JPS5940332B2 - Multi-channel tone oscillator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to, for example, currently used pagers,
367.5H2 to 1 on the radio line, like public relations radio communication.
A method in which one tone signal is selected from a total of 104 tone signals whose frequencies are set at 15H2 intervals up to 912.5Z, and sequentially transmitted and received to perform predetermined call commands, remote control, etc. The present invention provides a new and useful circuit configuration method for a tone signal oscillator with frequencies from 367.5H2 to 1912.5Πz used in a transmitting device in a communication system.

In the communication system of the above method, a reed filter is generally used in the receiving device, and since the passband width of this reed filter is very narrow, its output frequency is is required to be highly stable and accurate, and generally O, 5H2
Requires stability and accuracy within

This has a frequency stability and accuracy of 1 x 10-4 or higher, which is impossible to obtain with a general CR oscillator or LC oscillator, so conventionally, oscillators such as mechanical oscillators using Reid filters or crystal oscillators have been used. I've been exposed to it. FIG. 1 shows a block diagram of the configuration of a mechanical oscillator that oscillates three waves of tones using a conventional lead filter.

1, 3, and 5 are oscillation amplifiers, and 2, 4, and 6 are lead filters.

Each combination of 1 and 2, 3 and 4, and 5 and 6 operates as an oscillator, each generating a frequency from 367.5Hz to 1912.5Hz.
It oscillates and outputs one wave among the frequencies reaching .

Reference numeral 11 denotes a rotary switch or an electronic changeover switch, which selects one wave from each of the oscillator outputs 7, 8, and 9 as output 10.

Furthermore, since the bandwidth of the reed filter is very narrow, it takes a considerable amount of time from the time the power is turned on until the oscillation reaches a normal state, so a method is used in which the oscillator is operated at all times.

The mechanical oscillator using reed filters shown in FIG. 1 requires as many reed filters and oscillation amplifiers for the required frequencies, making the device large-scale in terms of cost, volume, and power consumption.

Figure 2 shows a method using a conventional crystal oscillator.
Reference numerals 1 and 219 are crystal oscillators whose oscillation frequencies are 967.5 and 150 Z, respectively. The output of 201 is divided by 1,000 by frequency divider 202 and sent to line 203 by 96
7.5Hz (this is one of the tone frequencies)
Any wave frequency is acceptable.

). On the other hand, the output 218 of 219 is also 10,0 by the frequency divider 217.
The frequency is divided by 00 to obtain 15Z on line 216. This 15Hz signal is converted to 1 by monostable multivibrator 215.
A narrow pulse signal containing a large amount of 5 Hz harmonics is output on line 214. Frequency mixer 204 is line 2
A frequency signal of the sum and difference of the 967.5 Hz signal of 03 and the signal of line 215 is generated on line 205. 206,
Reference numerals 207 and 208 are lead filters, which extract three desired waves onto lines 209, 210, and 211.

Switch 212 sends one wave out of these to line 213. The output frequency on line 213 is the crystal oscillator 20
1,218, which is extremely stable and highly accurate. However, this method also requires as many lead filters as the number of output frequencies required, which is problematic in terms of cost and size.
The present invention improves upon these drawbacks of conventional devices, and FIG. 3 is a block diagram of a multi-channel tone oscillator according to the present invention.

This device is composed of a phase lock loop, which divides the output (line 22) of the crystal oscillator 21 and divides the frequency of the output (line 24) of the reference frequency divider 23 (this is called the reference frequency). , is set to 7.5Hz, which is 1/2 of "15Hz, which is the frequency interval of each multi-channel tone" (this is one of the features of the present invention.) Therefore,
When the frequency division number of the reference frequency divider 23 is 10,000, the output frequency of the crystal oscillator 21 is 75Z. On the other hand, the output (line 26) of the general digital phase comparator 25 is filtered out of alternating current noise by a low-pass filter 27, becomes a direct current voltage (line 28), and is input to a voltage controlled oscillator 29. And the frequency of its output (line 30) is 15 between 367.5Hz and 1912.5Hz as follows:
It is controlled to any l wave of frequencies with a frequency interval of Hz. The output of the voltage controlled oscillator (line 30) is connected to variable frequency divider 3
The signal is input to the phase comparator 25 via the line 32 after being frequency-divided by the frequency division number set here.

Here, the variable frequency divider 31 sets the output frequency of the line 30 to 36
When the tone frequency is 7.5Hz, the frequency is divided by 49, and when the tone frequency is 382.5Hz, the frequency is divided by 51, etc., and each time the tone frequency increases by 15Hz, the frequency division number increases by "2", and at the highest frequency of 1912.5Z, it is divided by 255. becomes. The frequency division number setting terminals 33 to 40 of the variable frequency divider 31 are set with a binary code, for example +5.
V is a logic 1, and 0V is a logic 0. The setting terminal 33 is the least significant bit, and the setting terminals 34, 35, 3
The digits increase in the order of 6... and the setting terminal 40 is the most significant bit. The setting terminal 33 is always connected to +5V, and each of the setting terminals 34, 35, . . . , 40 is a lowest bit line 41, a second bit line 42, . Connected to the most significant bit line 47. The second feature of the present invention lies in the processing of the setting terminal 33 of the variable frequency divider 31 and the method of connecting the external frequency control lines 41 to 47 to the setting terminals 34 to 40. In other words, the frequency control line 41 from the outside
~47 is binary code 0, 1, 2, 3,...2
4...127, the frequency division numbers of the variable frequency divider 31 are set to 1, 3, 5, 7...49...255, respectively. However, since the frequency division number of the variable frequency divider 31 only requires numbers ranging from 49 to 51, 53...255 as described above, the binary code input to the frequency control lines 41 to 47 is is only 24, 25...127. In the following description of the present invention, for the sake of simplicity, it is assumed that the binary codes of the external frequency control line are not used from 0 to 23, but are used from 24 to 127. Dividing number setting terminal 3
By simply shifting the connections between 3 to 40 and external frequency control lines 41 to 47 by one bit as described above, the external frequency control lines 41 to 47
It is noteworthy that the required frequency division numbers 49, 51, . . . , 255 are obtained by giving a binary code to .about.47. Conventionally, a diode matrix was constructed for this part, and a complex conversion circuit was constructed by combining gate circuits. FIG. 4 is a block diagram of a multi-channel tone oscillator according to the present invention which includes additional features. The operation of the entire oscillator is almost the same as that of the entire oscillator shown in FIG. 3, and a phase lock loop is also used here. The crystal oscillator 51 outputs a frequency of 750 KHz as in FIG. Reference frequency divider 53
The frequency division number is 100, so the reference frequency is 750H.
It becomes z. The phase comparator 55 receives the reference frequency divider output (line 54) and the variable frequency divider output (line 62) as inputs, and outputs the phase difference signal (line 56) to the low-pass filter 57. The low-pass filter 57 filters this phase difference signal to convert it into a DC voltage and inputs it to the voltage controlled oscillator 59. The output of voltage controlled oscillator 59 (line 60) is 36.7
The frequencies range from 5 KHz to 191.25 KHz at intervals of 1500 Hz. This output 60 is then divided by 100 by an output frequency divider 78 to obtain the target frequency (36
7.5 Hz to 1912.5 Hz in 15 Hz intervals) are obtained at the output frequency divider output 79. The variable frequency divider 61 and its input and output sections operate exactly the same as the variable frequency divider 31 and its input and output sections shown in FIG. 3, except that the frequency to be processed is 100 times higher. The reference frequency in FIG. 4 and the frequency of the voltage controlled oscillator output 60 are both one of those in FIG.
Therefore, the frequency switching time (or channel switching time) of the multi-channel tone oscillator is greatly shortened. For example, according to experiments,
In the embodiment shown in FIG. 3, the longest switching time was about 1 second when switching between the lowest frequency 367.5 Hz and the highest frequency 1912.5 Hz, but in the embodiment shown in FIG. 4, it was about 10 msec. (i.e., 1/100). In the above application using this multi-channel tone oscillator, the transmission time of one wave is selected from 100 msec to about 1 second, so the frequency switching time must be kept within 10 msec, but the circuit configuration shown in Figure 4 satisfies this requirement.

Note that the frequency division number of the output frequency divider 78 may be increased, for example, 1.
,000 frequency division, the channel switching time becomes approximately 1/10 of that shown in FIG. 4, and is extremely responsive.
FIG. 5 is a block diagram of a multi-channel tone oscillator with new features added to the one shown in FIG.

Crystal oscillator 80, reference frequency divider 81, phase comparator 82, low-pass filter 83, voltage controlled oscillator 84, variable frequency divider 10
The voltage controlled oscillator output (line 101) is supplied with 36,750z to 19
Frequency output is obtained at 1500Hz intervals up to 1.25KHz. The frequency division number setting terminal 104 is connected to +5V, and the input terminals 105 to 111 are connected to external frequency control lines 112 to 118, respectively. According to the input, 36.75L, 3 is output to the voltage controlled oscillator output 101.
It generates frequencies corresponding to 8.25KZ...191.25KIIZ (the above is exactly the same as the multi-channel tone oscillator shown in Figure 4).
- Then, the output frequency of the voltage controlled oscillator (line 101) is divided by 100 by the output frequency divider 85 to obtain the target output frequency of the multi-channel tone oscillator. However, this output (line 86) is a rectangular wave and contains many harmonics, so if it is sent as is to a wireless line etc., there are problems such as interference with other channels. For this reason, new output low-pass filter groups 87, 88, 89, and 90 are provided, and the frequency divider output (line 86) is input to these to suppress harmonics, and then the line 9
5, a multi-channel tone oscillator output with a low distortion sinusoidal waveform is obtained.

In the embodiment shown in FIG. 5, four output low-pass filters 87, 88, 89, and 90 having different cut frequencies are used. For example, in this figure, the cut frequency of the output low-pass filter 87 is 472.5Hz, 188 is 952.5Hz, and 189 is 1.
43265Hz190 is selected as 1912.5z. In this case, the most significant bit 11 of the external frequency control line
8 and the immediately lower bit 117 are also input to the decoder 100, and the decoder 100 creates a 1-digit quaternary output from these 2-bit binary codes, and the signals on control lines 117 and 118 are respectively When it is 0, 0, only the decoder output (line 96) is logical 1, 1, 0, and only the decoder output (line 97) is 1, and so on. Any one of these decoder outputs (lines 96 to 99) is 1
When 1 of switches 91 to 94 connected to that line
The output on the line connected to the switched switch appears at the tone oscillator output 95. In other words, when the input on the external frequency control line is from 24 to 31, the cut frequency is 472.5Hz.
The output low-pass filter 87 works and the output ranges from 367.5Hz to 47Hz.
Outputs 2.5Hz to 95, and from 32 to 63, the output low-pass filter 88 of 952.5Hz works and outputs 487
, 5Hz to 952.5Hz to 95. Thus, 367.5Hz ~ 191
This removes all distortion of the rectangular wave in a wide frequency band of 2.5Hz, but if
When using a partial channel of 12.5Hz, for example, if only 16 waves from 357.5z to 592.5Z are used, the output low-pass filter group 8
7-90 is 592.5Hz cut output low-pass filter 1
The harmonics can be removed by passing only one signal from 367.5Hz to 592.5Hz. Figures 1 and 2
The conventional multi-channel tone oscillator using lead filters shown in the figure required as many lead filters as the number of channels required, which caused problems in terms of size and cost when using multiple channels. Examples of the invention (
In particular, in the case of the one shown in FIG.
All components except 90 can be configured with digital integrated circuits, and the output low-pass filter groups 87 to 90 can also be configured with active filters, so the multi-channel tone oscillator is extremely small and
Low price. The effects of performance improvement, size reduction, and cost reduction according to the present invention are large, and its industrial value is extremely high.

[Brief explanation of drawings]

FIG. 1: A block diagram of a conventionally used multi-channel tone oscillator, which is composed of a mechanical oscillator using a lead filter.

Claims (1)

[Claims] 1 For example, from 367.5Hz to 1912.5Hz1
A total of 10 frequencies set at equal frequency intervals Δf of 5Hz
Like a four-wave tone signal group, the frequency is the frequency interval Δf
(a) A multi-channel tone oscillator that outputs one wave out of a group of tone signals set to be an odd number multiple of 1/2 by specifying it with an external binary code.
A crystal oscillator, (b) a reference frequency divider that divides the output frequency of the crystal oscillator into a predetermined reference frequency, (c) inputs the reference frequency and the variable frequency divider output, and corresponds to the phase difference between the two inputs. (d) a low-pass filter that inputs the DC voltage output from the phase comparator and removes AC noise components contained therein; (e) a DC voltage output from the low-pass filter; a voltage controlled oscillator whose oscillation frequency is controlled; (f) dividing the output frequency of the voltage controlled oscillator into a frequency division number specified by a binary code from an external frequency control line and outputting the output to the phase comparator; (a) to (f) of the variable frequency divider that gives
When configured with a phase-locked loop consisting of, the reference frequency is set to 1/2 of the frequency interval Δf,
Moreover, the 1st bit, 2nd bit, 3rd bit, 7th bit, etc. from the lowest order of the external frequency control line inputted to the variable frequency divider in binary code are respectively input to the variable frequency divider. The 2nd bit, 3rd bit, 4th bit, etc. are moved from the lowest bit of the frequency division number setting terminal to the 8th bit and connected. 1
A multi-channel tone oscillator characterized in that the bit is connected to logic "1". 2. The frequency of each of the fixed frequency divider output and the voltage controlled oscillator output is multiplied by M (M is a positive integer), and at the same time, an output frequency divider with a frequency division number M is placed on the voltage controlled oscillator output. 2. The multi-channel tone oscillator according to claim 1. 3. The multi-channel tone oscillator according to item 2, characterized in that by inserting an output low-pass filter into the output of the output frequency divider, a sine wave with less harmonic distortion is obtained at the output of the output low-pass filter. .