JPS5860263A - Generation of marker signal - Google Patents

Abstract

PURPOSE:To facilitate the embodyment with a simple circuitry by a method wherein a beat signal as generated from a reference signal and a sweep frequency signal is applied to a frequency comparator once deviated by the intended frequency from the frequency of a marker signal to be generated and a resultant square wave is processed to produce a marker signal. CONSTITUTION:After shaped with an amplifier 5, a beat signal is applied to a frequency comparator 6 to obtain a square wave from a Q' output terminal. The frequency comparator 6 freely selects the frequency to be compared and determines whether the beat signal inputted is above or below the set frequency selected so that the logic outut from output terminals Q' and Q can vary when the beat frequency coincides with the set frequency. A square wave can be obtained from the Q' output terminal of the frequency comparator 6. The square wave is applied t a subsequent differentiation circuit 9 to generate a pulse signal by differentiation at the rising thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for generating marker signals used for frequency adjustment and measurement of various devices such as FM receivers and television receivers.

There are various ways to generate marker signals. One of them is to use a beat signal consisting of a sweep frequency signal and a reference signal, create a pulse with an appropriate width before and after the zero beat point of the beat signal, and then There is one that uses it as a marker signal.

However, because this marker signal has a wide pulse width, it is difficult to know which part of the pulse has the correct marker frequency, and the pulse width of the marker signal may become wider or narrower as the sweep width or sweep speed changes. , again, there was a problem that it was not possible to confirm the correct position of the marker frequency.

The present invention relates to a method for generating a marker signal that does not have such difficulties, and involves shifting a reference signal in advance by a predetermined frequency from the frequency of the marker signal to be generated, and generating a beat signal generated by the reference signal and the sweep frequency signal. A marker signal is generated using a rectangular wave obtained from a frequency comparator.

An example of the present invention will be described in detail below based on illustrated embodiments. The invention set forth in claim 1 is a method for generating a marker signal only at one point;
The invention described in item 1 is a method for simultaneously generating marker signals of different frequencies at two or more points.

Of these, the former is done as follows.

A sawtooth wave with good linearity (■ in Figure 3) oscillated from the sawtooth wave oscillator (1) is input to the sweep oscillator (2), and the frequency changes in proportion to the level of the sawtooth wave (■ in Figure 3). Obtain a sweep frequency signal (hereinafter simply referred to as the sweep signal) and input it to the mixer (3).The mixer (3) receives a reference frequency signal (hereinafter simply referred to as the reference signal) oscillated from the reference signal oscillator (4). Generate a beat signal (■ in Fig. 3) before and after the zero beat point fa by adding It is assumed that (set frequency f1 of a frequency comparator, which will be described later) is plus or minus. Therefore, the frequency fO of the marker signal to be generated is I
When OMH2 is set and the set frequency f1 of the frequency comparator is IMHz, the frequency f of the reference signal is IOMH
z±IMH2, ie 11 MHz or 9MH2.

In the present invention, the beat signal shown in Figure 3 (2) is input into an amplifier (5), shaped, and then input into a frequency comparator (6) to obtain the rectangular wave shown in Figure 3 (2) from its four output terminals.

As the frequency comparator (6), for example, as shown in FIG. 2, a one-shot multivibrator (7) capable of retrying and a D-type flip-flop circuit (8) is used. This frequency comparator (6)
By adjusting the volume VR shown in the figure, the frequency fl to be compared can be freely selected, and it is determined whether the beat signal f, which is the input signal, is higher or lower than the set frequency fl selected by the volume VR, The logical output from the output end prediction Q changes as follows at the time when the beat frequency f matches the set frequency fl.

Of the beat frequency f, the logic output is "0" in the frequency region Cf>f higher than the set frequency fl of the frequency comparator (6), and the logic output is "1" in the lower frequency region f<fl.
is obtained from the output terminal 4, and the logic output from the Q output terminal is opposite to the logic output from the Q output terminal, that is, the logic "
1'' and f<fl, an output of logic ``0'' is obtained.

Therefore, the rectangular wave shown in FIG. 3 is obtained from the four output terminals of the frequency comparator (6). The rising frequency of this rectangular wave is the frequency obtained by subtracting the set frequency f1 of the frequency comparator (6) from the reference signal fs, that is, the marker signal frequency fO to be generated.

This rectangular wave is input to the next-stage differential divider path (9), and the rising point of the wave is differentiated to generate the pulse signal shown in FIG. 3 (2).

The above explanation assumes that the reference signal frequency fs is the marker signal frequency fO to be generated plus the set frequency f= of the frequency comparator (6), but the present invention is not limited to this. The reference signal frequency fs may be set to f〇-fl as shown in FIG. 4 σ. The beat signal CM in Figure 4 at this time moves 2ft to the left from the beat signal (■ in Figure 4) when fs is fO + fl,
The rectangular wave C output from the Q output terminal of the frequency comparator (6) in FIG. 4 is also 4 when the reference signal fs is fO+fl.
It moves to the left by 2f1 (same as the movement of the beat signal) from the rectangular wave from the output terminal (Fig. 4 ■). Therefore, in this case, a differentiating circuit (9) that differentiates the falling edge of the rectangular wave shown in FIG. 4C is used, and the differentiated signal thus differentiated is used as the marker signal. This differential signal is generated at the desired marker signal frequency fO point as shown in FIG. 4.

Although what is shown in FIG. 1 is the case where the rectangular waves output from the four output terminals of the frequency comparator (6) are used, the present invention is not limited to this, and the Q output shown in FIG. 2 is used. A rectangular wave output from the end may also be used.

As mentioned above, the logic outputs of the rectangular wave output from the Q output terminal are "0" and "1" which are the opposite of the logic outputs "1" and "0" of the rectangular wave output from the 4 output terminal. Q when the reference signal frequency fs is the marker signal frequency fO to be generated plus the set frequency fl of the frequency converter (6), that is, fs = fO + fl.
The output rectangular waveform from the output end is as shown in FIG. 5 (■), and the output waveform from the Q output end when the reference signal frequency fs is fs=fOf'' is as shown in FIG. 5C.

Therefore, in the case of the rectangular wave shown in Figure 5 (■), the differential circuit (9
) to differentiate the falling edge of the same square wave, and 4
In the case of a rectangular wave as shown in FIG. 5C, a differentiating circuit (9) that differentiates the rise of the rectangular wave may be used.0 The invention of claim 3 is made as follows. The method of generating the marker signal itself is exactly the same as the invention claimed in claim 1, but since two or more marker signals of different frequencies are generated at the same time, the method shown in FIG. Sample and hold circuit (10) l (t
oX! Pressure comparator (11), differential circuit (one
Prepare as many marker signals as you want to generate and connect them in parallel, and also use a marker frequency setter (14) (14)
Prepare as many marker signals as you want to generate.

And marker frequency setter (14z <14) 2 (1
4), a is switched every time the sweep signal is swept by a switch 05) to change the reference signal, and a sample hold circuit (10) l shown by a virtual line in FIG.
The subsequent circuits are also switched, and the marker signal (■ in Figure 3) generated each time is changed to the sample and hold circuit (10), (10)2 (10)3, as shown in Figure 3■E. Hold on. Furthermore, this signal and the sawtooth wave (shown in Figure 3) are input to the voltage comparator (11), the levels of both signals are compared, and the point at which they match (the third
The logic output is ``1'' at the pulse signal generation point in Figure ■), and the logic output is ``0'' when the sawtooth wave level becomes zero to obtain a rectangular wave (as shown in Figure 3), and then differentiate the rising edge. This is designed to generate the pulse signal shown in Figure 3 (3). Note that the switch θ5) (1) is switched every time it is swept by the sawtooth wave shown in Fig. 3 (■), and the switch is made so that the marker frequency setter (14) 1 corresponds to the sample hold circuit 00) 1, and (14) 2 corresponds to 00)2 and (14)3 corresponds to (io)3, respectively, and are switched in conjunction with each other.

In this way, once the marker signal is generated, it is held by the sandal hold circuit (10), so by switching the marker frequency setter (14) 1 (14) 2 (14) 3, the marker signal with a different frequency can be set at each sweep. Even if a signal is generated, it does not disappear, so two or more marker signals with different frequencies can be generated at the same time.

As described above, the present invention does not set the reference signal fs oscillated from the reference signal oscillator (4) to the desired marker signal frequency fO, but only sets the frequency fO to the set frequency fl of the frequency comparator (6). Since the position of the desired frequency fO at which the marker signal is to be generated can be determined by differentiating the rising edge of the rectangular wave (■ in Figure 3) output from the frequency comparator (6), the position of the desired frequency fO can be determined by Moreover, since the marker signal is sharp and has no pulse width, it is not affected by changes in the sweep speed or sweep width. Therefore, in actual use, when the marker signal is displayed as a pulse or a brightness marker on the cathode ray tube surface, the marker frequency can be accurately confirmed, allowing highly accurate adjustment and measurement.

Furthermore, according to the present invention, the circuit configuration is extremely simple compared to conventional circuits of this type, making it easy to implement and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a block explanatory diagram showing an example of the present invention, FIG. 2 is an explanatory diagram showing an example of a frequency comparator used in the present invention, and FIGS. 3 to 5 are waveform explanatory diagrams showing the operating state of the present invention. be. (1) Sawtooth wave oscillator, (4) Reference signal oscillator, (6) Frequency converter, (7) Multifunction plater, (8) Flip-flop circuit, (14) 1 (14) 2... is a marker frequency setter.

Claims (4)

[Claims] (1) Input a beat signal consisting of a sawtooth wave sweep frequency signal and a reference signal obtained by adding or subtracting the set frequency of the frequency comparator to the desired marker frequency into the frequency comparator, and set the frequency comparator of the beat signal. A rectangular wave is formed in which the logic output is "1" or "0" in the frequency region lower than the frequency, and the logic output is "0" or "1", which is the opposite of the previous logic output, in the higher frequency region, and its rise or A marker signal generation method that differentiates the falling edge and uses it as a marker signal. (2) The marker signal generation method according to claim 1, wherein the frequency comparator is comprised of a one-shot multivibrator capable of retriggering and a D-type flip-flop circuit. (3) A beat signal consisting of a sawtooth wave sweep frequency signal and a reference signal obtained by adding or subtracting the set frequency of the frequency comparator to the desired marker frequency is input into the frequency comparator, and the beat signal has the set frequency of the frequency comparator. A rectangular wave is formed in which the logic output is "1" or "0" in the lower frequency region, and "0" or "1", which is the opposite logic output to the previous logic, in the higher frequency region, and the rise of this rectangular wave Alternatively, in a marker signal generation method in which the falling edge is differentiated to generate a marker signal, the frequency of the reference signal is switched every time a sweep is made, and a marker signal with a different frequency is generated each time, and each generated marker signal is held. A marker signal generation method that simultaneously generates two or more marker signals with different frequencies at multiple points. (4) The marker signal generation method according to claim 3, wherein the frequency comparator is comprised of a one-shot multivibrator capable of retrying and a D-type flip-flop circuit.