JPH062354Y2 - Diversity receiver - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] This invention applies to the medium-wave band or long-wave band / UHF band or VH.
The present invention relates to an improvement of a diversity receiver including an F band receiving function and a plurality of antennas for diversity receiving.

[Summary of the Invention] This invention has a function of receiving a UHF band or VHF band signal, and a medium wave band (hereinafter, referred to as MF band) to a long wave band (hereinafter, L
A diversity receiver that has a signal receiving function (referred to as F band) and performs diversity reception by switching a plurality of antennas for signal reception in the UHF band and the like, and connects the plurality of antennas in parallel when receiving the signal in the MF band and the like. In this way, the antenna gain is increased so that the reception quality can be improved even when a signal in the MF band or the like is received.

[Prior Art] In recent years, many receivers have a multi-band reception function. For example, a UHF band or VHF band signal (FM or TV direction signal, etc.) reception function and an MF band or LF band reception function are available. It has a function of receiving a signal (AM broadcast signal or the like).

By the way, when such a receiver is mounted on a vehicle or the like for mobile reception, fading noise or noise such as multipath noise is easily mixed in the received signal at the time of reception of FM broadcasting or the like, and a reception failure easily occurs. . As one means for solving this, a diversity reception system by switching a plurality of antennas is adopted at the time of receiving an FM broadcast or the like.

FIG. 3 shows an example of a diversity receiver having such a conventional FM / AM receiving function. In the figure,
Reference numeral U ₁ is an FM tuner, U ₃ is an AM tuner, and FM
The tuner U ₁ includes an FM high frequency stage 1, an FM intermediate frequency amplification stage 2, and an FM detector 3. Although not shown in the figure, an FM local oscillator is connected to the FM high frequency stage 1, and an FM received signal is transmitted to the FM local oscillator at this stage.
Converted to intermediate frequency. The AM tuner U ₃ is also provided with an AM high frequency stage 4, an AM intermediate frequency stage 5, and an AM detector 6 which are almost the same as the AM tuner U ₃ .

Two FM antennas ANT ₁ and ANT ₂ for diversity reception are provided in front of the tuners U ₁ and U ₃ . S ₁ is an FM antenna changeover switch, and the antennas ANT ₁ and ANT ₂ are connected to the fixed contacts a and b, respectively, and the changeover contact c is connected to the FM tuner U ₁ . As an antenna for AM reception, one of both FM antennas ANT ₁ and ANT ₂ is shared, and only one FM antenna ANT ₂ is connected to the AM tuner U ₃ .

The FM antenna change-over switch S ₁ automatically operates to switch between the FM antennas ANT ₁ and ANT ₂ when multi-path interference occurs at the time of receiving an FM signal, and sets the diversity reception state. A multipath interference detection circuit 7 and a switch control circuit 8 are provided as means for automatic operation. When the received signal is subjected to multipath interference, an amplitude modulation component due to multipath distortion appears in the intermediate frequency signal, so the multipath interference detection circuit 7
The amplitude modulation component due to the multipath distortion is extracted from the intermediate frequency signal, and a signal having an amplitude level corresponding to the degree of the multipath distortion is output. The switch control circuit 8 inputs the above-mentioned output signal and sends a switch switching signal to the FM antenna switching switch S ₁ .

S ₂ is an FM / AM detection signal changeover switch, whose fixed contacts a and b are connected to the output terminals of the FM tuner U ₁ and the AM tuner U ₃ , respectively, and the changeover contact c has a common audio amplifier 9 and The speakers SP are sequentially connected.

After the power switch (not shown) is turned on, when receiving the FM signal, the FM / AM detection signal switch S
₂ is switched to the FM receiving side (fixed contact a side). If there is multipath interference during FM signal reception, this is detected by the multipath interference detection circuit 7, and the FM antenna changeover switch S ₁ is operated via the switch control circuit 8. As a result, both FM antennas ANT ₁ and ANT ₂ are appropriately switched to enter the diversity reception state, noise such as multipath noise is reduced, and reception quality is improved. On the other hand, when the AM antenna signal is received, the FM / AM detection signal changeover switch S _{2 is set} to the AM reception side (fixed contact b
Side). At this time, of the two FM antennas, only one FM antenna ANT ₂ functions as an AM receiving antenna, and the AM broadcast signal is received.

[Problems to be Solved by the Invention] In the conventional diversity receiver having the FM / AM receiving function, the diversity receiving function operates only when the FM signal is received, and the reception quality is improved. But,
Although a plurality of antennas are equipped at the time of receiving an AM signal, these antennas do not contribute to the improvement of reception quality. Therefore, it has been desired to improve the reception quality by utilizing the plurality of antennas even when receiving the AM signal.

The present invention has been made in view of such circumstances, and improves the reception quality by using a plurality of UHF band or VHF band antennas for diversity reception even when receiving a medium wave band or long wave band signal. It is an object of the present invention to provide a diversity receiver capable of performing.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a plurality of antennas, a first receiving means for receiving a plurality of UHF band or VHF band signals, and a medium-wave band or long-wave band. Second receiving means for receiving the band, and a first switch for selecting and outputting one of the outputs of the plurality of first receiving means according to the receiving state of the first receiving means; Second input for connecting the output of the first switch to the output of the second receiving means for selecting and outputting the output of the first receiving means or the second receiving means. In the diversity receiver having the switch of (1), the output of the plurality of antennas is combined and added to the second receiving means.

[Operation] When a signal in the MF band or the LF band (such as an AM broadcast signal) is received, the output of the plurality of UHF band or VHF band antennas for diversity reception is combined by the antenna output combining means, and the signal in the MF band or the LF band is received. The antenna gain for is increased.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention. In this embodiment, the present invention is applied to a diversity receiver in which two FM tuners are provided for each of two FM antennas for diversity reception.

In FIG. 1 and FIG. 2 which will be described later, the same or equivalent components as the circuit devices and the like in FIG. 3 are designated by the same reference numerals as those used above, and a duplicate description will be omitted.

First, the configuration will be described. In this embodiment, each FM
Separate FM tuners U ₁ and U ₂ are provided for the antennas ANT ₁ and ANT ₂ , respectively. An FM tuner changeover switch S ₃ corresponding to the FM antenna changeover switch S ₁ is arranged at the rear stage of both FM tuners U ₁ and U ₂ . The output terminals of the FM tuners U ₁ and U ₂ are connected to the fixed contacts a and b of the FM tuner changeover switch S ₃ , and the changeover contact c is fixed to the FM changeover side of the FM / AM detection signal changeover switch S ₂ . It is connected to the contact a. Output terminals of the switch control circuit 8 is connected to the FM tuner selector switch S ₃ described above. Reference numeral 11 is a shared FM local oscillator, and its oscillation signal output terminal is
Each FM frequency stage 1a of M tuners _U 1, _{U 2,} 1
connected to b respectively.

The above and both FM tuner _U 1, _{U 2,} between the two FM antenna _ANT 1, ANT _2, upon reception of AM signals, the antenna output combining means is connected in parallel the two FM antenna ANT ₁ and ANT ₂ 12 Is provided.

The antenna output combining means 12 includes two FM antennas AN.
Two coils L ₁ connected in series between T ₁ and ANT ₂ ,
L ₂ , each FM antenna ANT ₁ , ANT ₂ and each capacitor C ₁ , respectively connected between the tuners U ₁ , U ₂ .
It is composed of C ₂ and.

The coils L ₁ and L ₂ each having a capacitance value of about several μH are used, and have sufficiently large impedance with respect to VHF or UHF signals that are frequencies of FM signals and the like, and AM signals and the like. It has a sufficiently small impedance for the signal of the frequency MF or LF. An intermediate connection point 13 between the coils L ₁ and L ₂ is connected to the AM tuner U ₃ .

On the other hand, as the capacitors C ₁ and C ₂ , those having a capacitance value of about 10 pF are used, and conversely to the above, they have a sufficiently small impedance for a signal of VHF or UHF and a signal of MF or LF. On the other hand, it has a sufficiently large impedance.

Next, the operation will be described.

When the FM / AM detection signal change-over switch S ₂ is switched to the FM receiving side to receive an FM signal, the capacitors C ₁ and C ₂ in the antenna output combining means 12 have sufficiently small impedances, and conversely, each coil L. ₁ and L ₂ have sufficiently high impedance. Therefore, the FM antennas ANT ₁ and ANT ₂ are connected to the corresponding FM tuners U ₁ and U ₂ , respectively, and the AM tuner U ₃ is cut off from the ANT ₁ and ANT ₂ .

Thus was FM signal is received by each FM tuner _U 1, _{U 2,} this either FM broadcast received by the FM tuner _U 1, _{U 2} is, FM tuner selector switch _S 3, FM /
The loudspeaker SP is audible through the AM detection signal changeover switch S ₂ and the audio amplifier 9.

If there is multipath interference during reception of such an FM signal,
This is detected by the multipath interference detection circuit 7, and the FM tuner changeover switch S _{3 is} sent via the switch control circuit 8.
Is activated. As a result, both FM antennas and both FM tuners (ANT ₁ and U ₁ , and ANT ₂ and U ₂ ) are appropriately switched to enter the diversity reception state, noise reduction such as multipath noise is achieved, and the FM direction The reception quality is considered good.

On the other hand, when the FM / AM detection signal change-over switch S ₂ is switched to the AM reception side to receive an AM signal, the capacitors C ₁ and C ₂ in the antenna output synthesizing means 12 have sufficiently large impedances, and vice versa. Coils L ₁ and L
₂ has a sufficiently small impedance, so that the FM antennas ANT ₁ and ANT ₂ are connected to the FM tuners U ₁ and U _{2 respectively.}
Is disconnected, and is connected in parallel through both coils L ₁ and L ₂ to be connected to the AM tuner U ₂ .

Here, the wavelength of the MF band or the LF band has a sufficiently large value with respect to the antenna length of each FM antenna ANT ₁ and ANT ₂ . Therefore, at the time of receiving a signal in the MF band or the LF band, if the overall antenna length or the antenna area is increased by using the above-described FM antennas ANT ₁ and ANT ₂ as a composite antenna, the antenna gain with respect to the signal in the MF band or the like is increased. Functioning as an extremely effective AM antenna.

Thus, as described above, both FM antennas ANT ₁ and ANT ₂
Are connected in parallel to form a synthetic antenna for AM reception, the reception sensitivity of the AM signal is increased, the S / N is improved, and the reception quality is improved even when the AM signal is received.

Although the above embodiment has described the case where the present invention is applied to the diversity receiver having the FM / AM receiving function, the present invention is directed to the receiving function of the UHF band or VHF band signal and the MF band or LF band. Any diversity receiver having a signal receiving function can be applied to other diversity receivers.

Further, in the embodiment shown in FIG.
The switch S ₄ may be replaced as shown in FIG.

Further, the present invention can be applied to an automobile FM / AM diversity receiver equipped with an AM rod antenna and a plurality of FM glass antennas for FM diversity reception. That is, if the present invention is applied to the plurality of FM glass antennas, it is possible to receive an AM signal with good sensitivity without extending the AM rod antenna. Therefore, when receiving an AM signal, good reception sensitivity can be obtained either by extending the AM rod antenna or by using a plurality of FM glass antennas as a composite antenna depending on the driver's preference or circumstances. You can

[Advantages of the Invention] As described above, according to the present invention, a UHF band or VHF band signal reception function and an FM band or LF band reception function are provided, and a plurality of antennas are used when a UHF band signal is received. In a diversity receiver for performing diversity reception by switching, an antenna output synthesizing means for synthesizing the outputs of the plurality of antennas is provided, and the outputs of the plurality of antennas are synthesized by this means when receiving a signal in the MF band or the like. Therefore, when a signal in the MF band or the like is received, the antenna gain is increased by utilizing such a plurality of antennas for diversity reception, the reception sensitivity is increased, and the reception quality is effectively improved even in the signal reception in the MF band or the like. The advantage that can be achieved is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a diversity receiver according to the present invention, FIG. 2 is a block diagram showing a modification of FIG. 1, and FIG. 3 is a block diagram of a conventional diversity receiver. ANT ₁ , ANT ₂ ... FM antenna C ₁ , C ₂ ... capacitor L ₁ , L ₂ ... coil S ₁ ... FM antenna changeover switch S ₂ ... FM / AM detection signal changeover switch, S ₃ ... FM tuner selector switch, _{S 4} ...... parallel connection changeover switch (antenna output combining means) _{U 1, U} 2 ...... FM tuner U ₃ ...... AM tuner, 12 ...... antenna output combining means.

Claims (3)

[Scope of utility model registration request] 1. A plurality of antennas, a plurality of first receiving means for receiving UHF band or VHF band signals from each of the antennas, and second receiving means for receiving a medium wave band or a long wave band. A first switch for selecting and outputting one of outputs of the plurality of first receiving means according to a receiving state of the first receiving means, and one input for outputting the output of the first switch A second switch connected to the output of the second receiving means, the other input being connected to the second switch for selecting and outputting the output of the first receiving means or the second receiving means, A diversity receiver comprising an antenna output combining means for combining outputs of the plurality of antennas and adding the combined outputs to the second receiving means. 2. The antenna output synthesizing means includes a medium-wave band and long-wave band cutting capacitor connected between each output of the antenna and each input of the first receiving means, and each of the antennas. UHF connected between the outputs of the
2. The diversity receiver according to claim 1, wherein the diversity receiver comprises a band and a VHF band cutting coil, and a connection point between the coils is connected to the second receiving means. 3. The antenna output combining means comprises a third switch connected to one output side of the antenna, one output of the third switch being one of the plurality of first receiving means. And the other output is connected to the output side of the other antenna and is input to the other first receiving means and the second receiving means. The diversity receiver according to item 1.