CN102571170B - 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

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

Background technology

Antenna array can utilize multiple small aperture antenna equivalences to become a larger antenna to realize and transmit and receive signal, is all to have huge advantage at the aspect such as construction cost or plant maintenance.Uplink antenna group battle array is a technology of just having risen in recent years, because each antenna in uplink antenna group battle array lacks reference source, signal carrier alignment becomes very difficult, if the carrier phase transmitting between the up group of each antenna of battle array is not alignd, will cause so the reduction of synthetic gain, therefore the greatest problem of uplink antenna group battle array is how to realize carrier wave alignment.In the uplink antenna group battle array calibration phase, can make by means such as phasescan methods the carrier wave alignment of each antenna, need in actual use uplink antenna group battle array to overcome link interference and keep carrier phase alignment, and the time longer uplink antenna group array 1 system keeping is more stable, therefore be necessary uplink antenna group battle array link change to carry out real time calibration.Name is called " Ground System Phase Estimation Techniques for Uplink Array Applications ", author is L.Paal, come from and in the document of " IPN Progress Report42-167 ", told about the ground system phase estimation technology in up group of battle array application of the U.S., mention a kind of method of real time calibration uplink antenna group battle array link change, the method is processed and is obtained error signal with reference to signal and feedback signal, and calibrate and compensate according to error signal, object is to make feedback signal and reference signal phase alignment.Although the method has successfully realized the real time calibration to uplink antenna group array 1 system link change, its weak point is: the method is obtained the processing of error signal and carried out at analog domain, but not numeric field.Analog signal does not have digital signal to be convenient to process, to transmit and storage, and flexibility is inadequate; Analog signal interference free performance is 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 more stable, and the interval between twice calibration of uplink antenna group array 1 system is longer, and using value is larger.The method of the uplink antenna group battle array real time calibration of in fact mentioning in document proposes in order to increase the stability of system, but realize and will inevitably affect calibration accuracy at analog domain, affect the stability of a system, thereby be necessary to realize in numeric field design the real time calibration of uplink antenna group battle array.

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 method for real time calibration uplink antenna group battle array link change, comprises the steps:

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

(2) first via input signal, through after AD sampling, carries out mixing with local NCO1, obtains I1, Q1 two paths of signals; The second road input signal, through after AD sampling, carries out mixing with local NCO2, obtains I2, Q2 two paths of signals; I1, Q1, I2, Q2Si road signal are sent to integral unit and are removed high fdrequency component, then carry out phase demodulation and obtain the phase difference of two-way input signal;

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

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

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

(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 large flexibility and a portability, improve the stability of signal after the precision of calibration and calibration, improved uplink antenna group array 1 system and overcome the ability of link change.

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

Brief description of the 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 situation of change at real time calibration and analog link.

Embodiment

Below in conjunction with the drawings and specific embodiments, 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; Real time calibration function; Change function with analog link.Find can make the prominent phase relation of receiving terminal time when baseband equipment carries out phasescan, need be placed in straight-throughly, and remember that reference phase is poor.Reference phase is poor is exactly after baseband equipment been scanned keeps certain phase place to export, the initial phase difference between input signal of the present invention.When find reference phase poor after, enter align mode.As need entrance link to change the calibration effect for pilot demonstration the inventive method, calibration circuit is placed in to link change analog functuion, the link change that real time calibration is introduced; If do not needed artificial entrance link to change, this calibration circuit is placed in to real time calibration function, the variation on physical link is calibrated.

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

Calibration steps of the present invention specifically comprises the steps:

1, the phase difference of corresponding two-way input signal of the present invention while carrying out phasescan searching receiving terminal power maximum, as the poor θ of reference phase ₂-θ ₁;

Poor in order to obtain reference phase, baseband equipment must carry out phasescan in 0～2 π, for example, allow 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 10 ° of velocity variations per second.Receiving terminal, two paths of signals synthesizes a road, and observe and synthesize the situation of change of signal power afterwards with frequency spectrograph, find the phase relation that makes the prominent baseband equipment two-way of receiving terminal output signal according to the size of power, after finding, baseband equipment keeps this phase relation to export, and gives the present invention as input.

Two-way input signal 1,2 of the present invention is through after AD sampling, carry out mixing with local NCO1 and NCO2 respectively, obtain I1, Q1, I2, Q2Si road signal is sent to integral unit and is removed high fdrequency component, then carrying out phase demodulation, can to obtain the reference phase of two-way input signal poor.

2, after acquisition reference phase is poor, carry out calibration process below, specifically comprise the steps:

1) two-way input signal 1,2, through after AD sampling, carries out mixing with local NCO1 and NCO2 respectively, obtains I1, Q1, I2, Q2Si road signal.Four road signals are sent to integral unit and are removed high fdrequency component, then carry out phase demodulation the real part to acquired results and the imaginary part tangent of negating, and obtain the phase difference of two-way input signal.If entrance link changes, can obtain the summation of the poor link change with introducing of reference phase.(introducing of link change is by adding certain phase place changes delta θ to realize at local NCO1 and NCO2 place).

2) for the phase difference value in cancellation loop, the phase value obtaining must be sent back to local NCO1 or local NCO2 through loop filter, form closed circuit.Specifically can be described as, loop filter can calculate according to identified result the frequency difference that cancellation loop difference need to be adjusted, and this frequency difference is added to the frequency control word of adjusting NCO1 in the frequency control word of NCO1.NCO1 can obtain corresponding phase place according to frequency control word, by realizing the adjustment to loop phase to the adjustment of NCO1 frequency control word, thus the phase difference value of successive elimination link.

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

Enumerate a specific embodiment below and illustrate that the present invention overcomes the process of link change:

Suppose that input signal is for the two-way 70M intermediate-freuqncy signal from the output of standard observing and controlling (TT & C) synthetical baseband, after the AD sampling of 56MHz, the initial phase of supposing the 1st road signal is θ ₁, the initial phase of the 2nd road signal is θ ₂, introduce phase place changes delta θ at the NCO1 on the 1st tunnel, so known:

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

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

I _nco1=cos (w ₁₄(t)+Δ θ), after pi/2, become I _nco1'=sin (w ₁₄(t)+Δ θ),

I _nco2=cos (w ₁₄(t)), after pi/2, become I _nco2'=sin (w ₁₄(t)).

After definite signal form, can derive and differ according to the annexation of circuit, detailed process is as follows:

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

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

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

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

After integration, can obtain respectively:

I ₁＝cos(θ ₁-Δθ)；Q ₁＝-sin(θ ₁-Δθ)；

I ₂＝cos(θ ₂)；Q ₂＝-sin(θ ₂)；

Integration is sent to phase demodulation after eliminating high fdrequency component,

(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 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 open loop situations, make Δ θ=0 just can find out benchmark and differ θ ₂-θ ₁(corresponding straight-through function).Under closed loop state, this is differed and returns 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, then by phasing unit, phase place 0 is put to NCO3 to phase theta ₂-θ ₁put to NCO4, so just completed phase calibration process.

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

Fig. 2 is the present invention changes calibration error in two kinds of situations situation of change at real time calibration and analog link.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 with reference phase is poor, can keep making the prominent signal phase difference of receiving terminal to export, therefore calibration error is less, real time calibration effect of the present invention is better.Fig. 2-a is the link change of simulation, the variation that Fig. 2-b is calibration error, and this two width figure is synchronous in time.When the present invention is during in real time calibration, as 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 in link change simulation model, the analog link of introducing 10 °/s changes, as shown in Fig. 2-a, this variable quantity exists during in link change simulation model in the present invention always, calibration error shown in Fig. 2-b plays first meeting and is subject to the interference that analog link shown in Fig. 2-a changes and becomes greatly gradually, but can progressively revert to zero subsequently, and remains near null value, overcome the impact of disturbing, confirmed the function that the present invention can 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. a method for real time calibration uplink antenna group battle array link change, is characterized in that: the method adopt digital mode can real time calibration link change in 1 °/s～10 °/s, specifically comprise the steps:

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

(2) first via input signal, through after AD sampling, carries out mixing with local NCO1, obtains I1, Q1 two paths of signals; The second road input signal, through after AD sampling, carries out mixing with local NCO2, obtains I2, Q2 two paths of signals; I1, Q1, I2, Q2Si road signal are sent to integral unit and are removed high fdrequency component, then carry out obtaining after the operation of phase demodulation and arc tangent the phase difference of two-way input signal; Described first via input signal, the second road input signal are 70M intermediate-freuqncy signal;

(3) phase difference obtaining is sent back to local NCO1 or local NCO2, the phase difference value existing in cancellation loop through loop filter;

(4) by phase theta _wput to NCO3, by phase place (θ _w+ reference phase is poor) put wherein θ to NCO4 _wfor arbitrary value; The signal that NCO3 produces and I1, Q1 mixing, change laggard line output through DA after the signal plus after mixing; The signal that NCO4 produces and I2, Q2 mixing, change laggard line output through DA after the signal plus after mixing.