JP7612200B2 - Electronics - Google Patents

Description

This disclosure relates to electronic devices installed in vehicles.

There is known a vehicle speed measuring device that measures the speed of a vehicle traveling on a road from outside the vehicle (see, for example, Patent Document 1). The vehicle speed measuring device is installed, for example, on the shoulder of the road for the purpose of policing speed violations. There is also known a laser-type vehicle speed measuring device that emits a light pulse signal toward the vehicle, receives the reflected light, and measures the traveling speed of the vehicle.

There is also known an electronic device that notifies a user of the presence of a vehicle speed measurement device when a signal is received from the vehicle speed measurement device (see, for example, Patent Document 2). This electronic device is mounted as an on-board device in a vehicle such as a four-wheeled automobile.

JP 2015-7572 A JP 2020-112357 A

However, the signal from the vehicle speed measurement device often does not reach the onboard unit as a complete signal, but as an incomplete signal with parts missing due to the influence of an obstruction. An example of an obstruction is another vehicle traveling in front of the vehicle equipped with the onboard unit.

Therefore, a method that determines whether a received signal is from a vehicle speed measurement device on the assumption that the received signal is in perfect condition may not be able to notify the user of the presence of a vehicle speed measurement device early on.

Therefore, according to one aspect of the present disclosure, it is desirable to provide a technology that can properly detect the reception of a transmission signal from a transmitter in an in-vehicle electronic device that receives a transmission signal from a transmitter outside the vehicle, even when an incomplete transmission signal reaches the receiving unit due to the influence of an obstruction or the like.

According to one aspect of the present disclosure, an electronic device mounted on a vehicle is provided. The electronic device includes a receiving unit configured to receive a specific signal transmitted from a transmitter outside the vehicle, and a determining unit configured to determine whether the receiving unit has received the specific signal based on the signal received by the receiving unit.

The specific signal includes a train of pulse signals arranged on a time axis according to a specific rule. The determination unit is configured to determine that the specific signal has been received when the received signal satisfies any of a plurality of conditions.

The first of the multiple conditions is that the received signal includes multiple pulse signals that exhibit a first regularity in the arrangement on the time axis that at least partially corresponds to a specific regularity. The second of the multiple conditions is that the received signal includes multiple pulse signals that exhibit a second regularity in the arrangement on the time axis that is different from the first regularity and that partially corresponds to the specific regularity.

With this electronic device, even if a specific signal from a transmitter arrives at the receiving unit as an incomplete signal due to an obstruction, it is possible to properly detect the reception of the specific signal based on a regularity contained in the incomplete signal that partially corresponds to the specific rule. With this electronic device, it is also possible to prevent the reception of a different signal, such as noise, that is not a specific signal from the transmitter from being erroneously determined as the reception of a specific signal.

According to one aspect of the present disclosure, the second condition can be defined as the second regularity using the regularity of the incomplete pulse signal sequence of the received signal when the receiving unit receives an incomplete pulse signal sequence in which some pulse signals are missing from the pulse signal sequence included in the specific signal.

According to one aspect of the present disclosure, the first condition can be defined as the first regularity using the regularity of the sequence of pulse signals contained in the received signal when the receiving unit receives the sequence of pulse signals contained in the specific signal without any missing pulse signals.

By determining whether or not a signal transmitted from a transmitter has been received according to the first and second conditions defined in this way, the electronic device can appropriately detect whether or not a signal transmitted from a transmitter has been received while minimizing the effects of signal loss caused by obstructions.

According to one aspect of the present disclosure, the specific signal may include two or more first pairs of pulse signals that are located a first specific time interval apart on the time axis, and one or more second pairs of pulse signals that are located a second specific time interval apart. The second specific time interval may be a time interval different from the first specific time interval.

In this case, the first condition may be that the received signal includes two or more of the first pairs. The second condition may be that the received signal includes one or more of the first pairs and one or more of the second pairs.

According to one aspect of the present disclosure, the specific signal may be a train of periodic pulse signals arranged at specific time intervals. When the second specific time interval is an integer multiple of the first specific time interval that is equal to or greater than twice the first specific time interval, the train of periodic pulse signals may include two or more of the first pair and one or more of the second pair.

According to one aspect of the present disclosure, in a case where the specific signal is a train of periodic pulse signals arranged at specific time intervals, the first condition may be that the received signal includes a predetermined number or more of pulse signals (greater than two) arranged periodically at specific time intervals.

The second condition may be that the received signal includes first, second, and third pulse signals in chronological order, the time interval between the first pulse signal and the second pulse signal is a first interval, and the time interval between the second pulse signal and the third pulse signal is a second interval. The first interval is a specific time interval, and the second interval may be an integer multiple of the specific time interval that is equal to or greater than twice the specific time interval.

According to the second condition, even when an incomplete specific signal in which some pulse signals are missing is received by the receiving unit, and the periodicity of the pulse signals is lost in the received signal, it is possible to properly detect the reception of the specific signal from the transmitter.

According to one aspect of the present disclosure, the multiple conditions may further include a third condition. The third condition may be that the received signal includes a first, second, third, and fourth pulse signal in chronological order, the first pulse signal and the second pulse signal are a first pair of pulse signals spaced a specific time interval apart, the third pulse signal and the fourth pulse signal are a second pair of pulse signals spaced a specific time interval apart, and the time interval between the second pulse signal and the third pulse signal is equal to or less than a predetermined allowable time that is longer than the specific time interval.

According to this third condition, like the second condition, it is possible to properly detect the reception of a specific signal from a transmitter even when periodicity is lost due to a missing pulse signal. If the third condition includes a condition regarding a predetermined allowable time, it is possible to reduce the possibility of erroneously detecting a received signal that is not a specific signal as a specific signal from a transmitter. The same condition as the third condition may be defined as the second condition.

FIG. 2 is a block diagram showing the configuration of an electronic device and an automatic speed violation detection device. FIG. 2 is a diagram illustrating the relationship between an electronic device, an automatic speed violation enforcement device, and a vehicle. 1 is a block diagram illustrating a configuration of a laser receiving unit in an electronic device. 2 is a functional block diagram showing functions realized by a control unit of the electronic device. FIG. 4 is a flowchart showing a measurement process executed by a control unit. 11 is a flowchart showing a determination process executed by a control unit. FIG. 7A is a diagram for explaining the characteristics of a complete signal without any missing parts, and FIGS. 7B, 7C, and 7D are diagrams for explaining a reception determination method for an incomplete signal. 10 is a flowchart showing a warning process executed by a control unit. FIG. 9A is a diagram for explaining a signal transmitted from an automatic speed violation enforcement device in the modified example, and FIG. 9B is a diagram for explaining a reception determination method in the modified example. FIG. 10A is a functional block diagram showing functions realized by a control unit of an electronic device in the second embodiment, and FIG. 10B is a diagram for explaining an evaluation method in the evaluation processing unit. 10 is a flowchart showing an evaluation process executed by a control unit in a second embodiment.

Exemplary embodiments of the present disclosure will now be described with reference to the drawings.
[First embodiment]
The electronic device 10 of this embodiment shown in FIG. 1 is configured to notify a user of the presence of an automatic speed violation enforcement device (hereinafter referred to as an "ORBIS") 50 when it detects a signal transmitted from the ORBIS 50.

As shown in FIG. 2, this electronic device 10 is mounted on a vehicle 1 such as a four-wheeled automobile. For example, the electronic device 10 is placed in a position within the vehicle cabin where it can receive a signal transmitted from an speed camera 50 installed outside the vehicle 1. For example, the electronic device 10 is placed near the rearview mirror, facing the windshield.

The speed camera 50 may be mobile or fixed. A mobile speed camera 50 is temporarily installed, for example, on the shoulder of the road and is used to check for speeding violations of vehicles 1, 5 traveling on the road.

While existing speed cameras that use loop coils or microwaves are known, the speed camera 50 described here is a laser-type speed camera. As shown in Figure 1, the speed camera 50 includes a laser transmitter/receiver unit 51 and a speed measurement unit 53.

The laser transmitting/receiving unit 51 is configured to emit a laser light signal and receive a reflected light signal that is generated when the laser light signal hits the vehicle 1 or 5 and is reflected. The laser light signal emitted from the laser transmitting/receiving unit 51 corresponds to the signal transmitted from the speed camera 50. Hereinafter, this laser light signal is also referred to as the speed camera signal.

The laser transmitter/receiver 51 emits a periodic pulsed light signal at a specific time interval Ts as the speed camera signal. In other words, the speed camera signal is a sequence of periodic pulsed light signals arranged at a specific time interval Ts. The specific time interval Ts, i.e., the period Ts of the pulsed light signal, is, for example, 80 milliseconds.

The speed measurement unit 53 measures the speed of the vehicles 1 and 5 based on the change in the positions of the vehicles 1 and 5, which is determined from the time difference between when the pulse light signal is emitted by the laser transmission/reception unit 51 and when the reflected light signal reflected by the vehicles 1 and 5 is received.

As shown in FIG. 1, the electronic device 10 that receives speed cameras includes a laser receiver 11, a display unit 13, a sound output unit 15, and a control unit 17.

The laser receiving unit 11 is configured to be able to receive speed camera signals. The display unit 13 is configured to be controlled by the control unit 17 and to display various information to the user in the vehicle cabin. The display unit 13 is configured, for example, as a liquid crystal display. The sound output unit 15 includes a speaker (not shown) and is configured to be controlled by the control unit 17 and to output warning sounds, guidance sounds, etc. to the user in the vehicle cabin.

The control unit 17 includes a processor 171 and a memory 175. The memory 175 includes a volatile memory (RAM) that is used as a working area when the processor 171 executes processing, and a non-volatile memory (NVRAM) such as an electrically rewritable flash memory. The non-volatile memory stores computer programs and various setting data that should be stored for a long period of time.

The processor 171 controls each part of the electronic device 10 by executing processes according to a computer program stored in the memory 175. The processes executed by the control unit 17 described below may be understood to be realized by the processes executed by the processor 171 according to the computer program.

Next, the laser receiving unit 11 will be described in detail. As shown in FIG. 3, the laser receiving unit 11 includes a light receiving unit 110, an amplifier 113, and a comparator 115. The light receiving unit 110 is configured to convert input light into an electrical signal and output it as a received signal. The received signal output from the light receiving unit 110 is amplified by the amplifier 113 and then input to the comparator 115.

The comparator 115 is configured to compare the received signal with a preset threshold, output a received signal equal to or greater than the threshold as a high signal "1", and output a received signal less than the threshold as a low signal "0". The received signal thus binarized by the comparator 115 is input to the control unit 17. The threshold is set taking into account the expected signal level of noise. For example, the threshold is set to approximately twice the signal level of noise.

When the light receiving unit 110 receives a complete speed camera signal with no missing pulsed light signals, a signal that periodically switches to a high signal, in other words a train of periodic pulse signals, is input from the laser receiving unit 11 to the control unit 17 as a received signal. Specifically, a train of pulse signals with a specific time interval Ts (e.g., 80 milliseconds) corresponding to the period Ts of the pulsed light signal contained in the speed camera signal is input to the control unit 17.

The control unit 17 functions as a measurement processing unit 17A, a judgment processing unit 17B, and an alarm processing unit 17C, as shown in FIG. 4, by executing processing according to the computer program stored in the memory 175.

The measurement processing unit 17A measures the input interval of the pulse signal as a signal interval Tm based on the received signal input from the laser receiving unit 11. The pulse signal here corresponds to the received signal input as a high signal "1". The signal interval Tm is the time interval between two pulse signals that are lined up on the time axis, in other words, between two pulse signals that are adjacent to each other with no other pulse signals in between. The measurement processing unit 17A further operates to record the measured signal interval Tm as time series data. The time series data is temporarily stored in the memory 175.

The determination processing unit 17B refers to the time series data and determines whether the arrangement of the received multiple pulse signals on the time axis has a regularity that corresponds to the arrangement of the pulse light signals in the speed camera signal. The determination processing unit 17B determines whether the speed camera signal has been received by the laser receiving unit 11 based on the presence or absence of this regularity.

When the judgment processing unit 17B judges that an speed camera signal has been received, the warning processing unit 17C controls the display unit 13 to display a warning message informing the user of the presence of a speed camera 50 on the display unit 13, and also causes the sound output unit 15 to output a warning sound informing the user of the presence of a speed camera 50. Based on this display and sound output, the user can be informed of the presence of a speed camera 50 in front of the vehicle.

However, as mentioned above, because speed cameras are laser light signals, they are highly directional, and at locations far from the speed camera 50, an incomplete speed camera signal is likely to reach the electronic device 10 due to the influence of obstructions located between the speed camera 50 and the electronic device 10.

For example, as shown in FIG. 2, if a vehicle 5 other than the vehicle 1 carrying the electronic device 10 is positioned between the speed camera 50 and the electronic device 10, the vehicle 5 acts as an obstruction, and the pulsed light signal is temporarily prevented from reaching the electronic device 10.

Therefore, in order to notify a user of the presence of an ORBIS 50 at an early stage when the user is located away from the ORBIS 50, it is desirable to be able to detect the ORBIS signal with high sensitivity even in a situation where the laser receiver 11 is receiving an incomplete ORBIS signal.

For this highly sensitive detection, the measurement processing unit 17A temporarily stores the signal intervals Tm for at least a predetermined number of past occurrences or a predetermined period of time as time series data as described above. The determination processing unit 17B determines whether or not an speed camera signal has been received based on the arrangement of pulse signals on the time axis identified from the time series data.

Next, the details of the measurement process executed by the control unit 17 to function as the measurement processing unit 17A, the judgment process executed to function as the judgment processing unit 17B, and the alarm process executed to function as the alarm processing unit 17C will be described with reference to Figures 5 to 8. The measurement process, judgment process, and alarm process are executed in parallel by the control unit 17.

The control unit 17 starts the measurement process shown in FIG. 5 immediately after starting the electronic device 10. When the measurement process starts, the control unit 17 determines whether a pulse signal has been received as a reception signal from the laser receiving unit 11 (S110).

The control unit 17 can determine that a pulse signal has been received when the received signal input from the laser receiving unit 11 switches to a high signal. Alternatively, the control unit 17 can determine that a pulse signal has been received when a high signal with a time width corresponding to the pulse width of the speed camera signal is input from the laser receiving unit 11.

When the control unit 17 determines that a pulse signal has been received (Yes in S110), it starts measuring the elapsed time from the time the pulse signal was received in order to measure and record the signal interval Tm (S120).

Thereafter, the control unit 17 continues to measure the elapsed time until the termination condition is satisfied by shutting down the electronic device 10 (S130) or until it is determined that a new pulse signal has been received (S140). In S140, the control unit 17 can determine whether or not a pulse signal has been received using a method similar to that of S110.

When the control unit 17 determines that a new pulse signal has been received (Yes in S140), it records the time that has elapsed up to that determination as the signal interval Tm (S150). That is, the control unit 17 additionally records the signal interval Tm as time-series data in the memory 175. The signal interval Tm recorded here is the time interval between the previously received pulse signal and the currently received pulse signal.

Then, the control unit 17 proceeds to S120 and starts measuring the elapsed time from the time when the newly received pulse signal was received. If the control unit 17 determines that the next pulse signal has been received (Yes in S140), it additionally records the measured elapsed time as the signal interval Tm (S150).

When the termination condition is satisfied (Yes in S130), the control unit 17 terminates the measurement process. In this manner, the signal interval Tm, which is the time interval of the pulse signal for at least the past predetermined number of times or for a predetermined period of time, is recorded in the memory 175 as time series data.

In parallel with this measurement process, the control unit 17 repeatedly executes the determination process shown in FIG. 6. In the determination process, the control unit 17 waits until it determines that the measurement processing unit 17A has received a pulse signal (S210).

When the control unit 17 determines that the measurement processing unit 17A has received a pulse signal (Yes in S210), it determines whether the signal interval Tm measured as the time interval between the most recent pulse signal received and the previous pulse signal is a specific time interval Ts, which is the period of the pulse light signal in the speed camera signal (S220).

The judgment in S220 may be made taking into account the measurement error. When the measurement error of the signal interval Tm is ε, the control unit 17 judges that the signal interval Tm is the specific time interval Ts when the signal interval Tm is in the time range Ts-ε≦Tm≦Ts+ε centered on the period Ts, and otherwise judges that the signal interval Tm is not the specific time interval Ts.

When it is determined that the signal interval Tm is the specific time interval Ts (Yes in S220), the control unit 17 further determines whether the signal interval Tm measured previously was also the specific time interval Ts, thereby determining whether the signal interval Tm is periodic (S230).

In S230, as shown in FIG. 7A, a positive judgment is made when the past three pulse signals, the first, second, and third pulse signals, are generated periodically at a specific time interval Ts. The first pulse signal is the pulse signal received two pulses ago, the second pulse signal is the pulse signal received previously, and the third pulse signal is the most recent pulse signal received this time.

As another example, the control unit 17 may determine whether the signal intervals are periodic by determining whether the signal intervals Tm measured not only last time but also the time before last are the specific time interval Ts. In this case, a positive determination is made when the first, second, third, and fourth pulse signals, which are the last four pulse signals received, are input periodically at the specific time interval Ts. The first pulse signal is the pulse signal received three pulses ago, the second pulse signal is the pulse signal received two pulses ago (i.e., two pulses ago), the third pulse signal is the pulse signal received last time, and the fourth pulse signal is the pulse signal received this time.

If the control unit 17 determines that the signal interval Tm is periodic (Yes in S230), it determines that an speed camera signal has been received (S250), and then temporarily ends the determination process.
On the other hand, when the control unit 17 determines that there is no periodicity (No in S230), it determines whether there is a record of a specific time interval Ts being measured as the signal interval Tm during a predetermined past period based on the time point at which the current pulse signal was received (S240), based on the time series data stored in the memory 175. The predetermined period can be a predetermined past time Tw (hereinafter referred to as the allowable time Tw) ending at the time when the current pulse signal was received.

The control unit 17 searches for a record in which the signal interval Tm is a specific time interval Ts within a range in which the sum of the signal interval Tm recorded in the memory 175 as time series data, from newer records to older records, does not exceed the allowable time Tw, thereby determining whether there is a record in which the specific time interval Ts was measured as the signal interval Tm during a specified period in the past.

In S240, a positive determination is made when, according to the time series data, first, second, third, and fourth pulse signals that satisfy the following condition are generated within the allowable time Tw. That is, as shown in FIG. 7B, a positive determination is made when the first, second, third, and fourth pulse signals, in which the first pulse signal and the second pulse signal are a first pair of pulse signals spaced a specific time interval Ts apart, and the third pulse signal and the fourth pulse signal are a second pair of pulse signals spaced a specific time interval Ts apart, are generated within the allowable time Tw. In FIGS. 7B-7D, the pulse signals indicated by dashed lines are missing pulse signals that do not exist in the received signal.

The allowable time Tw is set to a time sufficiently longer than three times the specific time interval Ts, such that the time interval between the second pulse signal and the third pulse signal is longer than one time the specific time interval Ts. For example, the allowable time Tw is set to a value between several seconds and about 10 seconds. The allowable time Tw can be set by the designer based on statistics of the time during which the electronic device 10 is unable to receive the pulse light signal due to an obstruction such as another vehicle 5.

When the control unit 17 determines in S240 that there is a record of a specific time interval Ts being measured as the signal interval Tm during a predetermined period in the past (Yes in S240), it determines that an speed camera signal has been received (S250).

On the other hand, if the control unit 17 determines in S240 that there is no record (No in S240), it determines that an speed camera signal has not been received (S280). Then, the determination process is temporarily terminated.

In addition, if the control unit 17 determines that the currently measured signal interval Tm is not the specific time interval Ts (No in S220), it determines whether the signal interval Tm is a time interval N*Ts that corresponds to an integer multiple of the specific time interval Ts (S260). N is an integer.

In S260, the control unit 17 determines whether the signal interval Tm is an integer multiple of the specific time interval Ts within a predetermined range of integer multiples. The determination can be made taking into account measurement errors, similar to the determination in S220. The range of integer multiples can be set to two or more. The range of integer multiples can be set to a predetermined multiple (e.g., three or four) that is two or more.

When it is determined that the signal interval Tm is an interval N*Ts corresponding to an integer multiple of the specific time interval Ts (Yes in S260), the control unit 17 determines whether the previously measured signal interval Tm was the specific time interval Ts (S270).

When the control unit 17 determines that the previously measured signal interval Tm was the specific time interval Ts (Yes in S270), it determines that an speed camera signal has been received (S250). In S270, if the previous signal interval Tm was the specific time interval Ts and the current signal interval Tm is an interval 2Ts that is twice the specific time interval Ts (see FIG. 7C), or an interval N*Ts that is N times the specific time interval Ts, which is three or more times the specific time interval Ts (see FIG. 7D), a positive determination is made.

If the control unit 17 judges in S270 that the speed camera signal has not been received (S280), it then temporarily terminates the judgment process.

In addition, the control unit 17 repeatedly executes the warning process shown in FIG. 8 in parallel with the above-mentioned judgment process, and if it is judged in the judgment process that an speed camera signal has been received (Yes in S310), it causes the display unit 13 to display a warning message notifying the presence of a speed camera 50 for the period during which the speed camera signal continues to be received, and causes the sound output unit 15 to output a warning sound notifying the presence of a speed camera 50 (S320).

When the control unit 17 determines that an speed camera signal has not been received (No in S310), it operates so that it does not output a warning message or warning sound, and if a warning message or warning sound had been output up until that point, it stops outputting the warning message and warning sound (S330).

According to the electronic device 10 of this embodiment described above, the control unit 17 assumes that an incomplete speed camera signal that is missing a pulsed light signal may be received, and performs a reception determination for the speed camera signal under multiple conditions.

The control unit 17 determines that an speed camera signal has been received if the first condition is that the received signal contains a predetermined number or more of pulse signals that are periodically spaced at a specific time interval Ts, specifically, three or more pulse signals or four or more pulse signals (Yes in S220, Yes in S230). The first condition corresponds to the received signal containing two or more consecutive pairs of pulse signals that are spaced apart by a specific time interval Ts on the time axis.

The control unit 17 determines that an speed camera signal has been received under the second condition that the received signal includes a first, second, and third pulse signal, the signal interval Tm between the first and second pulse signals is a specific time interval Ts, and the signal interval Tm between the second and third pulse signals is an integer multiple of the specific time interval Ts or more and a predetermined multiple or less (Yes in S260, Yes in S270). The second condition corresponds to the received signal including one first pair of pulse signals located a specific time interval Ts apart on the time axis, and one second pair of pulse signals located an integer multiple of the specific time interval Ts apart.

As a third condition, the control unit 17 determines that an speed camera signal has been received when the received signal includes a first, second, third, and fourth pulse signal, the first pulse signal and the second pulse signal are a first pair of pulse signals spaced a specific time interval Ts apart, the third pulse signal and the fourth pulse signal are a second pair of pulse signals spaced a specific time interval Ts apart, and the time interval between the first pair and the second pair is equal to or less than the allowable time Tw.

The allowable time Tw is determined so that the time interval between the second and third pulse signals is allowed to be twice the specific time interval Ts or a time interval longer than the range of integer multiples in the second condition, in order to differentiate from the reception determination based on the second condition. The third condition corresponds to including two or more pairs of pulse signals located on the time axis at a specific time interval Ts apart.

As such, in this embodiment, assuming that an incomplete signal arrives as an ORBIS signal, in addition to a reception judgment based on a first condition based on the received signal having a first regularity (specifically, periodicity), which is the regularity of the pulse signal sequence on the time axis contained in a complete ORBIS signal without missing pulsed light signals, a reception judgment based on a second condition based on the received signal having a second regularity (specifically, quasi-periodicity), which is the regularity of the pulse signal sequence on the time axis that partially corresponds to the first regularity contained in an incomplete ORBIS signal with missing pulsed light signals, and a reception judgment based on a third condition based on the received signal having a third regularity, which is the regularity of the pulse signal sequence on the time axis that partially corresponds to the first regularity and is different from the second regularity. For example, having a regularity that partially corresponds to the first regularity may correspond to a necessary condition for having the first regularity.

Therefore, according to this embodiment, even if the speed camera signal reaches the laser receiver 11 as an incomplete signal due to an obstruction, the electronic device 10 can detect the reception of the speed camera signal with high sensitivity. Moreover, the electronic device 10 can perform highly sensitive detection with high accuracy while suppressing the erroneous detection of reception of non-speed camera signals such as noise as reception of a speed camera signal.

The above describes a method for determining whether or not an speed camera signal is received, assuming that the speed camera signal is a series of pulsed light signals with a period Ts. However, the speed camera signal is not limited to this example.

For example, as shown in FIG. 9A, the speed camera 50 can be configured to emit a speed camera signal in which a pair of a first pulse signal and a second pulse signal, which are two pulsed light signals separated by a first time interval Ts1, are generated periodically at a specific time interval (Ts1+Ts2). The first time interval Ts1 is the time interval between the first pulse signal and the second pulse signal, and the second time interval Ts2 is the time interval between the second pulse signal and the subsequent first pulse signal.

In this case, as a modified example, the control unit 17 of the electronic device 10 may be configured to determine whether or not an speed camera signal has been received according to multiple conditions, such as the following:

As shown in FIG. 9A, the control unit 17 in the modified example can determine that an speed camera signal has been received when a first time interval Ts1 and a second time interval Ts2 are repeatedly measured alternately as the signal interval Tm for a predetermined number of times (first condition).

As shown in FIG. 9B, the control unit 17 can determine that an speed camera signal has been received on the condition that the first time interval Ts1 and the second time interval Ts2 are measured in sequence as the signal interval Tm, the first time interval Ts1 is measured, and then the signal interval Tm=Td-Ts1 is measured by subtracting the first time interval Ts1 from the signal interval Td=N*(Ts1+Ts2), which is an integer multiple of the specific time interval (Ts1+Ts2), and then the first time interval Ts1 and the second time interval Ts2 are measured in sequence.

As a third condition, the control unit 17 can determine that an speed camera signal has been received if, after the first time interval Ts1 and the second time interval Ts2 have been measured in sequence, the first time interval Ts1 and the second time interval Ts2 have been measured again in sequence within a predetermined time Tw, as shown in FIG. 9B.

The configuration of the control unit 17 in this modified example makes it possible to determine with high accuracy and sensitivity whether or not an ORBIS signal has been received, while minimizing the effect of missing pulsed light signals, even in cases where an ORBIS signal that is a periodic set of pulsed light signals is received from ORBIS 50.

[Second embodiment]
Next, the configuration of the electronic device 10 of the second embodiment will be described. In the electronic device 10 of the second embodiment, the contents of the processing executed by the control unit 17 are different from those of the first embodiment. In other respects, the electronic device 10 of the second embodiment is configured similarly to the first embodiment. The speed camera 50 is also configured similarly to the first embodiment. Therefore, in the following, the contents of the processing executed by the control unit 17 in the second embodiment will be selectively described, and other descriptions will be omitted by assigning the same reference numerals as in the first embodiment to the corresponding configurations.

By executing processing according to a computer program, the control unit 17 functions as an alarm processing unit 17C, a sampling unit 17E, and an evaluation processing unit 17F, as shown in FIG. 10A.

The sampling unit 17E is configured to sample the received signal input from the laser receiving unit 11 at a specific sampling period and store the sampled value in a buffer in the memory 175. When the received signal at the time of sampling is a high signal, a value of 1 is stored in the buffer as the sampled value of the received signal, and when the received signal at the time of sampling is a low signal, a value of 0 is stored in the buffer as the sampled value of the received signal.

By storing the sampled values for each sampling period, the buffer stores the sampled values of the received signal as a digital data string. In other words, the buffer stores a digital data string consisting of digital data of value 0 or value 1 corresponding to the sampled values of the received signal for each sampling period arranged in time series. Hereinafter, the number of digital data (in other words, sampled values) contained in the digital data string will be referred to as the number of data.

When the number of data is M, the buffer stores a digital data string including the most recent sampled value and the last M sampled values. When the most recent sampled value is written to the buffer by the operation of sampling unit 17E, the oldest sampled value is removed from the digital data string.

As shown in FIG. 10B, the evaluation processing unit 17F calculates an evaluation value of the similarity of the received signal to the reference signal by comparing the digital data string of the reference signal previously recorded in the memory 175 with the digital data string of the received signal stored in the buffer. The evaluation processing unit 17F further determines whether the laser receiving unit 11 has received an speed camera signal depending on whether the evaluation value exceeds a preset reference value.

The reference signal is stored in memory 175 as a digital data string, similar to the received signal. The digital data string of the reference signal is a digital data string that represents the shape of the received signal that would be input to control unit 17 if laser receiving unit 11 were to receive an ideal speed camera signal that is not affected by noise or obstructions, and corresponds to the digital data string of the received signal that sampling unit 17E stores in the buffer when this received signal is hypothetically input.

In other words, the digital data sequence of the reference signal is configured as an array of M sampled values of the received signal when the received signal has an ideal shape. The reference signal corresponds to a model of a received signal that is not affected by noise or obstructions and has no missing pulse signals.

The digital data string of the reference signal is prepared during the manufacturing stage of the electronic device 10 and stored in the memory 175. The digital data string of the reference signal in the memory 175 can be updated, for example, in the form of a firmware update.

The evaluation processing unit 17F compares each sampling value constituting the digital data string of the received signal stored in the buffer with the corresponding sampling value contained in the digital data string of the reference signal for each sampling period.

The sampled values to be compared are sampled values with the same sequence order. In other words, the mth sampled value from the beginning of the digital data string of the received signal is compared with the mth sampled value from the beginning of the digital data string of the reference signal, and it is determined whether these values match.

Based on this comparison, the evaluation processing unit 17F calculates an evaluation value of the similarity of the received signal to the reference signal, which is the number Z of sampled values that match the corresponding sampled values of the reference signal among the sampled values from the beginning (m=1) to the end (m=M) of the digital data string of the received signal. The evaluation value when all sampled values match is M. The evaluation value may be calculated as the match rate Z/M.

As another example, the evaluation processing unit 17F may calculate the sum Σ(X[m]·Y[m]) from m=1 to m=M of the product X[m]·Y[m] of the mth sampling value X[m] in the digital data string of the received signal and the mth sampling value Y[m] in the digital data string of the reference signal as the evaluation value. In this case, the product X[m]·Y[m]=1 only when X[m]=1 and Y[m]=1, so the degree of agreement between the pulse signal portion of the received signal (in other words, the high signal portion) and the pulse signal portion of the reference signal can be calculated as the evaluation value.

The evaluation processing unit 17F determines that an speed camera signal has been received by the laser receiving unit 11 when the evaluation value is equal to or greater than a predetermined reference value, and determines that an speed camera signal has not been received when the evaluation value is less than the predetermined reference value.

As in the first embodiment, when the evaluation processing unit 17F determines that an speed camera signal has been received, the warning processing unit 17C controls the display unit 13 to display a warning message notifying the presence of a speed camera 50 on the display unit 13, and also causes the sound output unit 15 to output a warning sound notifying the presence of a speed camera 50.

The control unit 17 can function as the alarm processing unit 17C by executing processing similar to the alarm processing shown in FIG. 8. Once the evaluation processing unit 17F determines that an speed camera signal has been received, the control unit 17 can operate to continue outputting a warning message and alarm sound for a certain period of time. The control unit 17 can also function as the evaluation processing unit 17F by executing the evaluation processing shown in FIG. 11 at each sampling period.

When the control unit 17 starts the evaluation process, it compares the digital data sequence of the received signal with the digital data sequence of the reference signal as described above to calculate an evaluation value (S410). The control unit 17 then determines whether the evaluation value is equal to or greater than a reference value (S420). If the control unit 17 determines that the evaluation value is equal to or greater than the reference value (Yes in S420), it determines that an ORBIS signal has been received by the laser receiver 11 (S430). If the control unit 17 determines that the evaluation value is less than the reference value (No in S420), it determines that an ORBIS signal has not been received (S440).

According to the electronic device 10 of the second embodiment, whether or not an speed camera signal has been received is determined based on the similarity of the received signal to an ideal signal, so that even if the speed camera signal changes to an incomplete signal shape, the reception of the speed camera signal can be determined with high accuracy and high sensitivity.

As a modification of the second embodiment, the electronic device 10 may store in the memory 175 as digital data strings second and third reference signals corresponding to a model of an incomplete received signal in which some pulse signals are missing, as shown in Figures 7B-7D, along with a first reference signal representing an ideal received signal that is not affected by noise or obstructions. In this case, the control unit 17 can calculate a first evaluation value regarding the similarity between the received signal and the first reference signal, a second evaluation value regarding the similarity between the received signal and the second reference signal, and a third evaluation value regarding the similarity between the received signal and the third reference signal.

The control unit 17 can further determine that an ORBIS signal has been received if any one of the following conditions is satisfied: a first condition that the first evaluation value is equal to or greater than a predetermined first reference value; a second condition that the second evaluation value is equal to or greater than a predetermined second reference value; and a third condition that the third evaluation value is equal to or greater than a predetermined third reference value; and can determine that an ORBIS signal has not been received if none of the conditions is satisfied. Depending on the complexity of the ORBIS signal, four or more reference signals including a fourth reference signal may be prepared. Each reference signal can be defined as a model of an incomplete received signal with a different way in which pulse signals are missing.

Using this method, the electronic device 10 can determine with high accuracy and sensitivity whether or not an speed camera signal has been received. The electronic device 10 of the second embodiment described above includes the following technical ideas.

An electronic device mounted on a vehicle, the electronic device comprising: a receiving unit configured to receive a specific signal transmitted from a transmitter outside the vehicle; and a determining unit configured to determine whether the receiving unit has received the specific signal based on the signal received by the receiving unit, the determining unit evaluating the similarity between the received signal and a reference signal corresponding to a predetermined model of the specific signal, determining that the specific signal has been received when the evaluation value of the similarity is equal to or greater than a reference value, and determining that the specific signal has not been received when the evaluation value of the similarity is less than the reference value.

In this electronic device, the specific signal may be a signal including a train of pulse signals arranged on a time axis according to a specific rule. The received signal and the reference signal may be binarized digital data trains. The similarity evaluation value may be calculated based on a comparison of each digital data value in the digital data train of the received signal with a corresponding digital data value in the digital data train of the reference signal. The similarity evaluation value may be calculated based on the degree of match of the digital data values (e.g., the number of matches or the match rate).

The reference signal may include a first reference signal corresponding to a complete model of the specific signal, and a second reference signal corresponding to an incomplete model of the specific signal. In this case, the determination unit may evaluate the similarity between the received signal and the first reference signal, and determine that the specific signal has been received when the evaluation value of the similarity is equal to or greater than a first reference value. Furthermore, the determination unit may evaluate the similarity between the received signal and the second reference signal, and determine that the specific signal has been received when the evaluation value of the similarity is equal to or greater than a second reference value.

[others]
Although the exemplary embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can adopt various aspects.

For example, the electronic device 10 may have both the speed camera signal reception determination function according to the first embodiment and the speed camera signal reception determination function according to the second embodiment. The present disclosure is not limited to periodic speed camera signals, and can be used to determine the reception of speed camera signals having any characteristics.

The functions of one component in the above embodiments may be distributed among multiple components. The functions of multiple components may be integrated into one component. Part of the configuration of the above embodiments may be omitted. At least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. All aspects included in the technical ideas identified from the wording of the claims are embodiments of the present disclosure.

10...electronic device, 11...laser receiving unit, 13...display unit, 15...sound output unit, 17...control unit, 17A...measurement processing unit, 17B...determination processing unit, 17C...alarm processing unit, 17E...sampling unit, 17F...evaluation processing unit, 50...speed camera, 51...laser transmitting/receiving unit, 53...speed measuring unit, 110...light receiving unit, 113...amplifier, 115...comparator, 171...processor, 175...memory.

Claims (2)

An electronic device mounted on a vehicle,
A receiving unit configured to receive a specific signal transmitted from a transmitter outside the vehicle;
a determination unit configured to determine whether the receiving unit has received the specific signal based on a signal received by the receiving unit;
Equipped with
The determination unit determines that the specific signal has been received when the received signal satisfies any one of a plurality of conditions;
the specific signal is a sequence of periodic pulse signals arranged at specific time intervals,
A first condition of the plurality of conditions is that the received signal includes a predetermined number (greater than two) of pulse signals that are periodically arranged at the specific time interval,
a second condition of the plurality of conditions being that the received signal includes first, second, and third pulse signals in time order, a time interval between the first pulse signal and the second pulse signal is a first interval, and a time interval between the second pulse signal and the third pulse signal is a second interval;
the first interval is the specific time interval,
the second interval is an integer multiple of the specific time interval that is equal to or greater than two,
A third condition among the plurality of conditions is that the received signal includes first, second, third, and fourth pulse signals in chronological order, the first pulse signal and the second pulse signal are a first pair of pulse signals arranged apart from each other by the specific time interval, the third pulse signal and the fourth pulse signal are a second pair of pulse signals arranged apart from each other by the specific time interval, and the time interval between the second pulse signal and the third pulse signal is equal to or less than a predetermined allowable time that is longer than the specific time interval . An electronic device mounted on a vehicle,
A receiving unit configured to receive a specific signal transmitted from a transmitter outside the vehicle;
a determination unit configured to determine whether the receiving unit has received the specific signal based on a signal received by the receiving unit;
Equipped with
The determination unit determines that the specific signal has been received when the received signal satisfies any one of a plurality of conditions;
the specific signal is a sequence of periodic pulse signals arranged at specific time intervals,
A first condition of the plurality of conditions is that the received signal includes a predetermined number (greater than two) of pulse signals that are periodically arranged at the specific time interval,
A second condition of the plurality of conditions is that the received signal includes first, second, third, and fourth pulse signals in chronological order, the first pulse signal and the second pulse signal are a first pair of pulse signals arranged apart from each other by the specific time interval, the third pulse signal and the fourth pulse signal are a second pair of pulse signals arranged apart from each other by the specific time interval, and the time interval between the second pulse signal and the third pulse signal is equal to or less than a predetermined allowable time that is longer than the specific time interval.

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