JP5161854B2 - Receiving device, antenna switching circuit of receiving device, and tuner module of receiving device - Google Patents

Description

  The present invention relates to a receiving device, an antenna switching circuit of the receiving device, and a tuner module of the receiving device, and more particularly to a receiving device having a simplified antenna switching unit, an antenna switching circuit of the receiving device, and a tuner module of the receiving device. .

  In PND (Personal Navigation Device) and portable TV (Television), digital terrestrial broadcasting is often received in a state where it is mounted on a car. Therefore, it is important that the reception sensitivity is good in expanding the reception area. Some mobile devices such as current cellular phones receive one-segment broadcasting, which is a kind of terrestrial digital broadcasting, using a ceramic chip antenna built in the device or a rod antenna attached to the device. On the other hand, in the PND and portable TV, in addition to a film antenna built in the device (often formed by incorporating a conductor such as copper on a flexible substrate) or a rod antenna attached to the device, for example, a vehicle body Many of them are used by connecting an external antenna with a built-in LNA (Low Noise Amplifier) attached to the. The use of an external antenna can be expected to greatly improve the reception sensitivity described above. On the other hand, an antenna switching circuit for switching a reception signal supplied to the reception circuit and its switching control are required.

  Patent Document 1 relates to an antenna switching circuit. When the reception state is a strong electric field state, the power supplied to the antenna switching circuit is turned off to obtain a signal output by inter-board isolation, so that even in a strong electric field area. A technique is disclosed that suppresses deterioration and distortion of video and audio and ensures a good reception state.

JP 2000-341185 A

  As described above, the receiving circuit of the PND or the portable TV needs an antenna switching circuit for selecting which antenna's received signal is supplied to the receiving circuit and its switching control. For this reason, an IC (Integrated Circuit) for switching is mounted between the antenna and the tuner module at the head of the receiving circuit, and the antenna is switched by a control signal from an MPU (Micro Processor Unit). Note that the LNA power of the external antenna is supplied from the receiving device side.

However, the antenna switching IC needs to include a large-sized MOSFET (Metal Oxide Semiconductor Field Effect Transistor) switch, which is large and expensive. In addition, since a control signal for switching control of the switch is necessary, it is not preferable for downsizing and simplifying the apparatus.
An object of the present invention is to solve these problems and provide a receiving device, an antenna switching circuit of the receiving device, and a tuner module of the receiving device, in which the antenna switching unit is simplified.

  In order to achieve the above object, the present invention provides a tuner module of a television broadcast receiving apparatus that receives a broadcast signal transmitted with a predetermined modulation and processes the received signal, and receives the television broadcast. The received signal supplied from the first antenna and the received signal supplied from the second antenna that receives the television broadcast and is amplified by the LNA that contains the received signal, and outputs the received signal. A diode switch that controls the ON / OFF operation by supplying a predetermined DC voltage to the diode switch, and further supplies an operation power to the LNA built in the second antenna; A supply terminal of a second power supply for supplying to the diode a DC voltage lower than a DC voltage supplied to the diode switch by the first power supply; The received signal that appears on the cathode side of the Iode switch is supplied, the frequency converter that converts the frequency into a predetermined frequency band, and the received signal converted by the frequency converter is supplied, and the modulation performed at the time of transmission And a demodulator that demodulates the signal.

  Further, the present invention is a television broadcast receiving apparatus that receives a broadcast signal that is data-compressed based on the MPEG system, is transmitted with a predetermined modulation, and processes the received signal. A first antenna that receives the television broadcast, and an input terminal that receives a received signal supplied from a second antenna that amplifies the received signal with an LNA that contains the received signal, and is supplied from the first antenna. A reception signal is supplied to the anode terminal, a reception signal supplied from the input terminal is connected to the cathode terminal, a DC voltage is supplied to the cathode terminal of the diode, and the LNA built in the second antenna operates. A first power source for supplying power and a direct current voltage lower than a DC voltage supplied to the cathode terminal by the first power source at the anode terminal of the diode; A second power source for supplying a voltage, a control unit for controlling ON / OFF of the first power source, and a frequency at which a reception signal appearing on the cathode side of the diode is supplied and frequency-converted to a predetermined frequency band A conversion unit, a reception signal converted by the frequency conversion unit is supplied, a demodulation unit that demodulates the modulation applied at the time of transmission, and a reception signal demodulated by the demodulation unit is supplied and applied at the time of transmission An MPEG decoding unit that decompresses and decodes data compression based on the MPEG system, an AV-IF unit that is supplied with a received signal decoded by the MPEG decoding unit, and converts the analog signal into a format suitable for image display; It has a monitor for displaying an image of the received signal converted by the AV-IF unit.

  The present invention is also an antenna switching circuit of a television broadcast receiving apparatus that receives a broadcast signal and processes the received signal, and the received signal supplied from the first antenna that receives the television broadcast is an anode terminal. A reception signal supplied from a second antenna that receives the television broadcast and amplifies the received signal with an LNA containing the reception signal; a diode connected to the cathode terminal; and a DC voltage to the cathode terminal of the diode; Furthermore, a first power source that supplies operating power to the LNA built in the second antenna, and a DC voltage lower than the DC voltage that the first power source supplies to the cathode terminal are supplied to the anode terminal of the diode. A second power source and a control unit for controlling the first power source to be turned on and off, and cuts off a reception signal appearing on the cathode side of the diode. It is characterized in that the example output.

  The present invention also provides a tuner module of a television broadcast receiving apparatus that receives a broadcast signal transmitted with a predetermined modulation and processes the received signal, the first antenna receiving the television broadcast. And a second input to which a received signal supplied from a second antenna for receiving the television broadcast and amplifying the received signal by an LNA containing the received signal is input. The input terminal, a reception signal supplied from the first input terminal to the anode terminal, a reception signal supplied from the second input terminal to the cathode terminal, and a direct current to the cathode terminal of the diode A first power supply terminal for supplying voltage and operating power to the LNA built in the second antenna, and an anode terminal of the diode are connected to the first power supply terminal. A supply terminal of a second power source for supplying a DC voltage lower than the DC voltage supplied to the cathode terminal by the source and a reception signal appearing on the cathode side of the diode are supplied, and this is converted into a predetermined frequency band. And a demodulator that receives the received signal converted by the frequency converter and demodulates the modulation applied at the time of transmission.

  Further, the present invention is a television broadcast receiving apparatus that receives a broadcast signal that is data-compressed based on the MPEG system, is transmitted with a predetermined modulation, and processes the received signal. A first antenna that receives the television broadcast, and an input terminal that receives a received signal received by a second antenna that amplifies the received signal using an LNA that contains the received signal, and is supplied from the first antenna. A first diode having a reception signal connected to an anode terminal, and a second diode having a reception signal supplied from the input terminal connected to the anode terminal and a cathode terminal connected to the cathode terminal of the first diode Supplying a DC voltage to the anode terminal of the second diode, and further supplying an operating power to the LNA built in the second antenna. A second power source for supplying a DC voltage lower than a DC voltage supplied to the anode terminal of the second diode by the first power source, and the first power source. A control unit that performs ON / OFF control of the signal, a reception signal that appears on the cathode side of the first and second diodes, and a frequency conversion unit that converts the frequency into a predetermined frequency band, and the frequency conversion unit A demodulator that demodulates the modulation applied at the time of transmission, to which the converted received signal is supplied, and a reception signal demodulated by the demodulator is supplied, and decompresses data compression based on the MPEG system applied at the time of transmission An MPEG decoding unit for decoding the received signal, an AV-IF unit to which a reception signal decoded by the MPEG decoding unit is supplied and converted into an analog signal in a format suitable for image display, It is characterized by having a monitor for image display the converted received signal.

  The present invention is also an antenna switching circuit of a television broadcast receiving apparatus that receives a broadcast signal and processes the received signal, and the received signal supplied from the first antenna that receives the television broadcast is an anode terminal. And a reception signal supplied from a second antenna that receives the television broadcast and amplifies the reception signal by an LNA that incorporates the reception signal is connected to an anode terminal, and a cathode terminal is connected to the first diode. A second diode connected to the cathode terminal of the diode; a first power supply that supplies a DC voltage to the anode terminal of the second diode; and further supplies an operating power to the LNA built in the second antenna; The first power supply is applied to the anode terminal of the first diode, and is directly below the DC voltage supplied to the anode terminal of the second diode. A second power source for supplying a voltage; and a control unit for controlling ON / OFF of the first power source, wherein the received signal appearing on the cathode side of the first and second diodes is used as a switching output. It is a feature.

  The present invention is also a tuner module of a television broadcast receiving apparatus that receives a broadcast signal transmitted with a predetermined modulation and processes the received signal, the first antenna receiving the television broadcast. And a second input to which a received signal supplied from a second antenna for receiving the television broadcast and amplifying the received signal by an LNA containing the received signal is input. An input terminal, a first diode to which a reception signal supplied from the first input terminal is connected to an anode terminal, a reception signal supplied from the second input terminal to an anode terminal, and a cathode terminal Supplies a second diode connected to the cathode terminal of the first diode, a DC voltage to the anode terminal of the second diode, and the second antenna. A direct current lower than the direct current voltage supplied to the anode terminal of the second diode by the first power supply terminal for supplying the operating power to the built-in LNA and the anode terminal of the first diode A supply terminal of a second power source for supplying a voltage, a frequency converter that receives a reception signal appearing on the cathode side of the first and second diodes, and converts the frequency into a predetermined frequency band; and the frequency The reception signal converted by the conversion unit is supplied, and a demodulation unit that demodulates the modulation applied at the time of transmission is provided.

  According to the present invention, it is possible to provide a receiving device with a simplified antenna switching unit, an antenna switching circuit of the receiving device, and a tuner module of the receiving device, and the effect that it is possible to contribute to downsizing of the device and improvement in usability associated therewith. is there.

It is a block diagram of the broadcast receiving part of the conventional receiver. It is a block diagram of the broadcast receiving part of the receiver in one Example of this invention. It is another block diagram of the broadcast receiving part of the receiver in one Example of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram of a broadcast receiving unit of a conventional receiving apparatus, and FIG. 2 is a block diagram of a broadcast receiving unit of the receiving apparatus in one embodiment of the present invention. First, after describing an example of the prior art, this embodiment will be described in detail.

In FIG. 1, reference numeral 1 denotes a film antenna built in the receiving device or a rod antenna attached to the receiving device, and reference numeral 2 denotes an outside of the LNA built in a mobile body (such as a car body) on which the receiving device is mounted. It is an attached antenna. The external antenna 2 often protrudes outside the vehicle body. 1A is an input terminal for a received signal received by the antenna 1, and 2A is an input terminal for a received signal received by the antenna 2. Since the antenna 2 is located away from the broadcast receiving unit as described above, the broadcast receiving unit has an input terminal 2A for connection to the antenna 2. On the other hand, since the antenna 1 is integral with the broadcast receiving unit, the input terminal 1A does not have to be conscious of as a component.
The received signal received by the antenna 1 is supplied to the input terminal of the antenna switching IC (4) through the capacitor C1. The received signal received by the antenna 2 is amplified by the LNA (3) to a predetermined level suitable for signal processing in the subsequent circuit, and then is input to the other antenna switching IC (4) via the capacitor C2. Supplied to the terminal.

  The LNA (3) requires an operating power supply, but the direct current power generated by the first power supply 11 (which often includes an IC) is smoothed by the capacitor C4 and then passed through the coil L1. To the LNA (3). In the figure, the output line of the LNA (3) supplies the received signal to the antenna switching IC (4) as described above, but the DC power supply is also superimposed on this signal line and supplied to the LNA (3). There are many cases. In addition, the coil L1 and the capacitor C4 supply the above-described DC power, and also have an effect of setting the input impedance viewed from the LNA (3) side to a predetermined value.

  An MPU (Micro Processor Unit) 12 is a control unit that controls at least the entire broadcast receiving unit of the receiving device. The MPU (12) sends an LNA power supply switching control signal for controlling whether or not to supply power to the first power supply 11, and performs ON / OFF control of the first power supply 11. In addition, an antenna switching control signal for controlling whether the received signal from the antenna 1 or 2 is selected is sent to the control terminal of the antenna switching IC (4) to select the received signal. When the received signal received by the external antenna 2 is selected as the antenna switching control signal, the LNA power switching signal is controlled to turn on the first power supply 11. On the contrary, when the former selects the received signal received by the antenna 1, the latter controls to turn off the first power supply 11.

The received signal selected by the antenna switching IC (4) based on the antenna switching signal is supplied to the tuner module 5 via the capacitor C3 and subjected to signal processing as described later. Note that the coil L2 and the capacitor C5 in the input section of the tuner module 5 form a filter circuit, and limit the band of the received signal input to the frequency conversion section 51.
The antenna switching IC (4) includes a large MOSFET having a small ON resistance, and since the size as a component is large, the occupied area on the substrate is large, and the price is likely to be expensive. There were problems such as the need for an antenna switching control signal.

A first embodiment of the present invention that solves these problems will be described in detail with reference to FIG.
2 is significantly different from FIG. 1 in that the antenna switching IC (4) is not used and a diode D1 is provided instead, and the antenna switching generated by the MPU (12) is associated therewith. A control signal is unnecessary.

In addition, since a large component such as the antenna switching IC (4) and the capacitor C2 are no longer necessary, peripheral components including the diode D1, the capacitors C3 and C4, the coil L1, and the resistor R1 are mounted on the tuner module 5 as illustrated. You may make it do. Of course, the capacitor C1 may also be mounted on the tuner module 5. As a result, the characteristics of the tuner module 5 as a single unit and the characteristics when mounted in the receiving apparatus can be brought close to each other, which contributes to shortening of the development process.
For the tuner module 5 as shown, unlike the case of FIG. 1, the input terminals 1A and 1B have a meaning as constituent elements to be cut.

  Next, the overall operation will be described based on the circuit block diagram of FIG. Here, the same components as those shown in FIG. 1 may be denoted by the same reference numerals. Capacitors C1, C3, C4, C5, coils L1, L2, and the like are assigned the same reference numerals to those having corresponding functions, but this does not necessarily mean that the values match. For example, in FIG. 1, a filter for limiting the band of the received signal input to the frequency converter 51 is formed by the coil L2 and the capacitor C5. However, in FIG. 2, the coils L1 and L2 and the capacitors C3 and C4 are mainly used. Since the corresponding filter is formed in C5, each value itself is often different.

  When the external antenna 2 is not connected to the apparatus as a receiving antenna and only the film antenna or the rod antenna 1 functions, the MPU (12) sends an LNA power switching control signal to the first power source 11, 1 is turned off. That is, no power is supplied to the LNA (3). On the other hand, a positive potential from the second power supply 9 is applied to the anode side of the diode D1 via the resistor R2. For this reason, the diode D1 becomes a forward bias, and a bias current flows from the second power source 9 via the resistor R2, the diode D1, the coil L1, and the resistor R1. This means that the diode D1 is in the switch ON state, and the reception signal received by the antenna 1 is supplied to the frequency converter 51 via the capacitor C1, the diode D1, and the capacitors C3 and C5.

  On the other hand, when the external antenna 2 is connected to the apparatus, the MPU (12) sends an LNA power supply switching control signal to the first power supply 11 to turn on the first power supply 11. That is, power is supplied to the LNA (3) via the coil L1 and the reception signal line. As a result, the reception signal received by the external antenna 2 and amplified to a predetermined level by the LNA (3) appears on the cathode side of the diode D1. Here, if the power supply voltage of the first power supply 11 is set higher than the power supply voltage of the second power supply 9, this condition is generally satisfied because the former is about 3V and the latter is about 5-8V. The diode D1 is turned off, and the reception signal received by the external antenna 2 is supplied to the frequency converter 51 via the capacitors C3 and C5, while the reception signal received by the antenna 1 is blocked by the diode D1. The

  That is, by using the diode D1, it can be seen that the antenna switching control signal of FIG. This is because the magnitude relationship between the voltage values output from the first power supply 11 and the second power supply 9 also functions as the antenna switching control signal in FIG. In particular, the second power supply 9 is involved in both the operation power supply to the LNA 3 and the antenna switching operation.

When the external antenna 2 is connected, it is good to use the received signal received by this. Of course, the antenna 2 attached to the vehicle body often has a better reception state than the antenna 1 attached to the receiving device.
On the other hand, when deciding which antenna to use the received signal, it may be set manually. Further, whether or not the external antenna 2 is connected may be automatically detected, and if it is connected, it may be selected. There are several methods for automatic detection. There may be a switch part for detection on the circuit board of the receiving device, and detection may be performed by whether or not a predetermined load current flows when the first power supply 11 is turned on.

  As described above, the received signal selected by the action of the diode D1 is supplied to the frequency converter 51. The frequency converter 51 converts the received high-frequency received signal into a frequency band suitable for performing demodulation by the next OFDM demodulator 52. Originally, heterodyne conversion for converting to an intermediate frequency band has been widely used, but recently, direct conversion for direct conversion to a baseband band is often used.

  The received signal frequency-converted by the frequency converter 51 is supplied to the OFDM demodulator 52. In terrestrial digital broadcasting, OFDM (Orthogonal Frequency Division Multiplex) modulation is performed at the time of transmission from a broadcasting station. This modulation is demodulated by an OFDM demodulator 52, and received data is demodulated. This data is subjected to MPEG (Moving Picture Experts Group) compression coding for compressing the capacity of data to be transmitted and received. Therefore, the compressed data demodulated by the OFDM demodulator 52 is supplied to the MPEG decoder 6 and returned to the data before MPEG compression.

  The data decoded by the MPEG decoding unit 6 is supplied to an AV-IF (Audio Video Interface) unit 7, becomes an analog signal in a format suitable for displaying an image on the LCD monitor 8, and further, an LCD (Liquid Crystal Display) monitor 8. The broadcast image is displayed to the viewer on the image display unit. The display unit of the monitor 8 is not limited to the LCD, and may be anything such as a plasma display panel (PDP), an electronic luminance display (ELD), or a cathode ray tube.

  The second power source 9 is supplied with a built-in battery or a power source 10 supplied from the outside, and is generated by regulating it. This is also used as a power source for each component including the tuner module 5, the MPEG demodulator 6, and the AV-IF (7). The MPU (12) generates a tuner control signal for controlling a channel to be tuned to the tuner module 5 in addition to the above-described LNA power supply switching control signal. Further, the MPU (12) further includes an MPEG decoding unit 6 and an AV-IF (7). The operation of the LCD monitor 8 and the second power source 9 is controlled, that is, at least the entire broadcast receiving unit of the receiving device is controlled.

The first power supply 11 may also be generated by regulating the power supply 10. For the tuner module 5, the first power supply 11 and the second power supply 9 are often external components. In this case, the illustrated input terminals 5A and 5B have the meanings of the constituent elements as power supply terminals.
As described above, according to the present embodiment, a component that is reduced in size and simplified is applied to the antenna switch unit, thereby eliminating the need for an antenna switching control signal and reducing the occupied area on the substrate of the component. Therefore, it is possible to reduce the size and price of the device.

Next, an embodiment of the present invention will be described based on the circuit block diagram of FIG. FIG. 3 is a block diagram different from FIG. 2 of the broadcast receiving unit of the receiving apparatus according to the embodiment of the present invention.
Compared to the case of FIG. 2, the diode D2 is provided between one end of the coil L1 and one end of the capacitor C3, and the diode D1 and the cathode side are connected in common, and the ON currents of the diodes D1 and D2 are The difference is that the flowing resistance is changed to R3 in FIG. 3 instead of R1 in FIG. Also in this case, the first power supply 11 is ON / OFF controlled in accordance with the LNA power supply switching control signal from the MPU (12), as in FIG.

  If the first power supply 11 is ON, the operating power from the first power supply 11 is given to the LNA (3), and the diode D2 is turned ON and the diode D1 is turned OFF, so that the external antenna 2 The received reception signal is supplied to the frequency conversion unit 51. Conversely, if the first power supply 11 is OFF, no operating power is supplied to the LNA (3), and the diode D1 is turned ON and the diode D2 is turned OFF, so that the received signal received by the antenna 1 is received. This is supplied to the frequency converter 51.

  In FIG. 3, when the diode D1 is turned on and the received signal received by the antenna 1 is supplied to the frequency converter 51, the circuit on the cathode side and the subsequent circuit portions are caused by the action of the diode D2 in the OFF state. Further, it is difficult to see the impedance of the long lead portion outside the tuner module 5 while reaching the LNA (3). For this reason, there exists an effect | action which reduces the problem that the frequency characteristic at the time of using the antenna 1 changes by the influence of this routing part. In other words, even when the distance between the receiving device and the external antenna 2 changes and the pattern routing on the circuit board is changed, there is an effect of preventing a significant change in characteristics. In general, the distance between the receiving device and the external antenna 2 and the state of cable routing vary greatly depending on the use situation and the mounted vehicle, and this is one of the characteristic effects of this embodiment.

  The above embodiment is merely an example, and the present invention is not limited to this. For example, many different examples can be considered for the components incorporated in the tuner module 5. In the embodiment, the TV broadcast receiving unit has been described and described, but there may be many other components including a mobile communication unit. Many other different embodiments are possible, all within the scope of the invention.

  1: antenna, 2: external antenna, 2A: input terminal, 3: LNA, 5: tuner module, 6: MPEG decoding unit, 7: AV-IF unit, 8: monitor, 9: second power supply, 11: First power source.

Claims (9)

A tuner module of a television broadcast receiving apparatus that receives a broadcast signal transmitted with a predetermined modulation and processes the received signal,
Select either the reception signal supplied from the first antenna that receives the television broadcast or the reception signal supplied from the second antenna that receives the television broadcast and amplifies the reception signal using an LNA that incorporates the reception signal. And a diode switch that outputs a received signal,
A first power supply terminal for supplying a predetermined DC voltage to the diode switch to control the ON / OFF operation, and for supplying an operating power to the LNA built in the second antenna;
A supply terminal of a second power supply for supplying to the diode a DC voltage lower than a DC voltage supplied to the diode switch by the first power supply;
A reception signal that appears on the cathode side of the diode switch is supplied, and a frequency conversion unit that converts the frequency into a predetermined frequency band;
A tuner module of a receiving apparatus, comprising: a demodulating unit that receives the received signal converted by the frequency converting unit and demodulates the modulation applied at the time of transmission. A television broadcast receiving apparatus that receives a broadcast signal that is data-compressed based on the MPEG system, is transmitted with a predetermined modulation, and processes the received signal.
A first antenna for receiving the television broadcast;
An input terminal for receiving a reception signal supplied from a second antenna that receives the television broadcast and amplifies the reception signal with an LNA containing the reception signal;
A reception signal supplied from the first antenna is connected to an anode terminal, and a reception signal supplied from the input terminal is connected to a cathode terminal; and
A first power source for supplying a DC voltage to the cathode terminal of the diode and further supplying an operating power source to the LNA built in the second antenna;
A second power supply for supplying a DC voltage to the anode terminal of the diode that is lower than the DC voltage supplied to the cathode terminal by the first power supply;
A control unit for controlling ON / OFF of the first power supply;
A reception signal that appears on the cathode side of the diode is supplied, and a frequency conversion unit that converts the frequency into a predetermined frequency band;
A demodulation unit that receives the reception signal converted by the frequency conversion unit and demodulates the modulation applied at the time of transmission;
An MPEG decoding unit which is supplied with the reception signal demodulated by the demodulation unit and decompresses and decodes the data compression based on the MPEG method performed at the time of transmission;
An AV-IF unit that is supplied with the reception signal decoded by the MPEG decoding unit and converts the signal into an analog signal in a format suitable for image display;
A receiving apparatus comprising: a monitor for displaying an image of the received signal converted by the AV-IF unit. An antenna switching circuit of a television broadcast receiving apparatus that receives a broadcast signal and processes the received signal,
The reception signal supplied from the first antenna that receives the television broadcast is received at the anode terminal, and the reception signal supplied from the second antenna that receives the television broadcast and amplifies the received signal with the LNA that incorporates the reception signal is the cathode. A diode connected to the terminal;
A first power source for supplying a DC voltage to the cathode terminal of the diode and further supplying an operating power source to the LNA built in the second antenna;
A second power supply for supplying a DC voltage to the anode terminal of the diode that is lower than the DC voltage supplied to the cathode terminal by the first power supply;
An antenna switching circuit of a receiving apparatus, comprising: a control unit that performs ON / OFF control of the first power supply, wherein the received signal that appears on the cathode side of the diode is used as a switching output. A tuner module of a television broadcast receiving apparatus that receives a broadcast signal transmitted with a predetermined modulation and processes the received signal,
A first input terminal to which a reception signal received by a first antenna that receives the television broadcast is input;
A second input terminal to which a received signal supplied from a second antenna that receives the television broadcast and amplifies the received signal by an LNA that incorporates the received signal;
A reception signal supplied from the first input terminal to the anode terminal, and a reception signal supplied from the second input terminal to the cathode terminal;
A first power supply terminal for supplying a DC voltage to the cathode terminal of the diode and further supplying an operating power to the LNA built in the second antenna;
A supply terminal of a second power source for supplying a DC voltage lower than a DC voltage supplied to the cathode terminal by the first power source to the anode terminal of the diode;
A reception signal that appears on the cathode side of the diode is supplied, and a frequency conversion unit that converts the frequency into a predetermined frequency band;
A tuner module of a receiving apparatus, comprising: a demodulating unit that receives the received signal converted by the frequency converting unit and demodulates the modulation applied at the time of transmission. A television broadcast receiving apparatus that receives a broadcast signal that is data-compressed based on the MPEG system, is transmitted with a predetermined modulation, and processes the received signal.
A first antenna for receiving the television broadcast;
An input terminal for receiving a reception signal received by a second antenna that receives the television broadcast and amplifies the reception signal using an LNA containing the reception signal;
A first diode in which a reception signal supplied from the first antenna is connected to an anode terminal;
A received signal supplied from the input terminal is connected to an anode terminal, and a cathode terminal is connected to a cathode terminal of the first diode;
A first power source for supplying a direct-current voltage to the anode terminal of the second diode and further supplying an operating power source to the LNA built in the second antenna;
A second power source for supplying a DC voltage lower than a DC voltage supplied to the anode terminal of the second diode by the first power source;
A control unit for controlling ON / OFF of the first power supply;
A reception signal that appears on the cathode side of the first and second diodes is supplied, and a frequency conversion unit that converts the frequency into a predetermined frequency band;
A demodulation unit that receives the reception signal converted by the frequency conversion unit and demodulates the modulation applied at the time of transmission;
An MPEG decoding unit which is supplied with the reception signal demodulated by the demodulation unit and decompresses and decodes the data compression based on the MPEG method performed at the time of transmission;
An AV-IF unit that is supplied with the reception signal decoded by the MPEG decoding unit and converts the signal into an analog signal in a format suitable for image display;
A receiving apparatus comprising: a monitor for displaying an image of the received signal converted by the AV-IF unit. An antenna switching circuit of a television broadcast receiving apparatus that receives a broadcast signal and processes the received signal,
A first diode in which a reception signal supplied from a first antenna for receiving the television broadcast is connected to an anode terminal;
A reception signal supplied from a second antenna that receives the television broadcast and amplifies the reception signal with an LNA that incorporates the reception signal is connected to an anode terminal, and a cathode terminal is connected to a cathode terminal of the first diode. A diode of
A first power source for supplying a direct-current voltage to the anode terminal of the second diode and further supplying an operating power source to the LNA built in the second antenna;
A second power source for supplying a DC voltage lower than a DC voltage supplied to the anode terminal of the second diode by the first power source;
An antenna switching circuit for a receiving apparatus, comprising: a control unit that controls ON / OFF of the first power supply, wherein the received signal that appears on the cathode side of the first and second diodes is used as a switching output. A tuner module of a television broadcast receiving apparatus that receives a broadcast signal transmitted with a predetermined modulation and processes the received signal,
A first input terminal to which a reception signal received by a first antenna that receives the television broadcast is input;
A second input terminal to which a received signal supplied from a second antenna that receives the television broadcast and amplifies the received signal by an LNA that incorporates the received signal;
A first diode having a reception signal supplied from the first input terminal connected to an anode terminal;
A reception signal supplied from the second input terminal is connected to an anode terminal, and a cathode terminal is connected to a cathode terminal of the first diode;
A first power supply terminal for supplying a DC voltage to the anode terminal of the second diode and further supplying an operating power to the LNA built in the second antenna;
A supply terminal of a second power supply for supplying a DC voltage lower than a DC voltage supplied by the first power supply to the anode terminal of the second diode at the anode terminal of the first diode;
A reception signal that appears on the cathode side of the first and second diodes is supplied, and a frequency conversion unit that converts the frequency into a predetermined frequency band;
A tuner module of a receiving apparatus, comprising: a demodulating unit that receives the received signal converted by the frequency converting unit and demodulates the modulation applied at the time of transmission.   6. The receiving apparatus according to claim 2, wherein the demodulating unit demodulates modulation by an orthogonal frequency division multiplexing system.   8. The tuner module of the receiving apparatus according to claim 1, wherein the demodulating unit demodulates modulation by an orthogonal frequency division multiplexing system. Tuner module.

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