CN101917372A - Pre-demodulating, frequency discriminating and demodulating method, pre-demodulator, frequency discriminator and demodulator - Google Patents

Abstract

The embodiment of the invention discloses a frequency shift keying (FSK) pre-demodulating, frequency discriminating and demodulating method applicable to digital devices, a pre-demodulator for realizing the pre-demodulating, a frequency discriminator for realizing the frequency discriminating method and a demodulator for realizing the demodulating method. The pre-demodulating method comprises the following steps of: pre-processing an FSK signal to obtain a to-be-demodulated digital signal, wherein a numerical value in the to-be-demodulated digital signal is an unsigned numerical value; and pre-demodulating the to-be-demodulated digital signal by using locally generated digital signals with different frequencies to obtain a plurality of comparison signals respectively, wherein the numerical values in both a locally generated sinusoidal digital signal and a locally generated cosinoidal digital signal are unsigned numerical values. Thus, because the numerical values in both the locally generated digital signal and the to-be-demodulated digital signal are unsigned numerical values, the mutual operation is unsigned operation and is suitable to be realized by using the digital devices.

Description

Pre-demodulating, frequency discrimination and demodulation method, and predemodulator, frequency discriminator and demodulator

Technical field

The present invention relates to the signal processing technology field, more particularly, relate to frequency shift keying pre-demodulating, frequency discrimination and demodulation method, and predemodulator, frequency discriminator and demodulator.

Background technology

(Frequency shift keying is to utilize the discrete value characteristics of binary system or multi-system baseband digital signal to go keyed carrier (carrier wave is for sinusoidal wave) frequency to transmit a kind of modulation system of information FSK) in frequency shift keying.

Comprise a plurality of different carrier frequency in the fsk signal by the generation of FSK modulation system, the system radix that the quantity of its carrier frequency and baseband digital signal are corresponding is identical, for example when baseband digital signal was binary system, the quantity of the carrier frequency that corresponding binary FSK signal (being designated as 2FSK) is comprised was 2.See also Fig. 1, among Fig. 1, f ₁The expression frequency is f ₁Carrier wave (sine wave), f ₂The expression frequency is f ₂Carrier wave (sine wave), S (t) expression binary system base band digital signal, 2FSK represents the 2FSK signal.In a code check period T, when S (t) symbol was 0, the frequency of 2FSK signal correspondence was f in this cycle ₁, and when S (t) symbol was 1, the frequency of fsk signal correspondence was f ₂In like manner, when baseband digital signal was quaternary numeral signal, the quantity of the carrier frequency that corresponding fsk signal is comprised was 4.

Fsk signal has multiple demodulation mode, wherein a kind ofly is: at first fsk signal is carried out pre-demodulating and handle to obtain a plurality of comparison signals, wherein, each comparison signal is corresponding with a certain carrier frequency.Then, implement the size of frequency discrimination-more above-mentioned a plurality of comparison signals, promptly decidable signal to be demodulated is at the carrier frequency of a certain code check correspondence in the cycle.Last corresponding relation according to symbol in carrier frequency that identifies and the baseband digital signal reduces to baseband digital signal, with the demodulation of final realization FSK.Be example still, in a code check period T, as respective frequencies f with signal shown in Figure 1 ₁Comparison signal greater than respective frequencies f ₂Comparison signal the time, the carrier frequency that identifies 2FSK signal correspondence is f ₁, and then decidable should the cycle in the symbol of S (t) be 0, and as respective frequencies f ₁Comparison signal less than respective frequencies f ₂Comparison signal the time, the carrier frequency that identifies 2FSK signal correspondence is f ₂, and and then judge that the symbol of S (t) is 1, so can realize reduction to S (t) signal.

Yet when implementing the invention, the inventor finds, the pre-demodulating of traditional F SK, frequency discrimination and demodulation mode are owing to there are shortcomings such as temperature is floated, limited reliability in a large amount of analog components that adopt, and therefore, using digital device that fsk signal is carried out pre-demodulating, frequency discrimination and demodulation is a kind of trend.And how to find the pre-demodulating, frequency discrimination and the demodulation mode that are suitable for digital device to become the problem that will solve of needing badly.

Summary of the invention

In view of this, embodiment of the invention purpose is to provide frequency shift keying pre-demodulating, frequency discrimination and the demodulation method that is suitable for digital device, and implement above-mentioned pre-demodulating predemodulator, implement the frequency discriminator of above-mentioned frequency discrimination method and implement the demodulator of above-mentioned demodulation method.

According to an aspect of the present invention, provide a kind of frequency shift keying FSK pre-demodulating method, this pre-demodulating method comprises:

Fsk signal is carried out preliminary treatment obtain digital signal to be demodulated, the numerical value in the described digital signal to be demodulated is unsigned value;

Use has this locality generation digital signal of different frequency and respectively described digital signal to be demodulated is carried out the pre-demodulating processing to obtain a plurality of comparison signals, the described local digital signal that generates comprises that frequency and all identical this locality of initial phase generate sinusoidal digital signal and the local cosine digital signal that generates, the described local numerical value that generates in sinusoidal digital signal and the local generation cosine digital signal is unsigned value, and the frequency of described local sinusoidal digital signal of generation and local generation cosine digital signal is corresponding one by one with the carrier frequency of described baseband digital signal keying;

Described pre-demodulating is handled and is comprised:

Signal to the gained that multiplied each other by described local sinusoidal digital signal of generation and described digital signal to be demodulated in the predetermined integral interval carries out integral processing, generate the sinusoidal demodulation integrated signal, the upper limit in described predetermined integral interval and the difference of lower limit are T, and described T is a code check cycle of baseband digital signal;

Signal to the gained that multiplied each other by this locality generation cosine digital signal and described digital signal to be demodulated in described predetermined integral interval carries out integral processing, generates cosine demodulation integrated signal;

Utilize described sinusoidal demodulation integrated signal and cosine demodulation integrated signal to obtain comparison signal.

According to another aspect of the present invention, provide a kind of frequency shift keying FSK frequency discrimination method, be used to differentiate the pairing carrier frequency of fsk signal that generates by baseband digital signal keyed carrier frequency that this frequency discrimination method comprises:

Described fsk signal is carried out preliminary treatment obtain digital signal to be demodulated, the numerical value in the described digital signal to be demodulated is unsigned value;

Use has this locality generation digital signal of different frequency and respectively described digital signal to be demodulated is carried out the pre-demodulating processing to obtain a plurality of comparison signals, the described local digital signal that generates comprises that frequency and all identical this locality of initial phase generate sinusoidal digital signal and the local cosine digital signal that generates, the described local numerical value that generates in sinusoidal digital signal and the local generation cosine digital signal is unsigned value, and the frequency of described local sinusoidal digital signal of generation and local generation cosine digital signal is corresponding one by one with the carrier frequency of described baseband digital signal keying;

From described a plurality of comparison signals, select maximum comparison signal, and obtain the carrier frequency of described fsk signal correspondence according to the pairing local frequency that generates digital signal of described maximum comparison signal;

Described pre-demodulating is handled and is comprised:

Signal to the gained that multiplied each other by described local sinusoidal digital signal of generation and described digital signal to be demodulated in the predetermined integral interval carries out integral processing, generate the sinusoidal demodulation integrated signal, the upper limit in described predetermined integral interval and the difference of lower limit are T, and described T is a code check cycle of baseband digital signal;

Signal to the gained that multiplied each other by this locality generation cosine digital signal and described digital signal to be demodulated in described predetermined integral interval carries out integral processing, generates cosine demodulation integrated signal;

Utilize described sinusoidal demodulation integrated signal and cosine demodulation integrated signal to obtain comparison signal.

According to a further aspect of the invention, provide a kind of frequency shift keying FSK demodulation method, be used for the fsk signal that is generated by baseband digital signal keyed carrier frequency is carried out demodulation, this demodulation method comprises:

Described fsk signal is carried out preliminary treatment obtain digital signal to be demodulated, the numerical value in the described digital signal to be demodulated is unsigned value;

Use has this locality generation digital signal of different frequency and respectively described digital signal to be demodulated is carried out the pre-demodulating processing to obtain a plurality of comparison signals, the described local digital signal that generates comprises that frequency and all identical this locality of initial phase generate sinusoidal digital signal and the local cosine digital signal that generates, the described local numerical value that generates in sinusoidal digital signal and the local generation cosine digital signal is unsigned value, and the frequency of described local sinusoidal digital signal of generation and local generation cosine digital signal is corresponding one by one with the carrier frequency of described baseband digital signal keying;

From described a plurality of comparison signals, select maximum comparison signal, and obtain the carrier frequency of described fsk signal correspondence according to the pairing local frequency that generates digital signal of described maximum comparison signal;

Corresponding relation according to symbol in the carrier frequency of described fsk signal correspondence and the baseband digital signal reduces to described baseband digital signal;

Described pre-demodulating is handled and is comprised:

Signal to the gained that multiplied each other by described local sinusoidal digital signal of generation and described digital signal to be demodulated in the predetermined integral interval carries out integral processing, generate the sinusoidal demodulation integrated signal, the upper limit in described predetermined integral interval and the difference of lower limit are T, and described T is a code check cycle of baseband digital signal;

Signal to the gained that multiplied each other by this locality generation cosine digital signal and described digital signal to be demodulated in described predetermined integral interval carries out integral processing, generates cosine demodulation integrated signal;

Utilize described sinusoidal demodulation integrated signal and cosine demodulation integrated signal to obtain comparison signal.

According to a further aspect of the invention, provide a kind of frequency shift keying predemodulator, this predemodulator comprises pretreatment unit and pre-demodulating unit, wherein,

Pretreatment unit is used for that described fsk signal is carried out preliminary treatment and obtains digital signal to be demodulated, and the numerical value in the described digital signal to be demodulated is unsigned value;

The pre-demodulating unit, be used to use this locality to generate digital signal and respectively described digital signal to be demodulated carried out the pre-demodulating processing to obtain a plurality of comparison signals with different frequency, the described local digital signal that generates comprises that frequency and all identical this locality of initial phase generate sinusoidal digital signal and the local cosine digital signal that generates, the described local numerical value that generates in sinusoidal digital signal and the local generation cosine digital signal is unsigned value, and the frequency of described local sinusoidal digital signal of generation and local generation cosine digital signal is corresponding one by one with the carrier frequency of described baseband digital signal keying;

Described pre-demodulating is handled and is comprised:

Signal to the gained that multiplied each other by described local sinusoidal digital signal of generation and described digital signal to be demodulated in the predetermined integral interval carries out integral processing, generates the sinusoidal demodulation integrated signal, and the upper limit in described predetermined integral interval and the difference of lower limit are T;

Signal to the gained that multiplied each other by this locality generation cosine digital signal and described digital signal to be demodulated in described predetermined integral interval carries out integral processing, generates cosine demodulation integrated signal;

Utilize described sinusoidal demodulation integrated signal and cosine demodulation integrated signal to obtain comparison signal.

According to a further aspect of the invention, a kind of frequency shift keying frequency discriminator is provided, this frequency discriminator comprises decision unit and above-mentioned predemodulator, described decision unit is used for selecting maximum comparison signal from described a plurality of comparison signals, and obtains the carrier frequency of described fsk signal correspondence according to the pairing local frequency that generates digital signal of described maximum comparison signal.

According to a further aspect of the invention, a kind of frequency shift keying demodulator is provided, this demodulator comprises decoding unit and the frequency discriminator of the above, and described decoding unit is used for according to the corresponding relation of the carrier frequency of described fsk signal correspondence and baseband digital signal symbol described baseband digital signal being reduced.

As seen, in pre-demodulating, frequency discrimination and the demodulation method that the embodiment of the invention provided, mainly be to utilize local generation digital signal and digital signal to be demodulated to carry out frequency discrimination, because the local numerical value that generates in digital signal and the digital signal to be demodulated is unsigned value, therefore its mutual multiplication, integral operation are no symbolic operation, this no symbolic operation is lower to the performance requirement of digital device, is suitable for using digital device to be realized.Accordingly, the embodiment of the invention also provides the predemodulator of implementing above-mentioned pre-demodulating method, implemented the frequency discriminator of above-mentioned frequency discrimination method and has implemented the demodulator of above-mentioned demodulation method.

Description of drawings

In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art, to do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art below, apparently, accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.

Fig. 1 is binary radix band signal, carrier wave and 2FSK signal waveform schematic diagram;

The FSK predemodulator structural representation that Fig. 2 a provides for the embodiment of the invention;

The FSK frequency discriminator structural representation that Fig. 2 b provides for the embodiment of the invention;

The computing schematic flow sheet of the formula 12 that Fig. 3 provides for the embodiment of the invention;

The pre-demodulating sub-unit structure schematic diagram that Fig. 4 provides for the embodiment of the invention;

The structural representation of the fsk demodulator that Fig. 5 provides for the embodiment of the invention;

The responder system structural representation that Fig. 6 provides for the embodiment of the invention;

The dash receiver structural representation that Fig. 7 provides for the embodiment of the invention;

The upper side frequency demodulator module structural representation that Fig. 8 provides for the embodiment of the invention;

The lower side frequency demodulator module structural representation that Fig. 9 provides for the embodiment of the invention.

Embodiment

For quote and know for the purpose of, hereinafter the technical term of Shi Yonging, write a Chinese character in simplified form or abridge and be summarized as follows:

TCC:Train Control Center, row control center, station;

FPGA:Field-Programmable Gate Array, i.e. field programmable gate array;

BTM:Balise Transmission Module, the transponder transmission unit;

FSK:Frequency Shift Keying, frequency shift keying;

Signal: signal often can be expressed as the function of time (or sequence), and the image of this function is called the waveform of signal;

Analog signal: all continuous signal of time and amplitude is called analog signal;

Digital signal: the signal that time and amplitude are all discrete is called digital signal.

Below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that is obtained under the creative work prerequisite.

Traditional F SK pre-demodulating, frequency discrimination and demodulation mode are owing to there are shortcomings such as temperature is floated, limited reliability in a large amount of analog components that adopt.

In view of this, the invention provides the frequency shift keying pre-demodulating, frequency discrimination and the demodulation method that are suitable for digital device, and predemodulator, frequency discriminator and demodulator.

For ease of describing, the present invention will and be demodulated into example with pre-demodulating, the frequency discrimination of 2FSK signal and describe.

Referring to the description in Fig. 1 and the background technology as can be known, in a code check period T, the frequency of 2FSK signal correspondence is a fixed numbers, and the symbol of this frequency and baseband digital signal has fixing corresponding relation, therefore, as long as respectively the 2FSK signal of each code check in the cycle carried out pre-demodulating and frequency discrimination, again according to the relation of the symbol of carrier frequency that is identified and binary radix band signal, just can reduce, to reach the purpose of demodulation to the binary radix band signal.Therefore, how to realize the pre-demodulating of 2FSK signal is become key.

Pre-demodulating principle/method of the present invention is as follows:

In a T, establishing the signal to be demodulated that the 2FSK signal obtains after preliminary treatment is x ₁(t), local generation sinusoidal signal is x _Sin(t), the two being carried out the sinusoidal demodulation integrated signal that integral processing obtains is y _Sin(t), x then ₁(t), x _Sin(t) and y _Sin(t) available formula 1 expression:

$\left\{\begin{array}{c}{x}_1\left(t\right)=A[{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="HSA00000238824800011.png,HSA00000238824800031.png"\; state="\{\{state\}\}">k</figure-callout>}}_1+\sin ({2\mathrm{\&pi;\&omega;}}_{1}t+p_1)]\\ y_{\sin }\left(t\right)=[k_2+\sin ({2\mathrm{\&pi;\&omega;}}_{\sin }t+p_{\sin })]\\ y_{\sin }\left(t\right)={\&Integral;}_0^T{x}_1\left(t\right)x_{\sin }\left(t\right)\mathrm{dt}\end{array}\right.---\left(1\right)$

If local generation cosine signal is x _Cos(t), cosine demodulation integrated signal is y _Cos(t), x then _Cos(t) and y _Cos(t) available formula 2 expressions:

$\left\{\begin{array}{c}{x}_{\cos }\left(t\right)=[k_2+\cos ({2\mathrm{\&pi;\&omega;}}_{\cos }t+p_{\cos })]\\ y_{\cos }\left(t\right)={\&Integral;}_0^T{x}_1\left(t\right)x_{\cos }\left(t\right)\mathrm{dt}\end{array}\right.---\left(2\right)$

Wherein, A is the amplitude of 2FSK signal, and ω is the signal angular frequency, and p is the signal initial phase, footnote 1 expression input, and footnote sin represents the local sinusoidal signal frequency that generates, footnote cos represents local cosine signal frequency, the k of generating ₁And k ₂Be the direct current biasing factor.k ₁And k ₂Value can be identical, also can be different, but all more than or equal to 1.

As from the foregoing, x ₁(t), x _Sin(t), x _Cos(t), y _Sin(t) and y _Cos(t) all more than or equal to 0.In addition, be pointed out that x ₁(t) can be considered 2FSK signal (Asin (2 π ω ₁T+p ₁)) added DC component Ak ₁

With y _Sin(t) as analytic target, with x ₁(t) and x _Sin(t) substitution can get formula 3:

$y_{\sin }\left(t\right)={\&Integral;}_0^T\left\{A\right[{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="HSA00000238824800011.png,HSA00000238824800031.png"\; state="\{\{state\}\}">k</figure-callout>}}_1+\sin ({2\mathrm{\&pi;\&omega;}}_{1}t+p_1)]\&CenterDot;[k_2+\sin ({2\mathrm{\&pi;\&omega;}}_{\sin }t+p_{\sin })\left]\right\}\mathrm{dt}$

$=A{\&Integral;}_0^T[k_1{k}_2+k_2\&CenterDot;\sin ({2\mathrm{\&pi;\&omega;}}_{1}t+p_1)+{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="HSA00000238824800011.png,HSA00000238824800031.png"\; state="\{\{state\}\}">k</figure-callout>}}_1\&CenterDot;\sin ({2\mathrm{\&pi;\&omega;}}_{\sin }t+p_{\sin })---\left(3\right)$

$+\sin ({2\mathrm{\&pi;\&omega;}}_{1}t+p_1)\&CenterDot;\sin ({2\mathrm{\&pi;\&omega;}}_{\sin }t+p_{\sin })]\mathrm{dt}$

General binary system code check period T generates the cycle of sinusoidal signal much larger than this locality, and is generally its integral multiple, so sin (2 π ω in the formula 3 ₁T+p ₁) and sin (2 π ω _SinT+p _Sin) integrated value in period T is 0.y _Sin(t) can turn to formula 4:

$y_{\sin }\left(t\right)=\mathrm{AT}{k}_1{k}_2-\frac{A}{2}{\&Integral;}_0^T\cos (2\mathrm{\&pi;t}({\mathrm{\&omega;}}_1+{\mathrm{\&omega;}}_{\sin })+{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="HSA00000238824800011.png,HSA00000238824800031.png"\; state="\{\{state\}\}">p</figure-callout>}}_1+p_{\sin })\mathrm{dt}$

(4)

$+\frac{A}{2}{\&Integral;}_0^T\cos (2\mathrm{\&pi;t}({\mathrm{\&omega;}}_1-{\mathrm{\&omega;}}_{\sin })+p_1-p_{\sin })\mathrm{dt}$

Same because in period T, comprise a plurality of carrier cycles, so cos (2 π t (ω in the formula 4 ₁+ ω _Sin)+p ₁-p _Sin) integrated value be 0, y _Sin(t) can turn to formula 5:

$y_{\sin }\left(t\right)=A{\mathrm{Tk}}_1{k}_2+\frac{A}{2}{\&Integral;}_0^T\cos (2\mathrm{\&pi;t}({\mathrm{\&omega;}}_1-{\mathrm{\&omega;}}_{\sin })+p_1-p_{\sin })\mathrm{dt}---\left(5\right)$

Introduce the local cosine signal x that generates _Cos(t) (x _Cos(t) angular frequency _CosGenerate sinusoidal signal x with this locality _Sin(t) angular frequency _SinEquate), make it replace x _Sin(t) carry out above-mentioned formula 3 to the identical calculation procedure of formula 4, can draw cosine demodulation integrated signal y _Cos(t), y _Cos(t) available formula 6 expressions:

$y_{\cos }\left(t\right)={\mathrm{ATk}}_1{k}_2+\frac{A}{2}{\&Integral;}_0^T\sin (2\mathrm{\&pi;t}({\mathrm{\&omega;}}_1-{\mathrm{\&omega;}}_{\cos })+p_1-p_{\cos })\mathrm{dt}---\left(6\right)$

The span of cosine is [1 ,-1], and k because just, ₁And k ₂All more than or equal to 1, therefore, y _Sin(t) and y _Cos(t) value is not less than ATk ₁k ₂/ 2, greater than 0.

To the y in the formula 5 _Sin(t) and the y in the formula 6 _Cos(t) remove DC component ATk ₁k ₂Can obtain y _Sin' (t) and y _Cos' (t).

y _Sin' (t) available formula 7 expressions:

${y_{\sin }}^{\&prime;}\left(t\right)=y_{\sin }\left(t\right)-{\mathrm{ATk}}_1{k}_2=\frac{A}{2}{\&Integral;}_0^T\cos (2\mathrm{\&pi;t}({\mathrm{\&omega;}}_1-{\mathrm{\&omega;}}_{\sin })+p_1-p_{\sin })\mathrm{dt}---\left(7\right)$

y _Cos' (t) available formula 8 expressions:

${y_{\cos }}^{\&prime;}\left(t\right)=y_{\cos }\left(t\right)-{\mathrm{ATk}}_1{k}_2=\frac{A}{2}{\&Integral;}_0^T\sin (2\mathrm{\&pi;t}({\mathrm{\&omega;}}_1-{\mathrm{\&omega;}}_{\cos })+p_1-p_{\cos })\mathrm{dt}---\left(8\right)$

In formula 7 and 8, and if only if ω ₁=ω _Sin=ω _CosThe time when equal (local generate sinusoidal signal and the local frequency that the generates cosine signal carrier frequency corresponding) with signal to be demodulated, y _Sin' (t) and y _Cos' (t) absolute value can be got maximum.y _Sin' (t) available formula 9 expressions:

${y_{\sin }}^{\&prime;}\left(t\right)=\frac{\mathrm{AT}}{2}\cos (p_1-p_{\sin })---\left(9\right)$

And y _Cos' (t) available formula 10 expressions:

${y_{\cos }}^{\&prime;}\left(t\right)=\frac{\mathrm{AT}}{2}\sin (p_1-p_{\cos })---\left(10\right)$

The result who it will be appreciated by persons skilled in the art that definite integral is actually a concrete numerical value, therefore, in a T, above-mentioned y _Sin(t) and y _Cos(t) be a concrete numerical value respectively, in like manner, y _Sin' (t) and y _Cos' (t) itself also be respectively a concrete numerical value.

Formula 9 shows that its result will be subjected to p if single one road signal to be demodulated and local sinusoidal signal that generates used multiplies each other ₁With p _SinThe influence of phase difference, have only the p of working as ₁=p _SinThe time, when promptly local generation sinusoidal signal and signal to be demodulated do not have phase difference, y _Sin' (t) value maximum.In like manner, if single one road signal to be demodulated and local cosine signal that generates of using multiplies each other, its result also will be subjected to p ₁With p _CosThe influence of phase difference.

Use y _Sin' (t) and y _Cos' (t) obtaining comparison signal y (t), the available formula 11 of y (t) is represented:

$y\left(t\right)={y_{\cos }}^{\&prime;2}\left(t\right)+{y_{\sin }}^{\&prime;2}\left(t\right)={\left[\frac{\mathrm{AT}}{2}\cos (p_1-p_{\sin })\right]}^2+{\left[\frac{\mathrm{AT}}{2}\sin (p_1-p_{\cos })\right]}^2---\left(11\right)$

In the formula 11, if p _Sin=p _Cos, then y (t) gets maximum

, this numerical value and p ₁Value irrelevant, thereby be not subjected to p ₁With p _SinPhase difference or p ₁With p _CosThe influence of phase difference.Because x _Sin(t) and x _Cos(t) signal is all local generation, p _Sin=p _CosThis condition is easy to reach.Also promptly, in the pre-demodulating principle/method of the present invention, and do not require that the initial phase of local generation sinusoidal signal and local generation cosine signal is identical with the initial phase of signal to be demodulated, these are different with the traditional coherent demodulation mode.

The above-mentioned local cosine signal that generates can be referred to as the local signal that generates with the local sinusoidal signal that generates.Because 2FSK utilizes binary system base band digital signal to go two kinds of carrier frequencies of keying (matching with first carrier frequency and second carrier frequency) to form, when frequency discrimination, can utilize frequency this locality identical with first carrier frequency to generate computing that signal carries out formula 1-11 to obtain a comparison signal, the computing that utilizes the frequency this locality generation signal identical with second carrier frequency to carry out formula 1-11 simultaneously obtains another comparison signal.As previously mentioned, and if only if ω ₁=ω _Sin=ω _CosThe time, y _Sin' (t) and y _Cos' (t) absolute value can be got maximum, and y (t) also can get maximum.Therefore, the size that compares two comparison signals, be the carrier frequency of decidable signal to be demodulated correspondence in a certain binary system code check cycle, thereby reach the purpose of frequency discrimination, and and then according to the final demodulation that realizes the 2FSK signal of the corresponding relation of carrier frequency that identifies and binary radix band signal symbol.

Need to prove, though above-mentioned introduction is pre-demodulating, frequency discrimination and the demodulation principle/method of 2FSK signal, one of ordinary skill in the art will appreciate that above-mentioned pre-demodulating, frequency discrimination and demodulation principle/method same being suitable for for non-binary multi-system fsk signal.For example when quaternary fsk signal (representing with 4FSK) is carried out frequency discrimination, there are 4 kinds (with ω owing to be used to modulate the frequency of the carrier wave of 4FSK signal ₁₀₁To ω ₁₀₄Expression), therefore can be with ω ₁₀₁Respectively as x _Sin(t) and x _Cos(t) angular frequency carries out the calculation procedure of formula 1 to 11, and finally obtains its corresponding comparison signal y ₁₀₁(t), in like manner with ω ₁₀₂To ω ₁₀₄Respectively as x _Sin(t) and x _Cos(t) angular frequency substitution formula 1-11, and finally obtain each self-corresponding comparison signal y ₁₀₂(t) to y ₁₀₄(t), find out y ₁₀₁(t) to y ₁₀₄(t) maximum in (being maximum comparison signal), the x of this maximum comparison signal correspondence _Sin(t) frequency is the carrier frequency of fsk signal correspondence, can reach the effect of pre-demodulating and frequency discrimination equally, and and then can carry out demodulation according to the frequency discrimination result.Also promptly, above-mentioned pre-demodulating provided by the present invention, frequency discrimination and demodulation principle/method are the general pre-demodulating of FSK, frequency discrimination and demodulation principle/method.

Therefore, the pre-demodulating that the embodiment of the invention provided, frequency discrimination and demodulation principle/method are not vulnerable to the local influence that generates the signal initial phase, and predemodulator/frequency discriminator/demodulator that uses analogue device and the predemodulator/frequency discriminator/demodulator that uses digital device all are suitable for.For the predemodulator/frequency discriminator/demodulator that uses digital device, because the computing before the formula 6 is non-negative computing, therefore, the pre-demodulating that the embodiment of the invention provided, frequency discrimination and demodulation method are removed or have been reduced symbolic operation, and do not have complex mathematical computings such as extraction of square root, division, be fit to digital device it is implemented.

To be application scenarios with the predemodulator that uses digital device below, the pre-demodulating method will be described.

In the present embodiment, FSK pre-demodulating method comprises the steps: at least

Step 1, fsk signal is carried out preliminary treatment obtain digital signal to be demodulated, the numerical value in the described digital signal to be demodulated is unsigned value;

Because fsk signal is an analog signal, therefore fsk signal need be carried out preliminary treatment, make it to be converted into digital signal.Above-mentioned preliminary treatment can have multiple implementation, now lifts dual mode and is illustrated.

Mode one: to fsk signal (Asin (2 π ω ₁T+p ₁)) stack DC component Ak ₁Obtain above-mentioned signal x to be demodulated ₁(t), make x ₁(t) minimum value is not less than 0, promptly becomes direct current signal;

To stack DC component Ak ₁After fsk signal (being signal to be demodulated) sample and obtain digital signal to be demodulated.

It should be noted that, above-mentioned A is not when fsk signal has DC component, equate with the amplitude of fsk signal, when fsk signal itself has had DC component, A equal the maximum of fsk signal and minimum value difference 1/2nd, but one of ordinary skill in the art will appreciate that amplitude also be maximum and minimum value difference 1/2nd.

Mode two, just has DC component at fsk signal itself, and this DC component is under 1/2nd situation of the difference of the maximum of fsk signal and minimum value, can go DC component treatment to fsk signal earlier, and then the DC component that superposes and suit the requirements, such as A, 1.1A, 1.2A etc., sample again.

No matter take which kind of mode, all will guarantee not change, and its sampled value all is not less than zero, is unsigned value through the frequency of pretreated digital signal to be demodulated.

Step 2, use have this locality generation digital signal of different frequency and respectively above-mentioned digital signal to be demodulated are carried out the pre-demodulating processing to obtain a plurality of comparison signals, this this locality generates digital signal and comprises that frequency and all identical this locality of initial phase generate sinusoidal digital signal and the local cosine digital signal that generates, the above-mentioned local numerical value that generates in sinusoidal digital signal and the local generation cosine digital signal is unsigned value, and the frequency of local sinusoidal digital signal of generation and local generation cosine digital signal is corresponding one by one with the carrier frequency of baseband digital signal keying;

Pre-demodulating in the step 2 is handled and is comprised:

Signal to the gained that multiplied each other by described local sinusoidal digital signal of generation and described digital signal to be demodulated in the predetermined integral interval carries out integral processing, generates sinusoidal demodulation integrated signal y _Sin(t), the upper limit in described predetermined integral interval and the difference of lower limit are T, and described T is a code check cycle of baseband digital signal;

Signal to the gained that multiplied each other by this locality generation cosine digital signal and described digital signal to be demodulated in above-mentioned predetermined integral interval carries out integral processing, generates cosine demodulation integrated signal y _Cos(t);

Utilize above-mentioned y _Sin(t) and y _Cos(t) obtain comparison signal y (t);

Comparison signal y (t) can by by the sinusoidal demodulation integrated signal that removes DC component after square processing, be formed by stacking after square processing with the cosine demodulation integrated signal that removes DC component.Also can otherwise obtain.

In other embodiments of the invention, above-mentioned pre-demodulating method also can comprise the step that generates the local digital signal before step 1.

Local sinusoidal digital signal and the cosine digital signal of generating can be through to above-mentioned x _Sin(t) and x _Cos(t) sampling and obtain, its sample frequency is identical with signals sampling frequency to be demodulated.In addition, because digital signal is formed by series of discrete numerical value, therefore, above-mentioned local sinusoidal digital signal of generation and cosine digital signal also can be the sine value and the cosine value of storage in advance.The later embodiment of the present invention will make detailed introduction to this.

Corresponding with it, the present invention also provides the FSK predemodulator, and Fig. 2 a shows its a kind of structure, comprise: pretreatment unit 201 and pre-demodulating unit 202, wherein, pretreatment unit 201 is used to implement above-mentioned steps one, and pre-demodulating unit 202 is used to implement above-mentioned steps two.

Need to prove, after step 2, add step 3: from a plurality of comparison signals, select maximum comparison signal (numerical value of described maximum comparison signal is greater than the numerical value of other comparison signals), and obtain the carrier frequency of fsk signal correspondence according to the pairing local frequency that generates digital signal of above-mentioned maximum comparison signal, then be the FSK frequency discrimination method.Above-mentioned frequency discrimination method is also at the row of protection scope of the present invention.

Corresponding with it, the embodiment of the invention also provides the FSK frequency discriminator, and Fig. 2 b shows a kind of structure of above-mentioned frequency discriminator 100, comprising:

Pretreatment unit 1 and digital processing element 2, digital processing element 2 comprises pre-demodulating unit 21 and decision unit 22 again, and wherein, pretreatment unit 1 is used to implement above-mentioned steps one, pre-demodulating unit 21 is used to implement above-mentioned steps two, and decision unit 22 is used to implement above-mentioned steps three.

When specific implementation, the function of pretreatment unit 1 can be realized by pre-process unit and modulus (AD) converting unit, wherein, the pre-process unit is used for fsk signal is carried out pre-process (DC component etc. of for example amplifying, superpose) to obtain direct current signal, the AD converting unit is used for this direct current signal is sampled, and obtains digital signal to be demodulated.

In other embodiments of the invention, above-mentioned pre-demodulating unit 21 or pre-demodulating unit 202 can comprise a plurality of pre-demodulating subelements, the frequency that this locality that wherein arbitrary pre-demodulating subelement is adopted generates sinusoidal digital signal is different from the frequency that this locality that other pre-demodulating subelements are adopted generates sinusoidal digital signal, and corresponding with a certain carrier frequency of described baseband digital signal keying.The quantity that also is the pre-demodulating subelement is identical with the radix of baseband digital signal, comparison signal of the last output of each pre-demodulating subelement.Be used for follow-up decision unit and carry out the carrier frequency judgement.

Because the y in the formula 7 and 10 _Sin' (t) and y _Cos' (t) span is [1,1], for further reducing the symbolic operation of digital device, in other embodiments of the invention, can use y _Sin(t) and y _Cos(t)) (y _Sin(t) and y _Cos(t) all greater than zero) replace the y among the above embodiment _Sin' (t) and y _Cos' (t) carry out pre-demodulating or frequency discrimination.Can get another expression formula 12 of comparison signal y (t) by formula 6,9 and 11:

y(t)＝y _cos′ ²(t)+y _sin′ ²(t)＝[y _cos(t)-ATk ₁k ₂] ²+[y _sin(t)-ATk ₁k ₂] ²

(12)

＝y _sin ²(t)+y _cos ²(t)-2ATk ₁k ₂[y _sin(t)+y _cos(t)]+A ²T ²k ₁ ²k ₂ ²

Y in the formula 12 _Sin ²(t), y _Cos ²(t), 2ATk ₁k ₂[y _Sin(t)+y _CosAnd A (t)] ²T ²k ₁ ²k ₂ ²All more than or equal to 0, therefore, with respect to using y _Sin' (t) and y _Cos' (t) carry out computing, still be no symbolic operation.

Because subtraction for once in formula 12 can be placed on subtraction last execution, thereby can guarantee in the calculating process to be no symbolic operation all, and then remove the performance requirement of symbolic operation to digital device, and reduce the structure complexity of system.

Referring to Fig. 3, in other embodiments of the invention, corresponding to formula 12, the concrete mode of utilizing sinusoidal demodulation integrated signal and cosine demodulation integrated signal to obtain comparison signal in the step 2 can be:

Above-mentioned sinusoidal demodulation integrated signal is carried out a square processing, obtain the first quadrature signal y _P1(t);

Above-mentioned cosine demodulation integrated signal is carried out a square processing, obtain the second quadrature signal y _P2(t);

With above-mentioned first quadrature signal, second quadrature signal and DC component A ²T ²k ₁ ²k ₂ ²Superpose, obtain the first superposed signal y _D1(t);

Will be by sinusoidal demodulation integrated signal y _Sin(t) and cosine demodulation integrated signal y _Cos(t) the signal y of stack back gained _Dm(t) amplification obtains the second superposed signal y _D2(t), the gain amplifier of described second superposed signal is 2ATk ₁k ₂

With y _D1(t) and y _D2(t) subtract each other, obtain comparison signal y (t).

Correspondingly, referring to Fig. 4, more than arbitrary pre-demodulating subelement among all embodiment comprise: generate sinusoidal demodulation integrated signal y _Sin(t) integrator 201, generation cosine demodulation integrated signal y _Cos(t) integrator 202 and comparison signal maker, comparison signal maker comprise first superpositing unit 203, second superpositing unit 204 and subtracter 205 again, wherein:

First superpositing unit 203 is used to generate the above-mentioned first superposed signal y _D1(t), second superpositing unit 204 is used to generate the above-mentioned second superposed signal y _D2And subtracter 205 is used for y (t), _D1(t) and y _D2(t) subtract each other, obtain comparison signal y (t).

The digital processing element among above-mentioned all embodiment or the function of pre-demodulating unit specifically can adopt FPGA to be realized.

Need explanation, more than frequency discrimination method among all embodiment can be used in the demodulating process of fsk signal in identifying a code check period T, behind the carrier frequency of fsk signal correspondence, also can finally realizing the demodulation of fsk signal as follows to the evaluation of carrier frequency:

Step 4, described baseband digital signal is reduced according to the corresponding relation of symbol in the carrier frequency of fsk signal correspondence and the baseband digital signal.

Accordingly, predemodulator among above-mentioned all embodiment or frequency discriminator also can be used for carrying out in the fsk demodulator pre-demodulating or carrier frequency is identified, Fig. 5 has provided a kind of structure of fsk demodulator, comprise frequency discriminator 100 and decoding unit 200, frequency discriminator 100 comprises pretreatment unit 1 and digital processing element 2, and digital processing element 2 comprises pre-demodulating unit 21 and decision unit 22, wherein, pretreatment unit 1 is used to implement above-mentioned steps one, pre-demodulating unit 21 is used to implement above-mentioned steps two, decision unit 22 is used to implement above-mentioned steps three, and decoding unit 200 is used to implement above-mentioned steps four.

Fsk signal has advantages such as antijamming capability is strong, long transmission distance, and the railway system also is extensive use of the 2FSK modulation system and transmits various control informations.To be that application scenarios carries out more detailed introduction to technical scheme of the present invention below with the railway system.

In the railway system, the structure of the responder system of row control center TCC system can mainly comprise ground transponder 61, car antenna 62 and BTM63 referring to Fig. 6, and BTM63 mainly comprises power board 631, dash receiver 632 and decoding control board 633.Wherein:

Car antenna 62 is a kind of duplexed antennas, and transponder 61 sends the energy signal of 27.095MHz earthward, and the centre frequency that reception is returned by ground transponder 61 is the 2FSK signal of 4.234MHz.The frequency of the upper side frequency that the 2FSK signal that ground transponder 61 sends adopts is 3.951MHz, and the frequency of lower side frequency is 4.516Hz;

Power board 631 is mainly used in the 2FSK signal that car antenna 62 is received and amplifies and export;

Dash receiver 632 is mainly used in handling through the fsk signal that amplifies, and the frequency that finally obtains this 2FSK signal is that upper side frequency still is the court verdict of lower side frequency;

Decoding control board 633 is mainly used in the frequency of the 2FSK correspondence of judging according to dash receiver 632 and the relation of binary system base band digital signal, restores above-mentioned binary radix band signal.

Dash receiver 632 is frequency discriminator, and dash receiver 632 has then been formed demodulator with decoding control board 633.

Fig. 7-9 shows a kind of concrete structure of above-mentioned dash receiver, comprises AD sampling A 71 and fpga chip 72.Its operation principle is as follows:

The 2FSK signal is before input AD sampling A 71, and the DC component that superposeed becomes direct current signal.After 71 pairs of above-mentioned direct current signals of AD sampling A are handled, generate 8 (2 ³) binary numeral (be aforementioned digital signal to be demodulated, in the present embodiment, also can be called the 2FSK data) the input fpga chip 72 of precision, use for the subsequent algorithm computing.In addition, AD sampling A 71 is controlled by the local generator module of fpga chip 72, to reach the purpose of coordinated operation.

Local frequency generator module is divided into upper side frequency frequency generator module 73 and lower side frequency frequency generator module 74, regularly exports following signal according to the upper and lower side frequency frequency of 2FSK signal respectively: the AD sampling trigger signal; Sine, cosine value (being aforementioned local sinusoidal digital signal and the local generation cosine digital signal of generating) through the generation of sine and cosine tables of data.Upper side frequency frequency generator module 73 is responsible for the output reset signal simultaneously to the integrator in upper side frequency demodulator module 710 and the lower side frequency demodulator module 711.The zero clearing time for default one digit number according to the position delivery time, be code check cycle of binary radix band signal.With 564.48Kbit/s is example, and the zero clearing time is fixed as 1.772 μ s.

Sine and cosine tables of data module 75 is used to store sine and cosine numerical value.Because frequency discrimination method provided by the present invention just be not subjected to, the local influence that generates cosine digital signal initial phase, only requires that two signal initial phases are identical, therefore, the initial phase of sinusoidal numerical value can be provided with arbitrarily.

In one-period T, frequency is that the wave number of the sine wave of upper side frequency is 8, is 7 and frequency is the wave number of the sine wave of lower side frequency.For the sine wave of upper side frequency, a waveform needs to sample 4 times at least, so in one-period T, be 32 to the minimum sampling number of 2FSK signal.The 2FSK signals sampling available 8K that counts is represented that wherein K is more than or equal to 4.

Therefore, when the sine and cosine numerical value that has a upper side frequency in use carries out pre-demodulating to the 2FSK data, only need 4 sinusoidal datas and 4 corresponding cosine data get final product, and above-mentioned cosine data can obtain by corresponding relation, also promptly only need get final product by 4 sinusoidal datas with sinusoidal data.

And frequency is the sine wave of lower side frequency owing to have 7 waveforms in a code check period T, each waveform can't be assigned to fixing sampling number, therefore, when the sine and cosine numerical value that has a lower side frequency in use carries out pre-demodulating to the 2FSK data, need 32 sinusoidal datas.

Because technical scheme provided by the invention is not done requirement to initial phase, so can be with the sinusoidal period five equilibrium, every the fixed angle value once.

Multiplier 76 can be used for realizing multiplying each other of sinusoidal numerical value corresponding with upper side frequency and 2FSK data, and multiplier 77 then is used to realize multiplying each other of cosine values corresponding with upper side frequency and 2FSK data.In like manner, multiplier 78 and 79 be respectively applied for realize corresponding with lower side frequency just, the multiplying each other of cosine values and 2FSK data.

Upper side frequency demodulator module 710 is used to carry out the computing of formula 12, and its internal structure can comprise first adder 81, second adder 82, first squarer 83, second squarer 84, multiplier 85, subtracter 86 and integrator 87 and 88 referring to Fig. 8.Wherein, integrator 87 is used for the output result of multiplier 76 is carried out integration, and integrator 88 is used for the output result of multiplier 77 is carried out integration.

Lower side frequency demodulator module 711 is used to carry out the computing of formula 12, and its internal structure and upper side frequency demodulator module 710 are similar.Comprise the 3rd adder 91, the 4th adder 92, the 3rd squarer 93, the 4th squarer 94, multiplier 95, subtracter 96, integrator 97 and 98.Wherein, integrator 97 is used for the output result of multiplier 78 is carried out integration, and integrator 98 is used for the output result of multiplier 78 is carried out integration.

Integrator 87,88,97 and 98 adopts accumulation mode, carries out zero clearing after receiving reset signal.

Judgement decoder module 712, be used for according to upper side frequency demodulator module 710 and lower side frequency demodulator module 711 input values size decision output 0,1 code, converge the FSK decoding figure place of a location number simultaneously, disposablely be defeated by follow-up CPU by data I/O oral instructions and carry out the message processing.The general use is 2 bytes, 16 bit data I/O mouths.

Each embodiment adopts the mode of going forward one by one to describe in this specification, and what each embodiment stressed all is and the difference of other embodiment that identical similar part is mutually referring to getting final product between each embodiment.For the disclosed device of embodiment, because it is corresponding with the embodiment disclosed method, so description is fairly simple, relevant part partly illustrates referring to method and gets final product.

The professional can also further recognize, the unit and the step of each example of describing in conjunction with embodiment disclosed herein can realize with electronic hardware, computer software or the combination of the two.For the interchangeability of hardware and software clearly is described, the composition and the step of each example described prevailingly according to function in the above description.These functions still are that software mode is carried out with hardware actually, depend on the application-specific and the design constraint of technical scheme.The both available integrated digital multiplier of the function of for example above-mentioned multiplier, adder, adder realized, also can use programming devices such as fpga chip and programme and realized.The professional and technical personnel can use distinct methods to realize described function to each specific should being used for, but this realization should not thought and exceeds scope of the present invention.

Each embodiment adopts the mode of going forward one by one to describe in this specification, and what each embodiment stressed all is and the difference of other embodiment that identical similar part is mutually referring to getting final product between each embodiment.For the disclosed system of embodiment, because it is corresponding with the embodiment disclosed method, so description is fairly simple, relevant part partly illustrates referring to method and gets final product.

To the above-mentioned explanation of the disclosed embodiments, make this area professional and technical personnel can realize or use the present invention.Multiple modification to these embodiment will be conspicuous concerning those skilled in the art, and defined herein General Principle can realize under the situation that does not break away from the spirit or scope of the present invention in other embodiments.Therefore, the present invention will can not be restricted to these embodiment shown in this article, but will meet and principle disclosed herein and features of novelty the wideest corresponding to scope.

Claims (12)

1. a frequency shift keying FSK pre-demodulating method is characterized in that, comprising:

Fsk signal is carried out preliminary treatment obtain digital signal to be demodulated, the numerical value in the described digital signal to be demodulated is unsigned value;

Use has this locality generation digital signal of different frequency and respectively described digital signal to be demodulated is carried out the pre-demodulating processing to obtain a plurality of comparison signals, the described local digital signal that generates comprises that frequency and all identical this locality of initial phase generate sinusoidal digital signal and the local cosine digital signal that generates, the described local numerical value that generates in sinusoidal digital signal and the local generation cosine digital signal is unsigned value, and the frequency of described local sinusoidal digital signal of generation and local generation cosine digital signal is corresponding one by one with the carrier frequency of described baseband digital signal keying;

Described pre-demodulating is handled and is comprised:

Signal to the gained that multiplied each other by described local sinusoidal digital signal of generation and described digital signal to be demodulated in the predetermined integral interval carries out integral processing, generate the sinusoidal demodulation integrated signal, the upper limit in described predetermined integral interval and the difference of lower limit are T, and described T is a code check cycle of baseband digital signal;

Signal to the gained that multiplied each other by this locality generation cosine digital signal and described digital signal to be demodulated in described predetermined integral interval carries out integral processing, generates cosine demodulation integrated signal;

Utilize described sinusoidal demodulation integrated signal and cosine demodulation integrated signal to obtain comparison signal.

2. the method for claim 1 is characterized in that, fsk signal is carried out the specific implementation that preliminary treatment obtains digital signal to be demodulated be:

To described fsk signal stack DC component Ak ₁

To stack DC component Ak ₁After fsk signal sample and obtain digital signal to be demodulated.

3. method as claimed in claim 2 is characterized in that,

In that being carried out, described fsk signal also comprises generating the local digital signal before preliminary treatment obtains digital signal to be demodulated.

4. as each described method of claim 1-3, it is characterized in that,

The described concrete mode of utilizing described sinusoidal demodulation integrated signal and cosine demodulation integrated signal to obtain comparison signal is:

Described sinusoidal demodulation integrated signal is carried out a square processing, obtain first quadrature signal;

Described cosine demodulation integrated signal is carried out a square processing, obtain second quadrature signal;

With described first quadrature signal, described second quadrature signal and DC component A ²T ²k ₁ ²k ₂ ²Superpose, obtain first superposed signal, wherein, A equal described fsk signal maximum and minimum value difference 1/2nd, k ₁And k ₂All be not less than zero, and Ak ₁Equal the DC component of described digital signal to be demodulated, k ₂Equal the described local DC component that generates sinusoidal digital signal;

To be amplified by the signal of described sinusoidal demodulation integrated signal and cosine demodulation integrated signal stack back gained and obtain second superposed signal, the gain amplifier of described second superposed signal is 2ATk ₁k ₂

Described first superposed signal and second superposed signal are subtracted each other, obtain described comparison signal.

5. as each described method of claim 1-3, it is characterized in that,

The described concrete mode of utilizing described sinusoidal demodulation integrated signal and cosine demodulation integrated signal to obtain comparison signal is:

Remove the DC component of described sinusoidal demodulation integrated signal and cosine demodulation integrated signal respectively;

Respectively sinusoidal demodulation integrated signal that removes DC component and the cosine demodulation integrated signal that removes DC component are carried out a square processing;

To superpose through two signals of square processing.

6. a frequency shift keying FSK frequency discrimination method is used for differentiating by baseband digital signal keyed carrier frequency

And the pairing carrier frequency of fsk signal that generates is characterized in that, comprising:

Described fsk signal is carried out preliminary treatment obtain digital signal to be demodulated, the numerical value in the described digital signal to be demodulated is unsigned value;

Use has this locality generation digital signal of different frequency and respectively described digital signal to be demodulated is carried out the pre-demodulating processing to obtain a plurality of comparison signals, the described local digital signal that generates comprises that frequency and all identical this locality of initial phase generate sinusoidal digital signal and the local cosine digital signal that generates, the described local numerical value that generates in sinusoidal digital signal and the local generation cosine digital signal is unsigned value, and the frequency of described local sinusoidal digital signal of generation and local generation cosine digital signal is corresponding one by one with the carrier frequency of described baseband digital signal keying;

From described a plurality of comparison signals, select maximum comparison signal, and obtain the carrier frequency of described fsk signal correspondence according to the pairing local frequency that generates digital signal of described maximum comparison signal;

Described pre-demodulating is handled and is comprised:

Signal to the gained that multiplied each other by described local sinusoidal digital signal of generation and described digital signal to be demodulated in the predetermined integral interval carries out integral processing, generate the sinusoidal demodulation integrated signal, the upper limit in described predetermined integral interval and the difference of lower limit are T, and described T is a code check cycle of baseband digital signal;

Signal to the gained that multiplied each other by this locality generation cosine digital signal and described digital signal to be demodulated in described predetermined integral interval carries out integral processing, generates cosine demodulation integrated signal;

Utilize described sinusoidal demodulation integrated signal and cosine demodulation integrated signal to obtain comparison signal.

7. a frequency shift keying FSK demodulation method is used for the fsk signal that is generated by baseband digital signal keyed carrier frequency is carried out demodulation, it is characterized in that, comprising:

Described fsk signal is carried out preliminary treatment obtain digital signal to be demodulated, the numerical value in the described digital signal to be demodulated is unsigned value;

Use has this locality generation digital signal of different frequency and respectively described digital signal to be demodulated is carried out the pre-demodulating processing to obtain a plurality of comparison signals, the described local digital signal that generates comprises that frequency and all identical this locality of initial phase generate sinusoidal digital signal and the local cosine digital signal that generates, the described local numerical value that generates in sinusoidal digital signal and the local generation cosine digital signal is unsigned value, and the frequency of described local sinusoidal digital signal of generation and local generation cosine digital signal is corresponding one by one with the carrier frequency of described baseband digital signal keying;

From described a plurality of comparison signals, select maximum comparison signal, and obtain the carrier frequency of described fsk signal correspondence according to the pairing local frequency that generates digital signal of described maximum comparison signal;

Corresponding relation according to symbol in the carrier frequency of described fsk signal correspondence and the baseband digital signal reduces to described baseband digital signal;

Described pre-demodulating is handled and is comprised:

Signal to the gained that multiplied each other by described local sinusoidal digital signal of generation and described digital signal to be demodulated in the predetermined integral interval carries out integral processing, generate the sinusoidal demodulation integrated signal, the upper limit in described predetermined integral interval and the difference of lower limit are T, and described T is a code check cycle of baseband digital signal;

Signal to the gained that multiplied each other by this locality generation cosine digital signal and described digital signal to be demodulated in described predetermined integral interval carries out integral processing, generates cosine demodulation integrated signal;

Utilize described sinusoidal demodulation integrated signal and cosine demodulation integrated signal to obtain comparison signal.

8. a frequency shift keying predemodulator is characterized in that, comprises pretreatment unit and pre-demodulating unit, wherein,

Pretreatment unit is used for that described fsk signal is carried out preliminary treatment and obtains digital signal to be demodulated, and the numerical value in the described digital signal to be demodulated is unsigned value;

The pre-demodulating unit, be used to use this locality to generate digital signal and respectively described digital signal to be demodulated carried out the pre-demodulating processing to obtain a plurality of comparison signals with different frequency, the described local digital signal that generates comprises that frequency and all identical this locality of initial phase generate sinusoidal digital signal and the local cosine digital signal that generates, the described local numerical value that generates in sinusoidal digital signal and the local generation cosine digital signal is unsigned value, and the frequency of described local sinusoidal digital signal of generation and local generation cosine digital signal is corresponding one by one with the carrier frequency of described baseband digital signal keying;

Described pre-demodulating is handled and is comprised:

Signal to the gained that multiplied each other by described local sinusoidal digital signal of generation and described digital signal to be demodulated in the predetermined integral interval carries out integral processing, generates the sinusoidal demodulation integrated signal, and the upper limit in described predetermined integral interval and the difference of lower limit are T;

Signal to the gained that multiplied each other by this locality generation cosine digital signal and described digital signal to be demodulated in described predetermined integral interval carries out integral processing, generates cosine demodulation integrated signal;

Utilize described sinusoidal demodulation integrated signal and cosine demodulation integrated signal to obtain comparison signal.

9. predemodulator as claimed in claim 8, it is characterized in that, described pre-demodulating unit comprises a plurality of pre-demodulating subelements, the frequency that this locality that wherein arbitrary pre-demodulating subelement is adopted generates sinusoidal digital signal is different from the frequency that this locality that other pre-demodulating subelements are adopted generates sinusoidal digital signal, and corresponding with a certain carrier frequency of described baseband digital signal keying;

Arbitrary pre-demodulating subelement comprises the integrator that generates the sinusoidal demodulation integrated signal, integrator and the comparison signal maker that generates cosine demodulation integrated signal, and described comparison signal maker comprises first superpositing unit, second superpositing unit and subtracter, wherein:

First superpositing unit, be used for described sinusoidal demodulation integrated signal is carried out a square processing, obtain first quadrature signal, described cosine demodulation integrated signal is carried out a square processing, obtain second quadrature signal, and with described first quadrature signal, described second quadrature signal and DC component A ²T ²k ₁ ²k ₂ ²Superpose, obtain first superposed signal, wherein, A equal described fsk signal maximum and minimum value difference 1/2nd, k ₁And k ₂All be not less than zero, and Ak ₁Equal the DC component of described digital signal to be demodulated, k ₂Equal the described local DC component that generates sinusoidal digital signal;

Second superpositing unit is used for obtaining second superposed signal with being amplified by the signal of gained after described sinusoidal demodulation integrated signal and the stack of cosine demodulation integrated signal, and the gain amplifier of described second superposed signal is 2ATk ₁k ₂

Subtracter is used for described first superposed signal and second superposed signal are subtracted each other, and obtains described comparison signal.

10. predemodulator as claimed in claim 9 is characterized in that, described pre-demodulating unit is specially field programmable gate array.

11. frequency shift keying frequency discriminator, it is characterized in that, comprise decision unit and as each described predemodulator of claim 8-10, described decision unit is used for selecting maximum comparison signal from described a plurality of comparison signals, and obtains the carrier frequency of described fsk signal correspondence according to the pairing local frequency that generates digital signal of described maximum comparison signal.

12. frequency shift keying demodulator, it is characterized in that, comprise decoding unit and frequency discriminator as claimed in claim 11, described decoding unit is used for according to the corresponding relation of the carrier frequency of described fsk signal correspondence and baseband digital signal symbol described baseband digital signal being reduced.

Images