JPS627509B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a frequency marker display device that displays only a center marker and necessary side markers on the tube surface of a cathode ray tube.

First, a conventional frequency marker display device will be explained, but before that, some terms will be defined. Here, the sweep signal refers to a signal having an arbitrary swept frequency range, and the sweep repetition signal refers to a signal that repeatedly sweeps the sweep signal.

Fig. 1 is a block diagram showing an example of a conventional frequency marker display device. 1 is a sweep repetition signal oscillator, which generates a signal as shown in Fig. 2 for sweeping at a sweep frequency Δf with respect to a center frequency _f0 . do. 2
is a sweep signal oscillator, for example a voltage controlled oscillator, and changes its oscillation frequency within a range of ±Δf around the center frequency f ₀ as the output of the sweep repetition signal oscillator 1 increases. Reference numeral 3 denotes a center marker reference signal oscillator, which generates a signal with a constant frequency of center frequency f ₀ . 4 is a mixer, which mixes both signals of frequency f ₀ ±Δf from the sweep signal oscillator 2 and center frequency f ₀ from the center marker reference signal oscillator 3, and generates a signal from 0 to Δf.
generates a signal. 5 is a first low-pass filter that passes only the 0 beats of the mixer 4 and outputs an output that becomes a center marker. 6 is an adder, 7 is a harmonic mixer, 8 is a side marker reference signal oscillator with a frequency f _s that determines the interval between side markers,
This output is added to the harmonic mixer 7, and N.f _s
An output of ±Δf is obtained. Reference numeral 9 denotes a second low-pass filter which outputs an output serving as a side marker, and this output is added to an adder 6. 10 is a detector,
The output from adder 6 is detected and the cathode ray tube (hereinafter referred to as
(referred to as CRT) 11.

An example of the display is shown in FIG. 3. That is, M _c is a center marker, indicating the center frequency f ₀ of the center marker reference signal oscillator 3, and M _s is a side marker, which is displayed at intervals of frequency f _s . Therefore, if f _s =1MHz, the interval between the side markers M _s will be 1MHz. Note that in FIG. 3, the center marker M _c is made larger than the side marker M _s , but this can be achieved by appropriately inserting and adjusting a level adjuster before the adder 6, but it is not possible to achieve this by inserting a level adjuster before the adder 6. It has been omitted here.

The above-described conventional frequency marker display device has a disadvantage in that it is complicated to read the required center marker M _c because a large number of side markers M _s are displayed around the center marker M _c .

This invention has been made to eliminate the above-mentioned drawbacks. This invention will be explained below.

FIG. 4 shows an embodiment of the present invention. In this figure, reference numeral 12 denotes a side marker voltage setting device, and by rotating a switch using a dial or the like, voltages of V ₁ , V ₂ , . . . , V _n can be set. These voltages correspond to f _s , 2f _s , . . . , mf _s of the side marker M _s shown in FIG. Reference numeral 13 denotes a variable local oscillator, for example, a voltage controlled oscillator is used, but it may also be controlled not only by voltage but also by current to oscillate at a desired frequency. 14 is a second mixer, 15 is a phase detector, these 13 to 15 constitute a phase synchronization circuit, and a side marker reference signal oscillator 8
The phase synchronization circuit operates based on the phase of the output. 16 is a third mixer, which mixes the output of the first mixer 4 (same as the one in FIG. 1, but will be called this for convenience) and the output of the second mixer 14. , and supplies its output to a second low-pass filter 9. The other configurations are the same as those in FIG.

Now, the variable local oscillator 13 generates a center marker reference signal oscillator 3 according to the voltage V _k (generally expressed as V _k ) set by the side marker voltage setter 12.
Oscillation is performed at a frequency of f _{0 +} k·f _s which is obtained by adding a frequency f _s corresponding to the interval between the side markers M _s shown in FIG. 3 to the frequency f 0 of . The second mixer 14 mixes the signal of the frequency f ₀ of the center marker reference signal oscillator 3 and the signal of the frequency f ₀ +k·f _s of the variable local oscillator 13, and generates a signal of 0 to k·f _s . output,
Add this to the third mixer 16. Therefore, from the third mixer 16, the target side marker M
_s , that is, in this example, only the CRT 11 is separated by k・f _s from the center marker M _c .
will be displayed. Of course, the center marker M _c
Displayed on CRT11.

In the above embodiment, the side marker voltage setter 12 has only been described to generate voltage, but when the variable local oscillator 13 is of a current drive type, it naturally sets the current. Therefore, the term "voltage" used herein also includes the meaning of current.

As described above in detail, the present invention includes a side marker voltage setting device that generates a voltage corresponding to the difference between the frequency of the side marker to be displayed and the frequency of the center marker. A phase-locked circuit is provided that forms a closed loop with a phase detector based on the signal from the oscillator, a variable local oscillator, and a second mixer, and the voltage set by the side marker voltage setting device is applied to the variable local oscillator. An oscillation of a frequency obtained by adding a frequency corresponding to the interval between the side marker and center marker to be displayed is outputted, and this frequency and the center frequency are added to a second mixer to obtain the output from the second mixer. Since the output of
Can be displayed on CRT. By using a fixed frequency crystal oscillator or the like as the center marker reference signal oscillator and the side marker reference signal oscillator, a highly accurate frequency marker display device can be easily obtained. Furthermore, since the conventional side markers are comb-shaped markers, reading the marker frequency from the CRT screen was extremely troublesome, but according to the present invention, the center marker and the frequency set by the side marker voltage setting device are Since only known side markers are displayed, it has the advantage that it is extremely easy to read the frequency on the CRT.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of a conventional frequency marker display device, Fig. 2 is a waveform diagram showing an example of the output of the sweep repetition signal oscillator shown in Fig. 1, and Fig. 3 is a display of a conventional frequency marker display device. FIG. 4 is a block diagram showing an embodiment of the present invention. In the figure, 1 is a sweep repetition signal oscillator, 2 is a sweep signal oscillator, 3 is a center marker reference signal oscillator,
4 is a first mixer, 5 and 9 are first and second low-pass filters, 6 is an adder, 8 is a side marker reference signal oscillator, 10 is a detector, 11 is a CRT, 1
2 is a side marker voltage setter, 13 is a variable local oscillator, 14 is a second mixer, 15 is a phase detector,
16 is a third mixer.

Claims (1)

[Claims] 1. A sweep repetition signal oscillator, a sweep signal oscillator whose frequency is changed according to the output of the sweep signal oscillator, a center marker reference signal oscillator, and a first sweep signal oscillator that mixes the output of the sweep signal oscillator and the output of the center marker reference signal oscillator. a mixer, an adder whose output is applied through a first low-pass filter, a side marker voltage setter which generates a voltage corresponding to the frequency difference between the center marker and the side markers to be displayed; a variable local oscillator that oscillates at a frequency equal to the applied center frequency plus the frequency difference; a second mixer to which this output and the output of the center marker reference signal oscillator are added; and a side marker reference signal generator. a phase detector that detects the phase based on this output and forms a closed loop with the variable local oscillator and the second mixer to form a phase locked circuit; and an output of the phase locked circuit and the first mixer. a third mixer that mixes the output of the adder, a second low-pass filter that adds this output to the adder, a detector that detects the output of the adder, and a center marker and a side marker of this output. A frequency marker display device comprising a cathode ray tube that displays.