; and harvesting, with the first electronic device, energy from the carrier signal. The method includes passing the carrier signal through a low pass filter having a cutoff frequency between a first frequency associated with a first type of data value and a second frequency associated with a second type of data value; and decoding, after passing the carrier signal through the low pass filter, the data from the carrier signal.

[0065] In one embodiment, a method includes receiving, with a first electronic device, a carrier signal transmitted from a second electronic device, the carrier signal including data encoded with an amplitude shift keying scheme. The method includes generating, with the first electronic device, an on-off keying signal from the carrier signal by passing the carrier signal through a low pass filter and decoding, with the first electronic device, the data from the on-off keying signal.

[0066] In one embodiment, an electronic device includes an antenna configured to receive, from a transmitting electronic device, a carrier signal including data encoded with an amplitude shift keying scheme. The electronic device includes a low pass filter configured to receive the carrier signal and generate an on-off keying signal from the carrier signal. The electronic device includes a controller configured to decode the data from the on-off keying signal.

[0067] The various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the detailed description. The terms used in the following claims should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims. Rather, the scope of the claims should be construed more broadly, in accordance with the principles of the patent laws. Thus, the claims are not limited to the embodiments described herein but are to be accorded the full scope consistent with the patent laws.

Claims

1. A method for wireless communication, comprising: receiving, with a first electronic device, a carrier signal transmitted from a second electronic device, the carrier signal comprising data encoded with a frequency shift keying scheme; demodulating the carrier signal to produce a demodulated signal in which data having a first binary state has a lower frequency than data having a second binary state; applying an edge detector to the demodulated signal; applying a low pass filter to a signal provided by the edge detector to produce an on-off keying signal, wherein: data having the first binary state is represented by a duration of a non-zero amplitude; and data having the second binary state is represented by a duration of a zero amplitude.

2. The method of claim 1, wherein binary 0 corresponds to the first binary state and binary 1 corresponds to the second binary state.

3. The method of claim 1, wherein the frequency shift keying scheme is a differential Manchester scheme.

4. The method of claim 3, wherein in the frequency shift keying scheme, binary 1 has a shorter characteristic length than binary 0.

5. The method of claim 1, further comprising harvesting energy with the electronic device from the carrier signal.

6. The method of claim 5, further comprising: generating a charging current by harvesting energy from the carrier signal; and charging a battery of the electronic device with the charging current.

7. The method of claim 1, wherein the carrier signal is a Qi standard carrier signal.

8. The method of claim 1, wherein the carrier signal is a near field communication signal.

9. The method of claim 1, further comprising passing the carrier signal through a frequency shift keying of the first electronic device prior to passing the carrier signal through the low pass filter.

10. The method of claim 1, wherein the low pass filter has a cutoff frequency that is greater than a first frequency associated with data values of the first binary state and the cutoff frequency is less than a second frequency associated with data values of the second binary state.

11. An electronic device, comprising: an antenna configured to receive a carrier signal from a transmitting electronic device, the carrier signal comprising data encoded with a frequency shift keying scheme; a demodulator configured to receive the carrier signal and deliver a demodulated signal in which data having a first binary state has a lower frequency than data having a second binary state; an edge detector configured to receive the demodulated signal; a low pass filter configured to receive a signal provided by the edge detector to produce an on-off keying signal, wherein: data having the first binary state is represented by a duration of a non-zero amplitude; and data having the second binary state is represented by a duration of a zero amplitude.

12. The electronic device of claim 11, further comprising energy harvesting circuitry coupled to the antenna and configured to harvest energy from the carrier signal. ​ ​ ​ 13. The electronic device of claim 12, further comprising a battery coupled to the energy harvesting circuitry, wherein the energy harvesting circuitry generates a charging current from the carrier signal and provides the charging current to the battery.

14. The electronic device of claim 11, wherein the amplitude shift keying scheme is a differential Manchester scheme.

15. The electronic device of claim 14, wherein in the amplitude shift keying scheme, a binary one has a shorter characteristic length than a binary zero.

16. The electronic device of claim 11, wherein the carrier signal is a Qi standard carrier signal.

17. A method for wireless communication, comprising: receiving, with an electronic device, a carrier signal encoded with data; harvesting, with first electronic device, energy from the carrier signal; demodulating the carrier signal to produce a demodulated signal in which data having a first binary state has a lower frequency than data having a second binary state; applying an edge detector to the demodulated signal; passing the demodulated signal through a low pass filter having a cutoff frequency between a first frequency associated with data values of the first binary state and a second frequency associated with data values of the second binary state, and converting the demodulated signal to an on-off keying signal, wherein: data having the first binary state is represented by a duration of a non-zero amplitude; and data having the second binary state is represented by a duration of a zero amplitude.

18. The method of claim 17, wherein the carrier signal is encoded with data in an amplitude shift keying format.

19. The method of claim 18, further comprising: decoding the data from the carrier signal in the on-off keying format.

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