JPS5989080A - Television synchronous receiver - Google Patents

Abstract

PURPOSE:To decrease the pull-in time of frequency by using a frequency pull-in circuit as an auxiliary circuit for frequency pull-in of a costus loop and then connecting the costus loop to a channel selector of PLL frequency synthesizer system to constitute a TV synchronous receiver. CONSTITUTION:A costus loop consists of a high frequency input part 27, a synchronous wave detectors 28 and 29, a phase detectors 34, a voltage control oscillator 36, a 90 deg. phase shifter 37, etc. While a frequency pull-in circuit comprises a sound IF amplifier 38, a frequency discriminator 39, a voltage subtractor 40, etc. The output of the frequency pull-in circuit is added to the output of an LPF35 through a voltage adder 42. Then a phase locked loop PLL is formed with a reference oscillator 43, a reference frequency divider 44, a prescaller 45, a variable frequency divider 46, a phase detector 47, an LPF35, an oscillator 36, etc. This PLL forms a frequency synthesizer device together with a channel selection control circuit 49 and a control signal input device.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to television receivers and VTR video chips.
The present invention relates to a television synchronization receiving device that can be used for television.

Conventional Structure and Problems In recent years, so-called electronic tuners using variable capacitance heavy diodes as tuning elements have been widely used in television receivers 1&Iff and V'I''R video tuners.

The electronic Qi-Qi has the advantages of being non-contact, so there is no problem of contact failure, and because it can be controlled electronically, it is convenient for multi-functions such as remote control. However, due to variations in the characteristics of variable capacitance diodes and the need for an inductor for tuning, there is no need to adjust the manufacturing process.
Difficult to automate.

Therefore, in order to configure a receiver that is easy to integrate without using a tuning circuit using a variable capacitance diode and an inductor, it is possible to use a synchronous reception method.

Although there are various synchronous reception methods, a synchronous carrier regeneration method is suitable for phase-synchronizing a synchronous carrier wave with a weak television signal.

This method is called Co5tas Loop.
known as the method.

FIG. 1 is a block diagram of main parts showing the configuration of a conventional synchronous carrier regeneration type television synchronous receiving apparatus using a Costas loop proposed by the inventor of the present invention. In this conventional example,
A frequency synthesizer type tuning device using a phase-locked loop (PLL) is coupled to the Costas loop.

Of these, the Costas loop consists of a high frequency manual input section 1 into which a modulated carrier input is input, a first synchronous detector 2 that synchronously detects the in-phase component of the modulated carrier input, a second synchronous detector 3 that synchronously detects the orthogonal component, Low-pass p-wave generators 4 and 5 that generate low-frequency p-waves from the outputs of these two synchronous detectors 1 and 2, and signal amplifiers 6 and 7 that amplify the outputs of these two low-frequency p-wave generators 4 and 5, respectively. , a phase detector 8 that multiplies the outputs of these two signal amplifiers 6 and 7 by voltage, a low-frequency P-wave device 9 that converts the output of this phase detector 8 into a low-frequency p-wave, and an output of this low-frequency p-wave device 9. It consists of a voltage controlled oscillator 10 which is controlled, and a 900 phase shifter 11 for the output of this voltage controlled oscillator 10. The frequency synthesizer type tuning device includes the above-mentioned voltage controlled oscillator 1.
A grease scaler 12 and a variable frequency divider 13 that divide the output of 0, a reference oscillator 14, a reference frequency divider 15 that divides the output of this reference oscillator, and an output of the variable frequency divider 13 and this reference frequency divider 15. a phase detector 16 for comparing the phases of the outputs of the
The output of this phase detector 16 is composed of a low-frequency wave transducer 17, and is connected to the Costas loop by analog switches 18 and 19.

20 is a control signal input device, and 21 is a channel selection control circuit.

Corresponding to the channel number input from the control signal input device 20, the output of the tuning control circuit 21 is transmitted to the variable frequency divider 13.
Give the division ratio to. After the PLL of the frequency synthesizer reaches a steady state, the tuning control circuit 21 also switches the analog switches 1B and 19 from the PLL side to the Costas loop side. 22 is a video signal amplifier, 23
2 is a video output device, 24 is an audio intermediate frequency amplifier, 25 is a frequency discriminator, and 26 is an audio output device.

In such a television synchronous receiving device, the frequency synthesizer operates so that the oscillation frequency of the voltage controlled oscillator 1Q is set within the frequency pull-in range of the Costas loop. However, if there is a frequency error in the arriving television signal, there is a problem in that it takes a long time to pull in the signal.

OBJECTS OF THE INVENTION An object of the present invention is to provide a television that can complete the pull-in operation in a short time without requiring a long time even if the oscillation frequency of the voltage-controlled oscillator is set within the pull-in range of the Costas loop using a frequency synthesizer. An object of the present invention is to provide a synchronous receiving device.

Structure of the Invention An uninvented television synchronous receiver includes a voltage controlled oscillator, a 900 phase shifter that shifts the phase of the output of the voltage controlled oscillator by 90 degrees, and a phase shifter that shifts the output of the voltage controlled oscillator by 90 degrees.
The output of the phase shifter is used as a synchronous carrier wave, and first and second synchronous detectors synchronously detect the in-phase and quadrature components of the video carrier signal using the respective synchronous carrier waves; a first phase detector that detects a phase difference in the output of the wave detector; a first low-frequency p-wave detector that converts the output of the first phase detector into a low-frequency reactor; A frequency discriminator that discriminates the frequency of the audio intermediate frequency signal generated by the detector, a second low-frequency P-wave device that converts the output of the frequency discriminator into a low-frequency P-wave, and this second low-frequency P-wave device. a reference oscillator, a reference frequency divider for dividing the output of the reference oscillator, and an output of the voltage controlled oscillator. a second phase detector that compares the phases of the output of the reference frequency divider and the output of the variable frequency divider;
It is configured to include a switch circuit that switches the output of the first phase detector and the output of the second phase detector and outputs the switched output to the first low-pass p-wave detector. , thereby shortening the frequency acquisition time of the Costas loop.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram of main parts of a television synchronized receiving apparatus in an embodiment of the present invention. In FIG. 2, 2 is a high frequency input section, 28 is a first synchronous detector, and 29 is a second synchronous detector.
, 30 and 31 are low-pass p-wave detectors, 32 and 33 are signal amplifiers, 34 is a first phase detector, 36 is a first low-pass p-wave generator, 36 is a voltage controlled oscillator, and 37 is a 90
° phase shifter, these form a Costas loop.

38 is an audio intermediate frequency amplifier, 39 is a frequency discriminator, 40
41 is a voltage subtracter, and 41 is a second low-frequency door converter, which constitutes a frequency pull-in circuit, and the output thereof is sent to a voltage adder 4.
2 is added to the output of the first low-pass p-wave generator 36. 4
3 is a reference oscillator, 44 is a reference frequency divider, 45 is a prescaler, 46 is a variable frequency divider, 47 is a second phase detector, 48
is a switch circuit, which constitutes a PLL together with the first low-frequency door transducer 35 and the voltage-controlled oscillator 36;
The LL, the tuning control circuit 49, and the control signal input device constitute a frequency synthesizer type tuning device. 51 is a video signal amplifier, 52 is a video output device, and 53 is an audio output device.

The operation of the non-embodiment television synchronous receiving apparatus configured as described above will be described below.

First, the operation when a television signal is received by a Costas loop type synchronous receiver will be explained.

The video 1 transmission signal of the desired reception channel input to the high frequency input section 2γ is vv (t), and the audio carrier wave signal is Z/
s [tl ttle. Since vv(t) is modulated with residual 0 (Uv band), it can be expressed as follows.

θy(tl = Re (CI(tl+j Q(tD
eXpj Cωvt ψvl l= I(tlcos[
ωv1+ψvl Q(t) sin [ωvj+ψv)・
(1) Here, l(e is the real part of the expression in parentheses).

1(t) is a signal having an in-phase component with respect to the relative transmission wave, and includes an image signal In. Q(t) is the direct variable component signal with respect to the general transmission wave, ωV is the angular frequency of the video JiiQ transmission, and ψV is the position of the first video carrier wave.

Voltage control] 1 The output of the oscillator 36 is vo (tl = AOcos ((IJOt +tp
o) −・−−−−−(2), and combine this with the video carrier wave vv(t) of equation (1) to the first circuit consisting of a voltage multiplier.
When added to the synchronous detector 28 of
t+ψ7〕Q(t)sin [ωy to 1ψv)) Ao
cos (ωot-1-ψ(1)= A o I (t
)cos Cωvt+ψvl residence (ωOt+ψ0)−AO
Q(tl sin I:ωv t-1−ψv) cos
((1) o t+ψo) ten [(rumor-ω0)t+ψV-
ψo〕)+sin [(ωV-ωo) to 1ψV-n])・
...(3) 1. When the voltage controlled oscillator output is synchronized with the video carrier wave, ω. = ω7, so...(4) When the 2ωV signal is removed by the low-pass P wave generator 30, here, ψ
is ψ7−ψ. is the phase difference between the video carrier wave and the voltage controlled oscillator output. If ψ=0, then vpv(jl−”) ・・・・・・・・・・・・・・・・・・・・・・・・(
6). In other words, the signal of the eye component is obtained as the detection output for the video carrier wave. However, the orthogonal component is
The signal is amplified by a signal amplifier 32 via a low-pass P wave amplifier 30, and outputted to a video output device 62 via a video signal amplifier 51.

The E-wave characteristics of the low-pass Pi device 30 are shown in FIG. The video signal is Pv'ed at baseband as shown in this figure. When a television signal is received using the conventional superheterodyne reception method, the overall baseband frequency line 1 is
It can be assumed that g is flat, but in a synchronous reception system such as the present invention, it must be considered as shown in Figure 4 (al).In other words, the voltage gain in the low frequency range is equal to that in the high frequency range. Therefore, in the embodiment of FIG. 2, this is corrected by changing the frequency characteristics of the video signal amplifier 510 as shown in FIG. 4(b).

Television broadcast audio carrier wave signal Z7s (tl is frequency modulated, so v5(t) - Ascos C[ωs + 5(t)l
t+ψsI] −=−・・−・−171. Here, As is the amplitude of the audio carrier signal, ω8 is the angular frequency of the audio carrier signal, S (t) is the audio signal, and ψ8 is the phase of the audio carrier signal.

? C(7)77Sft+ Equation (2) no vO(tl
When synchronous detection t&d% 2 B VC is added, the output is vps(tl=Ascos[I(ωs+5(tll
t+ψ8〕Aocos(ωO1+ψO)=-cos
C(ω5-1-ωo) t-1-5(tl t-1-
97s+ψo]S AO −1−cos C(ωs −ωo)tl5(tit+
ψS−ψ0〕・・・・・・・・・(8) When the frequency component of ω8+ω0 is removed by the low-pass P wave generator 30, ・・・・・・・・・(9) ωIF−ω8−ω. , ω. = ω7.

Z7ps (t) in equation (9) is nothing but the audio carrier signal shown in equation (a) converted into an audio intermediate frequency signal whose angular frequency is ωIF.

The P-wave characteristics of the low-frequency Pv device 3Q are designed to cover the frequency ωIF of the mid-range signal of the voice as shown in FIG. The audio intermediate frequency signal passes through this low-pass Pv device 30 and is amplified by a signal amplifier 32 and an audio intermediate frequency amplifier 38. The output is demodulated by the frequency discriminator 39 and the audio signal S
(tl is obtained.5(1) is supplied to the audio output device 63.

In this case, we have explained that there is no difference between the phase of the video carrier signal vv(t) and the phase of the output 't)O(tl) of the voltage controlled oscillator 36, that is, ψ=○, but this state is It can be obtained as follows.

The output of the 90° phase shifter 'l)q (tl has a difference of 90° from the output of the voltage controlled oscillator 36, so Z7Q (
t]=AOsin (ωQ t+ψo) ・−・
=・(11) When this is added to the second synchronous detector 29 consisting of a voltage multiplier along with Z7v (tl) of equation (1),
The output Z7pq(tl is 稗.(tl = (I(tl [ω7t+ψ7]−Q(
tl sin [Iωv + ψv]l AOstn
(ω□t+ψ0)= Ao I (t) cos Cω
V + ψvls stone (ωO1 + ψ0) - Ao Q (tl s
tn CωV+ψv〕5In(ωot+ψO)- and shout (
・Stone [(...+...)+ψ・+ψ・]-S stone [(ωV-
ωo)t+ψV-ψ0〕)+possible[(ωV-ωo)t+ψ
V-ψo':)i-...(12) Since ω0-ω7,...(13) When the 2O2 signal is removed by the low-pass filter 31, AoI(1
7AOQ(t) , , , , , (14) vp
Q(t)=: s stone ψ−one ψ′2
2 is obtained. This vpQ(t) is amplified by the signal amplifier 33 and added to the 1st position 4[] detector 34.

In the phase detector 34 consisting of a voltage multiplier, Z7pv(t)
and vpQ (tl are multiplied by voltage, and as a result, a control voltage 1)c(t) is generated.

vc(t) = vpv (jl・vpQ (tlAo
I(tl Ao Q(tl.

−(□−ψ−stnψ) 2 2 (AoI(−ψAoQ(t)−ψ) 2 2 ・・・・・・・・・(15) Here, θ=2ψ. The amplifier of the second signal amplifier is assumed to be 1 here.

Since the video 1 transmission signal vv(t) has residual sideband characteristics, the in-phase component I (tl is always thicker than the orthogonal component Q (tl). )'-Q(t
)21+O. At this time, the loop bandwidth is expressed as (15
) is narrow enough to remove the second term component of ), the voltage controlled oscillator 36 is controlled so that θ=0. That is, the phase error ψ between the video carrier signal vv(t) and the output Z7o(tl) of the voltage control oscillator 36 is in the state of ψ=O.

Next, the operation of the frequency pull-in circuit will be explained. The voice intermediate frequency signal vps (tl) can be obtained in 2 days using the synchronous detector, and this vps(t) passes through the low-frequency P-wave generator 3o, the signal amplifier 32, and the voice intermediate frequency amplifier 38, and then passes through the frequency discriminator 3.
As mentioned above, the signal S[t] is demodulated into the audio signal S[t] at step 9. The frequency pull-in circuit uses the frequency discrimination output obtained from this @wavenumber discrimination circuit 39 to pull in the frequency of the Costas loop, thereby shortening the pull-in time.

The audio intermediate frequency signal vps'(
t) sets the amplitude of equation (9) to a certain constant value ASL, and ωS
Let −ω0 be the sum of the intermediate frequency angular frequency ωIF and the error frequency Δω, and ψ8−ψ. By including the differential value of Δω in this Δω, it can be expressed by the following equation.

Zips' (tl= A's cos [ωIF+Δ
ω+5(t)] ]t−==−=16 ) but 2ω
IF=ω8−ω7.

Since the average value of the audio signal s(t) is 0, the average value of the instantaneous stratum corneum wave number of the audio intermediate frequency signal vpsl(t) is θ)
IF+Δω. Figure 5 (&) illustrates the frequency discrimination corresponding to this average value frequency and the 1 “1” force of 1ζ39.
become that way. The summed voltage Vs corresponds to the stratum corneum wave number ωIF. 'i [i pressure subtractor 40 subtracts voltage VS from this output so that the output voltage becomes OV when the carrier angle l1o1 wave number of the audio intermediate frequency signal is ωIF. The voltage subtracter output at this time is shown in FIG. 6 (bl).

If the cutoff frequency of the low-pass E wave generator 41 is set to be optically low in order to remove stt+bx, the output voltage from the low-pass Pv generator 41 corresponding to the polarity and magnitude of the error frequency Δω will be can get. This output voltage is applied to the voltage controlled oscillator 36 via the voltage adder 42.

The low-pass P-wave unit 41 can be configured with a voltage integrator. If the output of the voltage subtractor 40 has an error with OV as a reference, the voltage integrator output increases or decreases according to the sign of the error. is determined, and the rate of change of the integrator output changes according to its absolute value.When the frequency pulling operation is completed and the voltage subtracter output becomes OV, the integrator output no longer fluctuates.

In the end, the frequency pulling circuit consisting of the audio intermediate frequency amplifier 38, the frequency discriminator 39, the voltage subtractor 40, and the low-frequency p-wave filter 41 helps the frequency pulling operation of Costa Sloose.

Finally, the operation of the PLL frequency synthesizer will be explained, and the operation of the television receiver of this embodiment to select a desired reception channel and enter the reception state will be explained.

The output of the voltage controlled oscillator 36 is frequency-divided by a grease scaler 45 and a variable divider 46, and is applied to one terminal of a digit 1'g2 detector 47. The reference signal generated by the reference oscillator 43 is connected to the other terminal of the phase detector 47 and the reference signal generated by the reference oscillator 43 is connected to the reference splitter 4.
Add 4 to the list. The output of the phase detector 47 is sent to the voltage controlled oscillator 3 via the low-frequency P wave generator 36 of the switch circuit 48.41.
Control 6.

The variable frequency divider 46 is connected to the channel selection control circuit 49 in accordance with the desired reception channel input from the control signal input device 60.
is given the division ratio. The oscillation frequency of the voltage controlled oscillator 36 is controlled according to this division ratio. This is the operation of the PLL frequency synthesizer.

The output of this voltage controlled oscillator 36 is a synchronous carrier wave υo(tl
I'm aiming for 4. The synchronous carrier wave vo(t) and the audio carrier wave are added to the synchronous detection signal 28 to generate an audio intermediate frequency signal vps(t). When the PLL of the frequency synthesizer becomes open loop, the frequency The frequency of this audio intermediate frequency signal vps (tl) is broadcasted by the 1 inverse number pull-in circuit and the video carrier wave signal υv (carrier frequency ω7 of tl and 1iffl of the audio carrier wave signal v8(t)
i^ The synchronous carrier wave V so as to be equal to the difference in frequency ω8, that is, ωIF. The frequency of (1) is controlled t'. When this frequency V enters the frequency pull-in range of the Costas loop, the Costas loop rapidly enters a state of phase locking.

When the Costas loop is phase synchronized, the detector 28 outputs the video signal vpv(t) and the audio intermediate frequency signal vps(
t) is obtained. These signals pass through a low-frequency P wave generator 30, etc., and the video signal is sent to a video output device 52, the audio intermediate frequency signal is demodulated by a frequency discriminator 39, and the demodulated audio signal is output to an audio output device 63. According to the present invention, the frequency of the audio intermediate frequency signal generated from the synchronous detector of the television synchronous receiver using the Costas Loop is changed between the video carrier frequency and the backdoor carrier when the Costas loop enters the synchronized state. Focusing on the fact that the frequency is equal to the difference, a frequency pull-in circuit 'xM is constructed using the output of a frequency discriminator for audio signal demodulation. Therefore, only one of the audio intermediate frequency amplifier and frequency discriminator, which are essential to a television receiver, is used, and a frequency pull-in circuit can be constructed by simply adding a voltage subtractor and a low-frequency F wave filter. After creating such a frequency pull-in circuit as a Kamisuke circuit for frequency pull-in of the Costas loop, the Costas Loop is used as a PL.
Since the television synchronization receiving device is configured by combining with the L frequency synthesizer type tuning device, the acquisition time is shortened even if the frequency synthesized by the frequency synthesizer has an error with respect to the video W and transmission frequency. You can get the effect that you can.

In addition, in the present invention, since the control voltage obtained from the frequency discriminator output for audio signal demodulation is negatively fed back to the voltage controlled oscillator, even if the audio signal remains at the output of the low-frequency p-wave generator of the frequency pull-in circuit, This signal also has the effect of reducing interference to the sound and return signals caused by the image signal included in the low-frequency P-wave output of the Costas loop.

Furthermore, if the low-frequency Pe device of the frequency pull-in circuit is configured with a 4-pressure integrator, the input to the heavy-pressure integrator will be based on OV.
If there is an error as a seat, ゛t
Since the direction of increase/decrease in the output of the taIf integrator is determined, the effect of simplifying the control circuit of the voltage controlled oscillator is obtained.

[Brief explanation of drawings]

Figure 4g1 shows the main parts of a conventional television synchronization receiving device.
Figure 7 and Figure 2 show an embodiment of the present invention.
Figure 3 is a block diagram of the main parts of the synchronous receiver; Figure 3 is a frequency characteristic diagram of a low-band p-wave filter that transmits the output of the synchronous detector; Figure 4 is a diagram of the baseband frequency characteristics of the video signal; Figure (b) is a frequency characteristic diagram of the video signal amplifier, and Figure 5 (
al is the output characteristic diagram of the frequency discriminator, and Figure 5 (+)] is '
It is a city pressure reduction output characteristic diagram. 28...First synchronous detector, 29...
Second synchronous detector, 34... First phase detector, 35 Mountain... First low frequency wave detector, 36... Voltage controlled oscillator, 37...・・900 phase shifter, 38・
... Audio intermediate frequency amplifier, 39 ... Frequency discriminator, 40 ... Voltage subtractor, 42 ...
...Voltage adder, 43...Reference oscillator, 44.
River...Reference frequency divider, 46...Variable frequency divider, 47
...Second phase detector, 48...Switch circuit. Name of agent: Patent attorney Toshio Nakao and one other person Layer liquid @ (MHz) Figure 4b

Claims (2)

[Claims] (1) A voltage controlled oscillator, a 900 phase shifter that shifts the phase of the output of the voltage controlled oscillator by 90°, and a synchronous carrier wave that uses the output of the voltage controlled oscillator and the output of the 90° phase shifter, respectively. A first and a second circuit that synchronously detect in-phase and quadrature components of a video carrier signal using respective synchronous carrier waves.
a synchronous quarantine device, a first phase detector that detects the phase difference between the outputs of the first and second synchronous quarantine devices, and a first phase detector that detects a low-frequency P wave from the output of the first phase detector. A low-frequency P wave device,
a frequency discriminator that discriminates the frequency of the audio intermediate frequency signal generated by the first synchronous detector; a second low-frequency P-wave generator that converts the output of the frequency discriminator into a low-frequency P wave; means for feeding back the output of the low-pass F-wave generator together with the output of the first low-pass F-wave generator to the voltage controlled oscillator; a reference oscillator; a reference divider for frequency-dividing the output of the reference oscillator; a variable divider that divides the output of the controlled oscillator; a second phase detector that compares the output of the reference divider with the output of the variable divider; and an output of the first phase detector. and a switch circuit for switching the output of the second digit detector and outputting the switched output to the first low-frequency Pv device. (2) The television synchronous receiving device according to claim 1, wherein the low-frequency P-wave device for distributing the output of the frequency discriminator in the low range is constituted by a voltage integrator.