JPH08307790A - Mobile bs tuner - Google Patents

Abstract

PURPOSE: To stably perform the switch of a moving image and a still image by surely holding a set threshold level without being affected by vibration, etc. CONSTITUTION: A BS reception unit 11 performs a station selection for received broadcasting radio wave, converts the radio wave into a video signal and outputs the C/N level voltage value showing reception level intensity. A still image unit 12 converts the video signals from the BS reception unit 11 into digital signals, successively updates and stores the digital signals in a frame memory 22, further converts the signals into analog signals and makes still image video signals. A CPU 14 performs a digital conversion for the C/N level voltage value from the BS reception unit 11 and compares the value with the threshold which is preliminarily stored in an EEPROM 34. When the C/N level digital value is more than the threshold, the moving image video signal outputted from the BS reception unit 11 is selected. When the digital value is smaller than the threshold, a video switch 13 is controlled so as to select the still image video signal from the still image unit 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile BS (Broa) for tracking a satellite broadcast while a sightseeing bus, ship, etc. are traveling.
dcasting Satellite: satellite tuner.

[0002]

2. Description of the Related Art A mobile B mounted on a sightseeing bus or ship
The S tuner has a function to switch between moving images and still images. For example, in places with poor radio wave conditions such as tunnels or between buildings in urban areas, the still images previously stored in the frame memory are switched to the TV monitor. It is possible to cut a moving image display in which an image is distorted by displaying the image. By switching to the still image display when the image is disturbed in this way, a person watching the TV monitor can reduce the tiredness and fatigue of the eyes more than when watching the noise screen or the disturbed screen. effective.

Conventionally, a variable resistor (volume) provided on a front panel or a rear panel of a BS tuner sets a reception level for switching between a moving image and a still image. Therefore, by adjusting the variable resistor, it is possible to switch between a moving image and a still image at any reception level.

[0004]

In the conventional mobile BS tuner, the voltage value indicating the threshold level set by the variable resistor and the C / N indicating the reception level strength of the broadcast radio wave are set.
Two voltage values, (Carrier per Noise) level voltage value, are input to a comparator (comparator) to compare high and low voltages.

The BS tuner has a C /
If the N-level voltage value is higher, C that the user assumed
/ N level is determined to be secured, and the moving image is output to the TV monitor and displayed.

If the C / N level voltage value is lower than the threshold level, the C / N level assumed by the user is not secured, that is, the received broadcast wave is an image containing noise. Then, the still image is displayed on the TV monitor.

With the above method, it is possible to switch between a moving image and a still image at any reception level. However, in the above-mentioned conventional BS tuner for movement, since the threshold level is set by using the variable resistor, the setting position of the variable resistor is slightly deviated due to the vibration of the vehicle, etc. Could change.

The present invention has been made in view of the above circumstances, and can reliably hold a set threshold level without being affected by vibrations and the like, and can perform stable switching between a moving image and a still image. It is an object of the present invention to provide a mobile BS tuner capable of performing the following.

[0009]

Mobile BS according to the present invention
The tuner selects a designated channel for the broadcast radio wave received by the BS antenna, converts it into a video signal, and outputs a C / N level voltage value indicating the intensity of the reception level, and a BS reception unit for this BS reception. A still image unit for sequentially updating and storing a video signal output from the unit, and a video switch for selecting and outputting the video signal output from the BS receiving unit or the still image stored in the still image unit. An A / D conversion means for converting the C / N level voltage value output from the BS receiving unit into a C / N level digital value, a memory for storing the threshold level, and a memory for storing the threshold level. The threshold level and the C / N level digital value output from the A / D conversion means are compared to obtain C / N
Means for controlling the video switch so as to select the video signal output from the BS receiving unit when the level digital value is above the threshold level;
When the N level digital value is smaller than the threshold level, the still image unit memory update processing is prohibited, and
Means for controlling the video switch so as to select a still image stored in the still image unit. Further, the threshold level stored in the memory is configured to be switched to a different value by a threshold level changeover switch.

[0010]

The BS receiving unit selects a channel designated by the user from the broadcast waves received by the BS antenna and converts it into a video signal. Further, the BS receiving unit outputs a C / N level voltage value indicating the reception level strength of the received broadcast radio wave. The still image unit converts the video signal from the BS receiving unit into a digital signal and updates and stores it in a frame memory in frame units. The video signal stored in the frame memory is converted into an analog signal and output as a still image video signal.

C / output from the BS receiving unit
The N level voltage value is converted into a C / N level digital value by the A / D conversion means and compared with a threshold level stored in advance in the memory. C / N level ・ Digital value exceeds threshold level (C / N ratio is good)
In this case, the video signal output from the BS receiving unit that changes in real time, that is, the moving image video signal is selected by the video switch, and the C / N level digital value does not exceed the threshold level (C / N level). If the N ratio is bad), the still image video signal held in the still image unit is selected by the video switch. The video signal selected by the video switch is sent to the monitor TV and displayed. The threshold level stored in the memory is cyclically changed each time the user presses the threshold level changeover switch.

As described above, the C / N level output from the BS receiving unit is compared with the threshold level stored in the memory in advance, and the magnitude of the C / N level is discriminated. No electronic parts are required, the circuit configuration can be simplified, cost can be reduced, and maintainability can be improved. Further, since the variable resistor is not used, there is no fear that the threshold level will fluctuate due to the vibration of the vehicle or the like, and stable operation can be always performed.

[0013]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a mobile BS tuner according to an embodiment of the present invention.

In FIG. 1, 1 is a BS antenna, 2 is a mobile BS tuner, 3 is a monitor TV, and 4 is a threshold level changeover switch. The mobile BS tuner 2 is
It comprises a BS receiving unit 11, a still image unit 12, a video switch 13, and a CPU 14.

The BS receiving unit 11 operates according to a control command from the CPU 14, selects a designated channel from the broadcast radio waves received by the BS antenna 1 and converts it into a video signal, and the still image unit 12 and the video switch 13 are selected. Output to. In addition, the BS receiving unit 11 has a C / N (Ca
The level voltage value obtained by converting the rrier per noise) value into a voltage value is output to the CPU 14. The tuning data for the BS receiving unit 11 is C depending on the user's tuning operation.
It is given from PU14.

The still image unit 12 includes an A / D converter 2
1, a frame memory 22 and a D / A converter 23, and operates according to a control command from the CPU 14. A /
The D converter 21 samples the video signal from the BS receiving unit 11 at a constant cycle (time for the scanning line to scan one screen), converts it into a digital signal, and stores one screen of data in the frame memory 22. . The video signal stored in the frame memory 22 is updated at regular intervals. In this case, the still image unit 12 stops the process of updating the contents of the frame memory 22 by the control signal from the CPU 14 when the C / N ratio is bad, and holds the good data of one cycle before.

The D / A converter 23 is used for the still image unit 12
The digital video signal stored in is read back to the analog video signal and output to the video switch 13 as a still image video signal. This video switch 13 is C
A video signal from the still image unit 12 or a video signal from the BS receiving unit 11 is selected according to an instruction from the PU 14 and output to the monitor TV 3.

The CPU 14 includes an A / D converter 31, R
AM32, ROM33, EEPROM (Electrically E
rasable Programmable Reed-Only Memory) 34, the C / N level voltage value from the BS receiving unit 11 is A / D converted by the A / D converter 31, and the C / N level
The digital value is stored in the RAM 32. A control program is stored in the ROM 33, and a threshold level is stored in the EEPROM 34. The threshold level stored in the EEPROM 34 is cyclically changed by the CPU 14 each time the user presses the threshold level changeover switch 4.

The CPU 14 compares the C / N level digital value stored in the RAM 32 and the threshold level stored in the EEPROM 34 with each other to determine the C / N level.
If the digital value exceeds the threshold level (C / N ratio is good), control is performed to select and output the moving image video signal directly sent from the BS reception unit 11 to the video switch 13. , The C / N level digital value is smaller than the threshold level (the C / N ratio is bad), the still image video signal from the still image unit 12 is selected and output.

The video signal selected by the video switch 13 is sent to the monitor TV 3 and displayed. Figure 2
Shows the program configuration stored in the ROM 33 of the CPU 14. The ROM 33 includes a scheduler program 41, a threshold level storage processing program 42, a C / N level storage processing program 43,
A moving image / still image switching processing program 44 is stored.

Next, the C / N level determination process will be described with reference to the flow charts of FIGS. The scheduler program 41 operates as a kernel of the program unit as shown in FIG. 3, and has a threshold level storage processing program 42 and a C / N level storage processing program 43.
Then, the moving image / still image switching processing program 44 is sequentially activated (steps A1, A2, A3).

Threshold level storage processing program 42
Determines whether the threshold level changeover switch 4 is operated by the user as shown in FIG. 4, that is, whether there is a threshold level change request (step B).
1) If there is a threshold level change request, the threshold level is changed and written to the EEPROM 34, and the stored contents are updated (step B2). For example, 100 → 101 → 102 → 103 → 104 → 105 → 1 can be used to update the threshold level.
It is performed cyclically as in 00 → ... E as above
By storing the threshold level in the EPROM 34, the threshold level is held even when the mobile BS tuner 2 is powered off.

Instead of the EEPROM 34, a battery-backed RAM may be used. C /
The N level storage processing program 43 reads the C / N level voltage value from the BS reception unit 11 as shown in FIG. 5, and the C / N is read at a constant time interval by the A / D converter 31.
Convert to level digital value (step C1), RAM
It is stored in 32 (step C2).

Moving image / still image switching processing program 44
Is the C / N stored in the RAM 32 as shown in FIG.
The level digital value is compared with the magnitude of the threshold level stored in the EEPROM 34 (step D1), and "C /
It is determined whether or not N level ≧ threshold level ”(step D2). If the result of this determination is “C / N level ≧ threshold level”, set the video switch 13 to the moving image output side, that is,
Switch to the BS receiving unit 11 side (step D3).
In this case, the frame of the still image unit 12
The memory 22 is controlled so that new image data is sequentially fetched (step D4). If "C / N level <threshold level", the still image unit 12 is controlled so as to stop the operation of loading new image data into the frame memory 22 (step D5), and the video switch 13 is stopped. Switch to the image output side (step D6). Therefore, for example, in a place where the radio wave condition is bad, such as in a tunnel or between buildings in an urban area, the still image stored in the frame memory 22 is selected and displayed on the monitor TV 3.

As described above, the C / N level in the BS receiving unit 11 is taken into the CPU 14, and the EEPRO
It is compared with the threshold level stored in M34, and a moving image or a still image is selected according to the comparison result and sent to the monitor TV 3 for display.

[0026]

As described above in detail, according to the present invention, C
Since the CPU determines the / N level, electronic parts for C / N level comparison such as variable resistors and comparators are not required, and the circuit configuration can be simplified to reduce costs and improve maintainability. can do. Further, since the variable resistor is not used, there is no fear that the threshold level will fluctuate due to the vibration of the vehicle or the like, and stable operation can be always performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a mobile BS tuner according to an embodiment of the present invention.

FIG. 2 is a program configuration diagram of a CPU in the embodiment.

FIG. 3 is a flowchart showing a processing operation of a scheduler program in the embodiment.

FIG. 4 is a flowchart showing a processing operation of a threshold level storage processing program in the embodiment.

FIG. 5 is a flowchart showing a processing operation of a C / N level storage processing program in the embodiment.

FIG. 6 is a flowchart showing a processing operation of a moving image / still image switching processing program in the embodiment.

[Explanation of symbols]

 1 BS Antenna 2 Mobile BS Tuner 3 Monitor TV 4 Threshold Level Change Switch 11 BS Receiver Unit 12 Still Image Unit 13 Video Switch 14 CPU 21 A / D Converter 22 Frame Memory 23 D / A Converter 31 A / D converter 32 RAM 33 ROM 34 EEPROM

Claims (2)

[Claims] 1. A BS receiving unit for selecting a designated channel for a broadcast radio wave received by a BS antenna, converting the channel into a video signal, and outputting a C / N level voltage value indicating the intensity of a receiving level, A still image unit for sequentially updating and storing a video signal output from the BS receiving unit in units of frames, and a video signal output from the BS receiving unit or a still image stored in the still image unit is selected and output. A video switch, an A / D conversion means for converting a C / N level voltage value output from the BS receiving unit into a C / N level digital value, a memory for storing a threshold level, and a memory for storing in this memory. The threshold level thus generated is compared with the C / N level digital value output from the A / D conversion means, and the C / N level digital value is compared. Means for controlling the video switch to select the video signal output from the BS receiving unit when the threshold value is above the threshold level, and the C / N level digital value is below the threshold level. In this case, the mobile BS tuner is provided with means for controlling the video switch so as to select the still image stored in the still image unit, while prohibiting the still image unit storage update process. . 2. The mobile BS tuner according to claim 1, wherein the threshold level stored in the memory is changed to a different value by a threshold level changeover switch. Tuner.