JP2010232979A - Broadcast receiving apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a broadcast receiver that does not require processes, prior to an automatic channel selection operation, and that can carry out a proper automatic channel selection operation in response to the time of the altitude change of ionosphere which changes with the seasons. <P>SOLUTION: A broadcast receiving apparatus has a date and time calculating part consisting of a microcomputer 114 and a crystal 119 for clock for calculating current time and current date; and a sunset time data table memory 120 that stores information in which each date and each sunset time of the date correspond with each other. The microcomputer 114 refers to the sunset time data stored in the sunset time data table memory 120, by using information of the current time and date calculated by the date and time calculating part; determines whether or not the current time is before sunset or after sunset; and then changes a predetermined value of receiving sensitivity, depending on the determined result. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a broadcast receiver that can select a frequency with good reception state day and night regardless of the season without being affected by the reflection of broadcast radio waves due to the altitude change of the ionosphere.

  2. Description of the Related Art Conventionally, as an automatic channel selection device for a broadcast receiver, one that performs a process of determining a reference electric field strength prior to an automatic channel selection operation is known. That is, first, the frequency tuning unit changes the reception frequency in the radio wave reception unit stepwise by a predetermined number of samples, and detects and stores the sampling electric field strength for each reception frequency. Then, the sampled electric field strength is compared with the maximum electric field strength Y which is a very strong electric field strength set in advance in the control unit and the minimum electric field strength X which is a very weak electric field strength. Determine the field strength. Then, channel selection processing is performed based on the determined reference electric field strength (see, for example, Patent Document 1).

Further, as an automatic channel selection method for an AM radio receiver, an input electric field level determination sensitivity switching device automatically switches channel selection sensitivity based on a day / night discrimination signal output from a day / night discrimination device (patent). Reference 2).
JP-A-11-261429 JP-A-6-164325

  However, the method described in Patent Document 1 requires a process of measuring the electric field strength for each frequency prior to the automatic channel selection operation, and the processing time and power consumption for performing the above process in addition to the automatic channel selection operation. There was a problem that was necessary.

  In addition, the device described in Patent Document 2 is a device that uses a 24-hour clock as the day / night discriminating device or an optical sensor, but a device that uses a 24-hour clock only day and night. Because it is not possible to respond to the difference in time of the ionospheric altitude change depending on the season, and those that use light sensors to determine day and night are affected by sunlight conditions due to buildings and tunnels, There was a problem that it was not possible to tune in the optimum reception state.

  The present invention has been made to solve the conventional problems, and does not require the above-described processing prior to the automatic channel selection operation, and is suitable for automatic time selection corresponding to the time when the ionosphere varies in altitude depending on the season. An object of the present invention is to provide a broadcast receiver capable of station operation.

  The broadcast receiving apparatus of the present invention is a broadcast receiving apparatus that performs automatic channel selection that scans a reception frequency and selects a broadcast station having a predetermined reception sensitivity or higher, and a microcomputer that controls the operation of the automatic channel selection; Sunset stored as information in which the current time and the current date and time calculating section for calculating the current date and time, and each month and day of the year and the sunset time of each month and day are associated with each other A time data table memory, and the microcomputer uses the current time and date information calculated by the year / month / day time calculator to store sunset time data stored in the sunset time data table memory. , It is determined whether the current time is before sunset or after sunset, and the predetermined reception sensitivity value is changed according to the determination result.

With this configuration, it is possible to provide a broadcast receiving apparatus that does not require processing prior to automatic channel selection operation and that can perform appropriate automatic channel selection operation corresponding to the time when the ionosphere that varies depending on the season changes in altitude. it can.

  In the broadcast receiving apparatus according to the present invention, the year / month / day / time calculating unit includes the microcomputer and a crystal resonator.

  With this configuration, the date information and time information can be obtained with a simple circuit configuration.

  The present invention stores the current time and the current date as the information in which the date and time calculation unit for calculating the current date is associated with each month and day of the year and the sunset time of each month and day. By providing the sunset time data table memory, the processing prior to the automatic channel selection operation is not required, and the automatic channel selection operation can be performed appropriately in response to the time when the ionosphere varies depending on the season. It is possible to provide a possible broadcast receiving apparatus.

  Hereinafter, an AM radio receiver as an example of a broadcast receiver according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a block diagram of an AM radio receiving apparatus according to the first embodiment of the present invention.

  AM radio receiver 100 in the embodiment of the present invention employs a superheterodyne electronic tuning system.

  As shown in FIG. 1, the AM radio receiving device 100 is configured to receive broadcast radio waves at the forefront, similarly to a general AM radio receiver, and the frequency to be selected with the antenna input unit 101 that receives the broadcast radio waves. And a RF (Radio Frequency) AGC amplifier 103 that amplifies the desired reception frequency Fin obtained by the tuning unit 102.

  In the next stage, as a configuration for converting the desired reception frequency Fin obtained from the RF AGC amplifier 103, a mixer unit 104 that performs frequency conversion by mixing with the VCO unit 107 that outputs the local oscillation frequency Fosc is provided. .

  In order to configure a PLL (Phase Locked Loop) as a configuration for performing electronic tuning, a reference frequency divider 111 and a crystal 113 for generating a reference frequency, a programmable divider 112, a phase detector 110, an LPF unit 106, and a VCO unit 107 have.

  Furthermore, an IF (Intermediate Frequency) AGC amplifier 151 that amplifies the intermediate frequency f2-f1 obtained from the mixer unit 104 and a demodulation unit 105 are provided as a configuration for performing demodulation on the modulation signal.

  Finally, as a configuration for amplifying the demodulated signal, an audio amplifier unit 117, a speaker 118 for outputting the signal amplified by the audio amplifier unit 117, and a mute control unit 155 for muting the audio amplifier unit 117 are provided. Connected.

  In addition, the AM radio receiving apparatus 100 includes a seek button 154, a carrier level detection unit 108, a broadcast station detection unit 109, an IF count unit 115, and an IF count switch 116 in order to perform automatic channel selection (seek). Yes.

In order to control the entire apparatus in the AM radio receiver 100, a CPU or R
A microcomputer 114 having an OM and a RAM is electrically connected to each controlled component.

  Furthermore, the AM radio receiver 100 according to the present embodiment is provided with a watch crystal 119 and a sunset time data table memory 120 which are crystal resonators, and the watch crystal 119 and the time data table memory 120 are provided. It is connected to the microcomputer 114.

  The microcomputer 114 and the watch crystal 119 constitute a date / time calculation unit. That is, the microcomputer 114 vibrates the timepiece crystal 119 and counts the number of vibrations to calculate the time, and creates current time information. Furthermore, the current date information is created by counting the number of days using the created current time information. The created current time information and current date information are temporarily stored in the internal memory of the microcomputer 114.

  In FIG. 1, a tuning unit 102 has a role of tuning a desired frequency and matching with a next-stage RF AGC amplifier 103. As a method of changing the tuning frequency in accordance with the reception frequency, an electronic tuning method is generally used in which the tuning frequency is changed by changing the reverse bias voltage of the variable capacitance diode (varactor diode), and the desired reception frequency Fin is set to RF. Output to the AGC amplifier 103.

  The RF AGC amplifier 103 is an auto gain control amplifier that amplifies the power of a broadcast radio wave signal to an optimum gain in order to ensure low distortion and a high S / N ratio in subsequent signal processing.

  The VCO unit 107 is an oscillator that can change the oscillation frequency according to the supplied tuning voltage, and outputs a local oscillation frequency Fosc necessary for frequency conversion to the mixer unit 104.

  The mixer unit 104 is a frequency converter that converts the local transmission frequency Fosc output from the VCO unit 107 and the desired reception frequency Fin output from the tuning unit 102 into an intermediate frequency signal (intermediate frequency signal) and outputs the signal. That is, the mixer unit 104 has a multiplication function, and the desired reception frequency Fin output from the tuning unit 102 and the local oscillation frequency Fosc output from the VCO 107 are input to the mixer unit 104 and are intermediate frequency signals. Fosc-Fin and Fosc + Fin signals are output from the mixer unit 104.

  The programmable divider 112 is a so-called frequency divider, and receives the local transmission frequency and the frequency division ratio N output from the microcomputer 114, and outputs a signal having a frequency obtained by dividing the local transmission frequency by N. Hereinafter, this frequency is referred to as a frequency f (1 / N). A prescaler may be provided before the programmable divider 112.

  The reference frequency generation unit 111 includes a crystal oscillation circuit and a frequency division circuit, and oscillates the crystal 113, divides the oscillation frequency signal, generates a 9 kHz reference frequency signal, and outputs it.

  The phase detection unit 110 includes a phase comparator, a charge pump circuit, and the like, and a frequency f (1 / N) signal output from the programmable divider 112 and a reference frequency signal output from the reference frequency generation unit 111 are obtained. A phase difference signal indicating the phase difference between the two signals is generated by comparing the phases of these two signals, and then the charge pump circuit 3 outputs a high level voltage state, a low voltage state, and a high impedance state. The state pulse waveform is output. This output is hereinafter referred to as a charge pump output signal.

  The LPF unit 106 to which the signal output from the phase detection unit 110 is input has a low-pass filter function such as a lag filter, a lag lead filter, and an active filter, and integrates the input charge pump output signal. A DC signal is generated and the generated DC signal is output. This generated signal is referred to as the tuning voltage.

  The IF AGC amplifier 151 includes a band-pass filter circuit and a gain control amplifier circuit, and receives an intermediate frequency signal output from the mixer unit 104, and adjusts only an intermediate frequency signal around 450 kHz to an optimum level. Output.

  The demodulator 105 has an envelope detection function composed of a diode, a capacitor, a transistor, and the like, as in a general AM radio, and converts an intermediate frequency signal into an audio signal and outputs it. is there.

  The audio amplifier unit 117 receives the audio signal output from the demodulation unit 105, amplifies the audio signal input at a preset amplification factor, and outputs the amplified audio signal. The audio signal output from the audio amplifier unit 117 is converted into audio by the speaker 118 and output.

  The carrier level detection unit 108 used at the time of the seek operation has a rectifier circuit including a diode, a capacitor, a transistor, and the like. The intermediate frequency signal output from the AGC amplifier 151 for IF is input and the amplitude level of the intermediate frequency signal is input. And the amplitude level is output as a DC voltage.

  The broadcast station detection unit 109 provided at the subsequent stage of the carrier level detection unit 108 is configured by using a comparator, and the DC voltage output from the carrier level detection unit 108 is input, and whether the input DC voltage is equal to or higher than a specified level. By determining whether or not the broadcast station is less than the predetermined value and outputting it as a binary signal (High level or Low level), information indicating whether or not a broadcast station has been detected is sent to the microcomputer 114.

  The operation of the AM radio receiving apparatus 100 configured as described above will be described below with reference to FIGS.

  2 and 3 are flowcharts of software that is processed by the microcomputer 114 during the seek operation of the AM radio receiving apparatus 100. FIG.

  When the power of the AM radio receiving apparatus 100 is in an ON state, there are two statuses: a normal reception state and a seek up / down process.

  In the normal reception state, in addition to demodulating the reception frequency and outputting sound, the microcomputer 114 monitors whether or not the seek button 154 has been pressed, and when it is pressed, the seek up / down process shown in FIG. 2 is performed.

  FIG. 2 shows a flowchart related to the seek up / down process of the AM radio receiving apparatus 100, and the operation thereof will be described below.

  First, when seek up / down processing is started, ionospheric state determination processing, which will be described in detail later, is performed to determine whether the current time is after sunset or before sunset, and automatic stop setting sensitivity is determined (ST201). .

Based on the automatically set sensitivity determined in step ST201, the microcomputer 114 switches the gain of the RF AGC amplifier 102 (ST202).

  Next, the microcomputer 114 switches the IF count switch 116 to the B side shown in FIG. 1 to stop the IF frequency counting performed by the IF count unit 115 (ST203). Here, the reason for stopping the counting of the IF frequency is to prevent the search operation from being erroneously stopped by the counting operation.

  Hereinafter, the operation at the time of seek will be described as an example of the operation at the time of seek. For domestic AM radio, the reception frequency step is 9 KHz. In order to seek up, first, by dividing the frequency division ratio N by N + 1, when the current broadcast station frequency is 522 kHz (N = 108), the reception frequency is changed to +9 kHz, 531 kHz (N = 109) (ST204). . Similarly, when the frequency of the current broadcasting station is another frequency, the reception frequency is scanned by changing +9 kHz. The value of N will be described later.

  Next, broadcast station detection is performed (ST205). In step ST205, it is determined whether or not the broadcast station detection signal is recognized after waiting for a predetermined time until the PLL operates stably, and whether or not the broadcast station is detected every predetermined time. If the broadcast station detection is “present”, the IF count switch is connected to the A side to start IF count (ST206), and the IF count value is evaluated to determine whether a predetermined number of broadcast stations are detected every predetermined time. (ST207). If the broadcast station detection is “none”, the process returns to step ST204.

  If the IF count value is within the specified range in step ST207, the gain of the RF AGC amplifier is set to the normal state and returned to the normal reception state (ST208).

  If the IF count value is not within the specified range in step ST207, it is determined that there is an erroneous stop due to noise other than broadcast radio waves, and the process returns to ST203.

  Here, the frequency division ratio N and the reception frequency will be described. The value of N is based on the nature of superheterodyne operation, so that the oscillation frequency of the VCO section detects the upper side wave in the case of domestic AM radio, and requires a frequency that is higher by an intermediate frequency of 450 kHz when receiving 522 kHz. Therefore, 522 kHz + 450 kHz = 972 kHz. This is because the frequency division ratio input to the programmable divider at this time is the ratio of the reference frequency and N = 972 kHz / 9 kHz (reference frequency) = 108 from a general PLL operation.

  In the above, the sensitivity switching is performed by the RF AGC amplifier, but the IF AGC amplifier and the antenna input unit may be used. In some cases, the RF AGC amplifier, the IF AGC amplifier, and the antenna input unit are all or a plurality of parts.

  Next, the operation of the ionosphere state determination flow in step ST201 will be described with reference to FIGS. FIG. 3 is a flowchart showing a flow of ionospheric state determination, and FIG. 4 is a diagram showing a sunset time data table.

  First, the current date information is obtained from the current date information by calculation of the microcomputer 114 using the watch crystal 119 (ST301).

  Then, a reference destination address in the sunset time data table memory 120 shown in FIG. 4, which will be described later in detail, is calculated from the date information obtained in step ST301, and the current sunset time is obtained from the reference destination address (ST302). . Thereafter, current time information is obtained by calculation of the microcomputer 114 using the clock crystal 119 (ST303).

  Next, the current sunset time obtained in step ST302 is compared with the current time information obtained in step ST303 to determine whether the current time information is after the sunset time (ST304).

  If the result of determination in step ST304 is that the current time information is after the sunset time, the automatic stop sensitivity is set for the night (ST305), and if the current time information is before the sunset time, the automatic stop sensitivity is set. Set for daytime (ST306).

  It should be noted that the automatic stop sensitivity setting may be performed not only for switching between two values for nighttime and daytime but also for switching more than three values before and after the sunset time.

  The current date information and current time information can also be obtained by converting the radio timepiece, GPS, teletext year / month / day time information into an electrical signal that can be input to the microcomputer and connecting it to the microcomputer.

  The contents of the data stored in the sunset time data table memory 120 are information associating each month and day in one year with the sunset time of each month as shown in FIG. As information in the sunset time data table memory 120, fixed information in which the sunset time is uniquely determined in advance may be used, or when the AM radio receiver has a means for updating information, it is calculated from weather data. Information that is constantly updated may be used.

  In the above description, an AM receiver has been described as an example, but the present invention is not limited to an AM broadcast receiver.

  As described above, by obtaining the season and sunset time correlated with the ionospheric altitude change from the sunset time data table memory, by appropriately switching the automatic stop sensitivity setting of the seek that matches the ionospheric altitude, The problem of being unable to tune in the optimum reception state during seek can be improved without measuring the electric field intensity prior to the seek operation. Further, since measurement of the electric field strength is unnecessary, the time for measurement and the power consumption for measurement can be suppressed.

  As described above, the broadcast receiving apparatus according to the present invention includes a year / month / day / time calculating unit for calculating the current time and the current year / month / day, each month / day of one year, and sunset of each month / day. By providing a sunset time data table memory that is stored as information associated with time, processing prior to automatic channel selection becomes unnecessary, and the ionosphere that varies depending on the season changes in altitude. It has the effect of being able to perform an appropriate automatic channel selection operation, and is useful as a broadcast receiving device that performs automatic channel selection.

Block diagram of superheterodyne electronic tuning AM radio in an embodiment of the present invention Flow chart of seek up / down processing in the embodiment of the present invention Flow diagram of ionospheric state determination in an embodiment of the present invention The figure which shows an example of the sunset time data table memory in embodiment of this invention

DESCRIPTION OF SYMBOLS 101 Antenna input part 102 Tuning part 103 RF AGC amplifier 104 Mixer part 105 Demodulation part 106 LPF part 107 VCO part 108 Carrier level detection part 109 Broadcast station detection part 110 Phase detection part 111 Reference frequency dividing part 112 Programmable divider 113 Crystal 114 Microcomputer 115 IF count unit 116 IF count switch 117 Audio amplifier unit 118 Speaker 119 Clock crystal 120 Sunset time data table memory 151 AGC amplifier for IF 154 Seek button 155 Mute control unit

Claims (2)

A broadcast receiver that performs automatic channel selection by scanning a reception frequency and selecting a broadcast station having a predetermined reception sensitivity or higher,
A microcomputer for controlling the operation of the automatic channel selection; a date / time calculating unit for calculating a current time and a current date / time; a date for each year and a sunset time for each month; And a sunset time data table memory stored as associated information,
The microcomputer refers to the sunset time data stored in the sunset time data table memory using the current time and date information calculated by the year / month / day / time calculating unit, and the current time is A broadcast receiving apparatus characterized by discriminating whether it is before dawn or after sunset, and changing the value of the predetermined reception sensitivity according to the discrimination result.   The broadcast receiving apparatus according to claim 1, wherein the year / month / day / time calculation unit includes the microcomputer and a crystal resonator.