JPS58172012A - Identical broadcast discriminating receiver - Google Patents

Abstract

PURPOSE:To select a station having an intense received electric field automatically among plural stations which broadcast the same number by deciding on whether the contents of detection outputs of two tuners are the same or not, comparing the levels of both outputs with each other, and regarding one output with a higher level as an audio output. CONSTITUTION:A radio wave from an antenna 1 is supplied to tuners 3 and 4 through distribution 2. On the basis of set tuning frequencies C1 and C2 from a control circuit 10, the tuners 3 and 4 outputs detection outputs S1 and S2 to broadcast wave detecting and storing circuits 5 and 6 and level detecting circuits 7 and 8. By a control signal C3 from the circuit 10, the circuits 5 and 6 count and store the frequencies that detection output waveforms from the tuners cross a reference level and clock pulses of specific frequency at crossing time intervals to send pieces of information N1 and N2 for deciding on whether the detection outputs are the same or not and data P1 and P2 to the circuit 10. The circuits 7 and 8 rectify the signals S1 and S2 to make a comparison 9 between their levels and then send the results to the circuit 10. The circuit 10 when deciding that the signals S1 and S2 are the same by the pieces of information from the circuits 5 and 6 supplies one detection output with a higher level to a low-frequency amplifying circuit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a same broadcast identification receiver, and more particularly to:
The present invention relates to a receiver that can automatically select and receive the station with the best reception condition when the same program is being transmitted from a plurality of stations.

When broadcast radio waves are received by a receiver mounted on a means of transportation such as a car, it is difficult to maintain good reception conditions as the received radio waves are affected as the receiver moves. Such a phenomenon becomes noticeable when receiving FM broadcasts whose service area is relatively narrow, such as NHK's nationwide "network FM broadcasts."

That is, when driving long distances passing through multiple service areas broadcasting the same program, the reception level from one broadcast station gradually decreases as the vehicle travels, and the reception level from the next broadcast station gradually increases. At this time, the tuning frequency can be switched to the next broadcasting station when the magnitude of the reception level is reversed, but in order to properly switch, it is necessary to research the broadcasting frequency of each service area in advance, or to memorize it. Moreover, when the reception level is reversed, it is complicated to tune to each station and listen to it for comparison. Such complexity has the risk of seriously impeding safe driving.

Therefore, if the same program can be received from multiple stations,
It would be beneficial if it were possible to identify that the same program is actually being broadcast from multiple stations and automatically tune in to the station with the highest reception level. In this case, a possible method for determining whether the programs are the same is to simultaneously receive radio waves from two broadcast stations and compare the amplitude and phase of the respective detection outputs. However, with this method, if there is a time lag in transmission between transmitting stations, there is a possibility that the content of the same program may be determined to be different.

Therefore, an object of the present invention is to provide a same broadcast identification receiver that can accurately determine whether the same program is being transmitted from multiple stations, and can automatically select and receive the station with the best reception condition. It is to be.

The present invention will be explained in detail below according to examples.

FIG. 1 is a block diagram showing an embodiment of the same broadcast identification receiver according to the present invention. In Figure 1, the distributor (DR
) 2 feeds the radio waves coming from the antenna 1 to an electronic tuning tuner (TU) 3.4.

The electronic tuning tuners 3 and 4 output detection outputs Sl based on the set tuning frequencies C1 and C2K from the control circuit (CONT) 10.
, 32. The broadcast wave detection memory circuit (DM) stores information (N1.P) for determining whether the detection outputs are the same or not.
l, N2. P2) is sampled according to signal C3. The details will be described later.

Each detection output 31.32 of the electronic tuning tuners 3, 4 is also rectified by a level detection circuit (LD) 7.8, and compared in magnitude by a comparison circuit (GOMP) 9. The determination output is sent to the control circuit 10. The detected output S1 of the electronic tuner 3 is further amplified by a low frequency amplification circuit (AF) 11 and sent out from a speaker 13 as an audible signal.

The control circuit 10 is constituted by, for example, a microcomputer, and determines whether the contents of the detection outputs S1 and 82 are the same based on signals from the broadcast wave detection and storage circuits 5 and 6. When the detection outputs S1 and 82 are the same, the tuning frequency is set to 0 so that the one with the larger detection output is supplied to the speaker 13 via the low frequency circuit 11 according to the signal from the comparison circuit 9.
Adjust 1. Further, if the detected outputs 31 and 32 are different, the set tuning frequency 02 is changed and the determination is continued.

FIG. 2 is a detailed block diagram of the electronic tuning tuner (TU) shown in FIG. 1. In FIG. 2, 21 is a high frequency amplifier circuit (RF), 22 is a frequency mixing circuit (MIX), 2
3 is an intermediate frequency amplification circuit (IF), 24 is a detection circuit (DE
T), and the PLL is a phase e-locked loop circuit. As is well known, PLL is a voltage controlled oscillation circuit (VC
O) 25, programmable divider circuit (DIV)
26, low pass filter (LPF) 27, phase comparison circuit (PH) 28, reference frequency oscillation circuit (○5C) 29
It consists of Signal C from control circuit 10 (FIG. 1)
By changing the frequency division ratio of the programmable divider 26 using 1 or C2, it is possible to tune to a desired station and send out its detection output S1 or S2.

FIG. 3 is a detailed block diagram of the broadcast wave detection and storage circuit (DM) shown in FIG. 1. In Figure 3, the low pass
A filter (LPF) 31 cuts off high frequencies above the audio frequency, and a comparison circuit (GOMP) 32 compares the output of the low pass filter 31 with a predetermined reference voltage Vref. Trigger pulse generation circuit (TR) 33,
34, 36, 38 and 39 generate a pulse of a set width at the rising or falling edge of the applied signal, (R) means rising and (D) means falling. The detection storage circuit also includes OR gates 35 and 42, and a counter (COUN).
T) 37 and 44, AND gate 40, memory (M)
41, and a reference clock generation circuit (CLK) 43.

The operation of the same broadcast identification receiver of the present invention having the above configuration will be explained with reference to the waveform diagram of FIG. 4.

A tuning frequency signal C1 is applied from the operating section 12 to the tuner 3 via the control circuit 10. Tuner 3 detection output S
1 is amplified by the low frequency amplification circuit 11 and output from the speaker 13 for listening. Next, the control circuit 10 sends to the tuner 4 a tuning frequency signal C different from the signal C1 to the tuner 3.
2, and the tuner 4 sends out a detection output S2.

Detection outputs S1 and S2 of tuners 3 and 4 are given to husband detection storage circuits 5 and 6, which respectively output address signals N (Nl or N) according to signal C3 from control circuit 10.
2) and a data signal P (PI or P2). Since detection storage circuits 5 and 6 operate in the same manner, circuit 5 will be explained below with reference to FIGS. 3 and 4.

The detected output S1 from the tuner 3 has components above the audio band cut off by a bass filter (LPF) 3'l. An example of the waveform is shown in FIG. Comparison circuit (G
OMP) 32 is transformed into a logic 1.0 pulse signal according to its magnitude with respect to the reference signal Vref (ground level here). This signal is transmitted to trigger pulse generation circuits 33 and 3.
Since TR(R) 33 generates a pulse at the rising edge and TR(D) 34 generates a pulse at the falling edge, the output of the OR gate 35 is as shown in FIG. Here, the pulse widths generated by the husband's circuit are set equal to TI. The output signal of the OR gate 35 is supplied to a TR(R) 36 that generates a pulse on a rising edge, a TR('D) 38 that generates a pulse on a falling edge, and a C0UNT 37 that performs a counting operation on a falling edge. Therefore, TR(R)3
The output of 6 is as shown in the figure, and becomes a write signal of M only when C3 is output from the control circuit 10 that enables data writing to M41. Here, TR(R)
The output pulse width T2 of 36 is set to have the time width necessary for writing. Further, the output of TR(D) 38 has a pulse width T3 as shown in the figure, and is given as a clear signal to C0UNT44. Therefore, the pulse width T3 is C0
It is set to have a time width necessary for clearing the UNT 44. The output of C0UNT37 is used as the address of M41 and is supplied to the control circuit 10 as N1. This C0UNT37 is cleared by the output of TR(R)39 which generates a pulse at the rising edge of C3. Also, T.R.
Since the output of (R)39 is also used as a clear signal for C0UNT44, the output pulse width of TR(R)39 is T4.
is set to have a time width necessary for clearing C0UNT37 and C0UNT44. C0UNT44 is C
Count either the rising or falling edge of the clock pulse from LK43, and set the count value to M41.
Write data to . The frequency of this CLK43 is set to be more than twice the cutoff frequency of the LPF 31.

While the control circuit 10 (FIG. 1) holds C3 at a logic level, M41 is in a writable state.

At this rising edge of C3, the outputs of C0UNT 37 and 44 are cleared by the output pulse of TFI (R) 39. As mentioned above, C0UNT37 counts when the detection output S1 changes from positive to negative and from negative to positive. Therefore, when C3 falls, the control circuit 10 outputs C0UNT37.
By reading the output, the total number N1 of the detected output S1 changing from positive to negative and from negative to positive within a predetermined time can be determined. On the other hand, since the output of C0UNT37 is used as an address signal for M41, the count value of C0UNT44, which counts the clock pulses of CLK43 until a pulse is output from TR(D)38, is stored in the corresponding position of M41. . That is, the time it takes for the detection output S1 to change from positive to negative or from negative to positive is M4 as the number of clock pulses.
1 will be stored.

The above operation is similarly performed in the detection storage circuit (DM) 6 for the detection output S2. Then, the control circuit 10 first evaluates Nl and N2. If tuners 3 and 4 receive the same broadcast and their detection outputs are the same, N1 should be equal to N2. However, it is assumed that there is a time difference between each broadcast station, in which case N 1
-Does not become N2. Therefore, a certain tolerance value N(E) is set for the difference between Nl and N2, and if it is within this value, it is determined that there is a possibility of the same broadcast. Note that N (E) can be set based on the cutoff frequency of the LPF 31 for the detection outputs S1 and S2 and the time difference between broadcast stations that needs to be allowed. For example, set the cutoff frequency to j' (K
Hz), time lag n, (msec) and ttort N (
E)=f×10×ru×10×2=2fn can be set as the maximum error. Therefore, when the difference between N1 and N2 is within N(E), DM5 is set using other data stored in M41.
and 6, and it is determined whether or not the detected outputs S1 and 82 are the same.

The search for M41 of DM'5 and DM6 in this determination will be described below. For example, each M41 has a fifth
Assume that data as shown in the figure has been written. now,
If the time lag that must be allowed is rL (m8ec), then the count value P of CLK43 corresponding to this time is
If the frequency of Fi, CLK43 is /cr, K(KH2) (here, fQLK is more than twice the cutoff frequency of LPF31 as mentioned above), P=/CLKX lo”xn
xlo-8: fQLK @n becomes 0 where M41
The address of P is sequentially updated, then Pi is read, the addition is repeated, and when the added value becomes larger than P, the reading is skipped. Then, if Pl and P2 are compared and the search is completed in a continuously equal state, it can be determined that the detection outputs S1 and 82 are the same broadcast content. Also, if the detection output S1 is ahead of C2, the address (Nl-1
), and if the detected output Sl lags behind 82, it is clear that the search ends with the search for address (N2-1).

The control circuit 10 that performs the above processing is preferably a processing device such as a microcomputer, and in this case, a program that performs the above-mentioned calculations and control will be provided. Furthermore, in reality, the time C3 corresponding to the sampling time of the detection outputs Sl and C2 may be set to a time at which the number of data that can be compared is a predetermined number, taking into consideration the allowable time lag. then,
Even if the difference between Nl and N2 is within a predetermined tolerance, if N1 and N2 do not reach a sufficient number for continuous comparison, the determination can be easily made by sampling again. Furthermore, if a hysteresis characteristic is provided to the comparator circuit 32, it is possible to configure the comparator circuit 32 to sample again without counting when there is no modulation or when the modulation is shallow.

In this way, if it is determined that the detected outputs S1 and 82 have the same content, the control circuit 10 considers the signal from the comparison circuit 9. That is, when the detection output S1 is larger than C2, the tuned frequency signal C1 is left as is and the detection output from the tuner 3 is supplied to the speaker 13, but when the detection output S2 is larger than 81, the detection output from the tuner 3 is supplied to the speaker 13. When the tuning frequency signal C1 is changed to C2, the detection output $2 is better for the speaker 13.
be supplied to Through this process, it is possible to receive program broadcasts that are the same broadcast and have a large electric field strength.

As a result of the determination by the control circuit 10, when it is determined that the detected outputs S1 and 82 have different contents, and the detected outputs S1 and 82
2 have the same content, but if it is determined that Sl is larger than 82, the control circuit 10 sequentially changes the tuning frequency signal C2 and repeats the determination.

Although the invention has been described according to embodiments, other changes and modifications are possible within the scope of the invention. For example, it is possible to prepare antennas for each of the electronic tuners 3 and 4 and omit the distributor 2, or to connect the low frequency amplification circuit 11 to the tuner 3.4 via a switch circuit, so that the result of the determination by the control circuit 10 It is also possible to change the switch according to the following.

As described above, according to the same broadcast identification receiver of the present invention, when a car receives broadcast waves while driving a long distance, when the same program is being broadcast from multiple stations, the difference between the broadcast waves Even if there is a time lag between the two, it is possible to automatically maintain the best reception condition without the driver having to perform troublesome adjustment operations.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the same broadcast identification receiver according to the present invention, and Fig. 2 is an electronic tuning tuner (Fig. 1).
3 is a detailed block diagram of the broadcast wave detection storage circuit (first
The detailed block diagram of FIG. 4 and FIG. 5 are diagrams for explaining the operation of the broadcast wave detection and storage circuit. (Explanation of symbols) 1: Antenna 2: Distributor 3.4: Electronic tuning tuner 5.6: Broadcast wave detection storage circuit 7.8 Two-level detection circuit 9: Comparison circuit 10: Control circuit 11: Low frequency amplifier circuit 12: Operation Part 1
3: Speaker

Claims (1)

[Claims] Two tuners that receive broadcast radio waves and send out detected outputs; a control circuit that determines whether the detected outputs of the two tuners are the same; a detection circuit that counts the number of times the detected output waveform from the tuner passes a predetermined reference level, and counts clock pulses of a predetermined frequency at each time interval in which the detected output waveform passes the predetermined reference level; a level comparison circuit that compares the magnitude of each detection output, and the control circuit compares the level comparison circuit when the respective counts from the detection circuit and the clock pulse count are within a predetermined range. An identical broadcast identification receiver characterized in that it audibly outputs the detected output that is determined to be larger.