JPS6096054A - Pb oscillator of telephone set - Google Patents

Abstract

PURPOSE:To avoid a PB receiver from being malfunctioned even if a signal passes through a subscriber line system with deteriorated frequency characteristic by frequency-dividing a high frequency in response to a depressed PB button so as to form two signal waves and forming two pseudo sin waves at the highest level at no signal for one signal and the lowest level for the other signal. CONSTITUTION:An output of a reversible counter 4b is inerted, digital/analog conversion is applied, an output of exclusive OR circuits 7-9 goes to logical level ''0'' just before the start in the obtained pseudo sin waves f3, f4, an output of exclusive NOR circuits 13-15 goes to logical level ''1'', then the one goes to the minimum level at start and the other level goes to the highest level. In adding the pseudo sin waves f3, f4 at an adder 5, the DC level (at no signal) L1 just before the burst and the DC level L2 at signal are brought into an identical level, and the waveform is not distorted even if the signals are applied to a subscriber line system. Thus, the malfunction of the PB receiver is prevented.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a PE transmitter for a telephone.

[Background of the invention]

As a PE transmitter for a telephone, it divides the high frequency, performs digital synthesis, performs digital/analog conversion, and generates two
A device that mixes frequencies and sends the mixture to a subscriber line system is known. FIG. 1 is a diagram showing the configuration of the above-mentioned PE oscillator. Information on the press of the PR button 6 is transmitted to the one frequency divider 2α and 2AK via the decoder 1, and the high frequency f generated by the oscillator 3 is , into signal waves f, , f, of the required frequency.

The signal waves y:, f are further divided by one frequency by reversible counters 4α, 4h with exclusive OR circuits, and digital/analog converted by resistors R1 to R6, resulting in a pseudo sine wave f3 as shown in FIG. °f4 is formed. This pseudo sine wave f, , 7'4 is added by adder 5,
A burst PE signal wave is obtained. Figure 3 shows the pseudo sine waves f, , f4 and the addition of both (fs”fi).
It is a figure which shows the PE signal wave obtained. In this figure, the pseudo sine waves f, , f, are expressed macroscopically, unlike in Figure 2. As is clear from Figure 3, burst-shaped PE
In the signal wave, the DC level L1 when there is no signal is biased in a negative direction compared to the level L2 of the DC component when there is a signal. If this PB transmission wave is sent as it is to the subscriber line system, its frequency characteristics, especially the low frequency cutoff characteristics, will cause distortion and malfunction in the identification of the PE receiver.

FIG. 4 is a block diagram showing the main parts of the pB oscillator in detail, and will be explained in more detail using this diagram. That is, in FIG. 4, before the PR button is pressed, the reversible counters 4α and 4b have been reset, and the exclusive OR circuit 7
The output signals α to f through ~12 are all at logic level "0"
It becomes.

Therefore, the pseudo sine wave f3. f starts from the lowest potential point as shown in FIG. Therefore, when the PR transmission wave output from the addition book is applied to the subscriber line system, the output waveform becomes a distorted waveform as shown in Fig. 5(α) to Fig. 5(b)K. The pB receiver malfunctions at the head of the burst and immediately after the end of the burst.

[Purpose of the invention]

The present invention was made in view of the above-mentioned drawbacks of the prior art, and even when transmitted to a subscriber line system, no waveform distortion occurs, and the pB
It is an object of the present invention to provide a PR transmitter for a telephone that does not cause receiver malfunction.

[Summary of the invention]

The pB transmitter of the telephone of the present invention divides the high frequency according to the pressed PR button to form two signal waves.
circuit, a pair of pseudo sine wave forming circuits provided for each signal wave, which further divides the frequency of each signal wave, and then converting it into digital/analog to form a pseudo sine wave, and from each pseudo sine wave forming circuit. It consists of a synthesis circuit that synthesizes the output pseudo sine waves, and the two pseudo sine waves output from the above two pseudo sine wave forming circuits respectively have one at the highest level and the other at the lowest level when there is no signal. It is characterized by being

[Embodiments of the invention]

The present invention will be described in more detail below with reference to embodiments shown in the accompanying drawings.

FIG. 6 is a block diagram showing an embodiment of the present invention, and the same parts as those of the conventional PR transmitter shown in FIG. 4 are given the same reference numerals, and the explanation thereof will be omitted. The difference from the conventional example shown in FIG. 4 is that the exclusive OR circuits 10, 11, and 12 are replaced with exclusive ear circuits 13, 14, and 15.

That is, in the embodiment shown in FIG. 6, the output of the reversible counter 4h is inverted to perform digital/analog conversion. Pseudo sine wave f' obtained in this example
sf4 is such that the outputs of the exclusive OR circuits 7 to 9 are at logic level "0" immediately before the start, and the outputs of the exclusive OR circuits 13 to 1 are
Since the outputs of the circuits 5 and 5 are at the logic level "1", one is at the lowest level and the other is at the highest level at the start, as shown in FIG.

When these pseudo sine waves f, , f are added by the adder 5, the 8th
As shown in the figure, the DC level just before the burst (when there is no signal) L
1 and the DC level L2 at the time of the signal are at the same level, and even when applied to the subscriber line system, the waveform is not distorted as shown in FIGS. 9(α) and (h)K. Therefore, malfunction of the pB receiver is prevented.

〔Effect of the invention〕

According to the present invention, even if the PB transmission wave output from the 28 oscillator is passed through a subscriber line system with poor frequency characteristics, the PE receiver will not malfunction.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an example of a PR transmitter of a conventional telephone, Fig. 2 is a diagram showing a pseudo sine wave obtained by the pB transmitter shown in Fig. 1, and Fig. 3 is a block diagram showing the pB transmitter shown in Fig. 1. A diagram showing the synthesis state of two pseudo sine waves in the oscillator, Figure 4 is a detailed diagram of the main parts of the 28 oscillator shown in Figure 1, and Figure 5 (α)
, (b> is a waveform diagram when transmitting a PB oscillation wave through a subscriber line system, FIG. 6 is a block diagram showing an embodiment of the present invention, and FIG. 7 is obtained by the embodiment shown in FIG. 6. FIG. 8 is a diagram showing a pseudo sine wave, and FIG. 9 is a diagram showing a composite state of two pseudo sine waves in the embodiment shown in FIG. FIG. 2 is a waveform diagram when transmitting a PB transmission wave through a subscriber line system. 1・・・・・・・・・・・・・・・・・・・・・・・・・Leverage!
2α, 2A...W frequency divider 6...
・・・・・・・・・・・・・・・・Oscillator 4α, 4A
・・・・・・・・・Reversible counter 5...
・・・・・・・・・・・・・・・・・・・・・Adder 6...
・・・・・・・・・・・・・・・・・・・・・pB button 7-1
2...Exclusive OR circuit 13-15.
...Exclusive NOR circuit R1~R6...Resistance call 1 Figure 2 Figure 3 Figure 'i' irises M Figure 4 ■ Ward 5 Figure 6 Figure 7 Figure 9--2 Display of the incident Showa, 8th year special F +' request number. 26,2 Name of bow invention Person who plays telephone pB launcher lottery 112 Relationship with PI 9 Patent applicant K 14: ' 5 IQ + stock company il: II,
：＋'H Made by I (and 1 other person) Assistant agent JIE (D Target Column selection of the name of the invention in the specification 11
:, Contents of 7ter\

Claims (1)

[Claims] A first circuit divides the high frequency according to the pressed PR button and forms two signal waves, and a circuit is provided for each signal wave to further divide the frequency of each signal wave and then perform digital/analog conversion to generate a pseudo sine wave. In a PE oscillator consisting of a pair of pseudo sine wave forming circuits that form waves, and a synthesis circuit that synthesizes the pseudo sine waves output from each pseudo sine wave forming circuit, each of the above pairs of pseudo sine wave forming circuits A PE transmitter for a telephone set, characterized in that two pseudo sine waves output are configured such that one is at the highest level and the other is at the lowest level when there is no signal.