CN107493249B - A kind of ASK demodulation circuit based on analog switch - Google Patents
A kind of ASK demodulation circuit based on analog switch Download PDFInfo
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- CN107493249B CN107493249B CN201710600919.8A CN201710600919A CN107493249B CN 107493249 B CN107493249 B CN 107493249B CN 201710600919 A CN201710600919 A CN 201710600919A CN 107493249 B CN107493249 B CN 107493249B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/02—Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation
- H04L27/06—Demodulator circuits; Receiver circuits
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Abstract
The invention discloses a kind of ASK demodulation circuit based on analog switch, including two two-way analog switch chips, two differential amplifier circuits, two low-pass filters, an absolute value add circuit and a comparator；The present invention is by providing the square wave driving signal for being 50% with frequency, duty ratio with signal carrier for analog switch, differential signal is equivalent to square wave identical with ± a 1V, frequency, duty ratio, phase and driving signal after passing through analog switch, realizes the function of multiplier；By exporting trigonometric function amount sin θ and cos θ comprising phase information after difference amplifier, low-pass filter；Obtained by absolute value add circuit | sin θ |+| cos θ | value, then low and high level, recovering signal are obtained with threshold voltage compared with by comparator, to realize ASK demodulation.Demodulator circuit of the present invention replaces traditional multiplier chip or multiplier circuit using analog switch, realizes simply, and at low cost, demodulation effect is good.
Description
Technical field
The invention belongs to telecommunication circuit technical fields, and in particular to a kind of ASK demodulation electricity based on analog switch
Road.
Background technique
The citation form of data communication can be divided into two kinds in digital communication: baseband communication and band communication.Base band transmission is
It is directly transmitted on channel according to the original waveform of digital signal (with impulse form), base band transmission does not need modulation, demodulation, if
It is standby to spend less, it is suitable for small range of data and transmits；Frequency spectrum occupied by baseband communication be since zero-frequency or very low frequency,
And most channels are because with bandpass characteristics, in the method that many communication situations use band communication.
Frequency band transmission is a kind of using modulation, the transmission form of demodulation techniques, in transmitting terminal using modulation means to number
Signal carries out certain transformation, will represent binary one and " 0 " of data, is transformed into the analog signal with certain frequency range,
To adapt to transmit in analog channel；Vice versa is carried out by demodulation means in receiving end, the modulated signal of simulation is restored
For " 1 " or " 0 ".Common modulator approach has: (ASK Modulation), shift keying modulation (FSK are modulated in amplitude-shift keying
Modulation) and phase-shift keying (PSK) modulates (PSKModulation), and wherein amplitude-shift keying is realized simple, more normal in some occasions
It uses.
Amplitude-shift keying is to transmit digital information using the amplitude variation of carrier wave, and its frequency and initial phase remain
It is constant；In binary system amplitude-shift keying (2ASK), only there are two types of variable conditions for the amplitude of carrier wave, respectively correspond binary message
" 0 " or " 1 ".One kind is commonly also that simplest binary system amplitude-shift keying mode is " on-off " keying (OOK), expression formula
Are as follows:
The demodulation method of ASK has coherent demodulation and two kinds of non-coherent demodulation, coherent demodulation method are as follows: signal by multiplier with
After coherent wave is multiplied, demodulate to obtain digital signal by low-pass filter, decision device；Non-coherent demodulation method are as follows: signal passes through complete
Digital signal is obtained by decision device after wave rectifier, low-pass filter.The realization of non-coherent demodulation method is relatively simple, relatively more normal
With, but non-coherent demodulation method, there are threshold effect, output signal-to-noise ratio can sharply deteriorate with the decline of input signal-to-noise ratio.?
Some lesser occasions of signal-to-noise ratio, it is still necessary to use coherent demodulation method.
Coherent demodulation method can realize that analog circuit demodulation is to lead to signal carrier by analog circuit or digitial controller
It crosses after bandpass filter after being multiplied with coherent wave (with frequency carrier wave), digital arteries and veins is obtained by low-pass filter and sampling decision device
Signal is rushed, as shown in Figure 1.In analog demodulation circuit, multiplier circuit realizes complex, the cost of integrated multiplier chip
It is higher；Digital demodulation is that digitial controller samples signal, after portion carries out discrete Fourier transform (DFT) in the chip,
Digital signal is judged by decision threshold.Digital demodulation needs controller to have higher sample frequency, preferable floating-point operation
Ability, while calculating process needs to occupy certain cpu resource.
Summary of the invention
In view of above-mentioned, the present invention provides a kind of ASK demodulation circuit based on analog switch is opened using simulation
It closes to replace traditional multiplier chip or multiplier circuit, realizes simply, at low cost, demodulation effect is good.
A kind of ASK demodulation circuit based on analog switch, including two two-way analog switch chips, two difference
Amplifying circuit, two low-pass filters, an absolute value add circuit and a comparator；Wherein:
The two-way analog switch chip keeps two-way poor for realizing the function of multiplier when trigger signal is high level
Sub-signal multiplied by exporting after+1, make when trigger signal is low level two paths of differential signals multiplied by -1 after export, two two-way moulds
90 ° of trigger signal phase difference of quasi- switch chip；
The differential amplifier circuit is used to the two paths of differential signals for corresponding to the output of two-way analog switch chip being converted to list
End signal；
The low-pass filter is used to that the single-ended signal of corresponding differential amplifier circuit output to be made to carry out low-pass filtering；
After the absolute value add circuit is used to take absolute value to two filtered single-ended signals of low-pass filters output
Summation output；
The comparator is for making the output signal of absolute value add circuit be compared to obtain digital letter with decision threshold
Number.
Further, the trigger signal is square wave identical with differential signal carrier frequency, duty ratio 50%, by
Digitial controller or square wave generation circuit provide.
Further, two drivings of the two-way analog switch chip terminate same trigger signal, and first opens input
End and the second shutdown input termination vsig+, first, which turns off input terminal and second, opens input termination vsig-, the first output end and difference
The normal phase input end of amplifying circuit is connected, and second output terminal is connected with the inverting input terminal of differential amplifier circuit, vsig+And vsig-Point
The two paths of differential signals of positive and reverse phase is not corresponded to.
Further, the two-way analog switch chip uses the two-way analog switch of model TS5A23159.
Further, when the trigger signal of two-way analog switch chip is high level, differential amplifier circuit output is single-ended
Signal vo=ka(vsig+-vsig-)；When the trigger signal of two-way analog switch chip is low level, differential amplifier circuit output
Single-ended signal vo=ka(vsig--vsig+)；Wherein, kaFor amplification factor.
Further, the comparator is compared the output signal of absolute value add circuit with decision threshold, is greater than
Decision threshold then exports 1, then exports 0 less than decision threshold, to demodulate specific digital signal.
Demodulator circuit of the present invention makes differential signal by being equivalent to and ± 1V, frequency, duty ratio, a phase after analog switch
Position square wave identical with driving signal realizes the function of multiplier, and then realizes ASK demodulation；Demodulator circuit of the present invention utilizes mould
It is quasi- to switch to replace traditional multiplier chip or multiplier circuit, it realizes simply, at low cost, demodulation effect is good.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of tradition ASK coherent demodulation circuit.
Fig. 2 is the structural schematic diagram of demodulator circuit of the present invention.
Fig. 3 is the structural schematic diagram of absolute value add circuit.
Fig. 4 is the structural schematic diagram of differential amplifier circuit.
Fig. 5 is the eDRAM of circuit signals at different levels in present system.
Specific embodiment
In order to more specifically describe the present invention, with reference to the accompanying drawing and specific embodiment is to technical solution of the present invention
It is described in detail.
ASK demodulator circuit of the present invention includes: two two-way analog switch chips, two differential amplifier circuits, two low passes
Filter, an absolute value add circuit and a comparator, in which:
The input of two-way analog switch chip is differential signal, and NO1, NC2 pin of two-way analog switch chip connect input
The anode v of signalsig+, the negative terminal v of NO2, NC1 pin connection input signalsig-；Driving pin IN1 connects same driving with IN2
Signal, when driving signal is 0, the COM1 pin output of two-way analog switch chip is vsig+, COM2 vsig-；When driving is believed
Number be high level when, two-way analog switch chip COM1 pin output be vsig-, COM2 vsig+.Two two-way analog switch
The driving signal frequency of chip is square wave identical with signal(-) carrier frequency, duty ratio 50%, two chip drives signals
Phase difference is 90 °.
Two differential amplifier circuits are separately connected the output of two two-way analog switch chips, for analog switch to be exported
Differential signal become single-ended signal；Difference channel inputs anode vin+Two-way analog switch chip COM1 is connected, difference channel is defeated
Enter negative terminal vin-Connect two-way analog switch chip COM2.Then when analog switch drive level is high, the output v of difference channelo
=ka(vsig+-vsig-)；When analog switch drive level is low level, the output v of difference channelo=ka(vsig--vsig+),
Middle kaIt is the amplification factor of difference amplifier.
Two low-pass filters are separately connected the output of two differential amplifier circuits, for by the radio-frequency component of single-ended signal
It filters out；When communication carrier is Asin (ωcT+ θ), then the output valve of two-way low-pass filter is respectively kAsin θ and kAcos θ,
Middle k is proportionality coefficient.
Absolute value add circuit takes absolute value and sums to the output of two-way filter, exports result and is | kAsin θ |+|
kAcosθ|。
The output result of absolute value add circuit is compared by comparator with decision threshold level, when being greater than decision threshold
High level is exported, low level is exported when less than decision threshold, to demodulate specific digital signal.
The whole of above-mentioned PSK demodulator circuit realizes structure as shown in Fig. 2, differential signal accesses two analog switches: simulation
Switch 1 and analog switch 2；The specific type selecting of present embodiment two-way analog switch chip is TS5A23159 two-way analog switch.
The driving signal of analog switch 1 is Dcos, and the driving signal of analog switch 2 is Dsin, the frequency of two driving signals
Rate is identical as signal(-) carrier frequency, duty ratio 50%, and 90 degree of phase of Dcos delayed phase Dsin.
By taking analog switch 1 as an example, the anode v of NO1, NC2 pin connection input signal of chipsig+, NO2, NC1 pin company
Meet the negative terminal v of input signalsig-, pin IN1 is driven to connect same driving signal Dcos with IN2；When Dcos value is 1, COM1
It is connected with NO1, COM2 is connected with NO2, and difference channel output is vo1=ka(vsig+-vsig-)；When Dcos value be 0 when, COM1 with
NC1 is connected, and COM2 is connected with NC2, and difference channel output is vo1=ka(vsig--vsig+), wherein kaIt is the amplification of difference amplifier
Multiple.Work as kaWhen=1, that is, signal is multiplied with frequency together, duty ratio 50%, amplitude for the square wave of ± 1V.
DC component is 0, and the square wave that phase is 0 can be turned to by Fourier decomposition:
a1cos(ω0t)+a3cos(3ω0t)+a5cos(5ω0t)+…
Wherein: a1, a3... it is fourier coefficient；With signal Asin (ωcT+ θ) be multiplied after, higher hamonic wave disappears due to orthogonal
It removes, can only consider the result after fundamental wave is multiplied:
After through low-pass filter, radio-frequency component is filtered out, and filter output is kAsin θ；Similarly, another way is simulated
Output of the output of switch after difference amplifier, low-pass filter is kAcos θ, and k is proportionality coefficient.
Sum, obtain after seeking absolute value respectively to the output of two-way filter | kAsin θ |+| kAcos θ |, it is demonstrate,proved by mathematics
It is bright, be easy to get to:
By the way that reasonable decision level, available actual signal are arranged in a comparator.
For absolute value summing circuit as shown in figure 3, using three operational amplifiers, UA, UB constitute two-way precision detecting circuit,
UC is add circuit.
Differential amplifier circuit can choose circuit as shown in Figure 4, since ADC cannot sample negative voltage, need in difference
Amplification, low-pass filtering link is divided to add direct current biasing V to the output of demodulator circuitref, prevent negative value, differential amplification occur
Transmission function are as follows:
Also it can choose remaining differential amplifier circuit, such as traditional four impedance differential amplifiers；Electricity at different levels in present embodiment
The timing waveform of road signal is as shown in Figure 5.
The above-mentioned description to embodiment is for that can understand and apply the invention convenient for those skilled in the art.
Person skilled in the art obviously easily can make various modifications to above-described embodiment, and described herein general
Principle is applied in other embodiments without having to go through creative labor.Therefore, the present invention is not limited to the above embodiments, ability
Field technique personnel announcement according to the present invention, the improvement made for the present invention and modification all should be in protection scope of the present invention
Within.
Claims (2)
1. a kind of ASK demodulation circuit based on analog switch, it is characterised in that: including two two-way analog switch chips,
Two differential amplifier circuits, two low-pass filters, an absolute value add circuit and a comparator；Wherein:
The two-way analog switch chip believes two-pass DINSAR when trigger signal is high level for realizing the function of multiplier
Number multiplied by exporting after+1, make when trigger signal is low level two paths of differential signals multiplied by -1 after export, two two-ways simulations are opened
Close 90 ° of trigger signal phase difference of chip；
The differential amplifier circuit is used to the two paths of differential signals for corresponding to the output of two-way analog switch chip being converted to single-ended letter
Number；
The low-pass filter is used to that the single-ended signal of corresponding differential amplifier circuit output to be made to carry out low-pass filtering；
The absolute value add circuit is used to export after filtered single-ended signal takes absolute value two low-pass filters and sum
Output；
The comparator is for making the output signal of absolute value add circuit be compared to obtain digital signal with decision threshold；
The trigger signal is square wave identical with differential signal carrier frequency, duty ratio 50%, by digitial controller or
Square wave generation circuit provides；
Two drivings of the two-way analog switch chip terminate same trigger signal, and first opens input terminal and the second shutdown is defeated
Enter to terminate vsig+, first, which turns off input terminal and second, opens input termination vsig-, the positive of the first output end and differential amplifier circuit
Input terminal is connected, and second output terminal is connected with the inverting input terminal of differential amplifier circuit, vsig+And vsig-Respectively correspond as positive and
The two paths of differential signals of reverse phase；
When the trigger signal of two-way analog switch chip is high level, differential amplifier circuit exports single-ended signal vo=ka
(vsig+-vsig-)；When the trigger signal of two-way analog switch chip is low level, differential amplifier circuit exports single-ended signal vo
=ka(vsig--vsig+)；Wherein, kaFor amplification factor, vsig+And vsig-Respectively correspond the two paths of differential signals for positive and reverse phase.
2. ASK demodulation circuit according to claim 1, it is characterised in that: the comparator keeps absolute value addition electric
The output signal on road is compared with decision threshold, then exports 1 greater than decision threshold, then exports 0 less than decision threshold, to solve
Recall specific digital signal.
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| CN113777974B (en) * | 2021-08-18 | 2024-05-31 | 同济大学 | Double-sideband modulation signal demodulation device and demodulation method |
| CN114389924B (en) * | 2021-12-27 | 2024-04-05 | 浙江巨磁智能技术有限公司 | Demodulation method suitable for OOK modulation |
| CN114900409B (en) * | 2022-04-20 | 2023-07-18 | 深圳清华大学研究院 | Demodulation method and device for 2ASK signal and readable storage medium |
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| CN101257330A (en) * | 2008-03-25 | 2008-09-03 | 京信通信系统（中国）有限公司 | Feeding electric appliance embedded with modem function |
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| CN101257330A (en) * | 2008-03-25 | 2008-09-03 | 京信通信系统（中国）有限公司 | Feeding electric appliance embedded with modem function |
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| 模拟开关用于幅度调制与解调;包昌祥;《内江师范学院学报》;20021231;论文第2节 * |
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