JP5433267B2 - In-vehicle device - Google Patents

Description

  The present invention relates to an in-vehicle device, and particularly to an in-vehicle device that receives a broadcast signal modulated by OFDM (Orthogonal Frequency Division Multiplexing) diversity.

Conventionally, OFDM (Orthogonal Frequency Division Multiplexing) is known as a signal modulation method used in digital television broadcasting and the like. OFDM is a signal modulation scheme that improves communication efficiency by transmitting a plurality of data in parallel using a plurality of carriers orthogonal to each other.

In a transmitting station that transmits data using OFDM, a data string to be transmitted is mapped onto a complex plane, and the IFFT (Inverse Fast Fourier Transform) with the vertical axis of the complex plane as the real part and the horizontal axis as the imaginary part. ), IFFT data is D / A (digital / analog) converted, and broadcast signals assigned to a plurality of orthogonal carriers are transmitted.

  The receiving device that receives the broadcast signal performs A / D (analog / digital) conversion on the received broadcast signal, demodulates the signal by performing FFT (Fast Fourier Transform), and performs inverse mapping to obtain the data. Reproduce.

  Diversity reception is widely known as a reception method for receiving such broadcast signals by a mobile reception device. A mobile reception apparatus that performs diversity reception includes a plurality of antennas, and synthesizes broadcast signals received by the antennas, thereby enabling stable reception of signals during movement.

  As a method of combining broadcast signals received by the respective antennas, there is a combining method called MRC (Maximum Ratio Combining). In this MRC, the phase of a broadcast signal received by a reception system (hereinafter referred to as “branch”) corresponding to each antenna is synchronized, and the reception level (branch power) corresponding to each carrier of each broadcast signal is determined. The broadcast signal is synthesized by weighting.

  As a result, among broadcast signals received by multiple branches, a broadcast signal with a higher reception level has a stronger influence on the composite signal, so that it is possible to stably receive the broadcast signal in a mobile reception device whose reception environment changes. It becomes.

  As described above, the MRC can be used for a mobile reception device that performs diversity reception to stabilize signal reception. However, when the MRC is used for an in-vehicle device, there are some problems.

  When MRC is adopted in an in-vehicle device that performs diversity reception, the reception level of a specific carrier in a broadcast signal received by a certain branch due to noise from other electronic devices mounted on the vehicle is the broadcast signal. It may increase regardless of the reception state of.

  In this case, in the in-vehicle device, the reception level is increased due to noise and the weighting value for the broadcast signal is increased even though the carrier signal is mixed with noise. There is a problem that the quality of the reproduction data deteriorates because the influence is reflected.

  As a technique for appropriately weighting a broadcast signal affected by noise, a C / N ratio (Carrier to Noise ratio) is calculated for each symbol of the broadcast signal, and based on a relative C / N ratio for each branch. A technique is known in which a large weight is applied to a branch having a good C / N ratio (see, for example, Patent Document 1).

JP 2006-253915 A

  However, in the technique described in Patent Document 1, since the weight value is determined based on the C / N ratio for each symbol of the broadcast signal, the determined weight value is constant for all the carriers, On the other hand, fine weighting for each carrier unit could not be performed.

  In particular, in an in-vehicle device, it is assumed that a specific carrier of a received broadcast signal is affected by noise from other electronic devices mounted on the vehicle, and thus it is necessary to weight each carrier.

  The present invention has been made in view of the above, and when combining broadcast signals received by a plurality of branches, the broadcast signals received in each branch are weighted in units of carriers. An object of the present invention is to provide an in-vehicle device that can perform the above.

In order to solve the above-mentioned problems and achieve the object, the present invention is an in-vehicle device for diversity reception of a broadcast signal modulated by orthogonal frequency division multiplexing, and a plurality of reception units for receiving the broadcast signal; A weighting value setting unit for setting a weighting value according to a signal level of each broadcast signal received by the receiving unit; and for each broadcast signal corresponding to each carrier frequency received by the receiving unit, the weighting value setting unit And a signal synthesizer for performing a weighting process using the weighting value set according to the above and synthesize the maximum ratio of the broadcast signal after the weighting process, and the weight value setting unit detects a carrier frequency including noise from the received broadcast signal And a weighting value to be applied to the carrier frequency detected by the interference detection unit, rather than a weighting value according to the signal level. And having a weight value adjusting unit for setting the weighting values are.

  In the in-vehicle device, the present invention provides a storage unit that stores a plurality of types of weight values used for setting by the weight value adjustment unit, an operation unit that accepts a weight value setting operation by a user, and an input from the operation unit A control unit that selects a weighting value designated by the user from the storage unit based on the operation signal to be set, and sets the weighting value adjustment unit as a weighting value to be applied to the carrier frequency designated by the user. It is characterized by.

  Further, the present invention provides the in-vehicle device, wherein the storage unit includes a type of activation signal indicating that another electronic device mounted on the vehicle is activated, and a carrier frequency affected by activation of each electronic device. , And stores the weighting value in association with each other, and when the activation signal is input from the electronic device, the control unit assigns a weighting value to be applied to the carrier frequency corresponding to the activation signal to the weighting value adjustment unit. It is characterized by being set.

  Further, in the on-vehicle apparatus according to the present invention, the storage unit corresponds to interference frequency information indicating a carrier frequency detected by the interference detection unit and a weighting value applied to a broadcast signal corresponding to the interference frequency information. The weight value adjustment unit stores a weight value associated with the interference frequency information when a carrier frequency corresponding to the interference frequency information stored in the storage unit is received. It is characterized in that it is selected from the section and set.

  In the in-vehicle device according to the present invention, the interference detection unit includes a noise level determination unit that determines a noise level included in a carrier frequency, and the weight value adjustment unit is determined by the noise level determination unit. A weighting value corresponding to the noise level is set.

  ADVANTAGE OF THE INVENTION According to this invention, when the broadcast signal received by several branches is synthesize | combined, the vehicle-mounted apparatus which can perform the weighting in a carrier unit with respect to the broadcast signal received by each branch can be provided. .

It is a functional block diagram which shows the structure of the vehicle-mounted apparatus which concerns on this embodiment. It is a functional block diagram which shows the structure of the interference detection part of the vehicle-mounted apparatus which concerns on this embodiment. It is explanatory drawing which shows the signal level when noise mixes in a broadcast signal. It is explanatory drawing which shows MER when noise mixes in a broadcast signal. It is a timing chart which shows the adjustment timing of the weighting value by a signal synthetic | combination part. It is a flowchart which shows the process which the control part of the vehicle equipment which concerns on this embodiment performs.

  Hereinafter, an embodiment of the present invention will be specifically described with reference to the drawings. FIG. 1 is a functional block diagram showing the configuration of the in-vehicle device according to the present embodiment. Note that FIG. 1 illustrates only characteristic configuration requirements of the in-vehicle device according to the present embodiment, and omits illustration of general configuration requirements included in the in-vehicle device that receives a broadcast signal.

The in-vehicle device according to the present embodiment diversity receives a digital television broadcast signal (hereinafter referred to as “broadcast signal”) modulated by an orthogonal frequency division multiplexing method (hereinafter referred to as “OFDM: Orthogonal Frequency Division Multiplexing”). Device.

  As shown in FIG. 1, the in-vehicle device 1 sets a weighting value corresponding to the signal level of the broadcast signal received by the first receiver 10, the second receiver 20, and the first receiver 10 that receives the broadcast signal. Each of the broadcasts received by the weighting value setting unit 40, the weighting value setting unit 50 for setting the weighting value according to the signal level of the broadcast signal received by the second receiving unit 20, the first receiving unit 10 and the second receiving unit 20 A signal synthesizer 30 is provided that performs weighting processing on the signal using the weighting values set by the weighting value setting units 40 and 50, and synthesizes the broadcast signal after the weighting processing.

  Further, the in-vehicle device 1 includes a weight value setting memory 2 that stores a plurality of types of weight values, a setting operation unit 3 that accepts a weight value setting operation by a user, and weight values stored in the weight value setting memory 2. The control unit 4 is configured to cause the weighting value adjusting units 44 and 54 described later to set the weighting values by outputting the weighting value setting units 40 and 50 to the weighting value setting units 40 and 50.

  The first receiving unit 10 includes a tuner unit 11 connected to an antenna installed at the front of the vehicle, and an FFT (Inverse Fast Fourier Transform) unit 12.

  The second receiving unit 20 includes a tuner unit 21 connected to an antenna installed at the rear of the vehicle, and an FFT unit 22. In this embodiment, a case where antennas are provided at the front and rear of the vehicle will be described as an example. However, three or more antennas are provided, and a receiving unit and a weight setting unit are provided for each antenna. Also good.

  The weighting value setting unit 40 connected to the first receiving unit 10 sets a weighting value corresponding to the signal level of the broadcast signal received by the first receiving unit 10, and the signal level of the broadcast signal reflecting the weighting value ( It is a processing unit that outputs the power P) to the signal synthesis unit 30 for each carrier frequency.

  The weight value setting unit 40 includes a transmission line response unit 41, a power calculation unit 42, a disturbance detection unit 43, a weight value adjustment unit 44, and an integrator 45.

  Similarly to the weight value setting unit 40 connected to the first reception unit 10, the weight value setting unit 50 connected to the second reception unit 20 also includes a transmission line response unit 51, a power calculation unit 52, and interference detection. A unit 53, a weight value adjustment unit 54, and an integrator 55 are provided.

  As described above, the first receiving unit 10 and the second receiving unit 20 have the same configuration, and the two weighting value setting units 40 and 50 have the same configuration. The configuration of the weight value setting unit 40 will be described, and the description of the second receiving unit 20 and the weight value setting unit 50 will be omitted.

  The tuner unit 11 of the first receiving unit 10 performs predetermined frequency conversion processing and filter processing on the broadcast signal received by the antenna at the front of the vehicle, and then converts the broadcast signal to A / D (analog / digital). ) A processing unit that converts and outputs to the FFT unit 12.

  The FFT unit 12 converts the time domain broadcast signal input from the tuner unit 11 into a frequency domain broadcast signal by fast Fourier transform and demodulates the broadcast signal, and the signal synthesis unit 30 and the weight value setting unit 40. It is a processing part which outputs to.

  Based on the broadcast signal input from the FFT unit 12, the transmission line response unit 41 of the weight value setting unit 40 transmits a transmission line response corresponding to each carrier frequency (hereinafter referred to as “carrier”) included in the broadcast signal. It is a processing unit that calculates and outputs to the power calculation unit 42 and the interference detection unit 43.

  Based on the transmission path response input from the transmission path response unit 41, the power calculation unit 42 calculates the power P (reception strength) of each carrier corresponding to a plurality of carriers included in the broadcast signal as the signal level of each carrier. And a processing unit that outputs to the integrator 45.

  The interference detection unit 43 is a processing unit that detects a carrier including noise from a plurality of carriers included in the broadcast signal input from the FFT unit 12 and outputs the detection result to the weight value adjustment unit 44.

  FIG. 2 is a functional block diagram showing a configuration of the interference detection unit 43 of the in-vehicle device 1 according to the present embodiment. As illustrated in FIG. 2, the interference detection unit 43 includes a MER generation unit 61, a threshold generation unit 62, and a comparator 63.

  The MER generation unit 61 calculates a modulation error ratio (MER) for each of the plurality of carriers included in the broadcast signal demodulated by the FFT unit 12 and outputs the modulation error ratio (MER) to the threshold generation unit 62 and the comparator 63. Part.

  The threshold generation unit 62 includes an average MER generation unit 71, a switch 72, a fixed threshold 73, and an adder 74. The average MER generation unit 71 is a processing unit that calculates an average value of MER of each carrier input from the MER generation unit 61 (hereinafter referred to as “average MER”) and outputs the average value to the switch 72.

  The switch 72 is normally in an ON state, and when an operation signal (ON / OFF signal) input when a setting operation of a weight value related to a specific carrier is performed from the setting operation unit 3, The switch circuit is turned off when a MER of a specific carrier is input.

  The adder 74 adds the predetermined fixed threshold value input from the fixed threshold value 73 and the average MER input from the average MER generating unit 71 to generate a threshold value, and outputs the threshold value to the comparator 63. The adder 74 outputs a threshold value when the switch 72 is in an ON state, and stops outputting the threshold value when the switch 72 is in an OFF state.

  Note that the fixed threshold value output from the fixed threshold value 73 is a threshold value output from the threshold value generating unit 62 by causing the first receiving unit 10 to receive a test signal in which noise is mixed in advance and a test signal in which noise is not mixed. The threshold is set to be higher than the maximum MER of the test signal not mixed with noise and lower than the minimum MER of the test signal mixed with noise.

  The comparator 63 performs a comparison process between the MER corresponding to each carrier sequentially input from the MER generating unit 61 and the threshold input from the threshold generating unit 62, and when the MER is equal to or greater than the threshold, It is determined that noise is mixed in the corresponding carrier, and a signal indicating that is output to the weight value adjustment unit 44.

  Returning to the description of FIG. 1, when a signal indicating that noise is mixed in the carrier is input from the interference detection unit 43, the weight value adjustment unit 44 receives a broadcast signal corresponding to the carrier in which noise is detected. On the other hand, the weighting value is set by outputting a weighting value lower than the weighting value according to the signal level (for example, weighting value = 0) to the integrator 45.

  The integrator 45 integrates the power P of each carrier sequentially input from the power calculator 42 and the weight value input from the weight value adjuster 44 and outputs the result to the signal combiner 30.

  The signal combining unit 30 is a processing unit that combines broadcast signals input from the first receiving unit 10 and the second receiving unit 20 by MRC (Maximum Ratio Combining) and outputs a combined signal.

  In this signal synthesizer 30, after synchronizing the phases of the broadcast signals respectively input from the first receiver 10 and the second receiver 20, the weight value setting units 40, 50 for each carrier of each broadcast signal. The weighting process using the weighting values set by the above is sequentially performed, and the broadcast signal after the weighting process is synthesized.

  Specifically, the signal synthesizer 30 corresponds to each carrier by the equation A {D1 * (P1 * K1) + D2 * (P2 * K2)} / {(P1 * K1) + (P2 * K2)}. A weighting process is performed on the broadcast signal.

  In Formula A, D1 is data corresponding to each carrier received by the first receiver 10, P1 is power P corresponding to each carrier of the broadcast signal received by the first receiver 10, and K1 is first It is a weighting value corresponding to each carrier of the broadcast signal received by the receiving unit 10.

  In Formula A, D2 is data corresponding to each carrier received by the second receiving unit 20, P2 is power P, K2 corresponding to each carrier of the broadcast signal received by the first receiving unit 20, and It is a weighting value corresponding to each carrier of the broadcast signal received by the second receiving unit 20.

  When the signal synthesizer 30 detects a predetermined symbol included in the input broadcast signal, each carrier signal input from the weight value setting unit 40 at that time is counted by a carrier counter that sequentially counts up from the detection timing. Substituting the weighting values corresponding to (power P multiplied by the weighting values: P1 * K1, P2 * K2) into the formula A, the weighting processing of the broadcast signal corresponding to each carrier is performed.

  That is, when the carrier counter counts a number corresponding to a carrier in which noise is mixed (hereinafter referred to as “carrier number”), the signal synthesis unit 30 reduces the value corresponding to the carrier number. Is substituted into Formula A to perform weighting processing.

  Therefore, in the combined signal output from the signal combining unit 30, the influence of the carrier mixed with noise is reduced.

  The synthesized signal synthesized by the signal synthesizing unit 30 is subjected to error correction processing by FEC (Forward Error Correction), and then outputted to a predetermined display unit (not shown) and displayed as an image.

  Thus, in the in-vehicle device 1 of the present embodiment, when the broadcast signals input from the first receiving unit 10 and the second receiving unit 20 are respectively subjected to weighting processing for each carrier and synthesized, interference detection is performed. The carrier in which noise is mixed is automatically determined by the unit 43, and for a broadcast signal corresponding to the carrier determined to be mixed in, the weight value corresponding to the signal level of the broadcast signal is used. The broadcast signal is synthesized after applying a weighting process with a low weighting value.

  Therefore, when the broadcast signals received by the plurality of receiving units (the first receiving unit 10 and the second receiving unit 20) are combined, they are received by each receiving unit (the first receiving unit 10 and the second receiving unit 20). The broadcast signal can be weighted in carrier units.

  As a result, for example, when other electronic devices mounted on a vehicle such as a wiper, a power window, a car navigation system, etc. are activated, noise of a specific frequency is generated and the noise is mixed into a broadcast signal. However, since the broadcast signal can be synthesized by lowering the weight value of the specific carrier corresponding to the specific frequency, the signal quality of the synthesized signal can be kept good.

  In addition, in the in-vehicle device 1, the carrier specified by operating the setting operation unit 3 in addition to the function of automatically detecting the carrier in which noise is mixed as described above and lowering the weighting value for the carrier. Is provided with a function of reducing the weighting value applied to the carrier.

  In order to realize the weight value setting function by the user's operation, the weight value setting memory 2 of the in-vehicle device 1 stores a plurality of types of weight values used by the weight value adjustment units 44 and 54 for setting the weight values. Has been.

  Moreover, in this vehicle-mounted apparatus 1, it is comprised so that the carrier number and weighting value which lower a weighting value can be individually set for every antenna by a user operating the setting operation part 3. FIG.

  When the setting operation unit 3 receives a weighting value setting operation (setting start operation) by the user, an antenna specifying operation for decreasing the weighting value, a carrier number specifying operation for decreasing the weighting value, and a specifying operation for specifying a desired weighting value. The operation signal corresponding to each operation is output to the control unit 4.

  The setting operation unit 3 receives an operation signal (ON / OFF signal) including the designated carrier number when the operation for designating the carrier number of the carrier for setting the weighting value is performed by the user. To 53. When the carrier number is input from the setting operation unit 3, the interference detection units 43 and 53 stop determining noise regarding the carrier corresponding to the carrier number.

  The control unit 4 includes an information processing apparatus having a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory).

  In the control unit 4, the CPU reads a predetermined program from the ROM and executes the program using the RAM as a work area, so that the setting operation unit 3 by the user is based on an operation signal input from the setting operation unit 3. The weighting value setting process corresponding to the operation is performed. The processing executed by the CPU will be described in detail later.

  When an operation signal designating a carrier number and a weighting value for lowering the weighting value is input from the setting operation unit 3, the control unit 4 stores the weighting value setting memory 2 by executing a predetermined information processing program. The weighting value designated by the user is selected from the plurality of weighting values, and is output to the weighting value adjusting units 44 and 54 together with the carrier number designated by the user.

  Further, when an operation signal corresponding to an antenna designating operation for lowering the weight value is input, the control unit 4 sends the carrier number and the weight value to the weight value adjusting units 44 and 54 corresponding to the antenna designated by the user. Is output.

  The weight value adjustment units 44 and 54 output weight values to the integrators 45 and 55 at the timing when the carrier power P corresponding to the carrier number input from the control unit 4 is input to the integrator 45.

  As described above, the in-vehicle device 1 according to the present embodiment can perform the weighting process using the weighting value designated by the user on the carrier designated by the user based on the operation of the setting operation unit 3 by the user.

  In addition, when the antenna for setting the weight value is designated by the user, the in-vehicle device 1 selectively sets the carrier weight value designated by the user for the broadcast signal received by the antenna. can do.

  Therefore, according to this vehicle-mounted apparatus 1, the weighting process suitable for a user preference can be performed for every carrier of a broadcast signal according to the driving | running | working environment etc. of a vehicle.

  Further, in this in-vehicle apparatus 1, when the interference detection units 43 and 53 detect a carrier including noise, the weight value adjustment units 44 and 54 corresponding to the carrier number of the carrier as interference frequency information and the weight value setting memory 2 Output to and memorize.

  The weight value setting memory 2 stores the interference frequency information and a predetermined weight value (a value lower than the weight value corresponding to the signal level) in association with each other.

  Then, the weight value adjustment units 44 and 54 select the weight value associated with the carrier corresponding to the interference frequency information from the weight value setting memory 2 and output the selected value to the integrators 45 and 55.

  Thus, in the in-vehicle device 1 of the present embodiment, since the carrier number is stored in the weighting value setting memory 2 for the carrier once the noise is detected, when the carrier is received next time, The weighting process can be automatically performed with a predetermined weighting value lower than the signal level.

  Therefore, for example, before shipping the in-vehicle device 1, the in-vehicle device 1 can receive and learn a test signal in which noise is preliminarily mixed in a carrier in which noise is expected to be shipped.

  Moreover, in the vehicle-mounted apparatus 1 of this embodiment, when other electronic devices, such as a wiper, a power window, an electric mirror, and a car navigation system, which are equipped in the vehicle are activated or operated, an activation signal indicating that is provided. The control unit 4 is configured to receive from each electronic device.

  The weight value setting memory 2 is weighted according to the type of activation signal output from another electronic device mounted on the vehicle, the carrier number affected by the activation or operation of each electronic device, and the signal level. A predetermined weight value lower than the value is stored in association with each other.

  Then, when the activation signal is input from another electronic device mounted on the vehicle, the control unit 4 outputs the carrier number and the weight value corresponding to the activation signal to the weight value adjustment units 44 and 54. .

  The weight value adjustment units 44 and 54 output weight values to the integrators 45 and 55 at the timing when the carrier power P corresponding to the carrier number input from the control unit 4 is input to the integrator 45.

  Thereby, even if this electronic device 1 is a case where other electronic equipment starts or operates at arbitrary timing, it responds to the signal level with respect to the broadcast signal of the carrier affected by the operation of the electronic equipment. A weighting process using a predetermined weight value lower than the weight value can be performed.

  Next, the vehicle-mounted device 1 according to the present embodiment detects a carrier affected by noise, and performs a weighting process with a weighting value lower than the weighting value according to the signal level for the broadcast signal corresponding to the carrier. An example in the case of performing will be described with reference to FIGS.

3 is an explanatory diagram showing a signal level when noise is mixed in the broadcast signal, FIG. 4 is an explanatory diagram showing MER when noise is mixed in the broadcast signal, and FIG. 5 is a signal synthesis unit. 6 is a timing chart showing the adjustment timing of the weighting value by.

  Hereinafter, the broadcast signal reception system by the first reception unit 10 will be referred to as branch (1), and the broadcast signal reception system by the second reception unit 20 will be referred to as branch (2).

  Here, as shown in FIG. 3A, at a certain time, a broadcast signal including a plurality of carriers (here, carrier numbers 0 to 15) in which noise is not mixed is received by the branch (1). As shown in FIG. 3B, a case where a broadcast signal including a carrier mixed with noise is received by the branch (2) at time will be described.

  As shown in FIG. 3B, in the broadcast signal received by the branch (2), the carrier of the carrier number 4 receives noise, and the power P as the signal level is an extremely high value (here, 20). ).

  As described above, when a carrier whose power P has increased due to noise is weighted using a weighting value corresponding to the signal level, the quality of the broadcast signal corresponding to this carrier is degraded due to the noise. Nevertheless, the broadcast signal is weighted with a larger weighting value than the broadcast signal of carrier number 4 received in branch (1).

  As a result, in the composite signal, the broadcast signal of the carrier number 4 that is affected by the noise received by the branch (2) is emphasized, and the image quality when the composite signal is displayed as an image is deteriorated.

  In the in-vehicle device of this embodiment, the carrier affected by the noise is detected based on the MER of each carrier, and the weighting value related to the broadcast signal corresponding to the carrier affected by the noise is weighted according to the signal level. The weighting process is performed by changing to a value lower than the value.

  That is, when the second receiving unit 20 of the branch (2) receives the broadcast signal shown in FIG. 3B, the disturbance detecting unit 53 of the weight value setting unit 50 connected to the second receiving unit 20 is received. For each carrier included in the broadcast signal, MER is calculated in the order of the carrier number.

  At this time, as shown in FIG. 4, the interference detection unit 53 detects that the MER related to the carrier of the carrier number 4 exceeds the threshold, determines that noise is mixed, and outputs a signal indicating that. The data is output to the weight value adjustment unit 54.

  When the weight value adjustment unit 54 receives a signal indicating that noise is mixed in the carrier of the carrier number 4 from the interference detection unit 53, the power P of the carrier of the carrier number 4 is input to the accumulator 55. , “0” is output to the integrator 55 as a weighting value.

  When the weight value “0” is input from the weight value adjustment unit 54, the integrator 55 multiplies the carrier power P by the weight value “0” and outputs the result to the signal synthesis unit 30. If the weight value “0” is not input from the weight value adjustment unit 54, the integrator 55 multiplies the carrier power P by the weight value “1” and outputs the result to the signal synthesis unit 30.

  As shown in FIG. 5, the signal synthesizer 30 starts counting by the carrier counter when a predetermined symbol is input, and inputs each in the order of the carrier number from the branch (1) and the branch (2). A value obtained by multiplying the carrier powers P1 and P2 by the weighting values K1 and K2 corresponding to each carrier is substituted into the above-described equation A, and further, the data D1 and D2 received at each branch are substituted into the equation A. Then, the maximum ratio synthesis of the broadcast signal is performed.

  As can be seen from FIG. 5, the signal synthesizer 30 sets the weighting value K2 to be lowered from “1” to “0” for the carrier number 4 that has received noise, so that the carrier counter and the setting coincide with each other. The weighting value K2 is lowered.

  That is, in the weighting process by the signal synthesis unit 30, the weighting value K2 when the carrier counter counts “4” is “0”, so that the power P2 “20” increased by the influence of noise is weighted by the weighting value K2. The influence of the broadcast signal of the carrier number 4 received by the branch (2) by being multiplied by “0” is excluded from the synthesized signal.

  Next, processing executed by the control unit 4 of the in-vehicle device 1 when an operation signal from the setting operation unit 3 or an activation signal from another electronic device is input will be described. FIG. 6 is a flowchart illustrating processing executed by the control unit 4 of the in-vehicle device 1 according to the present embodiment.

  As shown in FIG. 6, when the vehicle-mounted device 1 is powered on, the control unit 4 determines whether or not an activation signal has been received from another electronic device mounted on the vehicle (step S1). If it is determined that the activation signal has been received (step S1: Yes), the carrier number and weighting value corresponding to the activation signal are output to the corresponding branch (step S2).

  At this time, the control unit 4 determines the electronic device that has transmitted the activation signal based on the input activation signal, and outputs the carrier number and the weight value to the branch closer to the determined electronic device. Thereafter, the control unit 4 ends the process.

  On the other hand, when it determines with having not received the starting signal (step S1: No), the control part 4 determines whether there was any weight value setting operation (setting start operation) by a user (step S3).

  If the control unit 4 determines that a weight value setting operation has been performed based on the operation signal from the setting operation unit 3 (step S3: Yes), the process proceeds to step S4. On the other hand, the control part 4 complete | finishes a process, when it determines with there being no weighting value setting operation (step S3: No).

  In step S4, the control unit 4 determines whether or not there has been an antenna designation operation by the user. If it is determined that there has been an antenna designation operation (step S4: Yes), the process proceeds to step S5. On the other hand, if the control unit 4 determines that the antenna designation operation has not been performed (step S4: No), the process proceeds to step S8.

  In step S5, the control unit 4 determines whether or not a carrier number has been designated by the user. If it is determined that the carrier number has been designated (step S5: Yes), the process proceeds to step S6. On the other hand, when it determines with the carrier number not being designated (step S5: No), the control part 4 repeats the determination process of step S5 until a carrier number is designated.

  In step S6, the control unit 4 determines whether or not a weighting value has been specified by the user. If it is determined that the weighting value has been specified (step S6: Yes), the process proceeds to step S7.

  On the other hand, when it determines with the weighting value not being designated (step S6: No), the control part 4 repeats the determination process of step S6 until a weighting value is designated. The control unit 4 is configured to accept not only “0” but also any value between “0” and “1” as a weighting value received from the user.

  In step S7, the control unit 4 outputs the carrier number designated by the user and the weighting value to the branch corresponding to the designated antenna, and ends the process.

  In step S8, the control unit 4 determines whether or not a carrier number has been designated by the user. If it is determined that the carrier number has been designated (step S8: Yes), the process proceeds to step S9. On the other hand, when it determines with the carrier number not being designated (step S8: No), the control part 4 repeats the determination process of step S8 until a carrier number is designated.

  In step S9, the control unit 4 determines whether or not a weighting value has been specified by the user. If it is determined that the weighting value has been specified (step S9: Yes), the process proceeds to step S10.

  On the other hand, when it determines with the weighting value not being designated (step S9: No), the control part 4 repeats the determination process of step S9 until a weighting value is designated. In step S10, the control unit 4 outputs the carrier number and weighting value designated by the user to all branches, and ends the process. In addition, the control part 4 will start a process from step S1 again, after complete | finishing a process.

  In the process shown in FIG. 6, when the user performs a weighting value setting operation, the weighting value specification by the user is an essential condition. However, when the weighting value specification is omitted and the carrier number is specified, The processing can be changed so that “0” is always output to the branch as the weighting value.

  In the processing shown in FIG. 6, the carrier number and the weighting value are output to the branch closer to the electronic device that has transmitted the activation signal to the control unit 4. The processing may be changed so that the carrier number and the weighting value are output.

  In the in-vehicle apparatus 1 according to the present embodiment, when the carrier in which noise is mixed is automatically detected by the interference detection units 43 and 53 and the weighting value is lowered, the weighting value is uniformly set to “0”. A weight value corresponding to the noise level mixed in the carrier may be set.

  In the case of such a configuration, the interference detection units 43 and 53 are configured to generate a plurality of types of threshold values by the threshold value generation unit 62 and compare each threshold value with the MER of each carrier to determine the noise level.

  The weight value adjustment unit 44 is configured to obtain a weight value having a magnitude inversely proportional to the noise level determined by the interference detection units 43 and 53 from the weight value setting memory 2 and output the weight value to the integrator 45. By adopting such a configuration, it is possible to finely adjust the weight value for each carrier.

  As described above, in the in-vehicle device 1 according to the present embodiment, the weighting value at the time of maximum ratio synthesis can be adjusted for each carrier included in the received broadcast signal. Even when noise is mixed in a specific carrier due to noise from an electronic device, adverse effects due to the noise can be excluded from the synthesized signal.

DESCRIPTION OF SYMBOLS 1 In-vehicle apparatus 10 1st receiving part 20 2nd receiving part 11, 21 Tuner part 12, 22 FFT part 30 Signal synthetic | combination part 40, 50 Weighting value setting part 41, 51 Transmission path response part 42, 52 Power calculation part 43, 53 Interference detection unit 44, 54 Weight value adjustment unit 45, 55 Accumulator 61 MER generation unit 62 Threshold generation unit 63 Comparator 71 Average MER generation unit 72 Switch 73 Fixed threshold 74 Adder 2 Weighting value setting memory 3 Setting operation unit 4 Control Part

Claims (4)

An in-vehicle device for diversity reception of a broadcast signal modulated by orthogonal frequency division multiplexing,
A plurality of receivers for receiving the broadcast signal;
A weighting value setting unit for setting a weighting value according to the signal level of each broadcast signal received by the receiving unit;
Signal synthesis for performing a weighting process on each broadcast signal corresponding to each carrier frequency received by the receiving unit using a weighting value set by the weighting value setting unit, and combining the broadcast signals after the weighting process with a maximum ratio. and parts,
A storage unit for storing the weighting value ;
The weight value setting unit includes a disturbance detection unit that detects a carrier frequency including noise from a received broadcast signal;
A weighting value adjusting unit that sets a weighting value lower than a weighting value corresponding to a signal level as a weighting value to be applied to the carrier frequency detected by the interference detection unit;
With
When the interference detection unit detects a carrier frequency including the noise, the interference detection unit associates interference frequency information indicating the carrier frequency with a weighting value applied to a broadcast signal corresponding to the interference frequency information. Remember
The weighting value adjustment unit selects a weighting value associated with the interference frequency information from the storage unit when a carrier frequency corresponding to the interference frequency information stored in the storage unit is received. An in-vehicle device characterized by setting . An operation unit that accepts the weighting value setting operation with the hot water over The,
Control for selecting a weighting value designated by a user from the storage unit based on an operation signal input from the operation unit and setting the weighting value adjusting unit as a weighting value to be applied to a carrier frequency designated by the user The vehicle-mounted device according to claim 1, further comprising: a unit. The storage unit stores a type of activation signal indicating that another electronic device mounted on the vehicle is activated, a carrier frequency affected by activation of each electronic device, and a weighting value in association with each other,
The control unit causes the weight value adjustment unit to set a weighting value to be applied to a carrier frequency corresponding to the activation signal when the activation signal is input from the electronic device. The in-vehicle device described. The interference detection unit includes a noise level determination unit that determines a noise level included in a carrier frequency,
The in-vehicle device according to any one of claims 1 to 3 , wherein the weight value adjustment unit sets a weight value according to the noise level determined by the noise level determination unit.

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