CN100546295C - The appraisal procedure of TD-SCDMA radio-frequency receiving system frequency error after locking - Google Patents

Abstract

The invention provides the appraisal procedure of a kind of TD-SCDMA radio-frequency receiving system frequency error after locking, it comprises the steps: step 1, imports the signal of a time slot of TD-SCDMA of a standard at the input of TD-SCDMA radio-frequency receiving system; Step 2, then the analog I signal input analog-to-digital converter of output, store after becoming digital signal; Step 3, after obtaining digital IQ signal, known training sequence with the standard time slot signal of described input carries out related calculation to digital IQ signal, calculate cross-correlation coefficient, thereby the accurate timing of training sequence in the acquisition received signal, the correlation function of the training sequence that calculates known training sequence then and receive utilizes this correlation function just can calculate the frequency error of this moment.Adopt method of the present invention after the locking time of above-mentioned definition, to calculate frequency error accurately, and to be accurate to 1Hz at any one moment radio-frequency receiving system.

Description

The appraisal procedure of TD-SCDMA radio-frequency receiving system frequency error after locking

Technical field

The present invention relates to the appraisal procedure of a kind of TD-SCDMA radio-frequency receiving system frequency error after locking.

Background technology

In the radio communication, a radio-frequency receiving system commonly used (comprising the TD-SCDMA receiving system) as shown in Figure 1.The radiofrequency signal that antenna receives is passed through down-conversion after this system, and is converted to the IQ signal output of simulation.An important part of radio-frequency receiving system is exactly phase-locked loop (PLL), and the work that he will finish is exactly the operating frequency of determining receiving system according to the frequency that antenna receives radiofrequency signal, realizes locking.Obviously the problem that in the process of locking, has locking time.Just be meant automatic adjustment so-called locking time, frequency error is adjusted to time within the certain limit, for example frequency error is adjusted to ± time within the 200Hz by phase-locked loop.The requirement of desirable receiving system is that locking time is short more good more, so the assessment of locking time and locking back frequency error is become one of the radio-frequency receiving system design very part and parcel.

What control pll lock is the control voltage of phase-locked loop, and he normally is input to phase-locked loop by external loop filter.The assessment of traditional phase lock loop lock on time is to obtain by directly measuring latch voltage with oscilloscope.But this method can only embody the amplitude of latch voltage, and can not embody the phase place of latch voltage, thereby make to be far longer than the locking time that embodies from the latch voltage amplitude, so the locking time of assessment radio-frequency receiving system that can not be correct and complete actual locking time.

In addition, also having the method for a kind of radio-frequency receiving system preferably locking time is (as shown in Figure 2): at first in frequency of input input of radio-frequency receiving system for one sine wave of frequency deviation in fact being arranged with the receiving system operating frequency; Use oscilloscope test output signal on the analog I of the output of radio-frequency receiving system then; At last determine locking time according to the waveform of output signal.Simultaneously the assessment that locks the back frequency error is generally directly realized (waveform of output signal and the sine wave of standard are compared) by the mode of one number time on oscilloscope, this process is owing to there being more manual participation, so error is bigger.

Summary of the invention

Technical problem to be solved by this invention provides the frequency error appraisal procedure of a kind of TD-SCDMA of being applied to radio-frequency receiving system after determining substantially locking time, make it possible to the frequency error of correct and complete assessment receiving system any time point after locking, thereby can instruct actual debugging and design work.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is: the appraisal procedure of a kind of TD-SCDMA radio-frequency receiving system frequency error after locking is provided, and it comprises the steps:

Step 1, at the signal of the time slot of TD-SCDMA of a standard of the input of TD-SCDMA radio-frequency receiving system input;

Step 2, then the analog I signal input analog-to-digital converter of output, store after becoming digital signal;

Step 3, after obtaining digital IQ signal, known training sequence with the standard time slot signal of described input carries out related calculation to digital IQ signal, calculate cross-correlation coefficient, thereby the accurate timing of training sequence in the acquisition received signal, the correlation function of the training sequence that calculates known training sequence then and receive utilizes this correlation function just can calculate the frequency error of this moment.

Adopt method of the present invention after the locking time of above-mentioned definition, to calculate frequency error accurately, and to be accurate to 1Hz at any one moment radio-frequency receiving system.

Description of drawings

Fig. 1 is the structural representation of existing radio-frequency receiving system.

Fig. 2 is the assessment schematic diagram of the frequency error method after existing locking time and the locking.

Embodiment

The present invention's frequency error appraisal procedure after locking comprises the steps:

Step 1, at the signal of the time slot of TD-SCDMA of a standard of the input of TD-SCDMA radio-frequency receiving system input;

Step 2, then the analog I signal of output input AD (modulus) transducer, store after becoming digital signal.

Step 3, after obtaining digital IQ signal, known training sequence (training sequences of 144 chips) with the standard time slot signal of described input carries out related calculation to digital IQ signal, calculate cross-correlation coefficient, thereby the accurate timing of training sequence in the acquisition received signal, the correlation function of the training sequence that calculates known training sequence then and receive utilizes this correlation function just can calculate the frequency error of this moment.

For difference frequency error constantly, can make the TD-SCDMA radio-frequency receiving system postpone different (200 μ s constantly, 300 μ s, 400 μ s etc., different delays is different acquisition of the unlatching moment by the starting point of TD-SCMDA time slot signal and radio-frequency receiving system, and for example 200 μ s are exactly that the TD-SCDMA time slot signal postpones 200 μ s arrival than radio-frequency receiving system.Accordingly, postpone 200 μ s, 300 μ s, the frequency error that 400 μ s are calculated open at a distance of 200 μ s with radio-frequency receiving system, 300 μ s, 400 μ s frequency error constantly) come received signal, thus obtain the different frequency errors constantly in locking back.

Concrete computational process for frequency error comprises the steps:

Step 31, at first accurately obtain the original position of training sequence by the maximum of seeking the waveform quality factor.

This step can be by getting relevant obtaining to training sequence.Suppose that in the resulting afterwards IQ sequence of ADC (analog to digital converter) be Z _k, and training sequence is R _0k, then define the waveform quality factor and getting after relevant be:

$\mathrm{\ρ}=\frac{{\left|\underset{k}{\mathrm{\Σ}}{Z}_k{R}_{0k}^{*}\right|}^2}{\underset{k}{\mathrm{\Σ}}{\left|R_{0k}\right|}^2\underset{k}{\mathrm{\Σ}}{\left|Z_k\right|}^2}$

Just can accurately obtain the original position of training sequence by the maximum of seeking the waveform quality factor, also be obtain accurately synchronous.

Step 32, carry out relevantly to obtaining training sequence that synchronous post-sampling obtains and canonical reference training sequence, its correlation function just is:

$P({\mathrm{\τ}}_0,0)=\underset{k}{\mathrm{\Σ}}{A}_0^2(t_k-{\mathrm{\τ}}_0)e^{\mathrm{j\Δ}{\mathrm{\ωt}}_k}$

A wherein ₀Refer to the training sequence amplitude, τ ₀Finger waveform quality factor is got the peaked moment, t _kBe illustrated in k constantly.

Step 33, calculating frequency error at this moment just are:

$\mathrm{\Δ\ω}=\frac{\mathrm{\π}}{T}\frac{\left|P({\mathrm{\τ}}_0,{\mathrm{\Δ\ω}}_0)\right|-\left|P({\mathrm{\τ}}_0,-{\mathrm{\Δ\ω}}_0)\right|}{\left|P({\mathrm{\τ}}_0,{\mathrm{\Δ\ω}}_0)\right|+\left|P({\mathrm{\τ}}_0,-{\mathrm{\Δ\ω}}_0)\right|}$

Δ ω wherein ₀=π/T.

Claims (2)

1, the appraisal procedure of a kind of TD-SCDMA radio-frequency receiving system frequency error after locking is characterized in that, comprises the steps:

Step 1, at the signal of the time slot of TD-SCDMA of a standard of the input of TD-SCDMA radio-frequency receiving system input;

Step 2, then the analog I signal input analog-to-digital converter of output, store after becoming digital signal;

Step 3, after obtaining digital IQ signal, training sequence known in the standard time slot signal with described input carries out related calculation to described digital IQ signal, calculate cross-correlation coefficient, thereby obtain training sequence in the described digital IQ signal accurately synchronously, the correlation function of the training sequence that calculates known training sequence then and receive utilizes this correlation function to calculate the frequency error of this moment;

The concrete computational methods of step 3 comprise the steps:

Step 31, at first accurately obtain the original position of training sequence by the maximum of seeking the waveform quality factor, the maximum of described waveform quality factor is by training sequence being got relevant obtaining: suppose that resulting IQ signal is Z after analog to digital converter _k, R _OkBe known standard exercise sequence, then define the waveform quality factor and getting after relevant be:

$\mathrm{\ρ}=\frac{{\left|\underset{k}{\mathrm{\Σ}}{Z}_k{R}_{0k}^{*}\right|}^2}{\underset{k}{\mathrm{\Σ}}{\left|R_{0k}\right|}^2\underset{k}{\mathrm{\Σ}}{\left|Z_k\right|}^2}$

Step 32, carry out relevantly to obtaining the training sequence that receives that synchronous post-sampling obtains and known training sequence, its correlation function just is:

$P({\mathrm{\τ}}_0,0)=\underset{k}{\mathrm{\Σ}}{A}_0^2(t_k-{\mathrm{\τ}}_0)e^{\mathrm{j\Δ}{\mathrm{\ωt}}_k}$

A wherein ₀Refer to the training sequence amplitude, τ ₀Finger waveform quality factor is got the peaked moment, t _kBe illustrated in k constantly;

The frequency error of step 33, this moment just is:

$\mathrm{\Δ\ω}=\frac{\mathrm{\π}}{T}\frac{\left|P({\mathrm{\τ}}_0,\mathrm{\Δ}{\mathrm{\ω}}_0)\right|-\left|P({\mathrm{\τ}}_0,{-\mathrm{\Δ\ω}}_0)\right|}{\left|P({\mathrm{\τ}}_0,{\mathrm{\Δ\ω}}_0)\right|+|P({\mathrm{\τ}}_0,-{\mathrm{\Δ\ω}}_0)|}$

Δ ω wherein ₀=π/T.

2, the appraisal procedure of TD-SCDMA radio-frequency receiving system according to claim 1 frequency error after locking, it is characterized in that, for difference frequency error constantly, make the TD-SCDMA radio-frequency receiving system postpone the different received signals of constantly coming, thereby obtain the different frequency errors constantly in locking back.

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