JPS59122298A - Comb filter - Google Patents

Abstract

PURPOSE:To reduce the number of adjusting part of an output level independently of the dispersion of a glass delay line by outputting a direct transmission signal as it is, inputting the output of the glass delay line to a differential amplifier variably to take out a difference signal and an added signal. CONSTITUTION:A video signal from a signal source 33 is amplified and applied to an ultrasonic solid-state delay line 30 through an antiresonator coil 31. The output of the delay line 30 is impressed to a constant current transistor (TR)4 in a differential amplifier 34 through a capacitor C1. The direct transmission signal is applied from a node between an antiresonator coil 31 and a resistor R2 to one input terminal of the differential amplifier 34 through a capacitor C2 and an added signal Y and a difference signal C are obtained from the collector of the TR2 and the collector of the TR3 respectively as the outputs of the differential amplifier 34.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a comb filter that separates interpolated multiplexed signals,
Especially in the Eitai equipment. The present invention relates to a comb filter that separates a video signal into a luminance signal and a color signal.

In the video input signal in the NTSC color television system, a color signal is interpolated and multiplexed onto a high frequency portion of a luminance signal in the form of a carrier number 1d. In this way, the signal is generally separated into a luminous signal and a chrominance signal using a comb (<C type difilm).
1 (1)-1 delay filter) is known, and its principle will be briefly explained. That is, as shown in FIG.
Delay one horizontal run time by H delay group 2, and make this 74
742 Circuit 3.4 Combines with power, direct reach, and abuse. A chrominance signal is taken out from the output of a C-type filter 5 which obtains both transmitters, and a 4-degree signal is taken out from the output of a Y-type filter 6 which obtains a sum signal of both. This circuit separates the video signal into a color signal and a luminance signal by combining a C-type filter with characteristics as shown in Figure 2 and a patented Y-type filter as shown in Figure 3 (comb filter). be able to.

萱、In general, in order to make the glass delay edition work well,
As shown in FIG. 4, anti-seat coils are inserted at the input and output of the Karasu delay line.

This comb filter applies a video input signal from a signal source 11 to both ends of a series circuit consisting of an input quadrature transducer 13 of an ultrasonic solid-state delay line 12 and a partial voltage load 14 connected in series thereto, and Output juicer 15 on line 12
The delayed output signal obtained from the above and the signals at both ends of the voltage dividing load 14 are combined to obtain an i:0 signal and a difference signal between the two. That is, the input signal is divided into both the delay source transducer 13 including the anti-resonant coil 16 and the voltage dividing load 14, and at low frequencies below the passband of the delay line, the signal applied to both ends of the voltage dividing load is It is sent to the output side, and within the passband of the delayed WE, the above-mentioned comfil! It has a function that effectively separates interpolated multiple input signals into two using special notes.

A specific example of the circuit shown in FIG. 1 is shown in FIG. Signal source 2
The video signal has a glass delay from 0! ! 21(i[-(delay line) input voltage is applied through transistors 24 and 25 to both ends of the antiresonant coil 22 and the partial voltage load 230 connected in parallel to the input transducer. The signal A is taken out by the regulator 2ti (variable anti-resonant coil) connected in parallel to the output transducer, and the direct signal B is adjusted by the regulator 27, which adjusts the amplitude of the voltage applied to the partial voltage load 23. The anti-resonant coil whose midpoint is adjusted by the adjuster 26 (adjuster 2t
It is guided to the midpoint of i). From the combined signals here, an amplifier 28 takes out a difference signal (color signal) C between the two, and an amplifier 29 takes out a sum signal (altitude signal) Y.

Since the difference signal C and the sum signal Y of this comb filter are required to be output at a predetermined level, when adjusting the level, the direct signal B is added to the signal A that has passed through the Crow delay line 21 to obtain the comb depth L) A+B 9. During this process, the level of signal A is fixed and adjuster 2
7, the amplitude of the direct signal B is reduced to approximately A;B. Therefore, the signal levels A+ and B after the separation of the difference signal C1 and the sum signal Y reflect the variation in insertion loss (usually ±3 dB) of the glass delay line as is. In order to keep the output level of the entire circuit constant, an amplifier 2B is added.
, '19, a level adjuster S27' is required, and the adjuster 27.2 is adjusted according to the variation in delay iθ.
7' is being adjusted.

The present invention is an improved version of the conventional comb filter described above, and outputs the direct signal in its sweet form, makes the output of the glass delay line variable and inputs it to a differential amplifier, from which a difference signal and a sum signal are output. It is an object of the present invention to provide a pigeon comb filter that makes the output level independent of variations in the glass delay line by taking out the conventional adjustment point)-(H).

An embodiment of the present invention will be described below with reference to FIG.

An anti-seat coil 31 is connected in parallel to the input transducer of the ultrasonic solid state delay line 30. The output transducer has one end grounded, and the other end connected in parallel with a variable anti-resonator coil 32, a resistor R1, and a variable resistor R1. On the input side, one end of the anti-resonate coil 31 is grounded via a resistor R2 with a partial voltage load. The video signal from the signal source 433 is applied to the base of the transistor Tri, amplified, and applied from the emitter to the other end of the anti-resonator coil 31 via the resistor R3i. In addition, the output of the delay line is transmitted from the variable terminal of the variable resistor V1 to the transistor Tr2.
, Tr3, Tr4, resistors R4 to R12, and a constant current transistor of the differential amplifier circuit 34 configured by the capacitor C1. The other input terminal of the delay source is a direct signal (B') from the connection point between the anti-coil 31 on the input side of the delay source and the resistor R2, which is connected to the base of the transistor Tr2 (C
applied.

The output of the differential amplifier circuit 34 is a sum signal Y from the collector of the transistor ``vI''2, and a difference signal C from the collector of the transistor Tr3.

The reason for the comb filter configured in this way is that when determining the comb depth, the direct signal B' applied to the partial pressure load LL2 is directly guided to the output side and remains constant without fluctuation. Is there a delay by fixing it and manually applying it to the differential amplifier circuit 34?
Signal A containing the variation in its insertion loss passed through the urine 30'
' by adjusting variable resistor VR1 to approximately A'S B/
Make it. Then, these signals are combined in a differential amplifier circuit 3.1 to obtain No. 1113 Y and a difference signal C. The signal level A'+B' after separation is always constant regardless of the insertion loss variation of the glass delay cliff.

Therefore, it is no longer necessary to adjust regulator 27' to match the output of glass delay line 30 as shown in FIG.

As is clear from the above embodiment (ti: according to the present invention, a direct signal is output as is, a signal that has passed through a delay line is outputted via a variable resistor, and the powers of both parts are combined by a differential amplifier circuit. The chrominance signal, which is a difference signal, and the luminance signal, which is a sum signal, are obtained.Therefore, the composite signal can be adjusted regardless of the variation in glass delay and insertion loss of the gland, and the adjustment points are Decrease - can be determined.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the principle of a comb filter, Figures 2 and 3 are passband characteristic diagrams of the filter shown in Figure 1, Figure 4 is a basic block diagram of a comb filter, and Figure 5 is a basic block diagram of a comb filter. is a conventional specific circuit diagram, and Fig. 6 is a circuit diagram of a comb filter according to the present invention. 21.30 ... Ultrasonic solid delay, - Urine 23.1 (2
...Partial pressure load 22.31 ...Anti-resonate coil 26.32
...Variable anti-resonate coil 27, VI (
, l...Variable resistance (adjuster) 34...
Differential Amplifier Circuit Agent Patent Attorney Moritani -O

Claims (1)

[Claims] A synthetic video input signal containing a luminance signal and a color signal is applied to both ends of the input quadrupler of the ultrasonic solid-state delay line and the partial pressure load connected to it, and the delay>i In the comb filter that obtains the difference signal between the delayed output obtained from the line output transducer and the signals at both ends of the voltage divider and separates the signal into a luminance signal and a chrominance signal, the voltage divider load The signals at both ends of - are output as they are, the delayed output obtained from the delay line output transducer is outputted by valving a variable resistor, and the two outputs are combined by a differential amplifier circuit to obtain the sum 1. A comb filter having two characteristics: obtaining a lucky signal and a difference signal.