JP5572216B2 - Reference signal generating apparatus, reference signal generating method, and information communication system - Google Patents

Description

  The present invention relates to a reference signal generating apparatus, a reference signal generating method for outputting a highly accurate 1 PPS (Pulse Per Second) signal or frequency signal in synchronization with a reference signal transmitted from a Global Navigation Satellite System (GNSS) satellite, and the like, and The present invention relates to an information communication system using the same.

  Currently, communication data multiplexing techniques are used in information communication systems such as terrestrial digital broadcasting and mobile communication, which are widely used, for example, time division multiple access (TDMA) or frequency division multiple access (FDMA). Is used. In such an information communication system, in order to synchronize the communication timing and communication frequency, a reference signal generator that outputs a reference timing signal (1 PPS signal) at a common interval of 1 second and a frequency signal of 10 MHz is required. .

The reference signal generator described in Patent Literature 1 uses IP control as a control method, and causes a 1 PPS signal and a frequency signal to follow a reference signal transmitted from a GNSS satellite. In this case, the transfer function G _M in I-P control is determined with reference to the binomial coefficients standard form model shown in equation (1).

  (Equation 1) is a model in which no overshoot occurs in the step response. Further, this step response coincides with a timing error between the 1PPS signal and the reference signal (hereinafter referred to as a tracking error). Therefore, by determining the transfer function of the IP control so as to satisfy the model of Equation 1, it is possible to quantitatively perform desired control without causing overshoot.

JP 2009-17408 A

Here, in the reference signal generating device described in Patent Document 1, the eigenvalue ω ₀ in the model of (Equation 1) is determined as in Equation 2.

f _peak represents a value at which the deviation of the frequency signal at the time of pull-in (at the time of transient response) becomes maximum, and is set in advance within a range that can be tolerated by the system provided with the reference signal generator. e ₀ represents the tracking error at the start of control, that is, the initial value of the tracking error.

The eigenvalue ω ₀ is a value determined only by the initial value e ₀ of the tracking error when f _peak is set by a system constraint or the like. Therefore, the eigenvalue omega ₀ is as the initial value e ₀ of the tracking error becomes large, with a small becomes such properties in an inverse relationship.

However, the model of Formula 1 has a characteristic that the settling time becomes longer as the eigenvalue ω ₀ becomes smaller. That is, the settling time as the initial value e ₀ of the tracking error becomes large becomes long. The tracking error and the settling time are in a proportional relationship as shown in FIG. The horizontal axis in FIG. 8 represents the elapsed time from the start of control, the vertical axis represents the tracking error, and the time until the tracking error becomes zero is the settling time.

Therefore, the present invention makes it possible to follow the reference signal in a shorter time than the conventional settling time while quantitatively performing desired control without occurrence of overshoot even when the initial value e ₀ of the tracking error becomes large. It is an object of the present invention to provide a reference signal generator that can be used. It is another object of the present invention to provide a reference signal generator that can increase the pull-in speed.

Means and effects for solving the problem

In order to solve the above problems, a reference signal generator according to the present invention compares a reference signal with a time signal and outputs a tracking error, and performs IP control using a binomial coefficient standard model having an eigenvalue. A control unit that calculates an operation amount based on the tracking error, an oscillation unit that oscillates according to the operation amount and outputs a frequency signal, and a detection unit that outputs the time signal based on the frequency signal. The control unit updates the eigenvalue according to the follow-up error output from the comparison unit. In particular, the control unit, characterized in that the tracking error is larger the eigenvalues as small again.

  In this way, by sequentially updating the eigenvalues in the binomial coefficient standard model, it is possible to reference the time signal or frequency signal in a shorter time than the conventional settling time while quantitatively performing desired control without overshoot. The signal can be tracked.

  Further, the control unit included in the reference signal generator described above updates the eigenvalue in accordance with the tracking error output from the comparison unit, and when the eigenvalue is equal to or greater than the predetermined value, the predetermined value is set to the eigenvalue. It is characterized by giving. In particular, the predetermined value is a stability limit value of a step response. In other words, the predetermined value is a value based on a time constant of the IP control in which at least five sampling points are obtained in the rising period of the step response of the IP control.

  In this way, it is possible to prevent the occurrence of a vibration response by preventing the eigenvalue from taking a value greater than or equal to a predetermined value, that is, by providing a maximum value for the eigenvalue.

  Further, the control unit included in the above-described reference signal generation device is characterized in that the transfer function of the I operation in the IP control method is multiplied by a predetermined value so that the maximum frequency deviation is not more than an allowable value. In particular, the control unit multiplies the transfer function of the I operation by a ratio between a frequency deviation set as a constraint condition at the start of control and a previously calculated maximum value of the frequency deviation.

  By correcting the transfer function of the I operation in this way, the maximum value of the frequency deviation can be corrected, and the frequency deviation can be kept within an allowable value in a system or the like provided with the reference signal generator.

  The reference signal generator further includes a steady state detection unit that detects a steady state when the zero crossing of the tracking error exceeds a predetermined number of times during a predetermined period, and the control unit includes the steady state detection unit. When a steady state is detected, a steady value is given to the eigenvalue in the binomial coefficient standard model.

  By detecting the steady state and switching to the control for the steady state in this way, from the control that emphasizes responsiveness for the purpose of shortening the settling time, etc. It is possible to shift to control accurately.

In order to solve the above-described problem, a reference signal generation method according to the present invention includes a step of comparing a reference signal and a time signal and outputting a tracking error, and an IP using a binomial coefficient standard model having an eigenvalue. A step of calculating an operation amount in control based on the follow-up error, a step of oscillating according to the operation amount and outputting a frequency signal, and a step of outputting the time signal based on the frequency signal . and updates the eigenvalues according to prior Symbol tracking error. In particular, it characterized that you set larger the eigenvalues as the tracking error is small.

  The information communication system according to the present invention is characterized in that communication timing or communication frequency is synchronized based on the time signal or frequency signal output from the reference signal generator.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a main configuration of a reference signal generator 10 according to the present embodiment. As shown in FIG. 1, the reference signal generator 10 includes a receiving unit 11, a comparing unit 12, a control unit 13, an oscillating unit 14, and a detecting unit 15. The control system of the present embodiment is feedback control that performs IP control. A value output from the receiving unit 11 is a target value r (a reference signal described later), and a value output from the comparing unit 12 is a tracking error e. A value output from the control unit 13 is an operation amount u, and a value output from the detection unit 15 via the oscillation unit 14 to be controlled is a control amount y (a 1 PPS signal described later).

  The receiving unit 11 generates a highly accurate 1PPS signal as a reference signal based on a positioning signal included in a radio wave received by an antenna (not shown) from a GNSS satellite, and outputs the 1PPS signal to the comparing unit 12.

  The comparison unit 12 compares the 1PPS signal output from the detection unit 15 in the previous cycle with the reference signal output from the reception unit 11 in the current cycle, and a tracking error that is a timing error (phase difference) between them. e is output to the control unit 13.

  The control unit 13 calculates the operation amount u using the follow-up error e output from the comparison unit 12 as an input amount. Specifically, the control unit 13 calculates the operation amount u by the IP control method, and each transfer function in the IP control method is obtained by a partial model matching method using a third-order binomial coefficient standard form as a model. Calculated. Details of this calculation method will be described later.

  Note that the IP control is so-called proportional preceding PI control, and has a feature that the control amount y output from the detection unit 15 is given as the input amount y of the P operation, unlike the normal PI control. Here, the input amount y of the P operation includes an error that can be regarded as being substantially constant with respect to a minute time fluctuation. Therefore, the control unit 13 obtains the input amount y to the P operation by sequentially adding the change Δy of the input amount using discrete means (increment method). By doing so, the input amount y that is not affected by the error as described above can be calculated, and the operation amount u with a small error can be obtained. About this discrete means, it is the same as the content of patent document 1, and detailed description is abbreviate | omitted.

  The response characteristics of the oscillating unit 14 with respect to the input signal are determined according to the type. That is, the time constant of the oscillation unit 14 is uniquely fixed depending on the type. However, if the time constant to be controlled is fixed, matching with the binomial coefficient standard model used in the present embodiment cannot be performed as will be described later. Therefore, the control unit 13 can be provided with an arbitrary time constant T, and includes a first-order lag filter that contributes to the response of the oscillation unit 14 that is a control target. By doing so, matching with the binomial coefficient standard model can be performed without being influenced by the time constant of the oscillation unit 14 to be controlled.

  The oscillation unit 14 is, for example, a VCO (Voltage Controlled Oscillator). The oscillating unit 14 oscillates at a frequency based on the operation amount u output from the control unit 13, and outputs a frequency signal such as a frequency of 10 MHz to a transmitting station for digital terrestrial broadcasting, a base station for mobile communication, and the detection unit 15. . Since the reference signal generator 10 uses the oscillation unit 14 that has a sufficiently high response speed to the input signal, the time constant of the oscillation unit 14 can be ignored.

  The detecting unit 15 detects a time signal based on the frequency signal output from the oscillating unit 14, and outputs the time signal to a digital terrestrial broadcasting transmitting station, a mobile communication base station, and the comparing unit 12. In particular, the time signal is a 1 PPS signal composed of timing pulses at intervals of 1 second.

  Hereinafter, a method of calculating each transfer function in the control unit 13 by the partial model matching method will be described with reference to FIG.

  A block diagram showing the control processing of the reference signal generator 10 is shown in FIG. In FIG. 2, r represents a target value in this control system and is a reference signal output from the receiving unit 11. Further, y represents a control amount, and is a 1PPS signal that is integrated with a deviation (hereinafter referred to as a frequency deviation) Δf of the frequency signal output from the oscillating unit 14. e represents a follow-up error obtained by the comparison unit 12, and is a difference between the target value r and the control amount y, that is, a time difference between the timing of the reference signal and the timing of the 1PPS signal. u is an operation amount obtained by the control unit 13.

The transfer function of the P operation in the control unit 13 is K _P , the transfer function of the I operation in the control unit 13 is K _i / s, the transfer function of the first-order lag filter in the control unit 13 is 1 / (T ₁ S + 1), and the oscillation unit 14 Is 1 and the transfer function of the detector 15 is 1 / S.

In the control system shown in FIG. 2, the transfer function G _yr of the controlled variable y from the target value r is given by ( _Equation 3).

Next, as a transfer function model in the partial model matching method, a third-order binomial coefficient standard form (equation 4) (same as (equation 1)) is given.

The model of (Equation 4) has a feature that no overshoot occurs in the step response. Further, as the value of the eigenvalue ω ₀ becomes larger, the settling time is shorter and the maximum value of the frequency deviation is larger. Note that the step response of (Equation 4) matches the response of the tracking error e, and the impulse response of (Equation 4) matches the response of the frequency deviation Δf.

By solving for equation (3) and the equation (4) relative to each dimension _{K i} and _{K p,} can be derived (5) and (6).

Here, in the control system of the reference signal generation device 10, the response of the frequency deviation Δf is equal to the differential of the response of the 1PPS signal, that is, the differential of the step response of (Equation 4). Therefore, the response of the frequency signal to the tracking error e can be expressed as (Equation 7).

Then, by substituting (Equation 4) into (Equation 7) and _{obtaining the} value f _PEAK that maximizes Δf (t), it becomes the maximum when t = 2 / ω ₀ and leads to (Equation 8). it can.

In ( _Equation 8), when f _PEAK is subjected to a frequency deviation constraint determined by a system or the like provided with the reference signal generator 10, the eigenvalue ω ₀ is unique based on the tracking error e ₀ at the start of control. To be determined.

By the way, the larger the eigenvalue ω ₀ is, the larger the pull-in amount becomes, and the settling time becomes shorter. In addition, since the control is performed so that the tracking error is eliminated, the tracking error is gradually reduced. Therefore, in the reference signal generation device 10, the eigenvalue ω ₀ is not a constant value but is a variable ω (e) that is updated according to the sampled tracking error e (t), and (Equation 8) is changed ( Equation 9) is used.

  As the eigenvalue ω is increased, the settling time is shortened, but the rise time in the step response is also shortened, so that the sampling points at the rise are reduced as shown in FIG. In FIG. 3, the vertical axis represents the step response, and the horizontal axis represents the elapsed time. Note that the sampling period is the same for each eigenvalue ω.

When the eigenvalue ω (e) exceeds a certain value ω _MAX , a sufficient sampling point cannot be obtained and a vibrational response occurs. Therefore, if the equation (9) sought eigenvalue omega (e) is omega _MAX above, the eigenvalues are switched so that the omega _MAX.

The maximum eigenvalue ω _MAX is a so-called stability limit value. Theoretically, at least 5 sampling points can be set to values obtained during the rising period in the step response. In addition, it can be determined by preliminary experiments or simulations. Here, when the maximum value ω _MAX is set, a value close to the stability limit value can be set relatively easily by theoretically determining the maximum value ω _MAX by a preliminary experiment.

Here, (Equation 10) can be derived from (Equation 9), and e _MAX corresponding to ω _MAX can be calculated. Since the tracking error e (t) is a value observed in the reference signal generator 10, whether the tracking error e (t) exceeds e _MAX or not, whether or not the eigen value ω (e) exceeds the eigen value ω _MAX . It may be determined whether or not.

Based on the eigenvalue ω (e) determined as described above, each transfer function can be determined from the relational expression shown in (Equation 5) and (Equation 6) (ω ₀ is changed to ω (e)). it can.

  Next, a simulation result is shown in FIG. 4A shows the time course of the tracking error, FIG. 4B shows the time course of the frequency deviation, and FIG. 4C shows the time course of the eigenvalue ω (e). Further, the conventional control is the control described in Patent Document 1, and the simulation result is represented by a dotted line. The simulation result of the reference signal generator 10 is represented by a solid line.

As an initial condition of the simulation, the tracking error at the start of control is 6 × 10 ⁻⁶ [sec], and the allowable frequency deviation, that is, the frequency deviation f _PEAK given as a constraint condition is 3 × 10 ⁻⁸ [10 MHz]. . The maximum eigenvalue is 0.123.

  As can be seen from FIG. 4A, in the conventional control (Patent Document 1), the time until the tracking error becomes 0 and stabilizes (settling time) is about 600 seconds. On the other hand, the settling time of the control according to the present embodiment is about 300 seconds. From FIG. 4A, it can be seen that the reference signal can be tracked in less than half the time compared with the prior art while enjoying the effects such as no conventional overshoot.

Here, as can be seen from FIG. 4B, in the control of the present embodiment, the eigenvalue is updated according to the sampled tracking error. As a result, the maximum value of the frequency deviation exceeds the constraint condition f _PEAK. End up. Then, the frequency deviation may not be allowed to exceed f _PEAK, for example, when the frequency deviation constraint condition f _PEAK is made equal to the allowable value in the system in which the reference signal generator 10 is provided. In such a case, it is possible to correct the maximum value of the frequency deviation so as not to exceed the allowable value by adjusting the transfer function of the I operation related to the response of the frequency deviation.

Specifically, as shown in equation (11), multiplied by the ratio between the maximum value _{f MAX} constraints _{f PEAK} and frequency deviation in the transfer function _{K i} of I operation.

FIG. 5 shows a simulation result when the control is performed using the corrected transfer function K _imod . The initial conditions of the simulation are the same as those shown in FIG. From FIG. 5B, it can be seen that the maximum value f _MAX of the frequency deviation can be controlled to be equal to the constraint condition f _PEAK . Further, it can be seen that the settling time is about 350 seconds, which is a little longer than before the correction of the transfer function K _i , but about half that of the conventional control.

  Moreover, the result of having performed simulation on the conditions different from FIG. 4 and FIG. 5 is shown in FIG. 4 and 5 show simulation results when the 1PPS signal and the reference signal are shifted, whereas FIG. 6 shows simulation results when the frequency signal is shifted in addition to the 1PPS signal.

  6 that the settling time is about 500 seconds in the conventional control (Patent Document 1), whereas the settling time is shortened to about 350 seconds in the control according to the present embodiment. In addition, an effect such as no conventional overshoot can be enjoyed.

  Next, a method for detecting that the reference signal generator 10 is synchronized with the reference signal, that is, a method for detecting the steady state, and a control method in the steady state will be described.

  In the actual machine of the reference signal generator 10, the frequency of occurrence of zero crossing increases as the tracking error decreases. Further, when the 1PPS signal accurately follows the reference signal that is normally distributed with accuracy 0 as the center, the frequency of occurrence of zero crossing is high. Therefore, when the tracking error zero cross exceeds a predetermined number of times within a certain period, the steady state is detected. By doing in this way, it can be determined whether it became the steady state. In addition, since the zero cross is used as a determination material, it is possible to prevent erroneous detection as a steady state from a response that is stable in a state where a steady deviation is added. This determination may be based on the zero cross of the moving average value of the tracking error, or a frequency deviation may be used instead of the tracking error.

When the steady state is detected, the eigenvalue is changed to the predetermined value ω _STEADY so that the time constant of the control unit 13 becomes longer. As a result, it is possible to appropriately shift from the control with an emphasis on responsiveness for the purpose of shortening the settling time to the control with an emphasis on stability for the purpose of improving the tracking accuracy of the reference signal.

Next, FIG. 7 shows a simulation result when the eigenvalue to be updated according to the tracking error is multiplied by a predetermined value. In the initial condition of the simulation result shown in FIG. 7, the initial condition different from the simulation shown in FIG. 4 is the maximum value of the frequency deviation and the eigenvalue. The frequency deviation f _PEAK is 3 × 10 ⁻⁹ [10 MHz], and the maximum eigenvalue is 0.092.

In the simulation shown in FIG. 7, the eigenvalue is four times the value calculated in (Equation 9). The determination for switching eigenvalue omega (e) a to eigenvalues omega _MAX is done by comparing the following 4 times the value of e _MAX calculated by (Equation 10) the error e (t). Furthermore, the corrected transfer function K _imod calculated by ( _Expression 11) for preventing the maximum value of the frequency deviation from exceeding the allowable value is multiplied by ¼.

  From FIG. 7, it can be seen that the settling time is about 6000 seconds in the conventional control (Patent Document 1), whereas the settling time is shortened to about 3000 seconds in the control according to the present embodiment. In addition, the frequency deviation can be steeply raised to an allowable value and can be sharply lowered from the allowable value. The fact that the frequency deviation is large can be regarded as an agreement with the fact that the pull-in speed is high, and it can be seen that the pull-in speed of the tracking error can be made as fast as possible.

  Thus, it can be seen that the pull-in speed can be increased by multiplying the eigenvalue ω (e) by a predetermined value. This feature appears more prominently when the allowable value (constraint condition) of the frequency deviation is smaller.

It is a block diagram which shows an example of the main structures of the reference signal generator by this Embodiment. It is a block diagram regarding control of the reference signal generator by this Embodiment. It is a figure for demonstrating the relationship between an eigenvalue and the number of sampling points. It is a figure which shows the simulation result in control of the reference signal generator by this Embodiment. It is a figure which shows the simulation result in control of the reference signal generator by this Embodiment. It is a figure which shows the simulation result in control of the reference signal generator by this Embodiment. It is a figure which shows the simulation result in control of the reference signal generator by this Embodiment. It is a figure which shows the simulation result in control of the conventional reference signal generator.

DESCRIPTION OF SYMBOLS 10 Reference signal generator 11 Reception part 12 Comparison part 13 Control part 14 Oscillation part 15 Detection part

Claims (7)

A comparison unit that compares the reference signal and the time signal and outputs a tracking error;
A control unit that calculates an operation amount in the IP control using the binomial coefficient standard model having an eigenvalue based on the tracking error;
An oscillating unit that oscillates according to the operation amount and outputs a frequency signal;
A detection unit that outputs the time signal based on the frequency signal;
The control unit sets the eigenvalue to be larger as the follow-up error is smaller, and multiplies the transfer function of the I operation in the IP control by a predetermined value so that the maximum frequency deviation is less than or equal to an allowable value . Reference signal generator. The reference signal generator according to claim 1 ,
Wherein the control unit, by multiplying the ratio of the maximum value of the frequency deviation which is calculated in advance with the frequency deviation to set as a constraint condition at the control start to the transfer function of the I operation, to a predetermined multiple of the transfer function of the I operation A reference signal generator. The reference signal generator according to claim 1 or 2 ,
A steady state detector that detects a steady state when the zero crossing of the tracking error exceeds a predetermined number of times during a predetermined period;
The reference signal generator according to claim 1, wherein the control unit gives a steady value to the eigenvalue in the binomial coefficient standard model when the steady state detection unit detects a steady state. A comparison unit that compares the reference signal and the time signal and outputs a tracking error;
A control unit that calculates an operation amount in the IP control using the binomial coefficient standard model having an eigenvalue based on the tracking error;
An oscillating unit that oscillates according to the operation amount and outputs a frequency signal;
A detection unit that outputs the time signal based on the frequency signal;
The controller is
When the eigenvalue is less than a predetermined value, update the eigenvalue according to the tracking error,
When the eigenvalue is equal to or greater than the predetermined value, the predetermined value is given to the eigenvalue;
The reference signal generator according to claim 1, wherein the predetermined value is a value based on a time constant of the IP control in which at least five sampling points are obtained in a rising period of the step response of the IP control.   Comparing a reference signal and a time signal and outputting a tracking error;
  Calculating an operation amount in the IP control using a binomial coefficient standard model having an eigenvalue based on the tracking error;
  Oscillating according to the manipulated variable and outputting a frequency signal;
  And outputting the time signal based on the frequency signal,
  A reference signal generation method characterized in that the eigenvalue is set to be larger as the follow-up error is smaller, and the transfer function of the I operation in the IP control is multiplied by a predetermined value so that the maximum frequency deviation is less than an allowable value. Comparing a reference signal and a time signal and outputting a tracking error;
Calculating an operation amount in the IP control using a binomial coefficient standard model having an eigenvalue based on the tracking error;
Oscillating according to the manipulated variable and oscillating a frequency signal;
And outputting the time signal based on the frequency signal,
When the eigenvalue is less than a predetermined value, update the eigenvalue according to the tracking error,
When the eigenvalue is equal to or greater than the predetermined value, the predetermined value is given to the eigenvalue;
The reference signal generation method according to claim 1, wherein the predetermined value is a value based on a time constant of the IP control in which at least five sampling points are obtained in a rising period of the step response of the IP control. Information communication system, characterized by claims 1 to based on the time signal or a frequency signal outputted from the reference signal generating apparatus according to any one of 4, communication timing or communication frequency is synchronized.

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