JP2011244202A - Filter coefficient setting method of digital receiver and digital receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter coefficient setting method of a digital receiver as well as a digital receiver, capable of reducing power consumption and improving communication throughput by shortening a learning process of the filter coefficient for eliminating noise if an intrinsic noise signal occurs always at each place.SOLUTION: A filter coefficient of a filter part 31 corresponding to an intrinsic noise signal Sn that occurs at respective places is stored, along with position information Pi, in a second memory 34a of an area selection control part 34. Every time a stop mode is shifted to a reception operation mode, a filter coefficient for a place of a digital receiver 1 is read out of the second memory 34a, and is set to be a filter coefficient of the filter part 31. With this configuration, when an intrinsic noise signal Sn is received at a place, the noise signal Sn is eliminated with no learning process, for omission of learning process.

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.

  This digital receiving apparatus includes an adaptive filter. The adaptive filter is a digital filter, and in the standby state, a filter coefficient is formed to remove the noise signal by calculating and sequentially updating the filter coefficient to remove the noise signal from the input noise signal. The

  When the desired wave signal is input to the digital reception device and the digital filter is determined to be the desired wave signal by the desired wave signal determination processing unit and the reception state is reached, the update of the filter coefficient applied to the digital filter is stopped. At this time, the digital filter removes the noise signal input together with the desired wave signal using the filter coefficient immediately before the update is stopped. Therefore, the digital receiver receives only the desired wave signal from which the noise signal has been removed by the digital filter.

  In this type of digital receiving apparatus, the desired wave signal determination processing unit performs determination processing each time a new signal is received. At this time, if it is determined from the determination result that the new signal is not the desired wave signal, the filter coefficient of the corresponding filter is set to a reset state (an initial state in which all signals are allowed to pass). Then, in order to remove the noise signal, the filter coefficient is calculated from the initial state and a learning process for sequentially updating is started to form a filter coefficient for removing the noise signal.

JP-A-2005-73163

  By the way, there is a case where a noise signal having a specific frequency is always output for each place. In this case, the digital receiving apparatus always receives the desired signal including the inherent noise signal as a new signal for each location. Then, the digital reception device temporarily resets the filter coefficient of the digital filter each time, performs learning processing from the reset state, and extracts a desired signal by removing a noise signal with the filter coefficient obtained by the learning processing.

  Therefore, in a place where a specific noise signal is always output at the same place, learning processing for noise removal is always performed, and further, it takes time from a state where the filter coefficient is reset. As a result, since the learning process takes time, power consumption increases and there is a problem in communication throughput.

  The present invention has been made in order to solve the above-described problem. The purpose of the present invention is to shorten the learning process of the filter coefficient for noise removal and reduce the power consumption when a unique noise signal is always output at each location. It is an object of the present invention to provide a filter coefficient setting method for a digital receiver and a digital receiver capable of reducing the above and improving the communication throughput.

  When the signal determination unit determines that the received signal is not the desired wave signal, the invention according to claim 1 removes a signal in a specific frequency band in the received signal as a noise signal while sequentially updating a filter coefficient, When the signal determination unit determines that the received signal is the desired wave signal, the filter coefficient updating is stopped, the filter coefficient is retained, the noise signal in the received signal is removed, and the desired wave signal is extracted. A filter coefficient setting method for a digital receiving apparatus including a filter unit that removes position information of each location in a storage unit in advance and a noise signal in a specific frequency band from the received signal received at each location. The filter coefficient of the filter unit for storing and before removing a noise signal of a specific frequency band in the received signal while sequentially updating the filter coefficient. That the filter coefficients obtained from the memory means in place, to remove the noise signal of a specific frequency band of the receiving signal is held in the filter unit the acquired filter coefficient.

  According to the first aspect of the present invention, the filter coefficient at the location where the digital receiver is located is read from the storage means and set as the filter coefficient of the filter unit. Therefore, the noise signal is removed without performing the process of removing the noise signal in a specific frequency band in the received signal while sequentially updating the filter coefficient, thereby improving the communication throughput and reducing the current consumption of the digital receiver. can do.

  According to the second aspect of the present invention, when the received signal is determined not to be the desired wave signal by the signal determining unit, the signal of the specific frequency band in the received signal is removed as a noise signal while sequentially updating the filter coefficient. When the signal determination unit determines that the received signal is a desired wave signal, the filter coefficient update is stopped, the filter coefficient is retained, the noise signal in the received signal is removed, and the desired signal is removed. A digital receiver including a noise removing unit for extracting a wave signal, wherein the noise removing unit removes a noise signal in the received signal and extracts the desired wave signal; and In the learning process in which the filter unit retains the filter coefficient when the noise signal of the specific frequency band in the received signal is removed while sequentially updating the filter coefficient, Stores filter control means for causing a desired wave signal, position information of each location, and filter coefficients of the filter unit for removing noise signals in a specific frequency band in the received signal received at each location. And the filter coefficient control for acquiring the filter coefficient at the current location from the storage means and setting and holding the acquired filter coefficient in the filter unit before the filter control means starts the learning process. Means.

  According to the second aspect of the present invention, the filter coefficient for removing the noise signal generated at each location by the filter unit is stored together with the position information in the storage unit. Then, the filter coefficient control means reads out the filter coefficient for the location where the digital reception device is located from the storage means and sets it as the filter coefficient of the filter unit before the filter control means starts the learning process. Accordingly, since the noise signal is removed without the filter control means performing the learning process for removing the noise signal in the specific frequency band in the received signal, the communication throughput is improved and the current consumption of the digital receiver 1 is improved. Can be reduced.

  According to a third aspect of the present invention, in the digital receiver according to the second aspect, the noise removing unit stores the filter coefficient obtained by the filter control means in the learning process together with the position information of the current location. The filter coefficient writing means to be stored in the means is provided.

  According to the third aspect of the present invention, when the digital reception device wants to receive a noise signal in a place that is not stored in the storage means, a learning process for removing the noise signal at that position is performed. The filter coefficient of the filter unit for the noise signal generated at the place is additionally stored together with the position information. Therefore, thereafter, communication at the same location can improve communication throughput and reduce current consumption.

  According to the present invention, when a unique noise signal is always output at each location, the filter coefficient learning process for noise removal can be shortened to reduce power consumption and improve communication throughput.

The system block diagram for demonstrating the digital receiver of embodiment.

  Hereinafter, a first 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) possessed by a vehicle user as a vehicle key will be described with reference to the drawings.

  Note that an electronic key possessed by a 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 receiver 1 receives a desired wave signal Sk transmitted from an electronic key (portable transmitter) 2 and preprocesses a received signal received by the receiving antenna 10. A pre-processing unit 20 is provided. The digital receiver 1 also receives a signal pre-processed by the pre-processing unit 20 and removes noise, and a signal from which noise has been removed by the noise removing unit 30 is input and demodulated into a received signal. Receiving section 40 for analyzing the contents.

The digital receiver 1 is turned on and off intermittently, that is, at regular intervals. When the power is turned on, the digital receiving device 1 enters the receiving operation mode, and when the power is turned off, the digital receiving device 1 enters the sleep mode.
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 signals input from the preprocessing unit 20 as a noise signal Sn, and includes a filter unit 31, a signal processing unit 32, and a filter control unit. 33, an area selection control unit 34 is provided.

The filter unit 31 is a digital filter, and constitutes an adaptive filter that removes the noise signal Sn based on electrically updateable filter coefficients.
The signal processing unit 32 outputs an extracted signal, which is a signal after the noise removal, to the receiving unit 40 so that the signal after the noise removal by the filter unit 31 can be demodulated in the subsequent stage.

  Further, the signal processing unit 32 calculates a difference between the signal after noise removal and the signal before noise removal. Then, the signal processing unit 32 calculates the difference (that is, in order to newly remove the signal component that has passed through the filter unit 31 without being removed by the current filter coefficient) A signal Sx) indicating a signal component is output to the filter control unit 33.

  Furthermore, the signal processing unit 32 filters the 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 control unit 33. Conversely, the signal processing unit 32 does not output the new signal detection signal Sd to the filter control unit 33 when the calculated difference is less than the predetermined value.

The filter control unit 33 includes a nonvolatile first memory 33 a that stores the filter coefficient of the filter unit 31.
The filter control unit 33 is a signal component that has passed through the filter unit 31 from the signal processing unit 32 when the new signal detection signal Sd is not output from the signal processing unit 32 (when the calculated difference is less than a predetermined value). When the signal Sx suggesting that is output, the filter coefficient of the new filter unit 31 that can remove the signal component is calculated.

  Then, the filter control unit 33 deletes the filter coefficient of the filter unit 31 previously stored in the first memory 33a, and sequentially stores and updates the newly calculated latest filter coefficient. At this time, the filter control unit 33 causes the filter unit 31 to remove the noise signal Sn based on the updated filter coefficient by reflecting (setting) the updated latest filter coefficient in the filter unit 31. The operation will be performed.

  Incidentally, the filter control unit 33 calculates the latest filter coefficient, and learns the process of removing the noise signal Sn by the filter unit 31 while updating the filter coefficient of the filter unit 31 to the latest filter coefficient. This is called processing.

  As described above, at the time when the filter coefficient is updated by the filter control unit 33, the filter coefficient before the update, that is, the signal after noise removal (extracted signal) based on the filter coefficient before the predetermined time is already the next stage. Are output to the receiver 40.

  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 the adaptive mode, the difference between the signal after noise removal and the signal before noise removal is converged by performing learning processing, that is, sequentially updating the filter coefficient, and eventually passes through the filter unit 31. The signal Sx indicating the signal component is not output from the signal processing unit 32.

  At this time, when the signal Sx indicating the signal component that has passed through the filter unit 31 is no longer output from the signal processing unit 32, the filter coefficient calculation and update learning process ends, and the filter unit removes the noise signal Sn. Thirty-one filter coefficients are formed. Then, the filter unit 31 removes the noise signal Sn based on the filter coefficient obtained after the learning process is completed.

  When the filter coefficient calculation and update learning process is completed, the filter control unit 33 stores the filter coefficient at that time in the first memory 33a, and sets and holds the stored filter coefficient as the filter coefficient of the filter unit 31. It has become. In addition, the filter control unit 33 outputs the filter coefficient that is set and held as the filter coefficient of the filter unit 31 to the area selection control unit 34 after the calculation and update learning process ends.

  Further, the filter control unit 33 outputs a filter coefficient request signal to the area selection control unit 34 and acquires the filter coefficient from the area selection control unit 34 when the mode is changed from the pause mode to the reception mode. The filter control unit 33 rewrites and holds the filter coefficient of the filter unit 31 set and held in the previous learning process to the acquired filter coefficient.

  The area selection control unit 34 includes a non-volatile second memory 34a. The area selection control unit 34 stores the filter coefficient to be set and held as the filter coefficient of the filter unit 31 from the filter control unit 33 in the second memory 34a. Further, the area selection control unit 34 inputs position information Pi at that time from a GPS (Global Positioning System) terminal 50 provided in the vehicle.

  Then, when the filter coefficient to be set and held as the filter coefficient of the filter unit 31 is input from the filter control unit 33, the area selection control unit 34 adds the current position information Pi from the GPS terminal 50 to the filter coefficient. And stored in the second memory 34a.

  Therefore, when the learning process for removing the noise signal Sn is performed in the second memory 34a and the filter coefficient of the filter unit 31 is obtained, the position information Pi at the location and the filter unit 31 at the location are obtained. The filter coefficient is stored. As a result, the second memory 34a stores the filter coefficient for the noise signal Sn unique to each location together with the position information Pi.

  The area selection control unit 34 receives a filter coefficient request signal from the filter control unit 33. The area selection control unit 34 responds to the filter coefficient request signal from the filter control unit 33, inputs the position information Pi from the GPS terminal 50, and sets the filter coefficient of the filter unit 31 for the position information Pi at that time to the first position. 2 Read from the memory 34 a and output the read filter coefficient to the filter control unit 33.

The filter control unit 33 sets the filter coefficient output from the area selection control unit 34 in the filter unit 31 as a filter coefficient that can remove the noise signal Sn received at this location.
(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 authorized owner of the electronic key 2 to get on the vehicle. Allow the engine to start.

  The determination control unit 42 receives the extracted signal after the noise removal by the noise removing unit 30 and determines whether the extracted signal is a desired wave signal 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, when the determination control unit 42 determines that the extracted signal is not the desired wave signal Sk, that is, when the received reception signal is determined to be 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 in the non-adaptive mode, the filter control unit 33 does not adapt the filter unit 31 until the new signal detection signal Sd is not input from the signal processing unit 32. Keep in mode.

  That is, by maintaining the filter unit 31 in the non-adaptive mode, 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. Stop and keep updating filter coefficients.

  Conversely, the filter control unit 33 switches the filter unit 31 to the adaptive mode when the noise determination signal Sjn is output from the determination control unit 42 in the non-adaptive mode. That is, by switching the filter unit 31 to the adaptive mode, the new signal previously estimated as the desired wave signal Sk is a noise signal Sn different from the estimation, so that the filter coefficient is calculated and updated so as to remove the noise signal Sn. That is, a learning process is performed.

Next, the operation of the digital receiver 1 will be described.
Now, the unique noise signal Sn generated at each location is stored in the second memory 34a of the area selection control unit 34 of the digital receiver 1 together with the position information Pi identifying each location. Then, the digital receiver 1 is turned on and off at regular intervals, and waits for reception of the desired wave signal Sk from the electronic key 2 in the reception operation mode that occurs intermittently.

  When the digital reception device 1 enters the reception operation mode state from the sleep mode, the filter control unit 33 outputs a filter coefficient request signal to the area selection control unit 34. In response to the filter coefficient request signal, the area selection control unit 34 inputs the position information Pi from the GPS terminal 50, and searches the second memory 34a for the filter coefficient of the filter unit 31 for the position information Pi located at that time. .

  That is, it is searched whether or not the filter coefficient of the filter unit 31 for removing the inherent noise signal Sn generated at the position is stored in the second memory 34a. When the filter coefficient for the position is stored, the filter coefficient is read out and output to the filter control unit 33. The filter control unit 33 sets and holds the filter coefficient output from the area selection control unit 34 as the filter coefficient of the filter unit 31.

  Therefore, when the digital reception device 1 is changed from the sleep mode to the reception operation mode, the filter coefficient of the filter unit 31 is set to the filter coefficient for removing the noise signal Sn at that location.

  When the noise signal Sn is received in the reception operation mode state, the filter control unit 33 receives the new signal detection signal Sd from the signal processing unit 32 and the signal Sx indicating the signal component that has passed through the filter unit 31. The As a result, the filter control unit 33 enters a non-adaptive mode in which the filter unit 31 calculates and updates a new filter coefficient, that is, does not perform a learning process.

  At this time, since the filter control unit 33 stops updating the filter coefficient, the filter unit 31 performs a filter operation based on the filter coefficient that is set and held when the filter unit 31 is changed from the sleep mode to the reception operation mode. Accordingly, the desired signal Sk from which the noise signal Sn is removed is input to the determination control unit 42 of the receiving unit 40 as the extracted signal extracted from the signal processing unit 32 through the filter unit 31. The determination control unit 42 analyzes whether or not the new signal is a desired wave signal. However, since the noise signal Sn is the desired wave signal Sk removed by the filter unit 31, the new signal is determined to be the desired wave signal Sk. To do. Therefore, the determination control unit 42 outputs the desired wave determination signal Sjk to the filter control unit 33.

The filter control unit 33 holds the filter coefficient of the filter unit 31 in response to the desired wave determination signal Sjk and maintains the non-adaptive mode.
Accordingly, when a unique noise signal Sn is received at a predetermined location, the learning process is not performed. As a result, the communication throughput can be improved and the current consumption of the digital receiver 1 can be reduced as much as the learning process is omitted.

  Conversely, when the filter coefficient for the position is not stored in the second memory 34 a, the area selection control unit 34 outputs a signal indicating that it is not stored to the filter control unit 33. The filter control unit 33 maintains the filter coefficient of the filter unit 31 without changing it.

  When the noise signal Sn is received as a new signal, the filter control unit 33 receives the new signal detection signal Sd from the signal processing unit 32 and the signal Sx indicating the signal component that has passed through the filter unit 31. As a result, the filter control unit 33 enters a non-adaptive mode in which the filter unit 31 calculates and updates a new filter coefficient, that is, does not perform a learning process.

In this case, since the filter control unit 33 stops updating the filter coefficient, the filter unit 31 performs a filter operation based on the last updated filter coefficient.
That is, at this time, the signal after noise removal (noise signal Sn) extracted from the signal processing unit 32 via the filter unit 31 is input to the determination control unit 42 of the reception unit 40. At this time, the determination control unit 42 analyzes whether or not the new signal is the desired wave signal, but since it is the noise signal Sn, the extracted signal after noise removal is not the desired wave signal Sk but the noise signal Sn. judge. Therefore, the determination control unit 42 outputs the noise determination signal Sjn to the filter control unit 33.

  In response to the noise determination signal Sjn, the filter control unit 33 calculates and updates the filter coefficient for removing the noise signal Sn from the new signal because the noise signal Sn cannot be removed by the previously set filter coefficient. The learning process for the filter coefficient of the filter unit 31 is executed.

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

  Further, the filter control unit 33 outputs the obtained filter coefficient to the area selection control unit 34. Then, when the filter coefficient to be set and held as the filter coefficient of the filter unit 31 is input from the filter control unit 33, the area selection control unit 34 adds the current position information Pi from the GPS terminal 50 to the filter coefficient. And stored in the second memory 34a.

  Therefore, the data of the filter coefficient of the filter unit 31 for removing the noise signal Sn at the new location and the location information Pi at that location are additionally stored in the second memory 34a and used thereafter.

  Even if the filter coefficient for the position is stored in the second memory 34a, the noise determination signal Sjn may be output from the determination control unit 42 to the filter control unit 33. This may be the case where the inherent noise signal Sn that has been generated so far disappears and a new noise signal Sn is generated.

  In this case, a learning process for a new noise signal Sn is performed, and a filter coefficient of the filter unit 31 for removing the noise signal Sn is obtained. Then, the area selection control unit 34 rewrites and stores the newly obtained filter coefficient of the filter unit 31 in the second memory 34a as the filter coefficient in the position information Pi.

  Accordingly, the second memory 34a stores the filter coefficient of the filter unit 31 for removing the new noise signal Sn rewritten with respect to the position information Pi of the location, and is used thereafter.

As described above, according to the present embodiment, the following operational effects can be achieved.
(1) According to this embodiment, the filter coefficient of the filter unit 31 for the unique noise signal Sn generated at each location is stored in the second memory 34a of the area selection control unit 34 together with the position information Pi. Each time the operation mode is changed from the sleep mode to the reception operation mode, the filter coefficient for the location where the digital receiver 1 is located is read from the second memory 34 a and set as the filter coefficient of the filter unit 31.

Therefore, when a unique noise signal Sn is received at that location, the noise signal Sn is removed without performing the learning process, so that the communication throughput is improved while the learning process is omitted. The current consumption of the receiving device 1 can be reduced.
(2) According to the present embodiment, when the digital reception device 1 receives the noise signal Sn in a place that is not stored in the second memory 34a, a learning process for removing the noise signal Sn at that position is performed. The filter coefficient of the filter unit 31 for the inherent noise signal Sn generated at that location is additionally stored in the second memory 34a together with the position information Pi. Therefore, thereafter, communication at the same location can improve communication throughput and reduce current consumption.

In addition, you may change the said embodiment as follows.
In the above embodiment, the filter coefficient of the second memory 34 a is set as the filter coefficient of the filter unit 31 when the reception mode is changed from the sleep mode. This may be performed by setting the filter coefficient of the second memory 34 a to the filter coefficient of the filter unit 31 when the reception operation mode is changed to the pause mode.

  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, 31 ... Filter part, 32 ... Signal processing part, 33 ... Filter control part (Filter control means, filter (Coefficient control means), 33a ... memory, 34 ... area selection control section (filter coefficient writing means), 34a ... second memory (storage means), 40 ... receiving section, 41 ... demodulation section, 42 ... determination control section (signal) Determination unit), 50 ... GPS terminal, Sd ... new signal detection signal, Sk ... desired wave signal, Sn ... noise signal, Sx ... signal, Sjk ... desired wave determination signal, Sjn ... noise determination signal, Pi ... position information.

Claims (3)

When the signal determination unit determines that the received signal is not the desired wave signal, the signal determination unit sequentially updates the filter coefficient and removes a signal in a specific frequency band from the received signal as a noise signal. A digital receiving device comprising a filter 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 the signal is a wave signal The filter coefficient setting method of
Preliminarily storing the location information of each location in the storage means and the filter coefficient of the filter unit for removing the noise signal of the specific frequency band in the received signal received at each location,
Before removing a noise signal in a specific frequency band in the received signal while sequentially updating the filter coefficient, the filter coefficient at the current location is acquired from the storage unit, and the acquired filter coefficient is stored in the filter unit. A filter coefficient setting method for a digital receiving apparatus, characterized in that a noise signal in a specific frequency band is removed from the received signal. When the received signal is determined not to be a desired wave signal by the signal determining unit, a signal of a specific frequency band in the received signal is removed as a noise signal while sequentially updating filter coefficients, and the received signal is the signal determining unit A noise removal unit that stops updating the filter coefficient, holds the filter coefficient, removes the noise signal in the received signal, and extracts the desired wave signal when the signal is determined to be a desired wave signal A digital receiver comprising:
The noise removing unit
A filter unit for removing the noise signal in the received signal and extracting the desired wave signal;
In the learning process in which the filter unit retains the filter coefficient when the noise signal of the specific frequency band in the received signal is removed while sequentially updating the filter coefficient of the filter unit, the desired wave signal from the filter unit Filter control means for
Storage means for storing position information of each location, and filter coefficients of the filter unit for removing noise signals in a specific frequency band in the received signal received at each location;
Before the filter control means starts the learning processing, the filter coefficient control means for acquiring the filter coefficient at the current location from the storage means, and setting and holding the acquired filter coefficient in the filter unit A digital receiver characterized by that. The digital receiver according to claim 2, wherein
The digital signal processing apparatus according to claim 1, wherein the noise removing unit includes a filter coefficient writing unit that stores the filter coefficient obtained by the learning process by the filter control unit in the storage unit together with position information of a current location. .

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