JPS6039933A - Fm receiver - Google Patents

Abstract

PURPOSE:To improve the total reception performance by fixing a harmonic component and a noise component in an FM detection output of all reception circuit to the state just before they reach a reference level or over to reduce the switching noise. CONSTITUTION:When the harmonic component and the noise component in any of FM detected outputs of the reception circuits 10A, 10B are below the reference level, a changeover switch 20 is switched so as to select and extract the smaller level. On the other hand, when the harmonic component and the noise component of the FM detection output of all the reception circuits are the reference level or over, the switch 20 selects and extracts the state just before the point of time when the harmonic component and the noise component in the FM detection outputs of all the reception circuits reach the reference level or over or the FM detection output of a specific reception circuit. Thus, the switching noise is reduced and the total reception performance is improved.

Description

[Detailed description of the invention] Industrial applications The present invention is an antenna and a front end, respectively.

A plurality of receiving circuits including an intermediate frequency amplification circuit and an FMi high frequency wave circuit are provided, and these plurality of receiving circuits receive FM broadcasts from the same broadcasting station, and the receiving circuits of these plurality of receiving circuits receive FM broadcasts from the same broadcasting station. This relates to a Ji''M receiver in which the FM detection output of the receiving circuit in the best condition is selected.

BACKGROUND TECHNOLOGY AND PROBLEMS The so-called diverti l"M receiver is provided with two receiving circuits each having an antenna, two front-end intermediate frequency amplification circuits, and an FMM wave circuit. When FM broadcasts from the same broadcasting station are received, the levels of harmonic components and noise components included in the FM detection output of each receiving circuit are compared with each other, so that the FM broadcasts from the same broadcasting station are relatively Some FM receivers detect whether the reception state of the circuit is good, and the detection output of the receiving circuit with the better reception state is selected by a changeover switch and taken out. When the detection output is switched, noise is generated in the output audio signal due to the transient response of the changeover switch. In particular, the Ii"M receiver is installed in a car and receives reception while moving, so each Since the receiving state of the receiving circuit constantly changes and the detection output is frequently switched by the changeover switch, noise frequently appears. In particular, the reception conditions of each receiving circuit were poor, and the audio S was originally low.

When the signal becomes worse than 4, the noise becomes noticeable.

OBJECTS OF THE INVENTION The present invention provides an FMFM receiver that reduces noise caused by switching detection outputs of a plurality of receiving circuits.・
-It is designed to improve Tal's love performance.

Summary of the Invention As mentioned above, the reception condition of each receiving circuit is poor,
Originally, when the vortex of the audio signal deteriorates, noise due to switching of detection outputs of multiple receiving circuits becomes noticeable. Furthermore, if the reception state of any of the plurality of reception circuits is worse than a certain limit, no matter which reception circuit's detection output is selected, a satisfactory audio signal will no longer be obtained.

In the present invention, focusing on this point, the F of all receiving circuits is
When the harmonic components and noise components in the M detection output are higher than a certain reference level, it is relatively important to determine which receiving circuit's M detection output has the lowest harmonic and noise component levels. Regardless, the switching of the FM detection output is stopped and the state immediately before the harmonic components and noise components in the li"M detection output of all receiving circuits are below this reference level, or a specific P of receiving circuit
Fix the state in which the M detection output is selected.

Embodiment FIG. 1 is an example of a 1-4 receiver according to the present invention, which has two receiving circuits IOA and 10B, including a receiving circuit 70A.

10B selects the same broadcasting station with FM broadcast signals received by antennas //A and //B and antennas //A and //B and converts them into FM intermediate frequency signals. Sulfuron 1-endo/, 2A, /2B,! :
, an intermediate frequency amplification circuit /3 that amplifies the FM intermediate frequency signal output from the front end /, 2A, /2B, /3
B, FM output of intermediate frequency amplifier circuit /3A, /3B
FM detection circuit/II that detects intermediate frequency signal F'M
A, /≠B, and the output is an FMM wave signal of 5A.
IS11 is obtained, and this FMM wave signal 5AISI] is supplied to the input terminals 2/A and 2/H of the changeover switch 20, and the changeover control terminal 22A of the switch 20, 2.2
Due to the switching signal, which will be described later, applied to B, the switch θ is
One of the signals S A + S 11 is selected and extracted from the output terminal , , 23, and the selected FM detection signal is supplied to the stereo demodulation circuit 30 to produce left and right sound signals. S b +SR is demodulated.

FMM detection signal A of the output of the receiving circuit IOA, 10B.

S11 is supplied to a sharp level comparison circuit θ, and the levels of the harmonic components and noise components included in the signal SAISU are compared with each other, so that the relative values of the signals SA, Sl, Which one has the lower harmonic component and noise component levels, that is, the receiving circuit IOA, 1
It is detected which of the 0Bs is in good reception condition.

Specifically, FMM detection signal A.

sn is supplied to pass filters ll-/A and #/B, and components NAINB of frequencies of, for example, 0 kHz or higher in the signal S A I S n are extracted, and these components NA.

NB is supplied to the rectifier circuit G and 2Aβ and B and is rectified, respectively, and the rectified voltages VA and V11 are supplied to the voltage comparison circuit 'l
-3 and are compared with each other, voltage comparison circuit l13
, that is, the two signals XA,
The harmonic components and noise components generated in the M detection circuit/I1-A are transferred to the FM detection circuit/I1 of the receiving circuit/013. The voltage vA is lower than that generated at B, and the voltage vA is the voltage V
When lower than II, signal XA is high level and signal XI
I becomes low level, the receiving condition of the receiving circuit 10B is better than that of the receiving circuit IOA, and therefore the I of the receiving circuit 10B becomes low level.
"The harmonic components and noise components generated in the M detection circuit/≠B are lower in level than those generated in the FM detection circuit/4'-A of the receiving circuit IOA, and the voltage V Tl is the voltage ■Δ
When it is lower, the result is that the signal XA is at a low level and the signal Xn is at a high level.

In the present invention, the present invention further determines whether any of the harmonic components and noise components of the FM detection signals S11 output from the receiving circuits IOA and 10B are below a certain reference level, or whether any of the harmonic components and noise components are It is determined whether the level is above this reference level, that is, the receiving circuit / (II; IA
, 10B is provided, and a level discrimination circuit 30 is provided to determine whether any reception condition of 10B is worse than a certain limit or whether any reception condition is worse than this limit. Now, the level comparison circuit 4t.

The output signals XA and X11 are just switches! 0 switching signal as a switch, 20 switching control terminal 22A
.

, 2. : Instead of being focused on 2B, signals XA and X1
1 is supplied to a special switching signal output circuit Otsu 0, and the output signal l A I 211 of this switching signal output circuit Otsu 0 is supplied.
The switching signal of the switch 20 is applied to the switching control terminals 2.2A and 2.2B of the switch 20, and at this switching time, the output circuit O0 is at the level! 1-IJ separate circuit jO
It is controlled by the output information WC.

Specifically, in the level discrimination circuit 5'0, the rectified currents Ie VA, VB of the outputs of the rectifier circuits 41, 2A, 2B of the level comparison circuit 1I-0 are connected to the voltage comparison circuits 3/A, 3;/B.
The output signals wA, w of the voltage comparator circuits 3-/A, , 3-/J3 are supplied to the AND gate circuit 3. ．． 2, the harmonic components and noise components of the 1"M detection signal SA I 814 of the output of the receiving circuit IOA, 10B do not meet a certain standard level, and the rectifier circuit Hiroshi, 2A,
The rectified voltage VA of the output of "Mo".

When either of V11 is less than the reference voltage VIt, the output signal W of the voltage comparator circuit J-/A and Shio/B
Either A, 'JJ I) becomes low level, and either the signal WG of the output of Antogame 1/circuit 5.2 becomes low level, or the J"M detection signal S A of the output of receiving circuits IOA and 10B becomes low level. + All harmonic components and noise components of S11 are above the reference level, and the rectifier circuits 1A, 2A,'
, '-, 2B output rectified voltages VA and V11 are both reference voltage V1 (, when the voltage comparator circuit 3/A
, 37B output signals wA, w, , all become high level, and the ant gate circuit shio! The output signal we becomes high level.

Furthermore, the switching signal output circuit Otsu 0 has, for example, a J'K-Noritz flop circuit Otsu/, and the output side from which the signals xA, x of the level comparison circuit G0 are obtained has a resistance of 2 A, O, 2.
It is connected to the preset terminal PR and clear terminal CL of the JK-flip-flop circuit Otsu/ through B, respectively, and connected to the bases of the ant gate transistors O≠A and Otsu4'B of the level discrimination circuit j0, respectively. 'The collector of A, B≠B is J
K-Flip-flop circuit B/preset terminal PR,
The terminals are connected to the clear terminal CL, the emitters are respectively grounded, the J terminal of the JK-flip-flop circuit B/, the clock terminals CP and ■ (terminals are respectively grounded, the Q terminal, the Q terminal switch, and the switching control of 20). Terminal.2
．． 2A, , 2.2B K-connected configuration.

Therefore, when any of the harmonic components and noise components of the t'M detection signals S A + S R output from the receiving circuits IOA and 10B do not meet the reference level, the signal WO output from the level discrimination circuit jO becomes low. level, transistors A and B are both turned off, and the output signals xA and x of the level comparator circuit G0 are turned off. That's the trick JK
- The signals YA + Y 11 of the preset terminal PR and clear terminal CL of the flip-flop circuit B/ are respectively applied, that is, the signal XA of the output of the level comparison circuit ≠0.

At this time, the switching signals ZA and +Z11 obtained at the 6 terminals and Q terminals of the JK-flip-flop circuit B/ are the same as the preset terminal PR and the clear terminal (signals YA and Y11 of CL). Since they are the same, in the end there are two switching signals, and Z11 is the level comparison circuit lZ.
They are the same as the output signal X A + X n of O.

Therefore, before time t/ and time 1. of FIG. As shown below, if the harmonic components and noise components of the signal s A'l output from the receiving circuit 10A are smaller than those in the signal S I'l output from the receiving circuit 10B, switch! At θ, diode, 24'A is on, diode-1
', 21l-B is turned off, the signal SA output from the receiver circuit IOA is taken out to the output terminal 23, and the harmonic components and noise components in the signal Sn output from the receiver circuit 1013 are output to the receiver circuit 1013. If the level in the signal SA of the output of 10A is smaller than that in the signal SA of the output of the receiving circuit 10B, the diode 2≠A is turned off in the switch 20, the dimer, 2II-B is turned on, and the signal SB of the output of the receiving circuit 10B is connected to the output terminal. 2
3, and the one of the signals SA and S o with lower harmonic component and noise component levels is selected.

FM detection signal A+ of output of receiving circuit IOA, 10B
Are any of the harmonic components and noise components of Sn based? Y,f
When the level is higher than the second level, the signal Wc of the output of the level-rll separate circuit θ becomes high level, so both the transistor Otsu 4'A and the O-tag B are turned on, and the JK-flip-flop circuit O is turned on. The potentials of the preset terminal 1]R and the clear terminal CL of / become the ground potential. Therefore, the β
As shown between time t/ and PJ point tλ in the figure, the output of the reception circuits 10h and 10H is relatively
+ S H The level comparison circuit ψ0
Regardless of the state of the output signal X A I l
In the state immediately before the L time t/, in the case of FIG. 2, the signal ZA is fixed at a low level and the signal Zfl is fixed at a high level. Therefore, switching of switch 20 is stopped, and switch 20 is also in the state immediately before time t/, in the case of FIG. 2 a diode, 2! A off, diode, 2
When II-B is on, the signal SB of the output of the receiving circuit/θB is fixed to the output terminal 23, and the FM detection signal of the output of one of the receiving circuits is unrelated to the levels of harmonic components and noise components. is selected.

In the example of FIG. 1, the output of the receiving circuit IOA, 10B is 1=
' When both harmonic components and noise components of the M detection signal S A + S R are equal to or higher than the reference level, the left and right audio signals S1 . .

S
Rectifier circuit ≠, 2 people, G, 2B output rectified voltage VA.

By V 11, left and right audio signals S +, + S
This is the case where the harmonic components and noise components contained in +t are blocked and the audible impact is softened.

That is, the left and right audio signals S I, S n of the output of the stereo demodulation circuit 30 are transmitted to the band control circuits 70L and 70H.
The band control circuits 70L and 70R are supplied to the input terminal 7/ and the resistor 7.2, respectively.
．． Condenser 73. It is grounded through a series circuit of the collector-emitter of the transistor 7≠ and the collector-emitter of the transistor 7j, and a control terminal 77 is led out from the base of the transistor 7 via the resistor divider circuit 7B, and from the base of the transistor 7 Another control Qi# is derived from resistors 7, . The output terminal 7 is derived from the connection point between 2 and the capacitor 73, and the level discrimination circuit jO
The output signal We is in the 41v range i1i control circuit 7θL, 7
01. t control & ii 6 and 7g respectively, level comparison circuit g θ rectifier circuit, 2A, g, 2B output 8!1≧flow? Ijj voltages V,, V□ are supplied to the adder circuit gθ, and the voltage control circuits 70L, 70 of the average value of both 317
They are respectively supplied to control terminals 77 of YL.

Therefore, the output of the receiving circuit /OA, /OB is 1.
゛When any of the harmonic components and noise components of the 4-detection signal S A + 313 does not meet the reference level, the signal We output from the level discrimination circuit 30 becomes a low level, so the band control circuits 70L and 70R The transistor 7j is off, and the left and right audio signals S1. +SI-L is led out to the output terminal 79' through the resistor 7.2 without any band limitation in the circuits 70L and 70R. On the other hand, J-? of the output of the receiving circuit IOA, 10B? M detection signal S A
+ S I'l When any of the harmonic components and noise components are above the reference level, the signal Wc output from the level discrimination circuit jO becomes high level, so the band control circuit 70
L.

Transistor 7j of 70R is turned on, and addition circuit g0
When the voltage Vo of the output of transistor 7/I exceeds a certain value,
- also turns on, the circuits 70L and 70R constitute a low-pass filter, and the left and right audio signals S b + S rt of the output of the stereo demodulation circuit 30 are converted into high-frequency signals including harmonic components and noise components in the circuits 70L and 70R. The components are blocked and led out to the output terminal 79. In this case, the J"M detection signal SA + 8 of the output of the receiving circuit IOA, 10B
The higher the average level of the harmonic components and noise components contained in the circuit 701. , 70R low-pass filters are lowered.

Note that instead of the voltage VC, which is the average value of the rectified voltages VA and V13, the rectified voltage 'V'At or V11 is applied to the control terminal 7.
7 may be supplied.

In the example of Fig. 1, the output F of the receiving circuits 10h and 10B is
1, switch, 2 when any harmonic component and noise component of M detection signal 5AIS11 are above the reference level.
0 switching signal Z A + Z 13 is the signal SA, S1
All harmonic components and noise components of 1 are fixed at the state immediately before they exceeded the reference level, and the switch 2
0 is fixed to the state immediately before the time when all harmonic components and noise components of the signal S A + 811 exceed the reference level, but the switching signals ZA and Zll of the switch 20 are in a specific state. , for example, the signal ZA is fixed at a high level and the signal Z 13 is fixed at a low level, and the switch 20 takes out the 1"M detection signal of the output of a specific receiving circuit to the output terminal 23. For example, a diode, 2≠
It may be fixed in such a state that A is on, the diode 21I-13 is off, and the FM detection signal SA output from the receiving circuit 10A is taken out to the output terminal 23.

In addition, as shown in the example in Figure 1, a special switching signal output circuit
is not provided, and the level comparison circuit≠00 output signal XA
,

2.2B, and the voltage comparison circuit 1I-3 of the level comparison circuit 11O is controlled by the signal WG of the output of the level discrimination circuit jθ.

When any of the harmonic components and noise components of the PM detection signal S A T S n of the output of 10B are higher than the reference level, the signal W becomes high level, so that the voltage comparison circuit 3 performs the voltage comparison. Operation is blocked and the rectifier circuit/
I-, 2A, 11. ．． 2B output rectified voltage V A +
Regardless of which of V11 is relatively high, the switching signals XA and XB of the output of the voltage comparator circuit≠3 are forced to a specific state, for example, the signal XA is at a high level and the signal Xn is at a low level. A configuration may also be used.

Application Example If the signal Wc output from the level discrimination circuit 30 described above is supplied to a suitable display circuit, the receiving circuit 70A.

When any reception condition of 10H is worse than a certain limit, a message to that effect can be displayed.

In addition, in a type of receiver in which the local oscillation frequency is automatically scanned to select a station, the signal Wct of the output of the level discriminator jO is used as a signal to start scanning, and the signal Wct of the output of the level discriminator jO is used as a starting signal for scanning, If the condition is worse than a certain limit, another station with better reception can be searched automatically.

Further, in a receiver having a memory for setting a broadcast station, the output signal We of the level discrimination circuit 0 is used as a readout signal of the memory, and the reception circuit #)A, 10
When the reception condition of any of the H is worse than 711, the preset broadcasting station is read from the memory,
It is also possible to automatically switch to that broadcasting station.

Effects of the Invention According to the present invention, when the reception condition of each receiving circuit is poor and the sound signal depth is originally poor, noise due to the switching of the detection outputs of the plurality of receiving circuits becomes noticeable, and the plurality of Focusing on the fact that if the reception condition in any of the receiving circuits is worse than a certain limit, no matter which receiving circuit's detection output is selected, a satisfactory audio signal will no longer be obtained. When the harmonic components and noise components in the FM detection output of
゛Regardless of whether the M detection output has the lowest harmonic component and noise component levels, l? By stopping switching of the M detection output, the state immediately before the harmonic components and noise components in the FM detection output of all receiving circuits exceed this level, or the state of a specific receiving circuit. Since the FM detection output is fixed in the selected state, noise caused by switching the detection outputs of the plurality of reception circuits is reduced, and the total reception performance is improved.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram of an example of the FM receiver of the present invention, and FIG. 2 is a waveform diagram for explaining its operation. In the figure, 10h and 10B are receiving circuits, //A and //B
is the antenna, /, 2A and 72B are the front end,
/"A and 73B are intermediate frequency amplification circuits, //I-A and //I-B are FM detection circuits 1..20 switching switches, 30 are stereo demodulation circuits, G0 is level comparison circuits, ≠
/A and 4'/B are no-pass filters, ll-, 2A
and ≠! B is a rectifier circuit, G3 is a voltage comparison circuit, JO is a circuit for each level R41, 5/A and 3/B are voltage comparison circuits, and B0 is a switching signal output circuit. Agent: Patent attorney Sadaaki Kanbara (′□,′:””::.

Claims (1)

[Claims] antenna and the FM received by this antenna, respectively.
A front end that selects a broadcasting station and converts it into a J"M intermediate frequency signal; an intermediate frequency amplification circuit that amplifies the I"M intermediate frequency signal output from this front end; A plurality of receiving circuits each equipped with a FM detection circuit that performs FM detection on the FM intermediate frequency signal output from the amplifier circuit, and a changeover switch that selects and extracts seven of the Ji''M detection outputs of the plurality of receiving circuits. Then, compare the levels of the harmonic components and noise components included in the 1·゛M detection output of each receiving circuit, and determine the level of the harmonic component and noise component of the FM detection output of which receiving circuit. A level comparison circuit detects whether the harmonic components and noise components in the FM detection output of any receiving circuit are below a certain reference level, or whether the harmonic components and noise components in the FM detection output of all receiving circuits are the lowest. and a level discrimination circuit that determines whether the wave components and noise components are above the above reference level, and when the harmonic components and noise components in the FM detection output of any of the receiving circuits do not meet the above reference level. , the changeover switch is switched to select and extract the one with the lowest harmonic component and noise component level among the FM detection outputs of the plurality of receiver circuits, and the J"M detection output of all the receiver circuits is switched. When the harmonic components and noise components in the FM detection output of all receiver circuits are at or above the above reference level, the changeover switch 1 is set to An FM receiver that is fixed in the previous state or in a state in which the 1.M detection output of a specific receiving circuit is selected and extracted.