JP5319604B2 - Filter coefficient setting method for digital receiver and digital receiver - Google Patents

Description

  The present invention relates to a filter coefficient setting method for a digital receiver and a digital receiver.

  In recent years, in each field, a desired wave signal, which is a modulated signal, is transmitted to a device from a portable transmitter owned by a user, and a receiving device provided in the device receives the desired wave signal and demodulates the desired wave signal. Various communication systems have been proposed for accurately specifying the content of the original signal before modulation and controlling the drive of the device. And in this communication system, the digitization of the receiving apparatus is progressing more and more (for example, patent document 1).

  The digital receiver shown in Patent Document 1 is an FSK (Frequency Shift Keying) digital receiver, which considers low power consumption, intermittently turns on and off the power at regular intervals, and receives when the power is turned on. Mode, and enters sleep mode when the power is turned off.

  In the reception operation mode when the power is turned on, there are a standby state in which reception of a desired wave signal as a modulation signal is received from the portable transmitter and a reception state in which the desired wave signal is received. Therefore, in the digital reception device, the desired wave signal is not input in the standby state, and only the ambient noise signal is input. In the reception state, the ambient noise signal is input together with the desired wave signal.

  In addition, this digital receiving apparatus includes an adaptive filter. The adaptive filter is a digital filter that performs learning processing for calculating and sequentially updating a filter coefficient to remove the noise signal from the input noise signal in the standby state, and removing the noise signal. A coefficient is formed.

  When a new signal (desired wave signal or new noise signal) is input to the digital receiving device in a standby state, the digital receiving device determines whether the new signal is a noise signal or not in the desired wave signal determination processing unit. Signal processing is performed to determine whether or not.

  When the desired wave signal determination processing unit determines that the new signal is the desired wave signal, the digital receiver uses the filter coefficient at that time to remove the noise signal and extract the desired wave signal. .

JP-A-2005-73163

  By the way, in the digital receiver, when the desired wave signal determination processing unit determines that the new signal is not the desired wave signal, learning is performed to sequentially update the filter coefficient of the corresponding filter by calculating the filter coefficient in order to remove the noise signal. Filter coefficients that are processed to remove noise signals are formed.

  The corresponding filter outputs an extracted signal obtained by removing the noise signal from the new signal with the filter coefficient set in the learning process to the desired wave signal determination processing unit, and the desired signal is determined by the desired wave signal determination processing unit. The signal was determined to be a wave signal.

  Therefore, in this case, after the new signal is determined not to be the desired signal by the desired signal determination unit, a learning process for setting a filter coefficient for removing the noise signal is performed for the filter coefficient of the corresponding filter. Therefore, it takes time for the desired wave signal determination processing unit to obtain a result.

  As a result, an undefined signal that does not know whether it is a desired signal or a new noise signal is extracted from the digital filter during that period, and the output data becomes undefined. That is, as a result of the determination, if the new signal is a desired wave signal, there is a problem that the output data of the desired wave signal is delayed by the time required for the determination and the communication throughput is lowered.

  On the other hand, when the new signal is not a desired signal but a new noise signal, the calculation and update of the filter coefficient for removing the noise signal is delayed by the time required for the determination, and the communication speed decreases. The operation time from the start of determination to the completion of noise signal removal becomes longer. As a result, the digital receiving apparatus has increased power consumption in the standby state.

  The present invention has been made to solve the above problem, and an object of the present invention is to provide a filter for a digital receiver capable of reducing power consumption required for determining whether a new signal is a desired wave signal. A coefficient setting method and a digital receiver are provided.

  According to the first aspect of the present invention, when the signal determination unit determines that the received signal is not the desired wave signal, a noise signal in the received signal is removed while sequentially updating a filter coefficient, and the received signal is determined as the signal determination. A filter unit for stopping the update of the filter coefficient, retaining the filter coefficient, removing a noise signal in the received signal, and extracting the desired wave signal when it is determined that the unit is a desired wave signal A filter coefficient setting method for a digital receiving apparatus, wherein a first filter unit and a second filter unit for removing a noise signal from the received signal and extracting the desired wave signal are provided, and a new received signal is received The first filter unit obtains a filter coefficient when a noise signal of a signal in a specific frequency band in the received signal is removed while sequentially updating the filter coefficient of the first filter unit. The second filter unit causes the second filter unit to output the received new received signal to the signal determination unit while holding the filter coefficient set in the previous learning process, When a new received signal output from the unit is determined as a desired wave signal by the signal determination unit, the filter coefficient of the second filter unit is held and the learning process of the filter coefficient of the first filter unit is stopped If the new received signal output from the second filter unit is determined not to be a desired wave signal by the signal determining unit, the filter coefficient learning process of the first filter unit is continued.

  According to the first aspect of the present invention, when a new received signal is received, the first filter unit sequentially updates the filter coefficient of the first filter unit while receiving a signal of a specific frequency band in the received signal. A learning process for obtaining a filter coefficient when the noise signal is removed is performed. In addition, when a new received signal is received, the second filter unit receives the filter coefficient set in the previous learning process of the first filter unit in the filter coefficient of the second filter unit. A new received signal is output to the signal determination unit.

  Then, when the new received signal output from the second filter unit is determined as the desired wave signal by the signal determination unit, the filter coefficient of the second filter unit is held, and the filter coefficient learning process of the first filter unit is held Stop. On the other hand, when the new received signal output from the second filter unit is determined not to be the desired wave signal by the signal determination unit, the filter coefficient learning process of the first filter unit is continued. As a result, the operation time in the standby state can be shortened, and the current consumption of the digital receiver can be reduced by the shortened operation time.

  According to the second aspect of the present invention, when the received signal is determined not to be a desired wave signal by the signal determining unit, a noise signal in the received signal is removed while sequentially updating a filter coefficient, and the received signal is Noise that stops the update of the filter coefficient, retains the filter coefficient, removes the noise signal in the received signal, and extracts the desired wave signal when the signal determination unit determines that the signal is a desired wave signal A digital reception device including a removal unit, wherein the noise removal unit removes a noise signal in the reception signal and extracts the desired wave signal, and a novel reception When a signal is received, a filter coefficient when a noise signal of a signal in a specific frequency band in the received signal is removed while sequentially updating the filter coefficient of the first filter unit based on the new received signal A filter that performs the required learning process and outputs the received new received signal to the signal determination unit via the second filter unit while retaining the first filter coefficient set in the previous learning process When a new received signal output from the control unit and the second filter unit is determined as a desired wave signal by the signal determination unit, the filter coefficient of the second filter unit is held, and the first filter unit When the filter coefficient learning process is stopped and the new received signal output from the second filter unit is determined not to be a desired wave signal by the signal determination unit, the filter coefficient learning process of the first filter unit The 2nd filter control part which continues this.

  According to a second aspect of the present invention, when the first filter control unit receives a new reception signal, the first filter control unit sequentially updates the filter coefficients of the first filter unit based on the new reception signal. A learning process for obtaining a filter coefficient when a noise signal of a signal in a specific frequency band is removed is performed. In addition, when the first filter control unit receives a new received signal, the first filter control unit sets the received new received signal to the second filter unit using the filter coefficient set in the previous learning process of the first filter unit. In the held state, the signal determination unit outputs the signal through the second filter unit.

  The second filter control unit holds the filter coefficient of the second filter unit when the new received signal output from the second filter unit is determined as the desired wave signal by the signal determination unit, and The filter coefficient learning process is stopped. Further, the second filter control unit continues the filter coefficient learning process of the first filter unit when the signal determination unit determines that the new received signal output from the second filter unit is not the desired wave signal. . As a result, the operation time in the standby state can be shortened, and the current consumption of the digital receiver can be reduced by the shortened operation time.

  According to the present invention, it is possible to reduce power consumption required for determining whether a new signal is a desired wave signal.

The system block diagram for demonstrating the digital receiver of this embodiment. The time chart for demonstrating the effect | action of the digital receiver of this embodiment. The time chart for demonstrating the effect | action of the conventional digital receiver.

  Hereinafter, an embodiment in which the present invention is embodied in a digital receiver that demodulates a modulation signal (desired wave signal) from an electronic key (portable transmitter) that a vehicle user possesses as a vehicle key will be described with reference to the drawings.

  The electronic key possessed by the vehicle user is generally referred to as a portable transmitter because of its possession. Then, the desired wave signal modulated by FSK (Frequency Shift Keying) from the electronic key is demodulated by the digital receiver on the vehicle side, whereby the content of the original signal before modulation is specified, and based on the specified content Various vehicle equipment controls are implemented.

  For example, as a result of analyzing the content specified by the digital receiver in the vehicle control system, when it is determined that the electronic key that is the transmission source of the desired wave signal is a legitimate electronic key suitable for the vehicle, the electronic key The door lock is released to allow the vehicle to be ridden by the authorized owner of the key, or the engine can be started by the authorized owner.

FIG. 1 is a system block diagram of a digital receiver 1 provided in a vehicle.
As shown in FIG. 1, the digital reception device 1 includes a reception antenna 10 that receives a desired wave signal Sk transmitted from an electronic key 2, and a preprocessing unit 20 that preprocesses a reception signal received by the reception antenna 10. And a noise removing unit 30 for inputting a signal pre-processed by the pre-processing unit 20 to remove noise, and a signal for receiving the noise removed by the noise removing unit 30 and demodulating the received signal to analyze the contents. Part 40 is provided.

The digital receiver 1 is turned on and off intermittently, that is, at regular intervals, and enters the receiving operation mode when the power is turned on, and enters the sleep mode when the power is turned off.
In the reception operation mode when the power is turned on, there are a standby state in which reception of the desired wave signal Sk subjected to FSK modulation from the electronic key 2 is waited and a reception state in which the desired wave signal Sk is received. Therefore, the digital receiver 1 receives only the ambient noise signal Sn in the standby state and receives only the ambient noise signal Sn, and in the reception state, the ambient noise signal Sn (ie, the ambient noise signal Sn). , The desired wave signal Sk, or the desired wave signal Sk and the noise signal Sn) are input.
(Receiving antenna 10)
The receiving antenna 10 is a medium for receiving the desired wave signal Sk from the electronic key 2. In the standby state, the reception antenna 10 receives ambient noise, which is a signal other than the desired wave signal Sk, that is, a noise signal Sn as a reception signal. In the reception state, the reception antenna 10 is combined with the desired wave signal Sk. Sn is input as a received signal.
(Pre-processing unit 20)
The preprocessing unit 20 receives a received signal received by the receiving antenna 10 as an input signal. The preprocessing unit 20 converts the frequency of the input signal to generate a signal having a difference between the frequency of the input signal and the frequency of the local oscillator, that is, a so-called intermediate frequency signal. Then, the preprocessing unit 20 performs analog / digital conversion on the intermediate frequency signal to generate a baseband signal, and outputs a band-limited signal to the noise removal unit 30.
(Noise removal unit 30)
The noise removing unit 30 constitutes a filter for removing a signal in a specific frequency band from the signal input from the preprocessing unit 20 as a noise signal Sn, and includes a first filter unit 31a, a second filter unit 31b, The first signal processing unit 32 a, the second signal processing unit 32 b, and the filter control unit 33 are included.

  The first filter unit 31a is a digital filter and has an electrically updatable filter coefficient calculated by the filter control unit 33, and a signal in a specific frequency band is a noise signal based on the updatable filter coefficient. An adaptive filter to be removed as Sn is configured.

  The first signal processing unit 32a calculates the difference between the signal after noise removal by the first filter unit 31a and the signal before noise removal. Then, the first signal processing unit 32a enables the first filter unit 31a to newly remove the calculated difference (that is, the signal component that has passed through the first filter unit 31a without being removed by the filter coefficient at that time). Therefore, a signal Sx) indicating the signal component is output to the filter control unit 33.

  Further, the first signal processing unit 32a generates a new signal detection signal Sd indicating that a new desired wave signal Sk may be input to the receiving antenna 10 when the calculated difference is equal to or greater than a predetermined value. Output to the filter control unit 33. Conversely, the first signal processing unit 32a does not output the new signal detection signal Sd to the filter control unit 33 when the calculated difference is less than a predetermined value.

The filter control unit 33 includes a nonvolatile memory 33a that stores the filter coefficient of the first filter unit 31a.
The filter control unit 33 is a case where the new signal detection signal Sd is not output from the first signal processing unit 32a (when the calculated difference is less than a predetermined value), and the first signal processing unit 32a to the first filter unit. When a signal Sx indicating a passing signal component that has passed through 31a is output, a new filter coefficient that enables the signal component to be removed is calculated.

  Then, the filter control unit 33 deletes the filter coefficient of the first filter unit 31a previously stored in the memory 33a, and stores and updates the newly calculated latest filter coefficient in the memory 33a. At this time, the filter control unit 33 reflects (sets) the updated latest filter coefficient in the first filter unit 31a, so that a signal (noise signal Sn) in a specific frequency band based on the updated filter coefficient. The filter forming operation for removing the first filter unit 31a is performed.

  Incidentally, the filter control unit 33 calculates the latest filter coefficient, updates the filter coefficient of the first filter unit 31a to the latest filter coefficient, and converts the signal (noise signal Sn) in the specific frequency band to the first filter. Processing that is removed by the unit 31a is referred to as learning processing.

  Here, a mode in which a signal in a specific frequency band is removed as the noise signal Sn while sequentially updating the filter coefficient is defined as an adaptive mode. In contrast, a mode in which updating of the filter coefficient is stopped, the filter coefficient at that time is retained, and a signal in a specific frequency band is removed as the noise signal Sn based on the retained filter coefficient is defined as a non-adaptive mode.

  In this adaptive mode, the learning process, that is, the filter coefficient is sequentially updated, so that the difference between the signal after noise removal and the signal before noise removal converges, and eventually passes through the first filter unit 31a. The signal Sx indicating the signal component to be output is not output from the first signal processing unit 32a.

  At this time, when the signal Sx indicating the signal component that has passed through the first filter unit 31a is no longer output from the first signal processing unit 32a, the filter coefficient calculation and update learning process ends, and the noise signal Sn is A filter coefficient of the first filter part 31a to be removed is formed.

  That is, when the learning process is completed, a filter coefficient for removing the noise signal Sn is set in the first filter unit 31a. When the learning process is completed, the filter control unit 33 enters the non-adaptive mode, and the filter coefficient of the first filter unit 31a is set and held in the filter coefficient of the second filter unit 31b and is stored in the memory 33a. It has become.

  The second filter unit 31b is a digital filter, and the filter coefficient obtained by the learning process by the filter control unit 33 is set and held in the filter control unit 33. The second filter unit 31b uses the filter coefficient set and held by the filter control unit 33 to remove the noise signal Sn from the signal input from the preprocessing unit 20 and outputs the noise signal Sn to the second signal processing unit 32b. It has become.

The second signal processing unit 32 b performs signal processing so that the signal after noise removal by the second filter unit 31 b can be demodulated by the demodulation unit 41 of the reception unit 40 as an extraction signal, and outputs the signal to the reception unit 40.
Further, the filter control unit 33 is a case where the new signal detection signal Sd is output from the first signal processing unit 32a (the calculated difference is equal to or greater than a predetermined value), and the first signal processing unit 32a outputs the first filter. When a signal Sx indicating a signal component that has passed through the unit 31a is output, a new filter coefficient of the first filter unit 31a that can remove the signal component is calculated.

  That is, the filter control unit 33 starts the filter coefficient learning process of the first filter unit 31a when receiving a new signal in which the new desired wave signal Sk may be input to the receiving antenna 10. At this time, the filter control unit 33 reflects the filter coefficient last stored and updated in the memory 33a on the second filter unit 31b. Therefore, the second filter unit 31b removes the noise signal Sn from the new reception signal with this filter coefficient.

In other words, the extraction signal output to the receiving unit 40 via the second filter unit 31b in which the filter coefficient of the first filter unit 31a obtained in the previous learning process is set is estimated as the desired wave signal Sk. Immediately, the determination control unit 42 of the reception unit 40 causes the determination process to be executed.
(Receiver 40)
The receiving unit 40 performs a receiving operation based on the extracted signal after noise removal by the noise removing unit 30. The receiver 40 includes a demodulator 41 that demodulates the extracted signal after noise removal, and a determination controller 42 that determines whether the extracted signal after noise removal is the desired wave signal Sk from the electronic key 2. ing.

  The demodulator 41 receives and demodulates the extracted signal after noise removal by the noise remover 30, generates a received signal, and outputs the received signal to the vehicle control system. The vehicle control system analyzes the received signal from the demodulator 41, that is, the content of the original signal before modulation by pattern matching, so that the electronic key 2 that is the transmission source of the modulated signal is a regular electronic key that matches the vehicle. 2 is determined.

  When the vehicle control system determines that the electronic key 2 is suitable for the vehicle, the vehicle control system releases the door lock to allow the vehicle to be ridden by the authorized owner of the electronic key 2, or this person Allow the engine to start.

  The determination control unit 42 receives the extracted signal after noise removal by the noise removing unit 30 and determines whether the extracted signal is the desired wave signal Sk from the regular electronic key 2 by pattern matching.

  More specifically, when the determination control unit 42 determines that the extracted signal is the desired wave signal Sk, the filter control unit 33 transmits the desired wave determination signal Sjk indicating that the desired wave signal Sk is input to the receiving antenna 10. Output.

  Conversely, if the determination control unit 42 determines that the extracted signal is not the desired wave signal Sk, that is, determines that the received signal is the noise signal Sn, the determination control unit 42 outputs the noise determination signal Sjn to the filter control unit 33.

  Then, when the desired wave determination signal Sjk is output from the determination control unit 42, the filter control unit 33 receives the filter coefficient of the second filter unit 31b until the new signal detection signal Sd is not input from the first signal processing unit 32a. Hold.

  That is, by holding the filter coefficient of the second filter unit 31b, the new signal previously estimated as the desired wave signal Sk is the desired wave signal Sk as estimated, so that the desired wave signal Sk is not removed. Then, the update of the filter coefficient is stopped and held.

  At this time, the filter control unit 33 ends the learning process for the first filter unit 31a, and sets the filter coefficient of the first filter unit 31a to the filter coefficient before the learning process.

  On the contrary, when the noise determination signal Sjn is output from the determination control unit 42, the filter control unit 33 determines that the new signal previously estimated as the desired wave signal Sk is a noise signal Sn different from the estimation. The calculation and update of the filter coefficient of the first filter unit 31a for removal, that is, the learning process is continued as it is. At this time, the filter control unit 33 sets and holds the filter coefficient of the second filter unit 31b as a filter coefficient for cutting a signal passing through the second filter unit 31b.

  The filter control unit 33 performs the same process as described above, and obtains the filter coefficient of the first filter unit 31a for removing the noise signal Sn. The filter control unit 33 sets and holds the obtained filter coefficient of the first filter unit 31a in the filter coefficient of the second filter unit 31b and stores it in the memory 33a.

  Then, the second filter unit 31b removes the noise signal Sn from the signal input from the preprocessing unit 20 using the filter coefficient set and held by the filter control unit 33, and outputs it to the second signal processing unit 32b. To do.

Next, the operation of the digital receiver 1 will be described.
The filter coefficients stored in the memory 33a of the filter control unit 33 are now in a reset state (the state in which all the signals pass and the transfer function corresponds to “1”). The filter coefficient at this time is stored. Therefore, at this time, the filter coefficients of the first filter unit 31a and the second filter unit 31b are both in a reset state.

  In this standby state, when a new signal (a new signal including the desired wave signal Sk and / or the noise signal Sn) is received, the filter control unit 33 receives the new signal detection signal Sd from the first signal processing unit 32a. The signal Sx indicating the signal component that has passed through the first filter unit 31a is input.

  In response to this, the filter control unit 33 calculates and updates the filter coefficient of the first filter unit 31a, that is, performs a learning process from the filter coefficient in the reset state so as to remove the noise signal Sn from the new signal. Start.

  On the other hand, the filter control unit 33 keeps the filter coefficient of the second filter unit 31b in the reset state, and includes the extracted signal (desired wave signal Sk and / or noise signal Sn) extracted from the second filter unit 31b. (New signal) is estimated (deemed) as the desired wave signal Sk and output to the determination control unit 42 of the reception unit 40.

  That is, at this time, the determination control unit 42 of the reception unit 40 includes the extracted signal (desired wave signal Sk and / or noise signal Sn) extracted from the second signal processing unit 32b via the second filter unit 31b. New signal) is input immediately. At this time, the determination control unit 42 analyzes whether or not the new signal is a desired wave signal.

If the determination control unit 42 determines that the extracted signal is the desired wave signal Sk, the determination control unit 42 outputs the desired wave determination signal Sjk to the filter control unit 33.
In response to the desired wave determination signal Sjk, the filter control unit 33 holds the filter coefficient of the second filter unit 31b until no new signal detection signal Sd is input from the first signal processing unit 32a (at this time, the reset signal is reset). Hold in the state).

  That is, by holding the filter coefficient of the second filter unit 31b, the desired signal Sk is removed because the new signal previously estimated (and considered) as the desired signal Sk is the desired signal Sk as estimated. The filter coefficient is retained so that there is no possibility.

  At this time, the filter control unit 33 ends the learning process for the first filter unit 31a, returns the filter coefficient of the first filter unit 31a to the filter coefficient before the learning process (in this case, the reset state), and holds it. Store in the memory 33a.

Therefore, at this time, the received new signal means that the desired wave signal Sk including no noise signal is input.
On the other hand, if the determination control unit 42 determines that the extracted signal is not the desired wave signal Sk, the determination control unit 42 outputs a noise determination signal Sjn to the filter control unit 33.

  In response to the noise determination signal Sjn, the filter control unit 33 is a noise signal Sn previously estimated (considered) as the desired wave signal Sk, which is different from the estimation, so the noise signal Sn is obtained from the new signal. In order to eliminate, the calculation and update of the filter coefficient of the first filter unit 31a performed from the beginning, that is, the learning process for the first filter unit 31a is continued as it is.

  Then, when the signal Sx indicating the signal component that has passed through the first filter unit 31a disappears and the filter coefficient of the first filter unit 31a for removing the noise signal Sn from the new signal is obtained, the filter control unit 33 obtains the filter coefficient. The filter coefficient of the first filter unit 31a is set and held in the filter coefficient of the second filter unit 31b and stored in the memory 33a.

  The second filter unit 31b removes the noise signal Sn from the signal input from the preprocessing unit 20 using the filter coefficient set and held by the filter control unit 33, and outputs the signal to the second signal processing unit 32b.

  As a result, the determination control unit 42 of the reception unit 40 extracts the extracted signal (desired wave signal Sk) obtained by removing the noise signal Sn from the new signal extracted from the second signal processing unit 32b via the second filter unit 31b. Is entered. The determination control unit 42 determines that the extracted signal is the desired wave signal Sk, and outputs the desired wave determination signal Sjnk to the filter control unit 33.

  In response to the desired wave determination signal Sjk, the filter control unit 33 holds the filter coefficient of the second filter unit 31b until no new signal detection signal Sd is input from the first signal processing unit 32a (at this time, learning is performed). Retained in the filter coefficient obtained by processing). That is, by holding the filter coefficient of the second filter unit 31b, the filter coefficient is held so that the desired wave signal Sk obtained by removing the noise signal from the new signal is not removed.

At this time, the filter control unit 33 returns the filter coefficient of the first filter unit 31a to the filter coefficient (reset state) before the learning process, and stores it in the memory 33a.
Therefore, at this time, the received new signal means that the desired wave signal Sk obtained by removing the noise signal from the new signal is input to the receiving unit 40.

Next, a case where a new new signal is received from this state will be described.
In response to this, the filter control unit 33 calculates and updates the filter coefficient of the first filter unit 31a, that is, performs a learning process from the filter coefficient in the reset state so as to remove the noise signal Sn from the new signal. Start.

  The filter control unit 33 also keeps the filter coefficient of the second filter unit 31b set and held previously, and extracts the extracted signal (desired wave signal Sk and / or noise) from the second filter unit 31b. A new signal consisting of the signal Sn) is estimated (considered) as the desired wave signal Sk and output to the determination control unit 42 of the receiving unit 40.

  That is, at this time, the determination control unit 42 of the reception unit 40 includes the extracted signal (desired wave signal Sk and / or noise signal Sn) extracted from the second signal processing unit 32b via the second filter unit 31b. New signal) is input. At this time, the determination control unit 42 analyzes whether or not the new signal is a desired wave signal.

When the determination control unit 42 determines that the extracted signal is the desired wave signal Sk, the determination control unit 42 outputs the desired wave determination signal Sjk to the filter control unit 33.
This is a case where the noise signal Sn included in the new signal is the same signal as the noise signal Sn removed in the previous learning process. Therefore, since the noise signal Sn is removed by the filter coefficient of the second filter unit 31b and the desired wave signal Sk is output to the receiving unit 40, the determination control unit 42 determines that the extracted signal is the desired wave signal. It determines that it is Sk, and outputs a desired wave determination signal Sjk.

  In response to the desired wave determination signal Sjk, the filter control unit 33 holds the filter coefficient of the second filter unit 31b until no new signal detection signal Sd is input from the first signal processing unit 32a (at this time, (Retained in the filter coefficient set earlier).

  That is, by holding the filter coefficient of the second filter unit 31b, the desired signal Sk is removed because the new signal previously estimated (and considered) as the desired signal Sk is the desired signal Sk as estimated. The filter coefficient is retained so that it does not occur.

At this time, the filter control unit 33 returns the filter coefficient of the first filter unit 31a to the filter coefficient (reset state) before the learning process, and stores it in the memory 33a.
Therefore, at this time, the received signal received means that the desired wave signal Sk not including the noise signal Sn is input.

  On the other hand, if the determination control unit 42 determines that the extracted signal is not the desired wave signal Sk, the determination control unit 42 outputs a noise determination signal Sjn to the filter control unit 33. This is a case where the noise signal Sn included in the new signal is a signal different from the noise signal Sn removed in the previous learning process. Therefore, the noise signal Sn is not removed by the filter coefficient of the second filter unit 31 b and is output to the receiving unit 40. As a result, the determination control unit 42 determines that the extracted signal is not the desired wave signal Sk, and outputs a noise determination signal Sjn.

  In response to the noise determination signal Sjn, the filter control unit 33 sets the filter coefficient for causing the second filter unit 31b to cut the signal passing through the second filter unit 31b. Thereby, the second filter unit 31b does not output a new signal (in this case, the noise signal Sn) to the receiving unit 40 (determination control unit 42).

  Further, in response to the noise determination signal Sjn, the filter control unit 33 is a noise signal Sn previously estimated (considered) as the desired wave signal Sk, which is different from the estimation. The calculation and update of the filter coefficient that has been performed from the beginning, that is, the learning process for the filter coefficient of the first filter unit 31a is continued as it is so as to remove Sn.

  Then, the filter control unit 33 performs a learning process until the signal Sx indicating the signal component that has passed through the first filter unit 31a disappears, and uses the filter coefficient of the first filter unit 31a that removes the noise signal Sn from the new signal. Ask. When the filter coefficient of the first filter unit 31a for removing the noise signal Sn is obtained, the filter control unit 33 sets and holds the filter coefficient of the first filter unit 31a in the filter coefficient of the second filter unit 31b. Store in the memory 33a.

  The second filter unit 31b removes the noise signal Sn from the signal input from the preprocessing unit 20 using the filter coefficient set and held by the filter control unit 33, and outputs the signal to the second signal processing unit 32b.

  As a result, the extracted signal (desired wave signal Sk) extracted from the second signal processing unit 32b through the second filter unit 31b is input to the determination control unit 42 of the receiving unit 40. The determination control unit 42 determines that the extracted signal is the desired wave signal Sk, and outputs the desired wave determination signal Sjk to the filter control unit 33.

  In response to the desired wave determination signal Sjk, the filter control unit 33 holds the filter coefficient of the second filter unit 31b until the new signal detection signal Sd is not input from the first signal processing unit 32a (obtained by learning processing). The filter coefficient). That is, by holding the filter coefficient of the second filter unit 31b, the filter coefficient is held so that the desired wave signal Sk obtained by removing the noise signal Sn from the new signal is not removed.

  At this time, the filter control unit 33 returns the filter coefficient of the first filter unit 31a to the filter coefficient (reset state) before the learning process, and stores it in the memory 33a. Therefore, at this time, the received new signal means that the desired wave signal Sk from which the noise signal has been removed from the new signal is input.

FIG. 2 shows a time chart of the above action.
In FIG. 2, when the noise signal Sn is received as a new signal at time t1 in the standby state, the new signal is input to the first filter unit 31a and the second filter unit 31b via the preprocessing unit 20. The Then, the first signal processing unit 32a outputs a new signal detection signal Sd, assuming that a new signal has been received. The signal input to the second filter unit 31b is output to the receiving unit 40 (determination control unit 42) via the second signal processing unit 32b.

  At time t2, in response to the new signal detection signal Sd, the filter control unit 33 immediately starts a learning process for the filter coefficient of the first filter unit 31a. At time t2, the determination control unit 42 starts a determination process as to whether or not the extracted signal input from the second filter unit 31b via the second signal processing unit 32b is the desired wave signal Sk.

  Then, at time t3, when the determination process by the determination control unit 42 is completed and the noise determination signal Sjn that the new signal is not the desired wave signal Sk is output from the determination control unit 42, the filter control unit 33 performs the second filter. The filter coefficient for cutting the extracted signal passing through the second filter unit 31b is set to the unit 31b.

Accordingly, thereafter, the second filter unit 31b does not output a new signal (in this case, a noise signal Sn), that is, an extraction signal, to the receiving unit 40 (determination control unit 42).
On the other hand, even if the noise determination signal Sjn is output, the filter control unit 33 continues the learning process for the filter coefficient of the first filter unit 31a as it is.

  At time t4, when the learning process is completed and the filter coefficient of the first filter unit 31a that removes the noise signal Sn is obtained, the filter coefficient of the first filter unit 31a is changed to the filter coefficient of the second filter unit 31b. Are stored in the memory 33a as filter coefficients of the second filter unit 31b.

  At this time, the filter control unit 33 holds the filter coefficient of the first filter unit 31a back to the filter coefficient (reset state) before the learning process, and stores the filter coefficient of the first filter unit 31a (reset state) in the memory 33a. ) Is memorized.

  As described above, the learning process of the filter control unit 33 is started simultaneously with the determination process of the determination control unit 42. Therefore, the operation time T1 in the standby state is a time required for the learning process from time t2 to time t4.

  On the other hand, in the conventional case, as shown in FIG. 3, when the determination control unit 42 ends the determination process and the determination control unit 42 outputs a noise determination signal Sjn that the new signal is not the desired wave signal Sk. From this, the learning process of the filter control unit 33 is started. As a result, conventionally, the start of the learning process of the filter control unit is delayed by the determination processing time of the determination control unit 42.

Therefore, the operation time T2 in the standby state is a time obtained by combining the time Ta required for the determination process and the time Tb required for the learning process.
Therefore, in the present embodiment, the operation time T1 in the standby state is shorter than the operation time T2 in the conventional standby state, and the current consumption of the digital reception device 1 can be reduced by an amount corresponding to the reduction.

  Next, in FIG. 2, when the desired wave signal Sk is received as a new signal at time t5, the new signal is input to the first filter unit 31a and the second filter unit 31b via the preprocessing unit 20. The And the signal input into the 1st filter part 31a by which the filter coefficient was set to reset is output to the 1st signal process part 32a. Further, the signal input to the second filter unit 31b set to the filter coefficient that removes the noise signal Sn and passes the desired wave signal Sk is output to the receiving unit 40 via the second signal processing unit 32b. .

  At time t6, in response to the new signal detection signal Sd, the filter control unit 33 immediately starts a learning process for the filter coefficient of the first filter unit 31a. At time t6, the determination control unit 42 determines whether the extracted signal (in this case, the desired wave signal Sk) input from the second filter unit 31b via the second signal processing unit 32b is the desired wave signal Sk. Start processing.

  Then, at time t7, when the determination process by the determination control unit 42 is completed, and the desired wave determination signal Sjk that the new signal is the desired wave signal Sk is output from the determination control unit 42, the filter control unit 33 The second filter unit 31b holds the filter coefficient of the second filter unit 31b, outputs a new signal (desired wave signal Sk), and continues to output it to the receiving unit 40.

  Incidentally, as shown in FIG. 3, conventionally, when the desired wave signal Sk is received as a new signal at time t <b> 5, until the determination control unit finishes the determination process, the second filter unit 31 b to the receiving unit 40. The signal (desired wave signal Sk) input to is treated as an indefinite signal. Therefore, after the determination control unit finishes the determination process and determines the desired wave signal Sk, the data is output from the digital receiver 1 as a data output.

  Therefore, in this embodiment, when the desired wave signal Sk not including the noise signal Sn is received as a new signal at time t5, the determination control unit 42 immediately determines the output data based on the desired wave signal Sk. Can be output without delay by the time required for the communication, and communication throughput is not reduced.

As described above, according to the present embodiment, the following operational effects can be achieved.
(1) According to the present embodiment, when a new new signal is received as a received signal, the filter control unit 33 uses the first filter unit 31a to remove the noise signal Sn from the received signal. The learning process for obtaining the filter coefficient of the first filter unit 31a is started immediately without waiting for the determination result of the determination control unit 42.

Therefore, the operation time T1 in the standby state can be shortened, and the current consumption of the digital receiver 1 can be reduced by the shortened time.
(2) According to the present embodiment, when a new new signal is received as a received signal, the filter control unit 33 estimates (deems) the new signal as the desired wave signal Sk, and the filter coefficient is The signal is output to the receiving unit 40 via the second filter unit 31b that is set and held.

  In the previous learning process, when the filter coefficient of the second filter unit 31b is set and held at the filter coefficient for removing the noise signal Sn and extracting the desired wave signal Sk, the determination process of the determination control unit 42 is performed. Without waiting, the new signal (desired wave signal Sk) is output to the receiving unit 40 as the desired wave signal Sk. Then, the output data based on the desired wave signal Sk is immediately output from the digital receiver 1.

Therefore, the output of the output data based on the desired wave signal Sk is not delayed by the time required for the determination process of the determination control unit 42, and the communication throughput is not reduced.
(3) Also, according to the present embodiment, when the noise determination signal Sjn that the new signal is not the desired wave signal Sk is output from the determination control unit 42 at time t4, the filter control unit 33 For 31b, the filter coefficient for cutting the extracted signal passing through the second filter unit 31b is set.

  Therefore, after that, the second filter unit 31b does not output the noise signal Sn to the receiving unit 40 (determination control unit 42), and indefinite output data based on the noise signal Sn is output from the digital receiving device 1. There is no.

In addition, you may change the said embodiment as follows.
In the above embodiment, when the determination control unit 42 outputs the noise determination signal Sjn that the new signal is not the desired wave signal Sk, the filter control unit 33 changes the second filter unit 31b to the second filter unit 31b. The filter coefficient for cutting the extracted signal passing through was set. This may be implemented by reflecting the filter coefficient of the first filter unit 31a, which is continuously updated as the learning process continues, in the filter coefficient of the second filter unit 31b.

  In the above embodiment, the present invention is embodied in an FSK modulation type digital receiver. This may be applied to a digital receiver of any modulation system such as an ASK (amplitude modulation) system or a PSK (phase modulation) system.

  DESCRIPTION OF SYMBOLS 1 ... Digital receiver, 2 ... Electronic key, 10 ... Receiving antenna, 20 ... Pre-processing part, 30 ... Noise removal part, 31a ... 1st filter part, 31b ... 2nd filter part, 32a ... 1st signal processing part, 32b ... second signal processing unit, 33 ... filter control unit (first filter control unit, second filter control unit), 33a ... memory, 40 ... receiving unit, 41 ... demodulation unit, 42 ... determination control unit (signal determination unit) ), Sd ... new signal detection signal, Sk ... desired wave signal, Sn ... noise signal, Sx ... signal, Sjk ... desired wave determination signal, Sjn ... noise determination signal, T1, T2 ... operation time.

Claims (2)

When the signal determination unit determines that the received signal is not the desired wave signal, the filter signal is sequentially updated to remove the noise signal in the received signal, and the signal determination unit determines that the signal determination unit is the desired wave signal A filter coefficient setting method for a digital reception device including a filter unit that stops updating the filter coefficient, retains the filter coefficient, removes a noise signal in the received signal, and extracts the desired wave signal. There,
A first filter unit and a second filter unit for removing the noise signal in the received signal and extracting the desired wave signal;
When a new received signal is received, the first filter unit sequentially updates the filter coefficient of the first filter unit, and the noise signal of the signal in the specific frequency band in the received signal is removed. A learning process for obtaining a coefficient is performed, and the second filter unit is caused to output the received new received signal to the signal determination unit while holding the filter coefficient set in the previous learning process,
When the new received signal output from the second filter unit is determined as the desired wave signal by the signal determination unit, the filter coefficient of the second filter unit is held, and the filter coefficient of the first filter unit The learning process is stopped, and when the new received signal output from the second filter unit is determined not to be a desired wave signal by the signal determination unit, the filter coefficient learning process of the first filter unit is continued. A filter coefficient setting method for a digital receiver. When the received signal is determined not to be the desired wave signal by the signal determining unit, the noise signal in the received signal is removed while sequentially updating the filter coefficient, and the received signal is converted to the desired wave signal by the signal determining unit. A digital receiver including a noise removing unit that stops updating the filter coefficient, holds the filter coefficient, removes a noise signal in the received signal, and extracts the desired wave signal when it is determined that there is There,
The noise removing unit
A first filter section and a second filter section for removing the noise signal in the received signal and extracting the desired wave signal;
Filter when a noise signal of a signal in a specific frequency band in the received signal is removed while sequentially updating the filter coefficient of the first filter unit based on the new received signal when a new received signal is received First, a learning process for obtaining a coefficient is performed, and the received new received signal is output to the signal determination unit via the second filter unit while holding the filter coefficient set in the previous learning process. One filter control unit;
When a new received signal output from the second filter unit is determined as a desired wave signal by the signal determination unit, the filter coefficient of the second filter unit is held and learning of the filter coefficient of the first filter unit is performed. The process is stopped, and when the new received signal output from the second filter unit is determined not to be a desired wave signal by the signal determination unit, the filter coefficient learning process of the first filter unit is continued. A two-filter control unit;
A digital receiver characterized by comprising:

Images