JP4821379B2 - Demodulator, distance measuring device, and data receiving device - Google Patents

Description

The present invention, for example, demodulation apparatus to obtain the phase of the signal by demodulation by the I and Q signals, the distance measuring device, and a data receiving apparatus.

  2. Description of the Related Art Conventionally, there has been provided a technique for demodulating electromagnetic waves such as radio waves and light using an I signal that is an in-phase component and a Q signal that is a quadrature component and obtaining a phase from the amplitude after demodulation. By obtaining the phase in this way, distance measurement using the phase difference, data communication using multi-value digital conversion of the phase, and the like can be performed.

Here, when the I signal and the Q signal are used for demodulation, a gain difference occurs between the I signal and the Q signal. For this reason, there is a problem that an accurate phase cannot be obtained unless some measure is taken for the gain difference. To be determined is correct phase, for example, the distance measurement error in measurement becomes large, the amount of data that can communicate at a time in the data communication is reduced. For this reason, it was preferable to eliminate the gain difference between the I signal and the Q signal.

  On the other hand, assuming that the error due to the gain difference between the I signal and the Q signal can be corrected, the actual data is grouped for each coordinate, and the parameters of the amplitude and central coordinate of the elliptic equation are estimated for each, and based on this parameter, the error A mobile communication terminal that automatically performs correction has been proposed (see Patent Document 1).

  However, in such a method, there is a problem that the algorithm becomes complicated and the parameter estimation accuracy decreases with respect to temperature changes and changes with time.

Japanese Patent Laid-Open No. 7-327059

This invention has been made in view of the above problems, it shall be the object of providing demodulation device capable of preventing a reduction in accuracy due to the gain difference between the I and Q signals, the distance measuring device, and a data receiving apparatus.

The present invention is a demodulator that demodulates a received signal received with an I signal that is an in-phase component and a Q signal that is a quadrature component, the phase shift means for shifting the phase of the received signal to a phase of 90 degrees, the first demodulated signal received signal and 90-degree shifted phase of the received signal and a respective demodulates and demodulating means for acquiring a second demodulated signal, the first demodulated signal and a second demodulated signal by combining a synthesizing means for obtaining a synthesized signal Te, the combining means, can be configured to divide by 2 by adding the phase of said second demodulated signal of the first demodulation signal.

Further, the present invention is a demodulator that demodulates a received signal received by an I signal that is an in-phase component and a Q signal that is a quadrature component, the phase shift means for shifting the phase of the received signal to a phase of 90 degrees, synthesis and demodulation means for obtaining a first demodulated signal and the second demodulated signal by demodulating the received signal and the 90 ° shifted phase of the received signal and, respectively, the first demodulated signal and a second demodulated signal Synthesizing means for obtaining a synthesized signal, wherein the synthesizing means divides the I component in the first demodulated signal by the Q component and the I component in the second demodulated signal by the Q component. It is possible to obtain a square root of a value obtained by dividing the first calculation signal by the second calculation signal and multiplying by -1 using the second calculation signal.

Further, the present invention receives the response signal of the non-contact IC tag in response to the demodulator, the signal transmission means for transmitting the response request signal, and the response request signal, and based on the phase of the composite signal by the received signal Thus, the distance measuring device can be provided with a distance estimating means for estimating the distance to the non-contact IC tag from the phase difference.

The present invention also provides the demodulating device, restoring means for shifting the phase of the synthesized signal to the phase of 0 degree by half the phase angle shifted by the phase shifting means, and using the restored signal as a restored signal. it is Ru can be a data receiving apparatus and a data reduction unit for data reduction and multi-level digital demodulation.

This invention, demodulation device capable of preventing a reduction in accuracy due to the gain difference between the I and Q signals, the distance measuring device, and can provide a data receiving apparatus.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows a block diagram of the distance measuring device 1.
The distance measuring device 1 includes a PLL unit 3, an oscillator 4, a modulation unit 5, a power amplification unit 6, a transmission antenna 7, a controller unit 9, a demodulation unit 10, a reception antenna 11, a distance estimation unit 12, and amplifiers 13 and 14. Has been.

  The demodulation unit 10 is unitized as one IC chip, and includes a phase shift unit 21, a phase switching unit 22, a BPF (Band-Pass Filter) 23, and quadrature demodulators 24 and 25. A reference signal input terminal 10a is provided before the phase shift unit 21, a reception signal input terminal 10b is provided before the phase switching unit 22, and an I signal output terminal 10d is provided after the quadrature demodulator 24. A Q signal output terminal 10 e is provided at the subsequent stage of the quadrature demodulator 25. In addition, a control signal input terminal 10 c for inputting a control signal for switching control is provided in the previous stage of the phase switching unit 22.

  Explaining each configuration, the controller unit 9 executes various controls including communication control, the PLL unit 3 switches the oscillating frequency, and the oscillator 4 uses the reference signal of the switched frequency as the modulator 5 and the phase. The data is input to the shift unit 21 and the quadrature demodulators 24 and 25.

The modulation unit 5 receives transmission data from the controller unit 9, modulates the transmission data with a reference signal to create a transmission signal, and inputs the transmission signal to the power amplification unit 6.
The power amplifying unit 6 amplifies the received transmission signal and sends it to the transmission antenna 7, which transmits the transmission signal.

The receiving antenna 11 receives, as a received signal, a response signal that the non-contact IC tag that is an object of distance measurement responds to the transmission signal, and inputs the received signal to the phase switching unit 22.
The phase switching unit 22 performs a process of delaying the phase by 90 ° by delaying the received signal according to the control of the distance estimating unit 12. Therefore, when the received signal is input to the BPF 23, it is input with the phase of 0 ° as it is, and is input with a phase of 90 ° which is delayed by 90 ° by delaying the received signal.

  The BPF 23 removes unnecessary band noise components from the input received signals having a phase of 0 ° or 90 °, and inputs them to the quadrature demodulators 24 and 25.

  The quadrature demodulator 24 frequency-converts the phase difference of the I component (in-phase component) between the reference signal received from the oscillator 4 and the received signal received from the BPF 23 and inputs the phase difference to the amplifier 13.

  The quadrature demodulator 25 calculates the phase difference between the Q component (quadrature component) of the 90-degree phase-shifted reference signal received from the oscillator 4 via the phase shift unit 21 and the received signal received from the BPF 23 as a frequency. The signal is converted and input to the amplifier 14.

  The phase shift unit 21 always shifts the phase of the reference signal received from the oscillator 4 by 90 ° and inputs the phase to the quadrature demodulator 25.

  The amplifiers 13 and 14 are composed of filters such as a low-pass filter (LPF) and a high-pass filter (HPF), and are input from the quadrature demodulators 24 and 25, respectively. The I signal and the Q signal are amplified and input to the distance estimation unit 12.

The distance estimation unit 12 calculates and compares phases from the received I signal and Q signal, and estimates the distance. In estimating the distance, as a first method for reducing the gain difference α, an average signal obtained by adding a 0 ° received signal and a 90 ° received signal shifted by the phase switching unit 22 and dividing the sum by 2 is obtained. The process of removing noise is also executed by creating.
Instead of the first method, as a second method for eliminating the gain difference α, the first switching signal obtained by dividing the I component in the 0 ° received signal by the Q component and the phase switching unit 22 are used. The square root of the value obtained by dividing the first calculation signal by the second calculation signal and multiplying by -1 using the second calculation signal obtained by dividing the I component in the 90 ° received signal by the Q component. It may be configured to execute processing for removing noise by obtaining.

  FIG. 2 is an explanatory diagram showing the relationship between the phase of the received signal, the phase of the signal shifted by 90 °, and the average phase. FIG. 3 shows the relationship between the I signal and the Q by taking the average phase when the Q signal is large. It is explanatory drawing explaining preventing the influence by the gain difference with a signal.

  As shown in FIG. 2, assuming that the initial phase A1 of the received signal having a phase of 0 ° received by the receiving antenna 11 (see FIG. 1) is located in the first quadrant E1, the phase switching unit 22 (see FIG. 1) The shift phase B1 of the shift signal obtained by shifting the phase of the reception signal by 90 ° is located in the second quadrant E2. The average phase C1 obtained by averaging the initial phase A1 and the shift phase B1 and dividing by 2 is located between the initial phase A1 and the shift phase B1.

As shown in FIG. 3, for example , when considering the case where the Q signal is larger than the I signal, what is supposed to be the initial phase A1 changes to the + side due to the gain difference between the I signal and the Q signal. The initial phase A2. On the other hand, the shift phase B2 obtained by shifting the phase of the initial phase A2 by 90 ° is located in the second quadrant E2, which is the quadrant opposite to the initial phase A2, and therefore changes to the minus side from the original shift phase B1. Yes. Then, the average phase C2 obtained by adding the initial phase A2 and the shift phase B2 and dividing by 2 is almost the same as the original average phase C1 because the change on the + side and the change on the − side are canceled, and the I signal and Q It is possible to avoid the influence due to the signal gain difference.

In this way, the fact that the average phase C2 is substantially the same as the average phase C1 and the gain difference between the I signal and the Q signal can be canceled will be described.
First, a first method capable of reducing the influence of the gain difference α will be described below using Equations 1 to 5.

The initial phase of the phase A1 phi _{0 deg,} the initial phase phases phi of A2 _{'0 deg,} the phase shift the phase B1 phi _90deg, phases phi of the shift phase B2' When _90deg, following equation 1 4 is required.

そうすると、平均位相Ｃ２の位相φ_AVEは、次に示す数式５で求められる。

Then, the phase φ _AVE of the average phase C2 is obtained by the following formula 5.

Next, a second method capable of eliminating the influence of α, which is the gain difference between the I signal and the Q signal, will be described below using Equations 6 to 11.
First, assuming that Q / I is a true value of the ratio of I and Q when there is no gain difference between the I signal system and the Q signal system, R which is this ratio can be defined as shown in Equation 6 below.

Ｉ信号系統の利得に対するＱ信号系統の利得の割合をα（未知数）とし、位相切替部２２において受信信号に対する位相シフト量が０°である場合のＱ信号とＩ信号の振幅比の観測値をＲ_0degとすると、次の数式７が得られる。

The ratio of the gain of the Q signal system to the gain of the I signal system is α (unknown number), and the observed value of the amplitude ratio between the Q signal and the I signal when the phase shift amount for the received signal is 0 ° in the phase switching unit 22 When R _{0 deg} is established, the following Expression 7 is obtained.

また、位相切替部２２において受信信号に対する位相シフト量が９０°である場合のＱ信号とＩ信号の振幅比の観測値をＲ_90degとすると、次の数式８が得られる。

Further, when the observed value of the amplitude ratio of the Q signal and I signal when the phase shift amount with respect to the received signal in the phase switching unit 22 is 90 ° and R _90deg, Equation 8 is obtained.

これらの数式に基づいて、Ｒ_0deg，Ｒ_90degからＲを得る式にαを含まない式が次のように求められる。
まず、上述の数式７と数式８の両辺をそれぞれ割り算すると、次の数式９が得られる。

Based on these equations, an equation that does not include α in the equation for obtaining R from R _0deg and R _90deg is obtained as follows.
First, by dividing the both sides of the above formulas 7 and 8, the following formula 9 is obtained.

したがって、真の値であるＲは、次の数式１０で求められる。

Therefore, R, which is a true value, is obtained by the following formula 10.

そうすると、真の位相であるθは次の数式１１で求められる。

Then, θ which is a true phase is obtained by the following formula 11.

この方式でθを求めることで、Ｉ信号系統の利得に対するＱ信号系統の利得の割合の影響を受けず、位相が高精度に求められることになる。従って、距離測定装置１によってθをもとに算出される距離の精度が向上する。また、θに関する誤差が無くなるので、多値位相変調方式のデータ受信装置に応用した場合に、多値位相変調方式における信号点配置を位相平面上で高密度にすることができ、データ通信速度を向上させることができる。

By obtaining θ by this method, the phase can be obtained with high accuracy without being affected by the ratio of the gain of the Q signal system to the gain of the I signal system. Therefore, the accuracy of the distance calculated based on θ by the distance measuring device 1 is improved. In addition, since there is no error related to θ, when applied to a multi-level phase modulation type data receiver, the signal point arrangement in the multi-level phase modulation mode can be increased on the phase plane, and the data communication speed can be increased. Can be improved.

  FIG. 4 shows a flowchart of the distance measuring operation of the distance measuring device 1, FIG. 5 is an image diagram showing a signal flow when measuring the distance to the non-contact IC tag 30, and FIG. 6 is a diagram when demodulating the signal. An image diagram is shown.

  The controller unit 9 of the distance measuring device 1 outputs an R / W request signal 33 (see FIG. 5) for requesting a response to the non-contact IC tag 30 from the distance measuring device 1 functioning as a reader / writer (R / W). (Step S1). At this time, the frequency f of the R / W request signal 33 is fixed to the first frequency f1 (see FIG. 6) and transmitted.

  The controller unit 9 transmits CW (continuous wave) to the non-contact IC tag 30 at the first frequency f1 (step S2). This CW is a continuous sine wave with no signal. At this time, the non-contact IC tag 30 receiving this CW transmits a tag response signal 35 at the first frequency f1.

  The distance measuring device 1 receives the response signal of the non-contact IC tag 30 at the first frequency f1 by the receiving antenna 11 (step S3). Then, the received signal at the first frequency f1 is demodulated by the reference signal 41 (see FIG. 5) at the first frequency f1, and data is taken in (step S4).

  The distance measuring device 1 switches the phase switching unit 22 from 0 ° to 90 ° under the control of the distance estimating unit 12, demodulates the received signal of the first frequency f1 ′ (see FIG. 6) after switching, and captures data ( Step S5). At this time, the phase switching unit 22 of the distance measuring device 1 switches the phase within the one-frame process in which the non-contact IC tag 30 transmits a signal at the first frequency f1. In other words, while transmitting one signal as viewed from the non-contact IC tag 30, the distance measuring device 1 performs two types of data capture, that is, data capture at a phase of 0 ° and data capture at a phase of 90 °. Do.

  The distance measuring apparatus 1 stands by until a predetermined time elapses (step S6: NO). When the predetermined time elapses (step S6: YES), the distance measuring device 1 confirms whether all frequencies have been completed (step S7).

(In this embodiment, three frequency from the first frequency f1 to the third frequency f3) all frequencies when not completed for (step S7: NO), the frequency f next frequency (e.g., second frequency Switch to f2) and return to step S1.

  If the processing has been completed for all frequencies (step S7: YES), the distance estimation unit 12 calculates the phase from the data of the I signal and Q signal of each frequency (step S9). At this time, for each frequency f, the data obtained by demodulating the frequency f acquired at the phase of 0 ° and the data obtained by demodulating the frequency f ′ acquired at the phase of 90 ° are added and the average phase data divided by 2 is obtained. Calculate each.

  And the distance estimation part 12 calculates distance from the calculated | required average phase (step S10), and complete | finishes a process.

  With the configuration and operation described above, distance measurement that is hardly affected by the gain difference between the I signal and the Q signal can be realized. Therefore, highly accurate distance measurement can be realized.

Specifically, in the prior art , as shown in FIG. 7A, an error of about tens of centimeters or more (maximum of 80 cm) has occurred since a phase error of about 3 ° in the vertical direction has occurred. As shown in FIG. 7 (B), the distance measuring apparatus 1 produces a phase error of about 0.04 ° in the vertical direction, and the measurement distance error can be drastically reduced to about several centimeters. In particular, the error can be minimized at the phase of ± 45 ° and ± 135 °, which has the largest error in the past.

  Further, the distance measuring device 1 does not need to measure the gain difference between the I signal and the Q signal in advance, and can be easily used without performing a detailed preliminary survey or the like.

  In addition, by shifting the phase by 90 °, the gain difference between the I signal and the Q signal can be canceled appropriately each time, and demodulation can be performed with high accuracy at all times without being affected by temperature changes or changes over time. Distance measurement can be performed with high accuracy.

  The distance measuring device 1 described above may be configured to include the phase switching unit 22 between the oscillator 4 and the phase shift unit 21 as shown in FIG. Even in this case, the same effect as the above-described embodiment can be obtained.

  Further, instead of the distance estimation unit 12, a reception data decoding device 28 may be configured by including a data decoding unit 29 as shown in FIG. In this case, the data decoding unit 29 creates an average signal obtained by adding the 0 ° received signal and the 90 ° received signal shifted by the phase switching unit 22 and dividing the sum by 2, and further adding the average signal to the 45 °. It is also preferable to perform processing for removing the noise and restoring the signal by returning to the I signal side. Then, the multilevel digital modulation of the multilevel phase modulation method is executed on the restored signal from which the noise has been removed to convert it into data, and this data may be temporarily stored in the storage unit. As a result, it is possible to provide the reception data decoding device 28 that is less affected by the gain difference between the I signal and the Q signal. Since the influence of the gain difference is small, the number of bits included in one signal can be increased, and even if the number of bits is increased, demodulation can be performed with high accuracy. Therefore, a large amount of data can be transmitted at once to improve the communication speed.

  Further, as indicated by a virtual line in FIGS. 8 and 9, a display unit 27 may be provided in the subsequent stage of the distance estimation unit 12 or the reception data decoding device 28. In this case, it is possible to self-diagnose the gain imbalance generated in the circuits of the distance measuring device 1 and the received data decoding device 28 based on the gain difference α, and the result of the self-diagnosis is displayed on the display unit 27. be able to.

  More specifically, by solving the equations obtained by multiplying both sides of Equation 7 and Equation 8 described above, the unknown α is obtained as follows.

このαの値を、本方式を用いた距離測定装置１または受信データ復号装置２８が検出できるので、これらの装置が内部回路に発生したゲインのアンバランスを自己診断することが可能となる。

Since the distance measurement device 1 or the received data decoding device 28 using this method can detect the value of α, it becomes possible for these devices to self-diagnose the gain imbalance generated in the internal circuit.

  Further, when the average signal level obtained by averaging the received signals at 0 ° and 90 ° is small, the distance measuring device 1 shifts the phase of the average signal K by the distance estimating unit 12 as shown in FIG. You may make it the structure shifted 45 degrees so that it may become. Here, the case where the level of the average signal is small can be a case where the phase of the average signal falls within the range of “± nπ / 2” when the integer is “n”. As a result, the levels of the I signal and the Q signal are increased, and the deterioration of the phase accuracy due to the influence of the quantization error and the S / N ratio decrease can be improved. In particular, a high effect can be obtained when the gain difference α between the I signal and the Q signal is 1.

  In addition, a one-frame signal transmitted by the non-contact IC tag 30 and received signals having a phase of 0 ° and 90 ° are obtained. However, for example, the non-contact IC tag 30 transmits a signal of the first frequency f1. Transmission may be performed twice, and the distance measurement apparatus 1 may be configured to perform processing with a phase of 0 ° for the first time and shift the phase by 90 ° for the second time.

  Further, although the BPF 23 is provided in the subsequent stage of the phase switching unit 22, it may be provided in the previous stage of the phase switching unit 22.

In correspondence between the configuration of the present invention and the above-described embodiment,
The demodulating device of the present invention corresponds to the distance measuring device 1 and the received data decoding device 28 of the embodiment,
Similarly,
The signal transmission means corresponds to the transmission antenna 7,
The combining unit and the distance estimating unit correspond to the distance estimating unit 12,
The phase shift unit and the phase switching unit correspond to the phase switching unit 22,
The demodulating means corresponds to the quadrature demodulator 24, 25,
The data receiving device corresponds to the received data decoding device 28,
The restoring means and the data converting means correspond to the data decoding unit 29,
The response request signal corresponds to the R / W request signal 33,
The received signal corresponds to the tag response signal 35 ,
The first phase corresponds to a phase of 0 °,
The second phase corresponds to a 90 ° phase,
The first demodulated signal corresponds to the data obtained by demodulating the first frequency f1,
The second demodulated signal corresponds to the data obtained by demodulating the first frequency f1 ′ ,
The composite signal corresponds to the average phase data,
The present invention is not limited only to the configuration of the above-described embodiment, and many embodiments can be obtained.

The block diagram of a distance measuring device. Explanatory drawing which shows the relationship of a phase. Explanatory drawing explaining the effect of an average phase. The flowchart which shows the distance measurement operation | movement of a distance measuring device. The image figure which shows the flow of the signal at the time of measuring distance. The image figure at the time of demodulating a signal with I signal and Q signal. Explanatory drawing of a phase error. The block diagram of the distance measurement apparatus of another structure. The block diagram of a received data decoding apparatus. Explanatory drawing of another Example.

DESCRIPTION OF SYMBOLS 1 ... Distance measuring device 7 ... Transmitting antenna 10 ... Demodulation unit 10a ... Reference signal input terminal 10b ... Reception signal input terminal 10d ... I signal output terminal 10e ... Q signal output terminal 12 ... Distance estimation part 22 ... Phase switching part 24, 25 ... Quadrature demodulator 28 ... Received data decoder 29 ... Data decoder 30 ... Non-contact IC tag 33 ... R / W request signal 35 ... Tag response signal

Claims (4)

A demodulator that demodulates a received signal using an I signal that is an in-phase component and a Q signal that is a quadrature component,
Phase shift means for shifting the phase of the received signal to a phase of 90 degrees;
Demodulating means for acquiring a first demodulated signal and the second demodulated signal by demodulating the received signal and the 90 ° shifted phase of the received signal and, respectively,
Combining means for combining the first demodulated signal and the second demodulated signal to obtain a combined signal;
It said combining means, demodulating apparatus which configured to divide by 2 by adding the phase of said second demodulated signal of the first demodulation signal. A demodulator that demodulates a received signal using an I signal that is an in-phase component and a Q signal that is a quadrature component,
Phase shift means for shifting the phase of the received signal to a phase of 90 degrees;
Demodulating means for acquiring a first demodulated signal and the second demodulated signal by demodulating the received signal and the 90 ° shifted phase of the received signal and, respectively,
Combining means for combining the first demodulated signal and the second demodulated signal to obtain a combined signal;
The combining means uses the first arithmetic signal obtained by dividing the I component in the first demodulated signal by the Q component and the second arithmetic signal obtained by dividing the I component in the second demodulated signal by the Q component. A demodulator configured to obtain a square root of a value obtained by dividing an arithmetic signal by the second arithmetic signal and multiplying by -1. A demodulation device according to any one of claims 1 and 2,
A signal transmission means for transmitting a response request signal;
Distance measurement means comprising: a distance estimation means for receiving a response signal of the non-contact IC tag in response to the response request signal and estimating the distance to the non-contact IC tag based on the phase of the synthesized signal by the received signal apparatus. A demodulation device according to any one of claims 1 and 2,
Restoration means for shifting the phase of the composite signal to the phase side of 0 degree by half the angle of the phase shifted by the phase shift means to obtain a restoration signal;
A data receiving apparatus comprising: data converting means for converting the restored signal into multi-value digital demodulated data.

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