JP2003249853A - High-frequency signal generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-frequency signal generator capable of miniaturizing a device and reducing the cost, without using interference countermeasure components such as a filter. <P>SOLUTION: This high-frequency signal generator is provided with a table means 51, where respective oscillation frequencies of a first oscillating means 11, a second oscillating means 13 and 15 corresponding to a specific frequency are preliminarily registered, a control means 5 for controlling respective oscillation frequencies of the first oscillating means and of the second oscillating means depending on a target frequency and the opening/closing of switches 14 and 16, and for controlling respective oscillation frequencies of the first oscillating means and second oscillating means to the oscillation frequency registered in the table means when the target frequency is the specific frequency. Consequently, the oscillation frequencies of the first oscillating means and the second oscillating means can be set to a value which is not influenced by the generation of the interference wave by registering the target frequency to be influenced by the occurrence of an interference wave and the oscillation frequencies of the first oscillating means and the second oscillating means in the table. Furthermore, it is not necessary to set disturbance countermeasure components such as a filter, and it is possible to miniaturize the device and reduce the cost. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency signal generator, and more particularly to a high frequency signal generator which variably generates a high frequency signal over a wide frequency band.

[0002]

2. Description of the Related Art Conventionally, when a high frequency signal over a wide frequency band is variably generated, the wide frequency band is divided into a plurality of frequency bands, and the signal of the frequency band is directly output for each divided frequency band. There are a method of providing an oscillator and a method of generating a signal of a target frequency by mixing an output of the oscillator whose frequency can be changed and a local oscillation signal whose frequency is fixed.

[0003]

For example, in the case of constructing a device for outputting a high frequency signal of a frequency of 90 to 770 MHz modulated by a video signal or an audio signal, in the prior art, for example, a video carrier frequency of VHF2 channel. When a signal with a frequency of 97.25 MHz is to be output, a harmonic component that is an integral multiple thereof is also generally generated. Usually, the lower order harmonics have stronger energy, and in this example, the second order harmonics are 194.Hz in the VHF8 channel band.
It occurs at 5 MHz.

This component is so-called spurious, and it is necessary to remove it by using a filter for each frequency band divided appropriately. Further, the device itself may be affected by an unspecified interfering wave signal generated in the device, and it is necessary to install an anti-interference component such as a filter. However, the improvement by the anti-jamming parts such as these filters has a problem that the device becomes large and the cost increases.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a high-frequency signal generator capable of reducing the size and cost of the device without the need of providing an anti-jamming component such as a filter. And

[0006]

According to a first aspect of the present invention, there is provided a high frequency signal generator for varying and generating a high frequency signal over a wide frequency band, wherein the oscillation frequency is varied to generate the first high frequency signal. First oscillating means, a second oscillating means that is provided with a switch to vary the oscillating frequency to generate a second high frequency signal, and the first high frequency signal and the second high frequency signal supplied by closing the switch. Mix
Mixing means for taking the difference signal and outputting a high frequency signal of the target frequency, table means for pre-registering the oscillation frequencies of the first oscillating means and the second oscillating means corresponding to a specific frequency, and Control the oscillating frequency of each of the first oscillating means and the second oscillating means and the opening / closing of the switch, and control the oscillating frequency of each of the first oscillating means and the second oscillating means when the target frequency is the specific frequency. By having the control means for controlling the oscillation frequency registered in the table means, the target frequency affected by the generation or influence of the interfering wave and the oscillation frequencies of the first and second oscillation means are registered in the table. 1, the oscillation frequency of the second oscillating means can be set to a value that is not affected or affected by the generation of interfering waves, and it is not necessary to provide an anti-interference component such as a filter. Downsizing and cost reduction of the location is possible.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A high frequency signal generator according to the present invention will be described with reference to the drawings.

FIG. 1 shows a block diagram of an embodiment of a test apparatus to which the apparatus of the present invention is applied. This test device outputs a high frequency signal amplitude-modulated by a video signal and frequency-modulated by an audio signal to each of VHF1 to 12 channels, UHF13 to 62 channels, and C13 to 63 channels.

In the figure, the test apparatus is a carrier signal generator 10.
, Video signal generator 20, modulator 30, and audio signal generator 4
0, control unit 50, input unit 80, and low-pass filter 6
It is generally composed of zero. Carrier wave signal generator 1
0, the video signal generating unit 20, the modulator 30, the audio signal generating unit 40, the input unit 80 and the control unit 50 are connected by a control bus 70.

The carrier signal generator 10 which is the device of the present invention.
Is a carrier signal which is a sine wave having a frequency band of 90 to 770 MHz and a frequency of 450 to 850 M.
Oscillator 11 which is generated by varying the oscillation frequency in the Hz band and is supplied to the mixer 12, and a frequency of 890 to 1050 MHz.
Oscillator 13 which is generated by varying the oscillation frequency in the band of
Oscillator 1 which is generated by varying the oscillation frequency in the band of 0 to 1270 MHz and is supplied to the mixer 12 via the switch 16.
It is composed of 5 and 5.

The mixer 12 mixes the high frequency signals supplied from the two oscillators by the heterodyne method to generate a high frequency signal (carrier signal) having a new frequency which is a difference frequency between the two high frequency signals. When the target frequency is input from the input unit 80, the control unit 50 controls the oscillation frequency of each of the oscillators 11, 13, 15 and the on / off control of each of the switches 14, 16. By the way, the control unit 50
Is a ROM 5 storing a control program, a specific frequency, etc.
1 (or a non-volatile memory).

FIG. 2 shows a flow chart of an embodiment of the carrier signal frequency setting process executed by the controller 50. In the figure, the control unit 50 first inputs the input unit 80 in step S10.
It is determined whether or not the target frequency input from is within the band of 450 to 770 MHz. Target frequency is 450-7
If it is within the band of 70 MHz, both the switches 14 and 16 are opened in step S12 to keep the high frequency signals output from the oscillators 13 and 15 from being supplied to the mixer 12,
In step S14, the oscillator 11 is controlled to oscillate at the target frequency. As a result, the high frequency signal output from the oscillator 11 is directly supplied to the modulator 30 via the mixer 12.

Generally, when a high frequency signal having a target frequency is generated by the oscillator 11, a harmonic of an integral multiple thereof is also generated, but the frequency of the harmonic in the oscillator 11 is at least 900.
Since it is higher than the maximum frequency 770 MHz of the signal used for transmission of terrestrial television, etc., it does not cause interference, and the low pass filter 60 allows the frequency 770 M.
Since the signal component above Hz is removed, it is not output from the test device to the outside.

In step S10, the target frequency is 45
If it is outside the band of 0 to 770 MHz, it is determined in step S16 whether or not the target frequency is within the band of 90 to 250 MHz. If the target frequency is within the band of 90 to 250 MHz, it is determined in step S18 whether the target frequency is the specific frequency. If the target frequency is not the specific frequency, the oscillator 11 is set to the fixed frequency 800 at step S20.
Control to oscillate at MHz. In addition, step S22
Then, the switch 14 is closed and the switch 16 is opened so that the high frequency signal output from the oscillator 13 is supplied to the mixer 12. Further, in step S24, the oscillator 13 is controlled to oscillate at the target frequency +800 MHz (= 890 to 1050 MHz).

As a result, the mixer 12 outputs a high frequency signal of 800 MHz output from the oscillator 11 and a high frequency signal of 890 to 1050 MHz output from the oscillator 11.
And the target frequency having a frequency of 90 to 250 MHz is generated and supplied to the modulator 30.

The harmonics generated by the oscillator 11 have a minimum frequency of 1600 MHz, and the harmonics generated by the oscillator 13 have a minimum frequency of 1780 MHz. In both cases, the maximum frequency of a signal used for transmission of terrestrial television is 770M.
Since it is higher than Hz, it does not cause interference, and since the low pass filter 60 removes signal components with a frequency of 770 MHz or higher, it is not output from the test apparatus to the outside.

Further, for example, when the target frequency is 200 MHz, a high frequency signal of 800 MHz output from the oscillator 11 and a high frequency signal of 1000 MHz output from the oscillator 13 are mixed in the mixer 12, and a difference frequency of 200
MHz is output as the target frequency. At this time, in the mixer 12, the sum frequency of the two high frequency signals is 1800 MHz.
However, since it is higher than the maximum frequency of 770 MHz of the signal used for transmission of terrestrial television, etc., it does not interfere, and the low pass filter 60 causes the frequency of 770 M.
Signal components above Hz are removed.

Since the lines from the oscillators 11, 13, 15 to the mixer 12 have frequency characteristics that attenuate as the frequency becomes higher, the frequency 160 generated by the oscillator 11 is reduced.
The second harmonic of 0 MHz is attenuated by the line up to the mixer 12, and the second harmonic and the frequency 10 output by the oscillator 13 are attenuated.
The signal level of frequency 600 MHz generated when the high frequency signal of 00 MHz is mixed in the mixer 12 is extremely small, and there is no possibility of causing interference.

However, the mixer 12 may generate an interfering signal within the intended frequency band of 90 to 770 MHz of the device of the present invention, and may be affected by an unspecified interfering signal generated in another circuit in the test device. In order to avoid this, steps S18, S26 and S28 are provided, and the oscillation frequencies of the oscillators 11 and 13 are adaptively switched according to the target frequency.

In this case, the specific frequencies at which the interference signal is generated are measured in advance by the device of the present invention, the specific frequencies at which the device of the present invention is interfered are measured, and the oscillators 11 and 13 capable of avoiding the interference at the specific frequencies. The relationship between the oscillating frequency of the oscillator is measured, and the specific frequency and the oscillating frequencies of the oscillators 11 and 13 are registered in advance in the ROM 51 as a table.

The target frequency is 250 to 450 MHz.
A specific frequency that causes or is subject to interference in the band
The oscillation frequencies of the oscillators 11 and 15 that can avoid the interference are measured in the same manner, and the specific frequencies and the oscillators 11 and 15 are measured.
The oscillation frequencies of are registered in the ROM 51 in advance as a table.

In step S18, the target frequency is ROM51.
If it is the specific frequency registered in step S26,
Then, the switch 14 is closed and the switch 16 is opened. Then, in step S28, the oscillator 1 is set to the registered value of the oscillation frequency of the oscillators 11 and 13 read from the ROM 51.
1 and 13 are controlled to oscillate.

For example, when the target frequency is 90 MHz, the oscillation frequency of the oscillator 11 is 800 MHz and the oscillation frequency of the oscillator 13 is 890 MHz, but when another circuit such as the control unit 50 generates an interfering wave near the frequency of 890 MHz. In order to avoid the influence of this interference wave, the oscillator 1 corresponding to the target frequency of 90 MHz is stored in the table of the ROM 51.
Oscillation frequencies 830 MHz and 920 MHz of 1 and 13 are registered. The control unit 50 controls the target frequency 9 in the table.
The registered values of the oscillators 11 and 13 corresponding to 0 MHz are read out, and the oscillators 11 and 13 have a frequency of 830 MHz,
It is controlled to oscillate at 920 MHz. As a result, it is possible to avoid the influence of the interference wave near the frequency of 890 MHz.

If the target frequency is outside the band of 90 to 250 MHz in step S16 of FIG. 2, step S3
At 0, it is determined whether or not the target frequency is within the band of 250 to 450 MHz. Target frequency is 250-450MHz
If it is within the band of, it is determined in step S32 whether or not the target frequency is the specific frequency. If the target frequency is not the specific frequency, the oscillator 11 is controlled to oscillate at a fixed frequency of 800 MHz in step S34. Further, in step S36, the switch 14 is opened and the switch 16 is closed so that the high frequency signal output from the oscillator 15 is supplied to the mixer 12. Further, in step S38, the oscillator 1
5 is the target frequency +800 MHz (= 1050 to 1250
Control to oscillate at (MHz).

As a result, the high frequency signal of 800 MHz output from the oscillator 11 and the high frequency signal of 1050 to 1250 MHz output from the oscillator 11 are mixed in the mixer 1.
A target frequency having a frequency of 250 to 450 MHz is generated by being mixed in 2, and is supplied to the modulator 30.

The harmonics generated by the oscillator 11 have a minimum frequency of 1600 MHz, and the harmonics generated by the oscillator 15 have a minimum frequency of 2100 MHz, both of which have a maximum frequency 770 of a signal used for transmission of terrestrial television or the like.
Since it is higher than MHz, it does not cause interference, and since the low pass filter 60 removes signal components with a frequency of 770 MHz or higher, it is not output from the test apparatus to the outside.

On the other hand, in step S32, the target frequency is RO
If it is the specific frequency registered in M51, the process proceeds to step S40 to open the switch 14 and close the switch 16. Then, at the oscillation frequency of the oscillators 11 and 15 read from the ROM 51 in step S42, the oscillators 11 and 1
5 is controlled to oscillate.

In this way, by registering the target frequency affected by the generation and influence of the interfering wave and the oscillation frequencies of the oscillators 11, 13, 15 in the table of the ROM 51, the oscillation frequencies of the oscillators 11, 13, 15 are disturbed. The value can be set so as not to be affected or generated by a wave, and it is not necessary to provide an anti-jamming component such as a filter, so that the device can be downsized and the cost can be reduced.

Returning to FIG. 1, the video signal generator 20 is composed of a pattern generator 21, a pedestal signal generator 22, and a superimpose circuit 23. When the pattern code and the display position are designated by the control unit 50, the pattern generator 21 generates a pattern video signal in which the carrier color signal is superimposed on the luminance signal for displaying the pattern indicated by the code at the display position. It is generated and supplied to the superimposing circuit 23. The pattern to be displayed may be a character / number or a color representing an arbitrary shape and a background color, or a fill (only background color). Further, the horizontal and vertical synchronization of the pattern video signal is performed in synchronization with the control from the control unit 50.

The pedestal signal generator 22 is a pedestal signal as a composite video signal including a horizontal synchronizing signal and a vertical synchronizing signal having a color burst signal in the back porch when the luminance signal and the carrier color signal are 0, that is, a black level. Is generated and supplied to the superimposing circuit 23. Horizontal and vertical synchronization of the pedestal signal is performed in synchronization with the control from the control unit 50.

The superimposing circuit 23 superimposes the pattern video signal from the pattern generator 21 on the video period of the pedestal signal from the pedestal signal generator 22 and supplies it to the modulator 30.

The audio signal generator 40 generates an audio signal according to an instruction from the controller 50 and supplies it to the modulator 30. The modulator 30 amplitude-modulates the carrier signal with a composite video signal for displaying a pattern, and at the same time, the carrier signal generator 1
The frequency is 4.5M based on the high frequency signal supplied from 0
An audio carrier with a high frequency of Hz is generated and frequency-modulated with an audio signal. The modulated signal obtained here is attenuated by the low-pass filter 60 to eliminate unnecessary high frequency components having a frequency of 770 MHz or higher and then output.

The ROM 51 built in the control unit 50 has 1
The screen is divided into a plurality of cells, and the cell number of each cell and the code of the pattern displayed in each cell are stored. Each cell number and the display position have a one-to-one relationship, and the control unit 50 responds to the above cell number from the ROM 51 according to the cell number on the screen synchronized with the control of the horizontal and vertical synchronization for the video signal generation unit 20. The code of the pattern is read out and supplied to the pattern generator 21.

Then, the control unit 50 sequentially reads out the code of the pattern from the ROM 51 and supplies it to the pattern generator 21 on the basis of the horizontal and vertical synchronizations, whereby the pattern generator 21 displays the pattern indicated by the code. To generate a pattern video signal in which the carrier color signal is superimposed on the luminance signal for

The oscillators 13, 15 and the switch 14,
16 instead of providing a frequency of 890 to 1270 MHz
It is possible to provide an oscillator for changing the oscillation frequency in the band of (3) and supplying it to the mixer 12 via the switch, and the present invention is not limited to the above embodiment.

The oscillator 11 corresponds to the first oscillating means, the oscillators 13 and 15 correspond to the second oscillating means, the mixer 12 corresponds to the mixing means, and the ROM 51 corresponds to the table means. The control unit 50 corresponds to the control means.

[0037]

As described above, the invention according to claim 1 is
First oscillating means for changing the oscillating frequency to generate the first high-frequency signal, second oscillating means provided with a switch for changing the oscillating frequency to generate the second high-frequency signal, and closing the first high-frequency signal and the switch. Mixing means for mixing the second high-frequency signal supplied by the composition, and taking the difference signal to output the high-frequency signal of the target frequency, and the oscillating frequency of each of the first oscillating means and the second oscillating means corresponding to the specific frequency. Is registered in advance, the oscillation frequency of each of the first oscillating means and the second oscillating means and the opening / closing of the switch are controlled according to the target frequency, and the first oscillating means and the second oscillating means are controlled when the target frequency is a specific frequency. By having control means for controlling the oscillation frequency of each of the oscillation means to the oscillation frequency registered in the table means, the target frequency and the first frequency affected by the interference wave By registering the oscillation frequency of the second oscillating means in the table, can be made first, a value which does not undergo the occurrence and influence of emission of the oscillation frequency of the second oscillating means,
Since it is not necessary to provide an anti-jamming component such as a filter, the device can be downsized and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a test apparatus to which the apparatus of the present invention is applied.

FIG. 2 is a flowchart of an embodiment of a carrier signal frequency setting process.

[Explanation of symbols]

10 Carrier wave signal generator 11,13,15 oscillator 12 mixers 14, 16 switch 20 Video signal generator 21 pattern generator 22 Pedestal signal generator 23 Superimpose circuit 30 modulator 40 Audio signal generator 50 control unit 51 ROM 60 low pass filter 70 control bus 80 Input section

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tsuyoshi Nakatogawa             2-2-1 Jinnan 2-chome, Shibuya-ku, Tokyo             Sending Association Broadcast Center (72) Inventor Rei Suzuki             2-2-1 Jinnan 2-chome, Shibuya-ku, Tokyo             Sending Association Broadcast Center (72) Inventor Ryu Ezaki             1-6-26 Daimon, Kokurakita-ku, Kitakyushu City, Fukuoka Prefecture             Japan Broadcasting Corporation Kitakyushu Broadcasting Station (72) Inventor Mitsuo Kusuhara             Sanya Electronics Co., Ltd. 1 Toyacho, Ueno City, Mie Prefecture             Within F term (reference) 5J106 PP02 QQ06 QQ12 RR05 RR14                       RR20                 5K042 BA11 CA23 LA03 LA11

Claims (2)

[Claims] 1. A high-frequency signal generator for generating a high-frequency signal by varying a high-frequency signal over a wide frequency band, the first oscillating means for varying a oscillating frequency to generate a first high-frequency signal, and an oscillating frequency provided with a switch. The second oscillating means for generating a second high-frequency signal by varying the frequency, the first high-frequency signal and the second high-frequency signal supplied by closing the switch, and the difference signal is taken to obtain the target frequency. Mixing means for outputting a high frequency signal, table means for pre-registering oscillation frequencies of the first and second oscillation means corresponding to a specific frequency, and the first and second oscillation means according to the target frequency. The oscillation frequency of each oscillation means and the opening / closing of the switch are controlled, and when the target frequency is the specific frequency, the first oscillation means and the second oscillation means are respectively controlled. A high-frequency signal generating apparatus characterized by comprising control means for controlling the oscillation frequency which is registered the oscillation frequency to the table means. 2. The high frequency signal generating device according to claim 1, wherein the oscillation frequency of the second oscillating means is a frequency higher than a frequency band of the high frequency signal generating device.