CN102571170A - Method for calibrating uplink antenna array link variations in real time - Google Patents

Abstract

The invention discloses a method for calibrating uplink antenna array link variations in real time. Firstly, phase scanning is performed so as to find input signals at two corresponding paths as the input signals when the power of a receiving end is maximal as input signals, and then to obtain a reference phase difference; a first-path input signal can be in frequency mixing with local NCO1 after AD sampling, and signals in two paths of I1 and Q1 can be obtained; a second-path input signal can be in frequency mixing with local NCO2 after AD sampling, and signals in two paths of I2 and Q2 can be obtained; signals in the four paths of I1, Q1, I2 and Q2 are sent to an integral unit for removing high-frequency components, and then phase difference of the input signals in the two paths is obtained through phase discrimination; the phase difference obtained through phase discrimination is sent to the local NCO1 or the local NCO2 through a loop filter, and the phase-difference value in a loop can be eliminated; and finally, the reference difference is output through modulation. The method provided by the invention can calibrate link variations in 1 DEG/s to 10 DEG/s in real time.

Description

A kind of method of real time calibration uplink antenna group battle array link change

Technical field

But the present invention relates to a kind of Digital Realization method of real time calibration uplink antenna group battle array link change.

Background technology

Antenna array a plurality of small aperture antenna equivalences capable of using become a bigger antenna to realize transmitting and receiving signal, are at aspects such as construction cost or plant maintenances huge advantage to be arranged all.Uplink antenna group battle array is a technology of just having risen in recent years; Because each antenna lacks reference source in the uplink antenna group battle array; It is very difficult that the signal carrier alignment becomes; If the carrier phase that transmits between up group of each antenna of battle array is alignment not, will cause the reduction of synthetic gain so, so the greatest problem of uplink antenna group battle array is how to realize the carrier wave alignment.In the uplink antenna group battle array calibration phase; Can make the carrier wave alignment of each antenna through means such as phasescan methods; Need uplink antenna group battle array to overcome link interference in actual use and keep carrier phase alignment; And the time long more uplink antenna group array 1 system that keeps is stable more, so be necessary uplink antenna group battle array link change is carried out real time calibration.Name is called " Ground System Phase Estimation Techniques for Uplink Array Applications "; The author is L.Paal; It is technological to come from the ground system phase estimation of having told about in up group of battle array application of the U.S. in the document of " IPN Progress Report42-167 "; Mentioned a kind of method of real time calibration uplink antenna group battle array link change; This method is handled reference signal and feedback signal and is obtained error signal, and calibrates and compensate according to error signal, and purpose is to make feedback signal and reference signal phase alignment.Though this method has realized that successfully its weak point is to the real time calibration of uplink antenna group array 1 system link change: this method is obtained the processing of error signal and is carried out at analog domain, but not numeric field.Analog signal does not have digital signal to be convenient to handle, to transmit and storage, and flexibility is not enough; The analog signal interference free performance is relatively poor, and analogue device stability does not have digital device good.For uplink antenna group battle array, the development that the stability of signal and anti-interference direct relation uplink antenna group battle array, signal is stable more, and the interval between twice calibration of uplink antenna group array 1 system is long more, and using value is big more.The method of the uplink antenna group battle array real time calibration of in fact mentioning in the document proposes for the stability that increases system; But realize to influence calibration accuracy at analog domain; Influence the stability of a system, thereby be necessary to realize the real time calibration of uplink antenna group battle array in the numeric field design.

Summary of the invention

Technical problem to be solved by this invention is: the method that high, the digital real time calibration uplink antenna group battle array link change of a kind of calibration accuracy is provided.

The present invention includes following technical scheme:

A kind of method of real time calibration uplink antenna group battle array link change comprises the steps:

(1) carry out phasescan and seek receiving terminal power pairing two-way input signal is as input signal when maximum, and it is poor to obtain its reference phase;

(2) first via input signal carries out mixing through after the AD sampling with local NCO1, obtains I1, Q1 two paths of signals; The second road input signal carries out mixing through after the AD sampling with local NCO2, obtains I2, Q2 two paths of signals; I1, Q1, I2, Q2 four road signals are sent to integral unit and are removed high fdrequency component, and carrying out phase demodulation again, to obtain the two-way phase of input signals poor;

(3) phase difference that phase demodulation is obtained is sent back to local NCO1 or local NCO2, the phase difference value that exists in the cancellation loop through loop filter;

(4) with phase theta _wPut to NCO3, with phase place (θ _w+ reference phase is poor) put θ wherein to NCO4 _wBe arbitrary value; Signal that NCO3 produces and I1, Q1 mixing, the signal plus output after the mixing; Signal that NCO4 produces and I2, Q2 mixing, the signal plus output after the mixing.

The present invention's beneficial effect compared with prior art is:

(1) method of the present invention adopts brand-new method for designing to realize the real time calibration of digitized uplink antenna group battle array multiple signals; Circuit is reliable and have very big flexibility and a portability; Improve the precision of calibration and the stability of calibration back signal, improved the ability that uplink antenna group array 1 system overcomes link change.

(2) change verification experimental verification through analog link, method of the present invention can the interior link change of 1 °/s of real time calibration～10 °/s.

Description of drawings

Fig. 1 is calibration circuit figure of the present invention.

Fig. 2 is the present invention changes calibration error under two kinds of functions at real time calibration and analog link a situation of change.

Embodiment

Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail.

In order to realize the real time calibration to uplink antenna group battle array link change, calibration circuit possesses three kinds of functions: straight-through function; The real time calibration function; Change function with analog link.Seek when can make the prominent phase relation of receiving terminal when baseband equipment carries out phasescan, need place straight-throughly, and remember that reference phase is poor.The reference phase difference is exactly after the baseband equipment been scanned keeps certain phase place to export, the initial phase difference between input signal of the present invention.After finding the reference phase difference, get into align mode.Change the calibration effect that is used for pilot demonstration the inventive method like the need entrance link, then calibration circuit is placed the link change analog functuion, the link change that real time calibration is introduced; As do not need artificial entrance link to change, and then this calibration circuit is placed the real time calibration function, the variation on the physical link is calibrated.

In order to possess above-mentioned functions, calibration circuit of the present invention is as shown in Figure 1.

Calibration steps of the present invention specifically comprises the steps:

Pairing two-way phase of input signals of the present invention is poor when 1, carrying out phasescan searching receiving terminal power maximum, as reference phase difference θ ₂-θ ₁

Poor in order to obtain reference phase, baseband equipment must carry out phasescan in 0～2 π, for example let the phase of output signal of the 1st roadbed carrying device remain unchanged, the phase of output signal of the 2nd roadbed carrying device in 0～2 π with the velocity variations of 10 ° of per seconds.Receiving terminal; Two paths of signals synthesizes one the tunnel; And with the synthetic situation of change of signal power afterwards of frequency spectrograph observation; Seek the phase relation that makes the prominent baseband equipment two-way of receiving terminal export signal according to the size of power, baseband equipment keeps this phase relation to export after finding, and gives the present invention as input.

Two-way input signal 1,2 of the present invention is through after the AD sampling; Carry out mixing with local NCO1 and NCO2 respectively; Obtain I1, Q1, I2, Q2 four road signals and send to integral unit and remove high fdrequency component, carrying out phase demodulation again, can to obtain the reference phase of two-way input signal poor.

2, after obtaining the reference phase difference, carry out following calibration process, specifically comprise the steps:

1) two-way input signal 1,2 carries out mixing with local NCO1 and NCO2 respectively through after the AD sampling, obtains I1, Q1, I2, Q2 four road signals.Four road signals are sent to integral unit and are removed high fdrequency component, carry out phase demodulation again and to gained result's real part and the imaginary part tangent of negating, it is poor to obtain the two-way phase of input signals.If entrance link changes, then can obtain the summation of the link change of reference phase difference and introducing.(introducing of link change is through realizing at local NCO1 and the certain phase change Δ θ of adding of NCO2 place).

2) for the phase difference value in the cancellation loop, must the phase value that obtain be sent back to local NCO1 or local NCO2 through loop filter, form closed circuit.Specifically can be described as, loop filter can calculate the frequency difference of cancellation loop difference needs adjustment according to identified result, and this frequency difference is added to the frequency control word of adjustment NCO1 in the frequency control word of NCO1.NCO1 can obtain corresponding phase place based on frequency control word, can realize the adjustment to loop phase through the adjustment to the NCO1 frequency control word, thereby progressively eliminate the phase difference value of link.

3) through closed loop differing and after link interference eliminates, need the benchmark phase difference modulation be exported with input signal 1,2.Concrete operations are with phase theta _wPut to NCO3, the generation phase place is θ _wFrequency is local signal and I1, the Q1 mixing of 70M, and the I1 after the mixing, Q1 road signal plus also export through behind the digital to analog converter; With phase place (θ _w+ benchmark differs) to put to NCO4, the generation phase place is (θ _w+ benchmark differs) frequency is local signal and I2, the Q2 mixing of 70M, the I2 after the mixing, Q2 road signal plus and through (the θ wherein of output behind the digital to analog converter _wCan be arbitrary value, be set to 0 usually).Can find out that output signal of the present invention can keep making the prominent benchmark of receiving terminal to differ output through after the phase place adjustment.

Enumerate a concrete embodiment below and explain that the present invention overcomes the process of link change:

Suppose that input signal is the two-way 70M intermediate-freuqncy signal from the output of standard tracking telemetry and command (TT&C) synthetical baseband, after the AD sampling through 56MHz, the initial phase of supposing the 1 road signal is θ ₁, the initial phase of the 2 road signal is θ ₂, the NCO1 the 1 tunnel introduces phase change Δ θ, can know so:

The 1 road signal is: I=cos (w ₁₄(t)+θ ₁),

The 2 road signal is: II=cos (w ₁₄(t)+θ ₂),

I _Nco1=cos (w ₁₄(t)+and Δ θ), become I through behind the pi/2 _Nco1'=sin (w ₁₄(t)+Δ θ),

I _Nco2=cos (w ₁₄(t)), become I through behind the pi/2 _Nco2'=sin (w ₁₄(t)).

After the signal form of confirming, can derive according to the annexation of circuit and differ, detailed process is following:

$I{\×I}_{\mathrm{nco}1}=\cos (w_{14}t+{\mathrm{\θ}}_1)\cos (w_{14}t+\mathrm{\Δ\θ})=\frac{1}{2}[\cos (2w_{14}t+{\mathrm{\θ}}_1+\mathrm{\Δ\θ})+\cos ({\mathrm{\θ}}_1-\mathrm{\Δ\θ})];$

$I\×{I_{\mathrm{nco}1}}^{\′}=\cos (w_{14}t+{\mathrm{\θ}}_1)\sin (w_{14}t+\mathrm{\Δ\θ})=\frac{1}{2}[\sin (2w_{14}t+{\mathrm{\θ}}_1+\mathrm{\Δ\θ})-\sin ({\mathrm{\θ}}_1-\mathrm{\Δ\θ})];$

$\mathrm{II}{\×I}_{\mathrm{nco}2}=\cos (w_{14}t+{\mathrm{\θ}}_2)\cos \left(w_{14}t\right)=\frac{1}{2}[\cos (2w_{14}t+{\mathrm{\θ}}_2)+\cos \left({\mathrm{\θ}}_2\right)];$

$\mathrm{II}\×{I_{\mathrm{nco}}}^{\′}=\cos (w_{14}t+{\mathrm{\θ}}_2)\sin \left(w_{14}t\right)=\frac{1}{2}[\sin (2w_{0}t+{\mathrm{\θ}}_2)-\sin \left({\mathrm{\θ}}_2\right)];$

After passing through integration respectively, can get:

I ₁＝cos(θ ₁-Δθ)；Q ₁＝-sin(θ ₁-Δθ)；

I ₂＝cos(θ ₂)；Q ₂＝-sin(θ ₂)；

Integration is eliminated after the high fdrequency component, sends to phase demodulation,

(I ₁+jQ ₁)(I ₂-jQ ₂)＝cos(θ ₁-θ ₂-Δθ)-jsin(θ ₁-θ ₂-Δθ)，

Be I=cos (θ ₁-θ ₂-Δ θ), Q=-sin (θ ₁-θ ₂-Δ θ).

In order to obtain phase difference, do the arc tangent operation, obtain:

$\arctan \frac{Q}{I}=\arctan \frac{-\sin ({\mathrm{\θ}}_1-{\mathrm{\θ}}_2-\mathrm{\Δ\θ})}{\cos ({\mathrm{\θ}}_1-{\mathrm{\θ}}_2-\mathrm{\Δ\θ})}=\arctan (-\tan ({\mathrm{\θ}}_1-{\mathrm{\θ}}_2-\mathrm{\Δ\θ}))$

$=\arctan (\tan \left(\mathrm{\Δ}\θ-({\mathrm{\θ}}_1-{\mathrm{\θ}}_2)\right)=\mathrm{\Δ\θ}-({\mathrm{\θ}}_1-{\mathrm{\θ}}_2)$

Under the open loop situations, make Δ θ=0 just can find out benchmark and differ θ ₂-θ ₁(corresponding straight-through function).Under the closed loop state this is differed and return to NCO1, make Δ θ-(θ ₁-θ ₂(we claim Δ θ-(θ here in) → 0 ₁-θ ₂) be calibration error).Calibration error becomes after 0, through phasing unit phase place 0 is put phase theta to NCO3 again ₂-θ ₁Put to NCO4, so just accomplished phase calibration process.

After the baseband equipment phasescan, the initial phase of two-way input signal of the present invention is respectively θ ₁And θ ₂, the reference phase difference is θ ₂-θ ₁Behind the entrance link changes delta θ, the phase difference of two-way output signal still is θ ₂-θ ₁, do not receive the influence of link change Δ θ, make benchmark differ (can make receiving terminal power maximum) and be able to keep.

Fig. 2 changes the situation of change of calibration error under two kinds of situation at real time calibration and analog link for the present invention.Phase difference value-reference phase between calibration error=modulated output signal is poor.Calibration error is that the phase difference of zero explanation modulated output signal equates that with the reference phase difference can keep making the prominent signal phase difference of receiving terminal to export, so calibration error is more little, real time calibration effect of the present invention is good more.Fig. 2-a is the link change of simulation, and Fig. 2-b is the variation of calibration error, and this two width of cloth figure is synchronous in time.When the present invention is in real time calibration, shown in Fig. 2-a, not introduce analog link and change, the fixed value of the calibration error shown in Fig. 2-b when straight-through is gradually varied to 0, and can keep stable; When being in the link change simulation model, the analog link of introducing 10 °/s changes, shown in Fig. 2-a; This variable quantity exists when the present invention is in the link change simulation model always; Calibration error shown in Fig. 2-b plays first meeting and receives the interference that the analog link shown in Fig. 2-a changes and become greatly gradually, but can progressively revert to zeroly subsequently, and remains near the null value; Overcome the influence of disturbing, but confirmed the function of the present invention's real time calibration link error.

The unexposed technology of the present invention belongs to general knowledge as well known to those skilled in the art.

Claims (1)

1. the method for a real time calibration uplink antenna group battle array link change is characterized in that: comprise the steps:

(1) carry out phasescan and seek receiving terminal power pairing two-way input signal is as input signal when maximum, and it is poor to obtain its reference phase;

(2) first via input signal carries out mixing through after the AD sampling with local NCO1, obtains I1, Q1 two paths of signals; The second road input signal carries out mixing through after the AD sampling with local NCO2, obtains I2, Q2 two paths of signals; I1, Q1, I2, Q2 four road signals are sent to integral unit and are removed high fdrequency component, and carrying out phase demodulation again, to obtain the two-way phase of input signals poor;

(3) phase difference that phase demodulation is obtained is sent back to local NCO1 or local NCO2, the phase difference value that exists in the cancellation loop through loop filter;

(4) with phase theta _wPut to NCO3, with phase place (θ _w+ reference phase is poor) put θ wherein to NCO4 _wBe arbitrary value; Signal that NCO3 produces and I1, Q1 mixing, the signal plus after the mixing is exported; Signal that NCO4 produces and I2, Q2 mixing, the signal plus after the mixing is exported.

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