CN106487426B - Capacitive coupling type human body communication transceiver aided design system and method - Google Patents
Capacitive coupling type human body communication transceiver aided design system and method Download PDFInfo
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- 238000013461 design Methods 0.000 title claims abstract description 17
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- H04B5/00—Near-field transmission systems, e.g. inductive or capacitive transmission systems
- H04B5/20—Near-field transmission systems, e.g. inductive or capacitive transmission systems characterised by the transmission technique; characterised by the transmission medium
- H04B5/22—Capacitive coupling
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04B17/00—Monitoring; Testing
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- H04B—TRANSMISSION
- H04B5/00—Near-field transmission systems, e.g. inductive or capacitive transmission systems
- H04B5/40—Near-field transmission systems, e.g. inductive or capacitive transmission systems characterised by components specially adapted for near-field transmission
- H04B5/48—Transceivers
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Abstract
The invention relates to a capacitive coupling human body communication transceiver aided design system and a method, which comprises an upper computer module, a data acquisition card, a power supply, an isolation circuit module and a human body channel, wherein a sending end and a receiving end of the human body channel respectively adopt a single electrode for transmission; the electrodes of the sending end and the receiving end are both contacted with the human body, the ground electrodes are both in a floating state, and the sending end and the receiving end transmit information through electric fields excited by the electrodes on the surface and around the human body; the electric field loop excited by capacitive coupling is composed of a transmitting end, a human body, air, a ground and a receiving end. The invention can provide convenience for rapid prototype creation and simulation work for developers in product development.
Description
Technical Field
The invention relates to the field of human body communication transceivers, in particular to a capacitive coupling type human body communication transceiver aided design system and a capacitive coupling type human body communication transceiver aided design method.
Background
The existing human body communication transceiver prototype is mainly based on hardware real objects, although human body channels have common characteristics, personalized differences still exist in real human body channels, and the human body communication transceiver device based on hardware consumes long time and is not easy to achieve personalized matching of hardware parameters and channels when parameter adjustment is carried out on different human body channel systems.
Disclosure of Invention
In view of the above, an objective of the present invention is to provide a system and a method for auxiliary design of a capacitive coupling type human body communication transceiver, which can provide developers with convenience for rapid prototyping and simulation in product development.
The invention is realized by adopting the following scheme: a capacitive coupling human body communication transceiver aided design system comprises an upper computer module, a data acquisition card, a power supply, an isolation circuit module and a human body channel; the upper computer module comprises a signal modulator, a signal demodulator, a parameter setting control and a data display module, and is used for setting and displaying dynamic parameters of modulation and demodulation and conditioning functions of baseband sending signals and baseband receiving signals; respectively adopting a single electrode to transmit at a transmitting end and a receiving end of the human body channel; the electrodes of the sending end and the receiving end are both contacted with the human body, the ground electrodes are both in a floating state, and the sending end and the receiving end transmit information through electric fields excited by the electrodes on the surface and around the human body; the electric field loop excited by capacitive coupling is composed of a transmitting end, a human body, air, a ground and a receiving end.
Further, the isolation circuit module can comprise an optical coupling isolation circuit and a pulse transformer isolation circuit.
The invention also provides a method for designing the system based on the capacitive coupling type human body communication transceiver, which comprises the following steps:
step S1: under different scenes, measuring the human body channel characteristics, and displaying the content of the measured channel characteristics in an upper computer module; the different scenes comprise different frequencies, different receiving and transmitting distances, different human body parts and different types of electrodes; the human body channel characteristics comprise channel capacity and channel gain;
step S2: setting parameters of a signal modulator, generating a modulation signal and displaying the modulation signal in an upper computer; the parameters of the signal modulator comprise a sending baseband sequence, a carrier frequency, a phase and a sending end signal amplitude;
step S3: the upper computer module writes a signal into the output end of the data acquisition card by calling a driving program of the data acquisition card;
step S4: the signals output by the data acquisition card pass through the isolation circuit module and are coupled to the receiving end from the transmitting end through a human body channel through an electric field excited around a human body by capacitive coupling;
step S5: the signal is input to the analog input end of the junction box of the data acquisition card through the receiving end electrode, and then the signal is transmitted to the upper computer module for demodulation;
step S6: according to the comparison between the demodulated baseband signal and the original baseband signal, adjusting the parameters of the signal demodulator to recover the baseband waveform of the transmitting terminal electrode; the parameters of the signal demodulator comprise amplification factors, a comparator decision threshold and filter cut-off frequency;
step S7: measuring the error rate of signal transmission, and finely adjusting parameters of a signal sending end, wherein the parameters of the signal sending end comprise baseband waveform parameters.
Further, the method for calculating the channel capacity adopts the following formula:
C＝Blog2(1+SNR)；
where B represents the signal bandwidth and SNR represents the signal-to-noise ratio.
Further, the channel gain is calculated according to the following formula:
wherein, UReceiveIs receiving a signal voltage, UTransmitIs the transmit signal voltage.
Preferably, the method for calculating the channel gain further adopts the following formula:
wherein, PReceiverIs the received signal power, PTransmitterIs the transmit signal power.
Compared with the prior art, the invention has the following beneficial effects: the invention provides an auxiliary design method of a personalized capacitor coupling type human body communication transceiver, which can provide convenience for rapid prototype creation and simulation work for developers in product development. The human body communication is reliably transmitted by measuring the human body channel in a personalized way through the virtual instrument and adjusting the module parameters of the human body communication transceiver of the upper computer software of the virtual instrument by combining the channel characteristics, so that the human body communication transceiver is matched with the personalized human body channel, an optimal human body communication transceiver system model is created, and the optimal human body communication transmission effect is achieved.
Drawings
FIG. 1 is a schematic block diagram of an embodiment of the present invention.
Fig. 2 is an interface schematic diagram of the upper computer module according to the embodiment of the present invention.
Detailed Description
The invention is further explained below with reference to the drawings and the embodiments.
As shown in fig. 1, the present embodiment provides a capacitive coupling type human body communication transceiver aided design system, which includes an upper computer module, a data acquisition card, a power supply, an isolation circuit module, and a human body channel; the upper computer module comprises a signal modulator, a signal demodulator, a parameter setting control and a data display module, and is used for setting and displaying dynamic parameters of modulation and demodulation and conditioning functions of baseband sending signals and baseband receiving signals; respectively adopting a single electrode to transmit at a transmitting end and a receiving end of the human body channel; the electrodes of the sending end and the receiving end are both contacted with the human body, the ground electrodes are both in a floating state, and the sending end and the receiving end transmit information through electric fields excited by the electrodes on the surface and around the human body; the electric field loop excited by capacitive coupling is composed of a transmitting end, a human body, air, a ground and a receiving end.
In this embodiment, the isolation circuit module may include an optical coupling isolation circuit and a pulse transformer isolation circuit.
The invention also provides a method for designing the system based on the capacitive coupling type human body communication transceiver, which comprises the following steps:
step S1: under different scenes, measuring the human body channel characteristics, and displaying the content of the measured channel characteristics in an upper computer module; the different scenes comprise different frequencies, different receiving and transmitting distances, different human body parts and different types of electrodes; the human body channel characteristics comprise channel capacity and channel gain;
step S2: setting parameters of a signal modulator, generating a modulation signal and displaying the modulation signal in an upper computer; the parameters of the signal modulator comprise a sending baseband sequence, a carrier frequency, a phase and a sending end signal amplitude;
step S3: the upper computer module writes a signal into the output end of the data acquisition card by calling a driving program of the data acquisition card;
step S4: the signals output by the data acquisition card pass through the isolation circuit module and are coupled to the receiving end from the transmitting end through a human body channel through an electric field excited around a human body by capacitive coupling;
step S5: the signal is input to the analog input end of the junction box of the data acquisition card through the receiving end electrode, and then the signal is transmitted to the upper computer module for demodulation;
step S6: according to the comparison between the demodulated baseband signal and the original baseband signal, adjusting the parameters of the signal demodulator to recover the baseband waveform of the transmitting terminal electrode; the parameters of the signal demodulator comprise amplification factors, a comparator decision threshold and filter cut-off frequency;
step S7: measuring the error rate of signal transmission, and finely adjusting parameters of a signal sending end, wherein the parameters of the signal sending end comprise baseband waveform parameters.
In this embodiment, the method for calculating the channel capacity adopts the following formula:
C＝Blog2(1+SNR)；
where B represents the signal bandwidth and SNR represents the signal-to-noise ratio.
In this embodiment, the channel gain is calculated by the following formula:
wherein, UReceiveIs receiving a signal voltage, UTransmitIs the transmit signal voltage.
Preferably, in this embodiment, the method for calculating the channel gain further adopts the following formula:
wherein, PReceiverIs the received signal power, PTransmitterIs the transmit signal power.
Preferably, in the human body communication application system, the signal transmitting and receiving parts are isolated from each other. However, when both the transmitting end and the receiving end are powered by the power supply of the acquisition card, the transmitting part and the receiving part may generate a common ground loop, resulting in an error in the experimental measurement result. The optical coupling circuit isolation module can isolate the common ground influence, so that the measurement result is closer to the scene of real human body communication full-floating ground power supply. After the human body channel parameters are measured by the virtual instrument, the human body communication transceiver is designed according to the measured channel characteristics.
As shown in fig. 2, fig. 2 is an interface schematic diagram of the upper computer module of the embodiment. The method comprises the steps of measuring and setting channel parameters, generating and setting baseband signals, modulating and demodulating, and displaying various waveform upper computers. There are three modulation and demodulation modes of ASK, FSK and BPSK, and a parameter adjustment key for each mode. The three human body communication modulation and demodulation units are all in an upper computer software program, and switching among different modes is facilitated. Firstly, setting channel parameter measurement, fixing channel length, setting fixed output voltage, measuring input voltage, observing signal change under different frequencies, and calculating output channel capacity and channel attenuation value according to a formula.
And basic setting of a baseband signal, and setting baseband parameters such as a baseband waveform, a baseband code element rate, code element duration and the like according to individual requirements. Besides, the system can set a plurality of parameters of a modulation unit (such as a sending carrier type, a carrier frequency, a phase, a sending end signal amplitude and the like) and a demodulation unit (such as an amplification factor, a comparator decision threshold, a filter cut-off frequency, frequency discrimination, identification and the like). And simultaneously, the system displays the amplitude-frequency characteristics, the sending baseband waveform, the acquisition card input waveform, the baseband recovery waveform and the like of the channel in a waveform manner.
In the channel characteristic parameter measurement, corresponding voltage and frequency can be set through the analog output end of the acquisition card to serve as test signals, and in the channel characteristic research process, signal gain (attenuation rate) is adopted to describe the signal transmission quality, and can be described as follows:
in the formula of UReceiveIs receiving a voltage, UTransmitIs the transmit voltage.
Channel capacity is a crucial parameter of instrument communication systems, and is described as:
C＝Blog2(1+SNR)
the baseband signal generator module of the human body communication sending end is designed and realized by a user-defined waveform module. Parameters such as baseband waveform can be adjusted and set. The baseband signal generator module is named binary sequence waveform. And the baseband sequence display resamples the baseband waveform by adopting a waveform resampling mode to form a baseband sequence. The module converts dynamic data into a single waveform through a dynamic data conversion module to transmit the waveform or demodulate the recovered baseband waveform output, then resamples the waveform, and sets sampling start time and sampling interval according to the code element rate of the baseband waveform by using a resampling waveform module. The recovered baseband waveform sequence can be stored in a spreadsheet for a subsequent error code calculation unit to calculate the error code rate by writing the sequence into the spreadsheet control.
The waveform is transmitted to upper computer software through an interface and a data acquisition card to process the configuration of the parameters of the data acquisition card. The signal waveform generated by the sending end through the upper computer software is a digitized waveform, the digital waveform needs to transmit data to the data acquisition card through an interface through a driving program of the hardware acquisition card, and then the digital signal is converted into an analog signal through a DA module of the data acquisition card and output. Similarly, the receiving end converts the received analog signal into a digital waveform through the AD module, and the waveform is transmitted to the upper computer software for processing through the interface and the data acquisition card.
In this embodiment, before the system platform is used, parameters (channel length, channel attenuation value, channel capacity, channel transmission frequency) of the human body channel characteristics need to be measured, and parameters of the human body communication transceiver system need to be selected and set according to the measured parameters. First, a system baseband waveform sequence, a symbol rate of a baseband signal, a symbol duration, a time interval of baseband waveform interpolation are set, and a single transmission or a cyclic transmission mode of a signal waveform can be selected. Then, parameters of a modulation part of the system are set, and the system can select ASK, FSK and BPSK modes, the frequency and amplitude of carrier signals, the carrier type and the like. After the system is operated, parameters such as the multiple of an amplifier of a demodulation part, the cut-off frequency of a filter and the like can be adjusted according to the recovery condition of a baseband waveform and by combining with parameters of a real human body channel, so that the mutual matching of a human body communication transceiver and a personalized human body channel is realized, and the optimal matching of the transceiver and the channel under the channel is achieved.
The system of the embodiment is a dynamic system with adjustable parameters, and under the capacitive coupling working mode, the system can measure the human body channel characteristics under different scenes of different frequencies, different transmission distances, different human body parts, different electrode types and the like by utilizing the measurement function of a virtual instrument, and the parameters of the human body communication transceiver module are continuously adjusted to realize the mutual matching of the human body communication transceiver and the personalized human body channel. The virtual instrument has the characteristics of strong measuring capability, convenient modification of functional parameters and the like, and can perform rapid prototype creation and simulation work for developers in product development, so that the platform can realize high-efficiency and rapid prototype creation of the human body communication transceiver, system transmission effect or performance evaluation, and provides guidance and reference for system hardware realization, thereby improving design efficiency, reducing hardware experiment cost and providing effectiveness and convenience for human body communication transceiver design. The technology can be applied to the fields of medical care and application, assistance of disabled people, consumer electronics products, user identification and the like.
The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.
Claims (5)
1. A capacitive coupling type human body communication transceiver aided design system is characterized in that: the device comprises an upper computer module, a data acquisition card, a power supply, an isolation circuit module and a human body channel; the upper computer module comprises a signal modulator, a signal demodulator, a parameter setting control and a data display module; respectively adopting a single electrode to transmit at a transmitting end and a receiving end of the human body channel; the electrodes of the sending end and the receiving end are both contacted with the human body, the ground electrodes are both in a floating state, and the sending end and the receiving end transmit information through electric fields excited by the electrodes on the surface and around the human body; the electric field loop excited by capacitive coupling consists of a sending end, a human body, air, a ground and a receiving end;
the design method comprises the following steps:
step S1: under different scenes, measuring the human body channel characteristics, and displaying the content of the measured channel characteristics in an upper computer module; wherein the different scenes comprise different frequencies, different receiving and transmitting distances, different human body parts and different types of electrodes; the human body channel characteristics comprise channel capacity and channel gain;
step S2: setting parameters of a signal modulator, generating a modulation signal and displaying the modulation signal in an upper computer; the parameters of the signal modulator comprise a sending baseband sequence, a carrier frequency, a phase and a sending end signal amplitude;
step S3: the upper computer module writes a signal into the output end of the data acquisition card by calling a driving program of the data acquisition card;
step S4: the signals output by the data acquisition card pass through the isolation circuit module and are coupled to the receiving end from the transmitting end through a human body channel through an electric field excited around a human body by capacitive coupling;
step S5: the signal is input to the analog input end of the junction box of the data acquisition card through the receiving end electrode, and then the signal is transmitted to the upper computer module for demodulation;
step S6: according to the comparison between the demodulated baseband signal and the original baseband signal, adjusting the parameters of the signal demodulator to recover the baseband waveform of the transmitting terminal electrode; the parameters of the signal demodulator comprise amplification factors, a comparator decision threshold and filter cut-off frequency;
step S7: measuring the error rate of signal transmission, and finely adjusting parameters of a signal sending end, wherein the parameters of the signal sending end comprise baseband waveform parameters.
2. The capacitive coupling type human body communication transceiver aided design system of claim 1, wherein: the isolation circuit module comprises an optical coupling isolation circuit and a pulse transformer isolation circuit.
3. The capacitive coupling type human body communication transceiver aided design system of claim 1, wherein: the channel capacity is calculated by the following formula:
C＝Blog2(1+SNR)；
where B represents the signal bandwidth and SNR represents the signal-to-noise ratio.
4. The capacitive coupling type human body communication transceiver aided design system of claim 1, wherein: the channel gain calculation method adopts the following formula:
wherein, UReceiveIs receiving a signal voltage, UTransmitIs the transmit signal voltage.
5. The capacitive coupling type human body communication transceiver aided design system of claim 1, wherein: the channel gain calculation method adopts the following formula:
wherein, PReceiverIs the received signal power, PTransmitterIs the transmit signal power.
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