JPH04315322A - Cordless telephone system - Google Patents

Abstract

PURPOSE:To improve S/N and to reduce the deterioration in sound quality even when the reference level of a radio circuit is increased by deciding the noise level of the radio circuit so as to vary the reference level of a compressor circuit. CONSTITUTION:This cordless telephone system composed of a base station connecting to a trunk line 1 and a mobile station connected in a radio signal is provided with carrier deciding circuits 23, 25 and reference level variable circuits 24, 26 varying a reference level by the carrier deciding circuits 23, 25. Then the noise level of the radio circuit is decided by the output of the carrier deciding circuits 23 and the reference level of the compressor circuit 4 provided on the cordless telephone system is made variable. Furthermore, the noise level of the radio circuit is decided by the output of the carrier deciding circuits 25 and the result of decision is sent to an opposite station to vary the reference level of the expander circuit 15 of an opposite station and the level of the compressor circuit 4 at a transmission side is made coincident with the reference level of the reception side expander circuit 15.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to cordless telephone equipment.

0002

2. Description of the Related Art FIG. 2 shows the structure of a conventional cordless telephone device. FIG. 2(a) shows a base station, and FIG. 2(b) shows a mobile station. In FIG. 2(a),
Reference numeral 27 denotes a central office line, which is connected to a communication circuit 28, which is connected to an amplifier circuit 29, and which is connected to a communication circuit 28.
is connected to a compressor circuit 30, the compressor circuit 30 is connected to a modulation circuit 31, the modulation circuit 31 is connected to a transmission circuit 32, and the transmission circuit 32 is connected to an antenna 33. Further, the antenna 33 is connected to a receiving circuit 34, the receiving circuit 34 is connected to a demodulating circuit 35, the demodulating circuit 35 is connected to an expander circuit 36, and the expander circuit 36 is connected to an amplifier circuit 37. The amplifier circuit 37 is connected to the communication circuit 28. In FIG. 2(b), 38 is an antenna, which is connected to the receiving circuit 39.
is connected to the demodulation circuit 40, the demodulation circuit 40 is connected to the expander circuit 41, and the expander circuit 4
1 is connected to an amplifier circuit 42, and the amplifier circuit 42 is connected to a receiver 43. Further, 44 is a microphone connected to an amplifier circuit 45, the amplifier circuit 45 is connected to a compressor circuit 46, the compressor circuit 46 is connected to a modulation circuit 47, and the modulation circuit 47 is connected to a transmission circuit 48. The transmitting circuit 48 is connected to the antenna 38.

Next, the operation of the above conventional example will be explained. In FIG. 2, at the base station, a voice signal obtained from a central office line 27 passes through a communication circuit 28 and is amplified by an amplifier circuit 29.
The amplified signal is band-compressed by a compressor circuit 30, then modulated by a modulation circuit 31, enters a transmitter circuit 32, becomes a transmission wave, and is transmitted from an antenna 33. The transmitted signal is then received by the receiving circuit 39 via the antenna 38 of the mobile station, and demodulated into an audio signal by the demodulating circuit 40.
After being band-expanded by an expander circuit 41, the signal is amplified by an amplifier circuit 42 and transmitted to a receiver 43. Furthermore, the audio signal obtained from the microphone 44 of the mobile station is transmitted to an amplifier circuit 45.
After being amplified by the compressor circuit 46 and band-compressed by the compressor circuit 46, it is modulated by the modulation circuit 47, enters the transmission circuit 48, becomes a transmission wave, and is transmitted from the antenna 38. The transmitted signal is received by the receiving circuit 34 via the antenna 33 of the base station, demodulated into an audio signal by the demodulating circuit 35, band-expanded by the expander circuit 36, and then amplified by the amplifier circuit 37. is connected to the telephone line 28 and enters the central office line 27.
can be conveyed to. In this way, even in the conventional cordless telephone device described above, noise in the wireless circuit can be reduced by the expander circuit and the compressor circuit.

0004

[Problems to be Solved by the Invention] However, in the above-mentioned conventional cordless telephone device, the reference levels of the expander circuit and the compressor circuit are fixed assuming the noise level of a certain radio circuit, so When the distance between the stations increases and the communication of radio waves deteriorates, the noise level of the radio circuit increases, and when noise higher than the reference level enters, there is a problem that a sufficient S/N ratio cannot be obtained. The present invention solves these conventional problems, and can improve the S/N even when the noise level of the wireless circuit becomes high. It is an object of the present invention to provide a cordless telephone that can reduce deterioration of sound quality while ensuring N.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a cordless telephone device with a carrier determination circuit and a reference level variable circuit, so that the reference levels of the compressor circuit and expander circuit of the cordless telephone device can be varied. This is how it was done.

[0006]

[Operation] Therefore, according to the present invention, the noise level of the wireless circuit is determined by the carrier determination circuit, and the reference level of the compressor circuit is adjusted by the reference level variable circuit so that the S/N ratio can be improved even when the noise level is high. It can be set with . In addition, the noise level of the wireless circuit is determined by the carrier determination circuit and transmitted to the other station, and the reference level of the expander circuit is adjusted to the above reference level by the reference level variable circuit, thereby reducing the deterioration of sound quality. can.

[0007]

[Embodiment] Fig. 1 shows the configuration of a cordless telephone device according to an embodiment of the present invention, with Fig. 1(a) showing a base station and Fig. 1(b) showing a mobile station. . Figure 1
, 1 is the office line, 2 is the communication circuit, 3, 11, 16,
19 is an amplifier circuit, 4, 20 is a compressor circuit, 5,
21 is a modulation circuit, 6 and 22 are transmission circuits, 7 and 12 are antennas, 8 and 13 are reception circuits, 9 and 14 are demodulation circuits, and 10
, 15 is an expander circuit, 17 is a receiver, 18 is a microphone, 23 and 25 are carrier determination circuits, and 24 and 26 are reference level variable circuits.
The output of the demodulation circuit 9 is connected to the demodulation circuit 9 and the carrier determination circuit 23, and the output of the demodulation circuit 9 is connected to the expander circuit 10 and the carrier determination circuit 23. The output of the carrier determination circuit 23 is connected to the modulation circuit 5 and the variable reference level circuit, and the output of the variable reference level circuit is connected to the compressor circuit 4 and the expander circuit 10. In the mobile station, the output of the receiving circuit 13 is connected to a demodulation circuit 14 and a carrier determination circuit 25, and the output of the demodulation circuit 14 is connected to an expander circuit 15 and a carrier determination circuit 25. The output of the carrier determination circuit 25 is transmitted to the modulation circuit 2
1 and a reference level variable circuit 26, and the output of the reference level variable circuit 26 is connected to an expander circuit 15 and a compressor circuit 20.

Next, an example will be described in which, in the above embodiment, the reference level of the mobile station is varied based on the received signal at the base station. The carrier determination circuit 23 of the base station obtains the received signal from the reception circuit 8 and determines the noise level of the radio circuit. Based on that, the reference level variable circuit 24
provides the compressor circuit 4 with a reference level that can ensure a sufficient S/N ratio. Further, the carrier determination circuit 23
The set reference level is sent to the modulation circuit 5, and transmitted as a transmission wave by the transmission circuit 6 to the mobile station by the antenna 7. The transmitted reference level is received by the reception circuit 13 through the antenna 12 of the mobile station, demodulated by the demodulation circuit 14, and then input to the carrier determination circuit 25. The carrier determination circuit 25 supplies the obtained reference level to the reference level variable circuit 26. The reference level variable circuit 26 passes the obtained reference level to the expander circuit 15. As a result, the reference levels of the base station compressor circuit 4 and the mobile station expander circuit 15 become equal, and deterioration in sound quality can be reduced. The voice signal obtained from the base station line 1 passes through the communication circuit 2, and the signal is amplified by the amplifier circuit 3.The signal is band-compressed by the compressor circuit 4, then modulated by the modulation circuit 5, and then transmitted. The signal enters the circuit 6, becomes a transmission wave, and is transmitted from the antenna 7. The received wave is received by the receiving circuit 13 via the antenna 12 of the mobile station, becomes an audio signal by the demodulating circuit 14, is band-expanded by the expander circuit 15, is amplified by the amplifier circuit 16, and is transmitted to the receiver 17. It will be done. Furthermore, the audio signal obtained from the microphone 18 of the mobile station is amplified by the amplifier circuit 19, band-compressed by the compressor circuit 20, modulated by the modulation circuit 21, and then enters the transmitter circuit 22 and becomes a transmission wave from the antenna 12. Sent. The received wave is received by a receiving circuit 8 via an antenna 7 of the base station, demodulated into an audio signal by a demodulating circuit 9, band-expanded by an expander circuit 10, and then sent to an amplifier circuit 1.
1 is amplified, enters the communication circuit 2, and is transmitted to the central office line 1. As described above, according to the above embodiment, in the base station, the carrier determination circuit 23 and the reference level variable circuit 24 provide a reference level to the compressor circuit 4 based on the received signal, and in the mobile station, the carrier determination circuit 23 and the reference level variable circuit 24 provide a reference level to the compressor circuit 4 based on the received signal. Since the reference level variable circuit 25 and the reference level variable circuit 26 give the same reference level to the expander circuit 15, it has the advantage that even if the noise level of the wireless circuit is high, the S/N can be improved and deterioration in sound quality can be reduced. .

[0009]

Effects of the Invention As is clear from the above examples, the present invention has the following effects. (1) Based on the received signal, the noise level of the wireless circuit is determined and the reference level of the compressor circuit is varied, so the S/N can be improved even when the noise level of the wireless circuit increases. can. (2) Determine the noise level of the wireless circuit based on the received signal, transmit it to the other station, and vary the reference level of the expander circuit of the other station to match the reference level in (1) above. This makes it possible to reduce deterioration in sound quality.

[Brief explanation of drawings]

1 is a block diagram of a cordless telephone device according to an embodiment of the present invention (FIG. 1(a) is a base station; FIG. 1(b) is a block diagram of a cordless telephone device according to an embodiment of the present invention;
is a mobile station).

FIG. 2 is a block diagram of a conventional cordless telephone device (FIG. 2(a) is a base station, FIG. 2(b) is a mobile station).

[Explanation of symbols]

1, 27... Office line, 2, 28... Call circuit, 3, 1
1, 16, 19, 29, 37, 42, 45... amplifier circuit,
4, 20, 30, 46...compressor circuit,
5, 21, 31, 47...Modulation circuit, 6, 22, 32, 4
8... Transmission circuit, 7, 12, 33, 38... Antenna,
8, 13, 34, 39...receiving circuit, 9, 14,
35, 40... demodulation circuit, 10, 15, 36, 41...
Expander circuit, 17, 43...receiver,
18, 44...Microphone, 23, 25...Carrier determination circuit, 24, 26...Reference level variable circuit.

Claims (2)

[Claims] 1. A cordless telephone device comprising a base station connected to a central office line and a mobile station wirelessly connected to the base station, comprising: a carrier determination circuit; and a reference level for varying the reference level by the carrier determination circuit. The noise level of the wireless circuit is determined based on the output value of the carrier determination circuit, and the reference level of the compressor circuit included in the cordless telephone device is varied, so that the S/N can be maintained even under conditions where there is a lot of wireless noise. A cordless telephone device characterized in that it can be improved. 2. A cordless telephone device comprising a base station connected to a central office line and a mobile station wirelessly connected to the base station, comprising: a carrier determination circuit; and a reference level for varying the reference level by the carrier determination circuit. A variable circuit is provided, which determines the noise level of the wireless circuit based on the output value of the carrier determination circuit, transmits the determination result to the other station, varies the reference level of the expander circuit of the other station, and controls the compressor circuit on the transmitting side. A cordless telephone device characterized in that the standard level of the expander circuit on the receiving side is made the same as that of the expander circuit on the receiving side, thereby reducing audio deterioration.