JPH036051Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a cordless telephone device, and in particular, a cordless telephone that can reliably transmit dial signals generated at a slave station to a master station. Regarding equipment.

(B) Prior Art FIG. 1 shows a block diagram of a conventional slave station in a cordless telephone device. It has a power amplification circuit 1, an RF amplification circuit 2, a modulation circuit 3, a guard tone signal generation circuit 4, a dial pulse generation circuit 5, and a keyboard 6. When making a call from a slave station to a telephone line, first operate a call switch (not shown) on the slave station side, which drives the guard tone signal generation circuit 4 and applies the guard tone signal to the modulation circuit 3. . Then, the carrier is modulated with a guard tone signal in the modulation circuit 3, and sent out from the antenna via the RF amplification circuit 2 and the power amplification circuit 1. When this guard tone signal is detected at the master station, an off-hook state (a state in which the handset is lifted from the telephone set) is realized. Next, when the keyboard 6 is operated to dial, the dial pulse generation circuit 5 outputs a number of dial pulses corresponding to the operated number. For example, dial pulses are output at a break rate of 60% and 10 PPS (see Figure 3a).
This dial pulse is applied to the guard tone signal generating circuit 4, and the guard tone signal is turned on and off based on the dial pulse, thereby creating a dial signal (tone burst wave) as shown in FIG. 3b. This dial signal is applied to the modulation circuit 3, which modulates the carrier. In this way, the dial signal is transmitted to the master station, and from the master station to the telephone line. Now, after the telephone line is connected, the voice signal input from the microphone 7 is amplified by the microphone signal circuit 8, applied to the modulation circuit 3, and then transmitted to the main station side, and further transmitted to the telephone line. It will be sent to

Incidentally, conventionally, the dial pulse generating circuit 5, the guard tone signal generating circuit 4, the modulating circuit 3, and the microphone signal circuit 8 were connected as shown in FIG. That is, the dial pulse output from the dial pulse generation circuit 5 is applied to the DC bias circuit (point X) of the guard tone signal generation circuit 4.
By controlling the DC bias on and off, a tone burst wave as shown in FIG. 3B was created. Therefore, during dial operation, voice, noise, etc. are input to the microphone 7 and are transmitted to the modulation circuit 3 via the microphone signal circuit 8.
, noise N will be generated in the dial signal as shown in FIG. 3C. Such noise causes malfunction.

(c) Purpose of the invention The purpose of the invention is to create accurate dialing signals without noise.

(d) Configuration of the invention A configuration in which three output lines of the guard tone signal generation circuit, microphone signal generation circuit, and dial pulse signal generation circuit are connected at one point, and this connection point is connected to the input side of the modulation circuit. That is.

(E) Embodiment FIGS. 4 and 5 show embodiments of the present invention. That is, the three output lines of the guard tone signal generation circuit 4, microphone signal generation circuit 8, and dial pulse signal generation circuit 5 are connected at one point Y, and this connection point Y is connected to the input side of the modulation circuit 3. It is something to do. According to such a configuration, the connection point Y
In this case, the guard tone signal (see FIG. 6b) output from the guard tone signal generation circuit 4 is controlled by the dial pulse (see FIG. 6a). Specifically, during the break period of the dial pulse,
Since the impedance of the connection point Y is lowered (the transistor in the dial pulse generation circuit 5 conducts and the connection point Y is grounded), even if there is an output (noise) from the microphone signal circuit 8, this will be suppressed. Since the signal is muted, noise is not mixed into the dial signal applied to the modulation circuit 3 (see FIG. 6C). The transistor in the dial pulse generating circuit 5 is equivalent to an open collector, and when voltage is supplied to the base, the impedance between the collector and emitter is low, and when no voltage is supplied, the transistor is high impedance.

In addition, in the conventional circuit, the DC level fluctuates at point There is no DC level fluctuation in X, and a clean tone burst wave (dial signal) can be obtained. still,
In the figure, capacitor C is a coupling capacitor.

(f) Effects of the invention According to the invention, it is possible to create a dial signal with a clean waveform without noise on the slave station side.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a conventional circuit, Fig. 2 is a diagram showing a specific example thereof, Fig. 3 is a diagram of its operation waveforms, Fig. 4 is a diagram showing a circuit according to the present invention, and Fig. 5 is a diagram showing a specific example thereof. FIG. 6 is a diagram showing its operation waveforms. 3 is a modulation circuit, 4 is a guard tone signal generation circuit, 5 is a dial pulse generation circuit, and 8 is a microphone signal circuit.

Claims (1)

[Scope of utility model registration request] A cordless telephone device consisting of a master station connected to a telephone line and a slave station wirelessly connected to the master station, the slave station having a guard tone signal generation circuit and a dial pulse. A signal generation circuit, a modulation circuit, and a microphone signal circuit are provided, and the output lines of the guard tone signal generation circuit, the dial pulse signal generation circuit, and the microphone signal circuit are connected, and this connection point is connected to the modulation circuit. and the impedance at the connection point is varied by the output from the dial pulse signal generation circuit, and during the dial pulse signal break period, the impedance at the connection point is lowered to lower the impedance at the connection point. A cordless telephone device characterized in that outputs from a guard tone signal generation circuit and a microphone signal circuit are prevented from being applied to the modulation circuit.