JP2003258660A - Receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a receiver that can reduce power consumption, and at the same time, can discriminate the presence or the absence of a broadcast service to a mobile unit. <P>SOLUTION: Power is supplied to a detection circuit 5, a control circuit 9, and a storage circuit 10, but power is not supplied to a high-frequency amplifier circuit 4, and a base-band demodulation circuit 8. Based on a power conversion table provided in the storage circuit 10 in advance, the control circuit 9 detects the received power by an antenna 1, according to an RSSI signal detected by the detection circuit 5. The control circuit 9 decides whether the received power at an antenna end is at least a threshold or larger (for example, -80 dBm or higher), and decides that a broadcast signal can be received, when the received power is at least the threshold level. In this case, the supply of power is started to the high-frequency amplifier circuit 4 and the baseband demodulation circuit 8, and normal broadcast signal reception operation is started. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving device such as a portable device for receiving a broadcasting service signal such as terrestrial digital broadcasting.

[0002]

2. Description of the Related Art Conventionally, there have been portable terminals which are premised on the movement capable of receiving terrestrial analog television broadcasting, but the transmission system is easily affected by multipath and the reception performance of antennas and the like. However, there are many cases where normal broadcast reception cannot be performed outdoors or in an environment where the user is moving. In order to solve the above-mentioned problems, in recent years, in terrestrial television broadcasting, the conventional analog system has been changed to OFDM.
A terrestrial digital television adopting an (Orthogonal Frequency Division Multiplex) system is being put into practical use. In the OFDM system, a high-speed data signal is converted into a low-speed narrow-band data signal and transmitted in parallel on the frequency axis, so that the symbol length can be lengthened and intersymbol interference occupying the whole can be reduced. ,
It has the advantages that it is unlikely to be affected by multipath, and that there are few problems such as screen interruptions even when receiving while moving.

In terrestrial digital television broadcasting, FIG.
As shown in (a), the transmission band 61 of about 6 MHz is set to 13
There is a method of dividing into 13 segments 62 and using all 13 segments for fixed reception of 1-channel HDTV (high definition television) or multiple channels of SDTV (standard definition television). Furthermore, FIG.
As shown in (b), it is possible to divide 13 segments into a maximum of three layers and set a mobile reception layer 65 in addition to the fixed reception layers 64 and 66.

Since the modulation method is arbitrarily determined in each layer, one segment located at the center of the frequency band is assigned to the layer for mobile reception in order to facilitate reception of radio waves and reduce the system load of the mobile reception device. As a modulation method, a DQPSK modulation method or the like which is resistant to interference and interference is used. As described above, in terrestrial digital broadcasting, attempts are being made to allow mobile devices such as PDAs and mobile phones to receive terrestrial digital broadcasting services for mobile reception.

[0005]

However, terrestrial digital broadcasting for mobiles may not be provided in the early morning or late at night due to viewing demand, maintenance, etc. However, it does not necessarily mean that the constant broadcast service can be received. Moreover, since the location of the mobile terminal is not fixed, the mobile terminal may go out of the area of the broadcasting service.

In such a situation, it is necessary to check whether the broadcasting service can be received temporally and spatially. As a method of confirming the broadcasting service, there is a method of performing carrier sense on the transmission frequency band of the layer 65 for mobile reception. As a configuration example of a receiver provided with carrier sense, the one shown in FIG. 7 is known. This receiver is
The antenna 101, the bandpass filter 102, the high frequency amplification circuit 104, the detection circuit 105, the local oscillator 107, the demodulation circuit 108, the control circuit 109, and the memory circuit 110 are included. The frequency converter 10 is provided in the demodulation circuit 108.
6 and the power distributor 103 are arranged.

In the receiving apparatus of FIG. 7, the detection circuit 105 connected to the power distributor 103 detects the received power,
It is necessary to constantly supply power to the high-frequency amplifier circuit 104 and the frequency converter 106 at least, and there is a problem when it is intended to suppress power consumption as in a mobile terminal. The power divider 103 and the frequency converter 106 can use passive elements, and it is not necessary to supply power to themselves, so that power consumption can be suppressed. However, when a passive mixer is used for the frequency converter 106, Has a problem that the loss of received power becomes large when the frequency of the received signal is converted. In this case, in order to operate the receiving device normally, it is necessary to compensate the loss of the received power, and the high frequency amplifier 104 needs a high gain, so that the power is consumed extra.

[0008] Therefore, in view of the above problems, an object of the present invention is to provide a receiving apparatus capable of reducing power consumption and determining whether or not there is a broadcasting service for mobile units.

[0009]

In order to solve the above-mentioned problems, a first invention is a receiving device for receiving a broadcast service signal, and a detection circuit for detecting a signal in a specific broadcast frequency band among the received signals. An amplifier circuit for amplifying a received signal, a demodulator circuit for demodulating the amplified signal of the amplifier circuit, and a power supply to the amplifier circuit if the signal detected by the detector circuit is at a level that can be demodulated by the demodulator circuit If there is no signal detected by the detection circuit or if the signal has a level that cannot be demodulated by the demodulation circuit, a control circuit that does not supply power to the amplification circuit is provided.

A second aspect of the present invention is the receiving apparatus according to the first aspect of the present invention, wherein the detection circuit is based on local oscillation means for outputting a local signal according to the specific broadcast frequency band, and based on the local signal. And a frequency conversion means for converting the received signal into an intermediate frequency signal or a baseband signal corresponding to the specific broadcast frequency, and a detection means for detecting the intensity of the intermediate frequency signal or the baseband signal. And

A third invention is the receiving apparatus according to the second invention, wherein the frequency converting means of the detecting circuit is a passive mixer.

A fourth invention is the receiving apparatus according to the first invention, wherein the demodulation circuit responds the received signal to the specific broadcast frequency based on a local signal output by the local oscillation means. The receiving apparatus according to claim 1, further comprising frequency conversion means for converting the intermediate frequency signal or the baseband signal, wherein the frequency conversion means is an active mixer.

According to a fifth aspect of the present invention, in a receiver for receiving a broadcast service signal, a bandpass filter for passing a signal in a specific broadcast frequency band among the received signals, and a detection circuit for detecting a signal passed through the bandpass filter. And an amplifier circuit for amplifying the signal passed through the bandpass filter, a demodulator circuit for demodulating the amplified signal of the amplifier circuit, and a signal detected by the detector circuit at a level that can be demodulated by the demodulator circuit, And a control unit that supplies power to the amplifier circuit and does not supply power to the amplifier circuit if there is no signal detected by the detection circuit or if the signal cannot be demodulated by the demodulation circuit. And

A sixth aspect of the invention is the receiver according to the fifth aspect of the invention, in which the bandpass filter is provided with filters for passing only the frequency band of one broadcast channel for the number of broadcast channels to be received. Further, a switch is provided for selecting a signal in a frequency band of a specific broadcast channel among signals passing through the band pass filter.

According to a seventh aspect of the present invention, in a receiving device for receiving a signal of a broadcast service, an amplifying circuit capable of switching a function of amplifying the received signal and a function of bypassing the received signal, and a specific one of the bypassed received signals are specified. Detection circuit for detecting a signal in the broadcast frequency band, a demodulation circuit for demodulating an amplified signal of the amplification circuit, a received signal is bypassed to the amplification circuit and detected by the detection circuit, and the detection signal of the detection circuit is Only in the case of a level that can be demodulated by the demodulation circuit,
A control circuit for amplifying a received signal is provided in the amplifier circuit.

In the present invention, if the level of the received signal detected by the detection circuit can be demodulated before the function of the amplifier circuit, the amplifier circuit is made to function, so that the power consumption is reduced and the moving object is moved. At the same time, it will be possible to determine whether or not there is a broadcasting service for

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment> FIG. 1 is a block diagram showing the arrangement of a receiving apparatus according to the first embodiment.
FIG. 2 is a flowchart showing a method of detecting a broadcast according to the first embodiment. The receiving apparatus of FIG. 1 includes an antenna 1, a bandpass filter 2, a power distributor 3, a high frequency amplifier circuit 4, a detection circuit 5, a first frequency converter 6, a baseband demodulation circuit 8, a control circuit 9, and a storage circuit 10. It is composed of. The detection circuit 5 is provided with a local oscillation means composed of a local oscillator 7 and a detection means composed of other functional blocks 11 in the detection circuit. The local oscillator 7 also has a function of supplying a local signal to the first frequency converter 6.

Next, the function of each block constituting the receiving apparatus and the processing of the broadcast received signal will be described. An antenna 1 for receiving terrestrial digital broadcasting for mobiles is connected to a band pass filter 2 having a wide pass band characteristic that allows the broadcasting frequency band of all channels to pass, and the band pass filter 2 is connected to a power distributor 3. There is. Power divider 3
Is connected to the low noise amplifier (LNA) 4a and the second frequency converter 5a, and has a function of dividing the received signal power of broadcasting into the first received signal (SIG11) and the second received signal (SIG12). There is. The first reception signal is input to the low noise amplifier 4a, and the first reception signal is amplified by the constant gain of the low noise amplifier 4a. The low noise amplifier 4a is connected to the variable gain amplifier 4b, and the variable gain amplifier 4b amplifies the power corresponding to the gain set by the control circuit 9 according to the received signal power.

The variable gain amplifier 4b is connected to the first frequency converter 6, and the first frequency converter 6 inputs the local signal corresponding to the broadcasting frequency band from the local oscillator 7 to receive the first reception signal. The signal is the first baseband signal (S
IG11B) down-converts. The first frequency converter 6 is connected to the low-pass filter 8a, and the low-pass filter 8a removes unnecessary frequency band noise from the first baseband signal.

The low-pass filter 8a is connected to the baseband signal amplifier 8b and is connected to the baseband signal amplifier 8b.
Adjusts the level of the first baseband signal so that the first baseband signal is adapted to the input voltage range of the second A / D converter 8c connected to the subsequent stage. First A
The / D converter 8c converts the first baseband signal from analog to digital, and is an OFD connected to the subsequent stage of itself.
The digitized baseband signal is sent to the M demodulator 8d. The OFDM demodulator 8d demodulates the digitized baseband signal and sends the demodulated broadcast signal to the television receiver.

On the other hand, the second received signal (SIG12) distributed from the power distributor 3 is the second frequency converter 5a.
Further, by inputting a local signal matched with the broadcast frequency band 63 from the local oscillator 7, the signal is down-converted to the second baseband signal (SIG12B). The second frequency converter 5a is connected to the low-pass filter 5b,
The low-pass filter 5b removes a noise component including a broadcast signal other than the tuned channel existing in the second baseband signal, and only a pure broadcast signal is connected to the latter stage of the RSSI (reception signal strength indication). Send to circuit 5c.

The RSSI circuit 5c outputs an RSSI current signal according to the power level of the second baseband signal,
By the current-voltage converter 5d connected to the latter stage of itself, R
Convert the SSI output current signal to an RSSI voltage signal. The current-voltage converter 5d is connected to the second A / D converter 5e, and the second A / D converter 5e converts the RSSI voltage signal from analog to digital and digitizes it in the control circuit 9. Send the RSSI signal.

The control circuit 9 detects the power level of the broadcast signal at the end of the antenna 1 based on the conversion table in which the RSSI signal is stored in the storage circuit 10 in advance. Further, the control circuit 9 controls gains of the variable gain amplifier 4b according to the detected power level at the antenna end, determines whether or not there is a broadcast wave, and controls each functional block such as frequency setting of the local oscillator 7. To do.

Next, a method of detecting terrestrial digital broadcasting for mobiles will be described mainly with reference to FIG. A terminal device equipped with the receiving device according to the first embodiment of the present invention is
When attempting to receive a terrestrial digital broadcast for a mobile body, in the first step S11, power is supplied to the detection circuit 5, the control circuit 9, and the storage circuit 10, and the high frequency amplification circuit 4 and the baseband demodulation circuit 8 are supplied. The power is not supplied to. Antenna 1, bandpass filter 2, power divider 3
With respect to the above, since it is a passive element and does not require power supply, the operation of detecting the broadcast functions normally.

In the next step S12, the number of detection tests N
Is initialized to 0, and in step S13, power is supplied to the detection circuit 5, the control circuit 9, and the storage circuit 10 to try to detect the broadcast signal. As a method of detecting the broadcast signal, the control circuit 9 detects the received power at the antenna 1 from the RSSI signal detected by the detection circuit 5 based on a power conversion table provided in the storage circuit 10 in advance.

In step S14, the number of detection tests is incremented by adding 1 to the number N of detection tests. In step S15, the control circuit 9 determines whether or not the reception power at the antenna end is equal to or higher than a threshold value (for example, -80 dBm or higher), and if the reception power is equal to or higher than the threshold value, the broadcast signal can be received. Judge and step S1
Go to 6. If the received power is less than the threshold value, the process proceeds to step S18. If the number N of detection tests is smaller than the specified number A of detection tests, step S1 is performed after a certain period of time.
At 3, try to detect the broadcast again.

If the detection test count N becomes equal to the specified detection test count A, it is determined in step S19 that the environment is not capable of receiving the broadcast, and the detection circuit 5, the control circuit 9, and the storage circuit 10 are instructed. The power supply of is stopped and the detection of the broadcast ends. The receiving device performs the detection of the broadcast a plurality of times because the mobile terminal equipped with the receiving device copes with the case where it cannot be received by chance due to the influence of a shadow or a shield. The detection accuracy of the broadcast signal is improved. In step S16, the supply of power to the high frequency amplifier circuit 4 and the baseband demodulation circuit 8 is started, and a normal broadcast signal receiving operation is started (step S17).

As described above, by providing the passive mixer (second frequency converter 5a) for down-converting the high frequency signal to the base band signal in the preceding stage of the detection circuit,
The received signal can be detected only by the operation of the circuit preceding the high-frequency amplifier circuit 4, and power is supplied to the high-frequency amplifier 4, the first frequency converter 6 (active mixer) of the demodulation circuit 8 and the like which consumes a large amount of power. Can be completely stopped.

Here, the first frequency converter 6 for down-converting the received signal preferably uses an active mixer in order to prevent the loss of the received signal. On the other hand, the second frequency converter 5a included in the detection circuit 5 only needs to be able to confirm the presence or absence of a signal, so that the loss amount of the passive mixer (7 to 10d).
(About B) is hardly a problem, a passive mixer can be used as the frequency conversion means. Further, since the local oscillator 7 included in the detection circuit 5 can be shared with the one used for the first frequency converter 6, it is not necessary to provide a local oscillation means separately. Therefore, it is possible to reduce power consumption and determine whether or not there is a broadcasting service for mobile units at the same time.

<Second Embodiment> FIG. 3 is a block diagram showing the arrangement of a receiving apparatus according to the second embodiment.
The receiving apparatus of FIG. 3 includes an antenna 1, a bandpass filter group circuit 22, a power distributor 3, a high frequency amplifier circuit 4, a detection circuit 25, a first frequency converter 6, a local oscillator 7, a baseband demodulation circuit 8, and a control unit. It is composed of a circuit 29 and a memory circuit 30.

Next, the function of each block constituting the receiving apparatus and the processing of the broadcast received signal will be described. The antenna 1 for receiving terrestrial digital broadcasting for mobiles is connected to the first high frequency switch circuit 22a. The first high-frequency switch circuit 22a, based on the control signal issued from the control circuit 29, according to the frequency band of the received broadcast,
The operation of switching the path of the received signal is performed.

In the first embodiment, the second frequency converter 5a has the function of detecting only one receiving channel from a plurality of broadcast channels and detecting the signal strength.
This is realized by changing the frequency of the local oscillator 7 input to the. However, in the second embodiment, it is realized by switching the bandpass filters (22c1 to 22cn) in the bandpass filter group circuit 22. There is.

The first high-frequency switch circuit 22a is connected in parallel with n band-pass filters from the band-pass filter (22c1) to the band-pass filter (22cn). The n is the number of channels to be received. The other of the n band pass filters is connected to a second high frequency switch circuit 22b that performs the same operation as the first high frequency switch circuit 22a.

Here, the reason why the first high-frequency switch circuit 22a and the second high-frequency switch circuit 22b are provided before and after the bandpass filter is that impedance matching between the antenna 1 at the front stage and the power distributor 3 at the rear stage is easy. This is to prevent the signal from sneaking into a path other than the selected signal path.

The other terminal of the second high frequency switch circuit 22b receives the received signal power of the broadcast as the first received signal (S
IG21) and the second reception signal (SIG22), which is connected to the power distributor 3 having a function of dividing. One of the output terminals of the power distributor 3 is connected to the low noise amplifier 4a and sends out the first received signal, and the other output terminal is connected to the second
Connected to the frequency converter 4a for transmitting the second received signal.

The low-noise amplifier 4a amplifies the first reception signal by a constant gain of itself, and sends the first reception signal to the variable gain amplifier 4b connected to the subsequent stage of itself. The variable gain amplifier 4b determines the gain amount based on the control signal set by the control circuit 29 according to the received signal power intensity, and amplifies the power.

The variable gain amplifier 4b is connected to the first frequency converter 6, and the first frequency converter 6 inputs the local signal matched to the broadcasting frequency band from the local oscillator 7 to receive the first reception signal. The signal is down converted to the first baseband signal (SIG21B). The first frequency converter 6 is connected to the low-pass filter 8a, and the low-pass filter 8a removes unnecessary frequency band noise from the first baseband signal.

The low-pass filter 8a is connected to the first baseband signal amplifier 8b, and the baseband signal amplifier 8b is connected to the latter stage of the first baseband signal of the first A / D converter 8c. Adjust the signal level to fit the input voltage range. First A / D converter 8c
Converts the first baseband signal from analog to digital and sends the digitized baseband signal to the OFDM demodulator 8d connected to the subsequent stage of itself. The OFDM demodulator 8d demodulates the digitized baseband signal and sends the demodulated broadcast signal to the television receiver.

On the other hand, the second received signal (SIG22) distributed from the power distributor 3 is sent to the RSSI circuit 25c, which outputs an RSSI current signal according to the power level of the second received signal and outputs its own signal. The current-voltage converter 25d connected to the subsequent stage converts the RSSI current signal into an RSSI voltage signal. The current-voltage converter 25d is connected to the second A / D converter 25e, and the second A / D converter 25e is
The RSSI output voltage signal is converted from analog to digital, and the digitally converted RSSI signal is sent to the control circuit 29.

The control circuit 29 detects the power level of the broadcast signal at the end of the antenna 1 based on the conversion table in which the RSSI signal is stored in the storage circuit 30 in advance. Further, the control circuit 29 performs gain control of the variable gain amplifier 4b according to the detected power level at the antenna end, determines the presence or absence of broadcast radio waves, and controls each functional block such as frequency setting of the local oscillator 7. To do. Second
The method of detecting the terrestrial digital broadcasting for a mobile body of the embodiment of the present invention can be performed by the same method as that of the first embodiment shown in FIG.

As described above, by providing the bandpass filter group circuit 22 which passes only the frequency band of one segment constituted by the hierarchy for mobile reception in the broadcast signal according to the number of channels, high frequency amplification is achieved. Since the power supply to the circuits directly related to the demodulation of the received signal after the circuit 4 can be completely stopped, the power consumption can be reduced and the presence or absence of the broadcasting service for mobile bodies can be determined at the same time.

<Third Embodiment> FIG. 4 is a block diagram showing the arrangement of a receiving apparatus according to the third embodiment.
FIG. 5 is a flow chart showing a broadcast detection method according to the third embodiment. The receiving apparatus of FIG. 4 includes an antenna 1, a bandpass filter 2, a high frequency amplifier circuit 34, and a detection circuit 3.
5, a first frequency converter 6, a local oscillator 7, a baseband demodulation circuit 38, a control circuit 39, and a storage circuit 40.

Next, the function of each block constituting the receiving apparatus and the processing of the broadcast received signal will be described. An antenna 1 for receiving terrestrial digital broadcasting for mobiles is connected to a bandpass filter 2 having a wide passband characteristic that allows the broadcast frequency band of all channels to pass, and the bandpass filter 2 is connected to a low noise amplifier 34a. . The low noise amplifier 34a selects whether to bypass or amplify the received signal based on the control signal issued from the control circuit 39. The low noise amplifier 34a is connected to the variable gain amplifier 34b, and the variable gain amplifier 34b
Selects whether to bypass or how much to amplify the received signal based on the control signal issued from the control circuit 39.

Here, the low noise amplifier 34a and the variable gain amplifier 34b have a function of bypassing the received signal, and since the amplifying operation is not performed while the received signal is bypassed, the state of the C-MOS switch is held. Only a small amount of power consumption is required.

The variable gain amplifier 34b is connected to the first frequency converter 6, and the first frequency converter 6 receives the local signal matched with the broadcast frequency band from the local oscillator 7 to base the received signal. Down-convert to band signal. The first frequency converter 6 is connected to the low-pass filter 8a, and the low-pass filter 8a removes unnecessary frequency band noise from the baseband signal.

The low-pass filter 8a is connected to the power divider 33, and the power divider 33 divides the baseband signal into a first baseband signal (SIG31B) and a second baseband signal (SIG32B). Power divider 3
One of the divided outputs, that is, the first baseband signal is input to the baseband amplifier 8b, and the other divided output, that is, the second baseband signal is the RSSI circuit 35c.
Entered in.

The baseband signal amplifier 8b adjusts the signal level of the first baseband signal so as to match the input voltage range of the first A / D converter 8c connected to the subsequent stage thereof. The first A / D converter 8c converts the first baseband signal from analog to digital, and sends the digitized baseband signal to the OFDM demodulator 8d connected to the subsequent stage thereof. The OFDM demodulator 8d demodulates the digitized baseband signal and sends the demodulated broadcast signal to the television receiver.

On the other hand, the second baseband signal is RSS
After being input to the I (received signal strength display) circuit 35c,
RSSI according to the power level of the second baseband signal
The output signal is output and the RSSI current signal is converted into an RSSI voltage signal by the current-voltage converter 35d connected to the latter stage of the output signal. The current-voltage converter 35d is connected to the second A / D converter 35e, and the second A / D converter 35e
Converts the RSSI output voltage signal from analog to digital and sends the digitally converted RSSI signal to the control circuit 39.

The control circuit 39 detects the power level of the broadcast signal at the end of the antenna 1 based on the conversion table in which the RSSI signal is stored in the storage circuit 40 in advance. Further, the control circuit 39 performs gain control of the variable gain amplifier 34b and determination of presence / absence of broadcast radio wave according to the detected power level at the antenna end, and controls each functional block such as frequency setting of the local oscillator 7. To do.

Next, a method of detecting terrestrial digital broadcasting for mobiles will be described mainly with reference to FIG. A terminal device equipped with the receiving device according to the third embodiment of the present invention is
When attempting to receive a terrestrial digital broadcast for a mobile body, in the first step S31, the high frequency amplification circuit 34
And the received signal that has passed through the bandpass filter 2 is directly input to the first frequency converter 6, passes through the lowpass filter 8a and the power distributor 33, and then enters the second baseband in the detection circuit 35. A signal is input. In this step S31, power is supplied to the detection circuit 35, the control circuit 39, the memory circuit 40, the first frequency converter 6, and the local oscillator 7, and the high-frequency amplifier circuit 34 uses a small power source only to save the switch state. Is supplied, and no power is supplied to the other baseband demodulation circuits 38. Since the antenna 1, the bandpass filter 2, and the power distributor 33 are passive elements and do not require power supply,
The operation of detecting the broadcast functions normally.

In the next step S32, the number of detection tests N
= 0, and in step S33, the detection circuit 3
5, the control circuit 39 and the storage circuit 40 are operated to try to detect the broadcast signal. As a method of detecting the broadcast signal, the control circuit 39 detects the received power at the end of the antenna 1 from the RSSI signal detected by the detection circuit 35 based on the power conversion table provided in the storage circuit 40 in advance.

In step S34, 1 is added to the number N of detection tests to count up the number of detection tests. In step S35, the control circuit 39 determines whether or not the reception power at the antenna end is equal to or higher than a threshold value (for example, -80 dBm or higher), and if the reception power is equal to or higher than the threshold value, the broadcast signal can be received. It is determined and the process proceeds to step S36. If the received power is less than the threshold value, the process proceeds to step S38. If the detection test count N is smaller than the specified detection test count A, the broadcast detection is tried again in step S33 after a certain period of time. If the detection test count N becomes equal to the specified detection test count A, it is determined in step S39 that the environment is not capable of receiving the broadcast, and power is supplied to the detection circuit 35, the control circuit 39, and the storage circuit 40. To stop the broadcast detection.

In step S36, the high frequency amplifier circuit 34
The bypass function is canceled to perform a normal received signal amplifying operation, power is supplied to the local oscillator 7 and the baseband demodulation circuit 38, and a normal broadcast signal receiving operation is started (step S37). ).

In this way, during the operation of detecting the broadcast signal,
Since the received signal bypasses the high-frequency amplifier circuit 34, the power supply of the high-frequency signal can be stopped or the supply amount thereof can be made very small, so that the power consumption can be reduced and the presence / absence of the broadcasting service for mobile bodies can be determined at the same time. When the detection of the broadcast signal is confirmed, the high-frequency amplifier circuit 34 is supplied with power to normally start the reception operation.

As described above, the receiving apparatus according to the above-described embodiments uses the direct conversion method in which the frequency band is directly down-converted from the high frequency (RF) signal to the base band signal. The problem can be solved even by using the method of once down converting to an intermediate frequency (IF) signal.

[0057]

According to the present invention, if the signal detected by the detection circuit is at a level that can be demodulated by the demodulation circuit, power is supplied to the amplification circuit and there is no signal detected by the detection circuit. Since it has a control circuit that does not supply power to the amplifier circuit if it is a level that cannot be demodulated with, power supply to the amplifier circuit that consumes a large amount of power can be completely stopped when it is not needed, resulting in low power consumption. It is possible to realize a receiving device that can determine whether or not there is a broadcast service for mobile bodies.

In particular, in detecting the presence or absence of broadcasting in a specific narrow frequency band, the detection circuit is provided with frequency conversion means for down-converting a high frequency signal into an intermediate frequency signal or a base band signal, so that before the operation of the amplifier circuit. In addition, the reception signal can be detected, and the power supply to the amplifier circuit can be completely stopped.

According to the present invention, among broadcast signals,
By providing a band-pass filter that passes only the frequency band of one segment configured in the hierarchy for mobile reception according to the number of channels, the power supply of the circuit directly related to the demodulation of the received signal after the high frequency amplifier circuit can be performed. Since it can be completely stopped, it is possible to reduce power consumption and determine whether or not there is a mobile broadcasting service.

Further, according to the present invention, during the detection operation of the broadcast signal, the received signal bypasses the amplifier circuit, so that the power supply of the high frequency signal can be stopped or the supply amount thereof can be made minute so that the power consumption can be reduced. At the same time, it becomes possible to judge whether or not there is a broadcasting service for mobile units. When the detection of the broadcast signal is confirmed, by supplying power to the amplifier circuit,
The reception operation is started normally. Therefore, it is possible to reduce power consumption and determine whether or not there is a mobile broadcasting service.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a receiving device according to a first embodiment.

FIG. 2 is a flowchart showing an operation of the receiving device according to the first embodiment and the second embodiment.

FIG. 3 is a block diagram showing a configuration of a receiving device according to a second embodiment.

FIG. 4 is a block diagram showing a configuration of a receiving device according to a third embodiment.

FIG. 5 is a flowchart showing an operation of the receiving device according to the third embodiment.

FIG. 6 is a diagram illustrating broadcast waves of a terrestrial digital television for mobile terminals.

FIG. 7 is a diagram showing an example of a conventional receiving device.

[Explanation of symbols]

1 antenna, 2 wide band high frequency band pass filter 3 high frequency signal power distributor 4 high frequency amplification circuit 4a low noise amplifier (LNA) 4b high frequency variable gain amplifier 5, 25, 35 detection circuit 5a second frequency converter 5b, 8a baseband Signal low-pass filters 5c, 25c, 35c RSSI circuits 5d, 25d, 35d Current-voltage converters 5e, 25e, 35e Second A / D converter (for signal detection) 6 First frequency converter 7 Local oscillator 8 Base Band demodulator 8b Baseband amplifier 8c First A / D converter (for demodulated signal) 8d OFDM signal demodulator 9, 29, 39 Control circuit 10, 30, 40 Storage circuit 11 Function block constituting detection means 22 band Pass filter group circuits 22a and 22b High frequency switch circuits 22c1 to 22cn Narrow band high frequency Bandpass filter 33 Baseband signal power divider 34 High frequency amplifier circuit (with high frequency signal bypass function) 34a Low noise amplifier (LNA) (with high frequency signal bypass function) 34b High frequency variable gain amplifier (with high frequency signal bypass function)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shunichi Sato             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company F-term (reference) 5C025 AA11 AA28 BA26 DA01                 5C026 EA09                 5K061 AA02 BB07 CC08 CC14 EF06                       EF09

Claims (7)

[Claims] 1. A receiving device for receiving a broadcast service signal, a detection circuit for detecting a signal of a specific broadcast frequency band in the received signal, an amplifier circuit for amplifying the received signal, and an amplified signal of the amplifier circuit demodulated. If the signal detected by the demodulation circuit and the detection circuit is at a level that can be demodulated by the demodulation circuit, power is supplied to the amplification circuit and there is no signal detected by the detection circuit, or A receiving device comprising: a control circuit that does not supply power to the amplifier circuit if the level is such that demodulation is not possible. 2. The detection circuit includes a local oscillator that outputs a local signal according to the specific broadcast frequency band, and an intermediate frequency signal corresponding to the specific broadcast frequency for the received signal based on the local signal. Alternatively, the receiving device according to claim 1, further comprising: a frequency converting means for converting into a baseband signal, and a detecting means for detecting the intensity of the intermediate frequency signal or the baseband signal. 3. The receiving device according to claim 2, wherein the frequency conversion means of the detection circuit is a passive mixer. 4. The demodulation circuit includes frequency conversion means for converting the received signal into an intermediate frequency signal or a baseband signal corresponding to the specific broadcast frequency based on a local signal output from the local oscillation means, The receiving device according to claim 1, wherein the frequency conversion means is an active mixer. 5. A receiving device for receiving a broadcast service signal, comprising: a bandpass filter for passing a signal in a specific broadcast frequency band among received signals; a detection circuit for detecting a signal passing through the bandpass filter; An amplification circuit that amplifies the signal that has passed through the pass filter, a demodulation circuit that demodulates the amplification signal of the amplification circuit, and if the signal detected by the detection circuit is at a level that can be demodulated by the demodulation circuit, the amplification circuit A receiving device comprising a control means for supplying power and not supplying power to the amplifier circuit if there is no signal detected by the detection circuit or if it is at a level that cannot be demodulated by the demodulation circuit. . 6. The band-pass filter is provided with filters that pass only the frequency band of one broadcast channel, the number of which corresponds to the number of broadcast channels to be received, and further, a specific broadcast among signals that pass through the band-pass filter. The receiver according to claim 5, further comprising a switch for selecting a signal in a frequency band of the channel. 7. A receiving device for receiving a signal of a broadcast service, an amplifier circuit capable of switching between a function of amplifying the received signal and a function of bypassing the received signal, and a specific broadcast frequency band of the bypassed received signal. Detection circuit for detecting the signal of, the demodulation circuit for demodulating the amplified signal of the amplification circuit, the received signal is bypassed by the amplification circuit to be detected by the detection circuit, the detection signal of the detection circuit is the demodulation circuit. A receiving device, comprising: a control circuit for amplifying a received signal in the amplifier circuit only when the level is a demodulatable level.