CN101695004B - Separation system of radio signals - Google Patents

Abstract

The invention discloses a separation system of radio signals, which comprises an analog-to-digital conversion controller. The analog-to-digital conversion controller is used for converting inputted analog signals into digital signals, signals outputted from the analog-to-digital conversion controller are divided into two paths, one path of signals is inputted into an FIR filter to perform single-frequency filter and converted into voice signals via the analog-to-digital conversion controller to be output, and the other path of signals is separated to form PTT control signals to be output after sequentially passing through a time-frequency conversion unit, a threshold detecting unit and a stable processing unit. The separation system has the advantages of (1), high filter effect, (2) high frequency detecting precision, (3) low noise coefficient, (4) simple technique, and (5) fine stability.

Description

A kind of piece-rate system of radio signals

Technical field

The present invention relates to a kind of piece-rate system of radio signals, particularly the piece-rate system of a kind of radio station PTT control signal and speech.

Background technology

In general, the half-duplex operation mode is adopted in radio station (hereinafter to be referred as " radio station ") communication, and a side can not receive the opposing party's voice signal when sending voice signal.Therefore the communication interface in radio station is divided into two parts, and a part is the voice signal interface, is used for sending and receiving speech, and another part is PTT control signal interface, is used for the state that sends and receives in control radio station.

Yet, many communication equipments are arranged at present, such as (hereinafter to be referred as " interior logical equipment ") such as the intercommunication of civil aviaton, maritime affairs, railway traffic and emergency communications, in order to realize the Remote in radio station, and saving channel resource, the simple signal that the PTT control signal is modulated into 2930Hz sends with voice signal, guarantees the reliability of PTT control signal transmission.

When interior logical equipment directly linked to each other with the radio station, interface was incompatible.Therefore need a kind of radio interface modular converter of design, simple signal and the voice signal of 2930Hz can be separated, communicating by letter with interior logical equipment in the realization radio station, adopts as shown in Figure 1 analog circuit to realize.

Current radio PTT control signal realizes with the pattern that is the employing analog circuit separating of speech.On the one hand, the combination of employing analogue device, adopt the multiple filter cascade system, realize that centre frequency is the band stop filter of 2930Hz, filtering 2930Hz simple signal obtains purer voice signal, on the other hand, adopt the analog frequency testing circuit, realize the detection of 2930Hz simple signal, be used for generation and the transmission of control PTT control signal.

Radio station PTT control signal and the speech separation method of present analog circuit pattern can practical functions.But owing to reasons such as systems, also there is following defective in analog circuit: (1) filter effect is relatively poor.The stopband attenuation ability of analog filter is relatively poor, and the filtering of 2930Hz simple signal is unclean, affects the reception of speech; (2) frequency detection accuracy is lower.Detect frequency range generally more than 100Hz, so that the rising of simple signal false drop rate causes PTT control signal control error; (3) noise factor is higher.General analog circuit all can produce-ground wire noise about 10db; And the multiple filter cascade, also can introduce larger noise, affect the reception of speech; (4) production, testing and measuring technology complexity, and adaptability is relatively poor.Because the discreteness of analogue device, need to adjust parameters such as the filter frequencies of every equipment, gains by adjusting the components and parts such as a large amount of resistance and electric capacity in the production process, time-consuming; (5) poor stability.Analogue device consistency and temperature characterisitic are bad, easily are subjected to the variable effect of temperature or device property behind the product export, and the parameter that causes adjusting is drifted about, and the equipment performance index are descended or inefficacy.

Summary of the invention

Goal of the invention: technical problem to be solved by this invention is for the deficiencies in the prior art, and a kind of piece-rate system of radio signals is provided.

The objective of the invention is the weakness for the above analog circuit, adopt digital signal processing method to design a kind of new method, realize the separation function of radio station PTT control signal and speech; The method can overcome some weaknesses of the described analog circuit of upper joint simultaneously, greatly improves tonequality, anti-interference and the extensibility of station telecommunication.

Technical scheme: the invention discloses a kind of piece-rate system of radio signals, comprising:

A/D converter controller, the analog signal conversion that is used for input is digital signal;

Be divided into two-way from the signal of A/D converter controller output, one tunnel input FIR filter carries out single-frequency filtering, exports after then process digital-to-analogue conversion controller is converted to voice signal; Another road is successively through isolating the output of PTT control signal behind time-frequency converting unit, threshold detection unit and the stable processing unit.

Among the present invention, preferably, the sample frequency of described A/D converter controller and digital-to-analogue conversion controller is 6～12KHz.

Among the present invention, preferably, described input FIR filter carries out single-frequency filtering, may further comprise the steps:

Step (1) is determined desirable linear phase band stop filter, and its formula is:

$h_d\left(n\right)=\frac{\sin \left[\mathrm{\π}(n-\mathrm{\α})\right]}{\mathrm{\π}(n-\mathrm{\α})}-\frac{\sin \left[{\mathrm{\ω}}_h(n-\mathrm{\α})\right]}{\mathrm{\π}(n-\mathrm{\α})}+\frac{\sin \left[{\mathrm{\ω}}_l(n-\mathrm{\α})\right]}{\mathrm{\π}(n-\mathrm{\α})}$

h _dThe endless non-causal sequence of the even symmetry that (n) to be central point order at α, ω _h, ω _lIt is the cut-off frequency of filter;

Step (2) is chosen window function ω (n) and h _d(n) multiply each other, the finite length sequence that to obtain one section sequence length be N, that is:

$h\left(n\right)=h_d\left(n\right)\×\mathrm{\ω}\left(n\right)=\left\{\begin{array}{cc}h\left(n\right)& 0\≤n\≤N-1\\ 0& \mathrm{otherwise}\end{array}\right.;$

Order $\mathrm{\α}=\frac{N-1}{2},$ Then h (n) is required FIR band stop filter;

The digital signal of input is carried out convolution algorithm with length for the finite length sequence h (n) of N, obtain filtering out the digital signal of simple signal.

Among the present invention, preferably, described sequence length is N value 256.

Among the present invention, preferably, described cut-off frequency is:

${\mathrm{\ω}}_h=\frac{2930\mathrm{Hz}}{f_s/2}\mathrm{\π}+\mathrm{\Δ\ω};$

${\mathrm{\ω}}_l=\frac{2930\mathrm{Hz}}{f_s/2}\mathrm{\π}-\mathrm{\Δ\ω};$

Δ ω defines according to the stability of the 2930Hz simple signal that interior logical equipment sends, and guarantees that simple signal exists $[\frac{f_s\·{\mathrm{\ω}}_l}{2\mathrm{\π}},\frac{f_s\·{\mathrm{\ω}}_h}{2\mathrm{\π}}]$ Change in the interval, and Δ ω is minimum.

Among the present invention, preferably, described window function is selected second order Cosine Window, i.e. Blackman window:

$\mathrm{\ω}\left(n\right)=\left\{\begin{array}{cc}0.42-0.5\cos \left(\frac{2\mathrm{\πn}}{N-1}\right)+0.08\cos \left(\frac{4\mathrm{\πn}}{N-1}\right)& 0\≤n\≤N-1\\ 0& \mathrm{otherwise}\end{array}\right..$

Among the present invention, preferably, described time-frequency conversion unit transforms to frequency sequence F (k) on the frequency domain with the time series t on the time domain (n): do 2 ^NThe FFT of point, the detection frequency range of single-frequency, namely the sampling interval of frequency domain is $\mathrm{\Δf}=\frac{f_s/2}{2^{N-1}}=f_s/2^N,$ The sense cycle that single-frequency detects is the time of finishing a FFT, i.e. T _D=2 ^N/ f _sWherein get N=9, the detection bandwidth delta f ≈ 16Hz of single-frequency, the sense cycle T that single-frequency detects _D=64ms.

Among the present invention, preferably, described threshold detection unit definition simple signal is at [f ₁, f ₂] medium and small amplitude variation f ₁≤ 2930Hz≤f ₂, calculate k according to formula ₁And k ₂:

f ₁×Δf≤f ₁≤(k ₁+1)×Δf

(k ₂-1)×Δf≤f ₂≤k ₂×Δf

Wherein Δ f is the detection frequency range of single-frequency, the i.e. sampling interval of frequency domain;

Computation interval [k ₁, k ₂] in the energy of frequency sequence F (k) $W(k_1,k_2)=\underset{i=k_1}{\overset{k_2}{\mathrm{\Σ}}}\left|F\left(k_i\right)\right|,$ The threshold value TH that sets is if W is (k ₁, k ₂) greater than threshold value TH, judge that then this sense cycle detects simple signal, otherwise, judge that this sense cycle does not detect simple signal.

Among the present invention, preferably, described stable processing unit may further comprise the steps:

Define a counter, initial value is 0, and Counter Value is defined between 0 to T, and T＞0 if make Counter Value greater than T, then is saturated to T with Counter Value in add operation; If in reducing, make counter less than 0, then Counter Value be saturated to 0;

Step (11) detects measured value and whether crosses threshold value, if cross threshold value, Counter Value adds m, carries out step (12); If threshold value but, Counter Value subtracts n, carries out step (14);

Step (12) is if Counter Value greater than the T value, then is saturated to the T value;

Step (13), the detection counter value if Counter Value equals T, then starts output PTT control signal, and finishes; If Counter Value, is then kept last PTT control signal output state less than T, and finish;

Step (14) is if Counter Value less than 0, then is saturated to 0 value;

Step (15), the detection counter value, if Counter Value equals 0, then cancellation output PTT control signal, and end; If Counter Value, is then kept last PTT control signal output state greater than 0.

Realize separating of voice signal and PTT control signal among the present invention, need to realize following three functions:

Input and output: the voice signal of logical equipment is converted into digital signal in receiving on the one hand, is used for subsequent treatment; On the other hand, the digital signal of processing is converted to voice signal, exports to the radio station.The key of this function is choosing of digital signal samples frequency.

Single-frequency filtering: the voice signal of logical equipment in receiving, adopt the FIR filter, the 2930Hz simple signal in the filtering voice signal sends to the radio station with the voice signal after the filtering.The key of this function is the design of FIR filter.

Single-frequency detects: the voice signal of logical equipment in receiving, detect the 2930Hz simple signal in the voice signal, and generate accordingly the PTT control signal, send to the radio station; The realization of this function is divided into time-frequency conversion, threshold test and three steps of stable processing.

Beneficial effect: as shown in Figure 5, the present invention compares with conventional art and has the following advantages: (1) filter effect is better: adopt the FIR filter, stopband attenuation can be arrived-below the 74dB; (2) frequency detection accuracy is high: the frequency detection accuracy of simple signal can reach 16Hz; (3) noise factor is low: adopt the Digital Signal Processing mode, be not subjected to the ground wire noise effect; In addition, digital filter can not introduced extra noise.Adopt this method, noise factor can reach-below the 30dB; (4) technique is simple, strong adaptability: without the device discreteness, need not the components and parts of every equipment are adjusted, only need by the software parameters; (5) good stability: function is not subjected to the impact of device consistency and temperature characterisitic, can be at steady operation under the varying environment.

Description of drawings

Below in conjunction with the drawings and specific embodiments the present invention is done further to specify, above-mentioned and/or otherwise advantage of the present invention will become apparent.

Fig. 1 is that the traditional station interface modular converter uses block diagram among the present invention.

Fig. 2 is functional block diagram of the present invention.

Fig. 3 is desirable band stop filter frequency characteristic figure.

Fig. 4 stablizes the processing unit processes flow chart among the present invention.

Adopt analog circuit and this method to realize the performance comparison figure that radio station PTT control signal is separated with speech among Fig. 5.

Embodiment:

As shown in Figure 2, the invention discloses a kind of piece-rate system of radio signals, comprising: A/D converter controller, the analog signal conversion that is used for input is digital signal; Be divided into two-way from the signal of A/D converter controller output, one tunnel input FIR filter carries out single-frequency filtering, exports after then process digital-to-analogue conversion controller is converted to voice signal; Another road is successively through isolating the output of PTT control signal behind time-frequency converting unit, threshold detection unit and the stable processing unit.The present invention is based on Digital Signal Processing, the voice signal of interior logical equipment is converted into digital data transmission to the input block by ADC, digital voice signal passes through the FIR band stop filter on the one hand, filtering 2930Hz simple signal, send to output buffer, be converted into voice signal by DAC again, be transferred to the radio station; On the other hand, by time-frequency conversion, threshold test and three unit of stable processing, detect the 2930Hz simple signal, produce accordingly the output of PTT control signal.

More particularly, the realization of function of the present invention comprises following part:

One, input/output signal is processed

The input and output of digital signal realize by ADC and DAC.The voice signal of interior logical equipment is converted into digital data transmission to the input block by ADC, for the treatment of; And the data communication device of processing crosses DAC and is converted into voice signal, is transferred to the radio station.In the design of input and output, the sample frequency of ADC/DAC is the key of design.

The frequency of general speech is 300～3000Hz, and the simple signal that needs to detect is 2930Hz.According to sampling thheorem, the sample frequency of ADC/DAC should be greater than 6KHz.In order to reduce the amount of calculation of software, sample frequency should be in the situation that to satisfy function low as far as possible.The characteristic that is used for the ADC/DAC chip of audio frequency according to great majority is designed to 8KHz with the sample frequency of ADC/DAC proper.Both satisfy functional requirement, reduced again the amount of calculation of software, be applicable to simultaneously most of audio ADCs/DAC chip.

Two, single-frequency filter function

Narrow-band band-elimination filter filtering 2930Hz simple signal centered by 2930Hz of the Functional Design of single-frequency filtering, the present invention adopts the FIR filter to realize.

The window design method is adopted in the design of filter, and the specific design step is as follows:

At first determine desirable linear phase band stop filter, its formula is:

$h_d\left(n\right)=\frac{\sin \left[\mathrm{\π}(n-\mathrm{\α})\right]}{\mathrm{\π}(n-\mathrm{\α})}-\frac{\sin \left[{\mathrm{\ω}}_h(n-\mathrm{\α})\right]}{\mathrm{\π}(n-\mathrm{\α})}+\frac{\sin \left[{\mathrm{\ω}}_l(n-\mathrm{\α})\right]}{\mathrm{\π}(n-\mathrm{\α})};$

The endless non-causal sequence of the even symmetry that to be central point order at α, ω _h, ω _lThe cut-off frequency of filter, its frequency characteristic as shown in Figure 3: next seeks suitable window function ω (n), with h _d(n) multiply each other, obtain a segment length and be the finite length sequence of N, that is:

$h\left(n\right)=h_d\left(n\right)\×\mathrm{\ω}\left(n\right)=\left\{\begin{array}{cc}h\left(n\right)& 0\≤n\≤N-1\\ 0& \mathrm{otherwise}\end{array}\right.$

In order to guarantee that h (n) is causal sequence, order $\mathrm{\α}=\frac{N-1}{2},$ Then h (n) is required FIR band stop filter.

To can obtain filtering out the digital signal of 2930Hz simple signal with long for the finite length sequence h (n) of N carries out convolution algorithm by the digital signal that ADC transforms, and be converted into voice signal by DAC and can be transferred to the radio station.

In the design of FIR band stop filter, three key points are arranged: definite, the cut-off frequency ω of sequence length N _h, ω _lDetermine and the determining of window function ω (n).

When determining sequence length N, because the AD sample rate is f _s=8KHz, the effective bandwidth of FIR band stop filter then is f _s/ 2=4KHz.The N value is larger, and the frequecy characteristic of FIR band stop filter is just better.But consider the actual operation speed of digital signal processing module, N should get moderate value, usually is advisable with N=256.

Cut-off frequency ω _h, ω _lDetermine: FIR band stop filter main application is the 2930Hz simple signal in the signal that logical equipment sends in the filtering.So the bandwidth that the stopband of this filter should be centered by 2930Hz is the arrowband of 2 Δ ω.So cut-off frequency is:

${\mathrm{\ω}}_h=\frac{2930\mathrm{Hz}}{f_s/2}\mathrm{\π}+\mathrm{\Δ\ω}$

${\mathrm{\ω}}_l=\frac{2930\mathrm{Hz}}{f_s/2}\mathrm{\π}-\mathrm{\Δ\ω}$

Δ ω defines according to the stability of the 2930Hz simple signal that interior logical equipment sends, and guarantees that simple signal exists $[\frac{f_s\·{\mathrm{\ω}}_l}{2\mathrm{\π}},\frac{f_s\·{\mathrm{\ω}}_h}{2\mathrm{\π}}]$ Change in the interval, and Δ ω is minimum.

Window function ω (n) determines: the sensitivity of people's ear is very high, and the distortion of sound and the faint noise that is mingled with are easy to identification.Be the effect of assurance single-frequency target signal filter, and the audio distortions degree is as far as possible little, needs very high side lobe attenuation; The simultaneously decay of stopband also requires very large.Therefore, the present invention selects second order Cosine Window, i.e. Blackman window:

$\mathrm{\ω}\left(n\right)=\left\{\begin{array}{cc}0.42-0.5\cos \left(\frac{2\mathrm{\πn}}{N-1}\right)+0.08\cos \left(\frac{4\mathrm{\πn}}{N-1}\right)& 0\≤n\≤N-1\\ 0& \mathrm{otherwise}\end{array}\right.$

Second order Cosine Window side lobe peak decays to-57dB, and minimum attenuation in stop band is-74dB that to the distortion control successful of sound, the simple signal filtering is clean.

Three, single-frequency measuring ability

The function that single-frequency detects is whether to have the 2930Hz simple signal in the output voice signal of logical equipment in detecting, if exist, namely exports the PTT control signal to the radio station.This function mainly realizes by time-frequency conversion, threshold test and three unit of stable processing.

Time-frequency conversion unit: detect the signal of a certain frequency, just detection coordinates system need to be transformed into frequency domain from time domain, so the first step of 2930Hz single-frequency signal detection is exactly time-frequency conversion.The present invention adopts the fast algorithm fast Fourier transform (FFT) of discrete Fourier transform, a kind of quick time-frequency conversion algorithm that is applicable to Computer Processing is realized time-frequency conversion, and the frequency sequence F (k) that the time series t on the time domain (n) is transformed on the frequency domain processes.

According to sampling thheorem, at sample frequency f _sIn the situation of=8KHz, do 2 ^NThe FFT of point, the detection frequency range of single-frequency, namely the sampling interval of frequency domain is $\mathrm{\Δf}=\frac{f_s/2}{2^{N-1}}=f_s/2^N.$

And the sense cycle that single-frequency detects is the time of finishing a FFT, i.e. T _D=2 ^N/ f _s

Therefore the sense cycle of the resolution of frequency and single-frequency detection is relation reciprocal each other, the relation that namely mutually restricts, and the detection frequency range of single-frequency has narrowed down, and the sense cycle that single-frequency detects will increase; Vice versa.Usually get N=9, then the detection bandwidth delta f ≈ 16Hz of single-frequency; And the sense cycle T that single-frequency detects _D=64ms is comparatively suitable.The detection frequency range of 16Hz can reduce the false drop rate of simple signal greatly, and the delay of 64ms can not affect the speech quality of whole system.

Threshold detection unit: the stability of the 2930Hz simple signal that sends according to interior logical equipment, the definition simple signal is at [f ₁, f ₂] medium and small amplitude variation (f ₁≤ 2930Hz≤f ₂), can calculate k ₁And k ₂, satisfy:

f ₁×Δf≤f ₁≤(k ₁+1)×Δf

(k ₂-1)×Δf≤f ₂≤k ₂×Δf

Wherein Δ f is the detection frequency range of single-frequency, the i.e. sampling interval of frequency domain.

Computation interval [k ₁, k ₂] in the energy of frequency sequence F (k) $W(k_1,k_2)=\underset{i=k}{\overset{k_2}{\mathrm{\Σ}}}\left|F\left(k_i\right)\right|,$ Set a suitable threshold value TH, if W is (k ₁, k ₂) greater than threshold value TH, think that then this sense cycle detects simple signal, otherwise, think that this sense cycle does not detect simple signal.

Stablize processing unit: because on the channel or the interference of hardware itself, the measured value of single sense cycle surpasses threshold value or below threshold value, can not represent this cycle to have produced simple signal or do not had generation.The threshold test of voucher sense cycle and produce the unsteadiness that the PTT control signal can be brought speech control only.So, before the PTT control signal produces, to increase the stable process of processing.The number of times that surpasses threshold value when continuous a plurality of sense cycle measured values deducts measured value and is no more than the number of times of threshold value greater than certain value, think that then interior logical equipment has sent simple signal, so send the PTT control signal to the radio station, wherein, this certain value is not the fixed value of presetting, but by the step-length m of counter of definition, n determines, as described in hypomere; Otherwise, the number of times that is no more than threshold value when continuous a plurality of sense cycle measured values deducts measured value and surpasses the number of times of threshold value greater than this certain value, think that then interior logical equipment has not sent simple signal, so the PTT control signal is sent in cancellation to the radio station, wherein, this certain value is not the fixed value of presetting, but by the step-length m of counter of definition, n determines, as described in hypomere.Accuracy and the adaptability in the PTT control signal that produce through stable the processing are strengthened greatly.Concrete processing is as follows, and flow process as shown in Figure 4.

For realizing this function, need a self-defined counter, initial value is 0, Counter Value is defined between 0 to T (T＞0).If in add operation, make Counter Value greater than T, then Counter Value be saturated to T; If in reducing, make counter less than 0, then Counter Value be saturated to 0.

Step 11 detects measured value and whether crosses threshold value, if cross threshold value, Counter Value adds m, carries out step (12); If threshold value but, Counter Value subtracts n, carries out step (14);

Step 12 is if Counter Value greater than T, then is saturated to the T value;

Step 13, the detection counter value if Counter Value equals T, then starts output PTT control signal, and finishes; If Counter Value, is then kept last PTT control signal output state less than T, and finish;

Step 14 is if Counter Value less than 0, then is saturated to 0 value;

Step 15, the detection counter value, if Counter Value equals 0, then cancellation output PTT control signal, and end; If Counter Value, is then kept last PTT control signal output state greater than 0.

Among the present invention, the size that the selection of m, n value is depended on the channel or hardware itself disturbs.To go out the error probability of simple signal not larger for flase drop if there is simple signal, and then the value of m should be less; Otherwise to go out the error probability of simple signal not smaller for flase drop if there is simple signal, and then the value of m can be larger.In like manner, the error probability that does not detect simple signal if simple signal is arranged is larger, and then the value of n should be less; Otherwise the error probability that does not detect simple signal if simple signal is arranged is smaller, and then the value of n can be larger.

Among the present invention, along with the development raising of hardware performance, as long as the arithmetic speed of hardware can satisfy the demand of Digital Signal Processing, the sequence length of the sample rate of ADC/DAC and FIR filter can suitably increase, and improves speech quality and accuracy of detection.In the single-frequency filter function, the methods such as all right proportion sampling Design method of the design of FIR filter realize.In the single-frequency filter function, the selection of the window function of FIR filter also has multiple, and such as Hamming window, Hanning window etc., effect is not quite similar.In the single-frequency measuring ability, the method for time-frequency conversion has a variety of, and fast Fourier transform (FFT) is wherein the most frequently used a kind of fast algorithm, and other mapping algorithm also can be realized, such as discrete cosine transform etc.

The invention provides a kind of thinking and method of piece-rate system of radio signals; method and the approach of this technical scheme of specific implementation are a lot; the above only is preferred implementation of the present invention; should be understood that; for those skilled in the art; under the prerequisite that does not break away from the principle of the invention, can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.In the present embodiment not clear and definite each part all available prior art realized.

Claims (5)

1. the piece-rate system of a radio signals is characterized in that, comprising:

A/D converter controller, the analog signal conversion that is used for input is digital signal;

Be divided into two-way from the signal of A/D converter controller output, one tunnel input FIR filter carries out single-frequency filtering, exports after then process digital-to-analogue conversion controller is converted to voice signal; Another road is successively through isolating the output of PTT control signal behind time-frequency converting unit, threshold detection unit and the stable processing unit;

The sample frequency of described A/D converter controller and digital-to-analogue conversion controller is 6～12KHz;

Described input FIR filter carries out single-frequency filtering, may further comprise the steps:

Step (1) is determined desirable linear phase band stop filter, and its formula is:

h _dThe endless non-causal sequence of the even symmetry that (n) to be central point order at α, ω _h, ω _lIt is the cut-off frequency of filter;

Step (2) is chosen window function ω (n) and h _d(n) multiply each other, the finite length sequence that to obtain one section sequence length be N, that is:

Order

Then h (n) is required FIR band stop filter;

The digital signal of input is carried out convolution algorithm with length for the finite length sequence h (n) of N, obtain filtering out the digital signal of simple signal;

Described threshold detection unit definition simple signal is at [f ₁, f ₂] medium and small amplitude variation f ₁≤ 2930Hz≤f ₂, calculate k according to formula ₁And k ₂:

k ₁×Δf≤f ₁≤(k ₁+1)×Δf

(k ₂-1)×Δf≤f ₂≤k ₂×Δf

Wherein Δ f is the detection frequency range of single-frequency, the i.e. sampling interval of frequency domain;

Computation interval [k ₁, k ₂] in the energy of frequency sequence F (k)

The threshold value TH that sets is if W is (k ₁, k ₂) greater than threshold value TH, judge that then this sense cycle detects simple signal, otherwise, judge that this sense cycle does not detect simple signal;

Described stable processing unit may further comprise the steps:

Define a counter, initial value is 0, and Counter Value is defined between 0 to T, and T＞0 if make Counter Value greater than T, then is saturated to T with Counter Value in add operation; If in reducing, make counter less than 0, then Counter Value be saturated to 0;

Step (11) detects measured value and whether crosses threshold value, if cross threshold value, Counter Value adds m, carries out step (12); If threshold value but, Counter Value subtracts n, carries out step (14);

Step (12) is if Counter Value greater than the T value, then is saturated to the T value;

Step (13), the detection counter value if Counter Value equals T, then starts output PTT control signal, and finishes; If Counter Value, is then kept last PTT control signal output state less than T, and finish;

Step (14) is if Counter Value less than 0, then is saturated to 0 value;

Step (15), the detection counter value, if Counter Value equals 0, then cancellation output PTT control signal, and end; If Counter Value, is then kept last PTT control signal output state greater than 0.

2. the piece-rate system of a kind of radio signals according to claim 1 is characterized in that, described sequence length is N value 256.

3. the piece-rate system of a kind of radio signals according to claim 1 is characterized in that, described cut-off frequency is:

Δ ω defines according to the stability of the 2930Hz simple signal that interior logical equipment sends, and guarantees that simple signal exists

Change in the interval, and Δ ω is minimum.

4. the piece-rate system of a kind of radio signals according to claim 1 is characterized in that, described window function is selected second order Cosine Window, i.e. Blackman window:

5. the piece-rate system of a kind of radio signals according to claim 1 is characterized in that, described time-frequency converting unit transforms to frequency sequence F (k) on the frequency domain with the time series t on the time domain (n): do 2 ^NThe FFT of point, the detection frequency range of single-frequency, namely the sampling interval of frequency domain is

The sense cycle that single-frequency detects is the time of finishing a FFT, i.e. T _D=2 ^N/ f _sWherein get N=9, the detection bandwidth delta f ≈ 16Hz of single-frequency, the sense cycle T that single-frequency detects _D=64ms.

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