CN105471789B - Demodulator circuit - Google Patents
Demodulator circuit Download PDFInfo
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- CN105471789B CN105471789B CN201410452555.XA CN201410452555A CN105471789B CN 105471789 B CN105471789 B CN 105471789B CN 201410452555 A CN201410452555 A CN 201410452555A CN 105471789 B CN105471789 B CN 105471789B
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Abstract
The invention discloses a kind of demodulator circuits.Two integrating circuit receive carrier (boc) modulated signals and local carrier signal, in two cycle times section of each local carrier signal, take wherein 1 period, are integrated respectively with second half of the cycle carrier (boc) modulated signals to half of cycle carrier modulated signal before the period；Two filter circuits filter out I, Q two-way baseband signals from two-way down-conversion signal respectively；Two energy accumulation circuits respectively to the I in same amount of time, accumulated by the absolute value of the amplitude of Q two-way baseband signals；One decision circuit exports court verdict after the difference of two-way accumulation results is more than certain threshold value；According to court verdict, that bigger roadbed band signal of the accumulated value of output amplitude absolute value exports one selection circuit as baseband signal；Simultaneously according to court verdict, the related circuit on smaller that circuit of accumulated value of respective amplitude absolute value is closed.The present invention realizes simply, highly practical, and can effectively improve receiver performance.
Description
Technical field
The present invention relates to field of wireless communication, more particularly to a kind of improved demodulator circuit.
Background technology
Generally there are two types of realization methods for demodulator circuit.
One is directly local carrier is multiplied with the modulated signal of reception with analog multiplication circuit, according to modulation /demodulation original
Reason, the result after multiplication include baseband signal and the high-frequency signal being modulated in 2 times of carrier frequencies, are then inhibited with filter circuit
2 frequency-doubled signals, to filter out baseband signal.
Another kind is the modulated signal received with local carrier frequency sampling with sampling hold circuit, then same filtering
Circuit filters out baseband signal；According to sampling principle, modulated signal, can be in carrier frequency integral multiple after aforesaid way samples
All there is original signal in frequency, then inhibits other harmonic signals with filter circuit, obtain baseband signal.
The analog multiplication circuit of the first is more complicated in realization, and the second way needs Phase synchronization, that is to say, that
It must be a fixed value to need the difference of the phasetophase of carrier wave in the phase of local carrier and the modulated signal of reception, so
It can guarantee that the value amplitude of the modulated signal sampled is bigger, conversely, receptivity will greatly be influenced.But this is in practical fortune
Used time with regard to extremely difficult, because according to the difference postponed on radio communication channel, the phase of local carrier and the modulation of reception are believed
The difference of the phasetophase of carrier wave is also just different in number, that is to say, that the change of distance all can cause phase not between each transceiver
It is synchronous.
Invention content
The technical problem to be solved in the present invention is to provide a kind of demodulator circuit, realize it is simple, it is highly practical and can effectively change
Kind receiver performance.
In order to solve the above technical problems, the demodulator circuit of the present invention, there are two input signal, one is carrier modulation letter for it
Number, the other is in the carrier (boc) modulated signals twice of carrier frequency local carrier signal；Including：
One roads I integrating circuit receives carrier (boc) modulated signals and local carrier signal, at two of each local carrier signal
In cycle time section, wherein 1 period is taken, to half of cycle carrier modulated signal before the period and second half of the cycle carrier wave tune
Signal integration processed, integral result are exported as the roads I down-conversion signal；
One roads Q integrating circuit receives carrier (boc) modulated signals and local carrier signal, at two of each local carrier signal
In cycle time section, wherein 1 period is taken, to half of cycle carrier modulated signal before the period and second half of the cycle carrier wave tune
Signal integration processed, integral result are exported as the roads Q down-conversion signal；
One roads I filter circuit, is connected with the roads I integrating circuit, and I roadbeds are filtered out from the down-conversion signal of the roads I
Band signal simultaneously exports；
One roads Q filter circuit, is connected with the roads Q integrating circuit, and Q roadbeds are filtered out from the down-conversion signal of the roads Q
Band signal simultaneously exports；
One roads I energy accumulation circuit, is connected with the roads I filter circuit, takes a message to the I roadbeds in a period of time
Number the absolute value of amplitude accumulated, the roads output I energy accumulation value signal；
One roads Q energy accumulation circuit, is connected with the roads Q filter circuit, is carried out with the roads the I energy accumulation circuit
In the same amount of time of accumulation, the absolute value of the amplitude of the Q roadbeds band signal is accumulated, the roads output Q energy accumulation value
Signal；
One decision circuit is connected with the output end of the roads the I energy accumulation circuit and the roads Q energy accumulation circuit, in I, Q
The difference of two-way energy accumulation value is more than output court verdict after certain threshold value, according to court verdict, I, Q two-way product before closing
Parallel circuit that road integrating circuit smaller with the accumulated value of the absolute value of corresponding amplitude in I, Q two-way filter circuit, filtering
Circuit and energy accumulation circuit；
One selection circuit is connected with the output end of the roads I filter circuit and the roads Q filter circuit, according to court verdict,
That bigger roadbed band signal of the accumulated value of the absolute value of output amplitude, exports as final baseband signal.
The present invention due to the use of twice of carrier frequency local carrier so that the integral of I, Q two paths of signals becomes easy reality
It is existing.
The scheme that the use of integrating circuit and I, Q two-way baseband signal automatically select in the present invention, it is existing eliminating
While scheme Phase synchronization requires, the performance of receiver is also effectively improved.
In the present invention, the threshold design of decision circuit adapts to various application environment noises and signal energy, with more real
The property used.
Description of the drawings
The present invention is described in further detail with specific implementation mode below in conjunction with the accompanying drawings：
Attached drawing is one example structure block diagram of the demodulator circuit.
Specific implementation mode
In conjunction with shown in attached drawing, there are two input signals for the demodulator circuit, and one is carrier (boc) modulated signals, the other is institute
The local carrier signal for stating twice of carrier frequency in carrier (boc) modulated signals, exports baseband signal；The decoding circuit is integrated by two
Circuit, two filter circuits, two energy accumulation circuits, a decision circuit and a selection circuit are constituted.
The demodulator circuit is based on sampling hold circuit principle, is improved on its basis, improvement is to take one
Series of measures eliminate phase locked requirement.In order to avoid to be all located at amplitude in modulated signal relatively low for the value sampled every time
Place, replace impulse sampling with integrating circuit.Integrating circuit can be equivalent to one low-pass filter of Natural Sampling heel.Root
According to sampling principle, after Natural Sampling, can all there be original signal on the integer multiple frequency of sample frequency, so when sampling
When frequency is equal to carrier frequency, just there is signal in base band, can filter out this base band letter with a low-pass filter after this
Number.In the demodulator circuit, the equivalent low-pass filter of integrating circuit contributes to filter out base band letter with filter circuit later
Number.In order to obtain the integrated value of bigger, the higher place integral of Amplitude Ratio in modulated signal is needed, for this purpose, with 2 products
Parallel circuit is respectively within the carrier wave adjacent a quarter period to modulating signal integration, since integration interval is a quarter carrier wave
In the period, in this way when an integrating circuit falls the lower part of the Amplitude Ratio in modulated signal, another integrating circuit is centainly fallen
The higher part of Amplitude Ratio in modulated signal.And why integration lengths are also a quarter carrier cycle, there are two former for this
Cause, first reason are realized in fairly simple, and the local of twice of carrier frequency has just been used to carry in the demodulator circuit
Wave signal assists to realize, i.e., in two cycle times of each local carrier signal section, takes wherein 1 period, two products
Parallel circuit respectively carrys out half of cycle carrier modulated signal before this period with second half of the cycle carrier (boc) modulated signals integral real
It is existing.Second the reason is that, the bandwidth of the integrator of this integration lengths, its equivalent low-pass filter is sufficiently wide, so as to protect
The very little that the baseband signal that card needs is attenuated.
Next it to solve the problems, such as to be how to select the bigger signal output of amplitude from this two-way baseband signal,
The demodulator circuit energy accumulation circuit gets up the energy accumulation of two-way baseband signal, and then two energy accumulation values are sent
To a decision circuit, it is big to adjudicate any road energy.As soon as court verdict gives a selection circuit, selection circuit is corresponding energy accumulation
Big that of value exports all the way, simultaneously closes off small that of energy comparison those of involved circuit all the way.Above-mentioned way is in the application
It also needs to solve a key problem, that is, to judge to receive the presence of signal.Because if in the absence of receiving signal,
The above circuit is all run in the case where input is noise, and such energy court verdict is clearly inaccurate.In order to
Solve the problems, such as this, the decision circuit of the demodulator circuit adjudicates electricity before exporting court verdict, provided with having to meet
Road is more than such a condition of certain threshold value in the difference of two-way accumulation results, why is more than certain threshold with the difference of two paths of signals
Value, rather than (for example with arbitrary accumulation results be all the way more than centainly there are judgment condition with existing relatively common signal
Threshold value receives condition existing for signal as judgement), this is because be not easy to be influenced by environmental noise power with difference, that is,
It says if merely with energy accumulation value itself exceeding condition as certain threshold value, this threshold value is difficult to set, this
Be because of demodulator circuit the case where needing to take into account various ambient noises and signal energy, when the setting of this threshold value it is bigger when,
Small signal is probably worked as noise, when this threshold value setting it is smaller when, it is more likely that noise is worked as signal.The present invention uses
The difference of the energy value of two-way is as judgment condition, with regard to solving the problems, such as this, because ambient noise is identical to two-way, just
It is subtracted, then threshold value can be differed from two paths of signals needs merely, just be may require that and distinguished this angle to be arranged
.This is just only related with the subsequent receiving sensitivity of demodulator circuit, this is the performance of receiver itself, is not become with environment
Change, is easy to so setting up.
Although the present invention is illustrated using specific embodiment, the present invention's is not intended to limit to the explanation of embodiment
Range.One skilled in the art is by reference to explanation of the invention, without departing substantially from the spirit and scope of the present invention
In the case of, it is easy to carry out various modifications or embodiment can be combined.
Claims (1)
1. a kind of demodulator circuit, it is characterised in that：There are two input signals for it, and one is carrier (boc) modulated signals, the other is institute
State the local carrier signal of twice of carrier frequency in carrier (boc) modulated signals；Including：
One roads I integrating circuit receives carrier (boc) modulated signals and local carrier signal, in two periods of each local carrier signal
In period, wherein 1 period is taken, half of cycle carrier modulated signal before the period is believed with second half of the cycle carrier modulation
Number integral, integral result as the roads I down-conversion signal output；
One roads Q integrating circuit receives carrier (boc) modulated signals and local carrier signal, in two periods of each local carrier signal
In period, wherein 1 period is taken, half of cycle carrier modulated signal before the period is believed with second half of the cycle carrier modulation
Number integral, integral result as the roads Q down-conversion signal output；
One roads I filter circuit, is connected with the roads I integrating circuit, and filtering out I roadbeds from the down-conversion signal of the roads I takes a message
Number and export；
One roads Q filter circuit, is connected with the roads Q integrating circuit, and filtering out Q roadbeds from the down-conversion signal of the roads Q takes a message
Number and export；
One roads I energy accumulation circuit, is connected with the roads I filter circuit, to the I roadbeds band signal in a period of time
The absolute value of amplitude is accumulated, the roads output I energy accumulation value signal；
One roads Q energy accumulation circuit, is connected with the roads Q filter circuit, is accumulated with the roads the I energy accumulation circuit
Same amount of time in, the absolute value of the amplitude of the Q roadbeds band signal is accumulated, output Q roads energy accumulation value signal；
One decision circuit is connected with the output end of the roads the I energy accumulation circuit and the roads Q energy accumulation circuit, in I, Q two-way
The difference of energy accumulation value is more than output court verdict after certain threshold value, according to court verdict, I, Q two-way integral electricity before closing
Road that road integrating circuit, the filter circuit smaller with the accumulated value of the absolute value of corresponding amplitude in I, Q two-way filter circuit
With energy accumulation circuit；
One selection circuit is connected with the output end of the roads I filter circuit and the roads Q filter circuit, according to court verdict, output
That bigger roadbed band signal of the accumulated value of the absolute value of amplitude, exports as final baseband signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410452555.XA CN105471789B (en) | 2014-09-05 | 2014-09-05 | Demodulator circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410452555.XA CN105471789B (en) | 2014-09-05 | 2014-09-05 | Demodulator circuit |
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| CN105471789A CN105471789A (en) | 2016-04-06 |
| CN105471789B true CN105471789B (en) | 2018-10-26 |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6898252B1 (en) * | 2000-07-21 | 2005-05-24 | Intel Corporation | IQ mismatch cancellation |
| CN101184255A (en) * | 2006-11-13 | 2008-05-21 | 深圳市好易通科技有限公司 | System and method for performing digital demodulation to frequency modulated signal in digital wireless intercom system |
| CN101815056A (en) * | 2010-03-05 | 2010-08-25 | 华为技术有限公司 | IQ unbalanced calibration method and equipment of baseband signals in wireless communication receiving machine |
| CN102045278A (en) * | 2010-12-31 | 2011-05-04 | 芯通科技（成都）有限公司 | Preprocessing method for base band signal |
-
2014
- 2014-09-05 CN CN201410452555.XA patent/CN105471789B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6898252B1 (en) * | 2000-07-21 | 2005-05-24 | Intel Corporation | IQ mismatch cancellation |
| CN101184255A (en) * | 2006-11-13 | 2008-05-21 | 深圳市好易通科技有限公司 | System and method for performing digital demodulation to frequency modulated signal in digital wireless intercom system |
| CN101815056A (en) * | 2010-03-05 | 2010-08-25 | 华为技术有限公司 | IQ unbalanced calibration method and equipment of baseband signals in wireless communication receiving machine |
| CN102045278A (en) * | 2010-12-31 | 2011-05-04 | 芯通科技（成都）有限公司 | Preprocessing method for base band signal |
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| Publication number | Publication date |
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| CN105471789A (en) | 2016-04-06 |
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