Digital differential system

专利摘要:
A microprocessor controlled subscriber line circuit for interfacing analog telephone lines and trunks to a digital switching system is disclosed. All processing of incoming analog signals is accomplished by the line circuit, including the interface between the line and a digital switching matrix, measuring, monitoring, testing of the signals associated with the speech path. Additionally, the dc signal powering the carbon microphone on the handset is generated as well as ringing and other tones. Equalization and providing the two-wire to four-wire conversion with acceptable echo performance and minimized cross-office transmission loss are also accomplished. Analog-to-digital and digital-to-analog conversions are accomplished under microprocessor control as are the tone and power generation functions in a programmable power supply configuration utilizing pulse duration modulated feedback control in a programmable signal generator. The described subscriber circuit is particularly advantageous in that it is designed to maximize its implementation using solid state circuit techniques including large scale integration as opposed to conventional components and relays.
公开号:SU1191001A3
申请号:SU782585299
申请日:1978-03-02
公开日:1985-11-07
发明作者:Трайбер Роберт
申请人:Интернэшнл Стандарт Электрик Корпорейшн (Фирма)；
IPC主号:

专利说明:

/

i.
The invention relates to communication technology, in particular, to devices for dividing transmission and reception directions.
The purpose of the invention is to increase the transient attenuation between the transmitting and receiving paths of the four-wire line.
. The drawing shows a functional electrical circuit of a digital differential system.
The digital differential system contains the first adder 1, the second adder 2, the analog filter 3, the digital filter 4, the analog-digital converter 5, the digital-analog converter 6 and the additional digital filter 7.
Digital differential system works as follows.
The analog signal from the two-wire line comes through the first sum of the matrix 1 and is converted to digit 012
an even form in the analog-digital converter 5 and after filtering in, the digital filter 4 through the second adder 2 enters in digital form into the transmission path of the four-wire line. From the receive path of the four-wire line, the incoming signal is converted to analog in a digital-to-analog converter 6,
filtered by analog filter 3 and fed through the first adder 1. to a two-wire line and to a transmission path, where it is digitized and fed through a digital filter to a second adder 2, to the subtracting input of which a signal is fed from an additional digital filter 7. Because the received signal and the signal passed from the path (circuit)
the reception in the transmission circuit is the same; in the second adder 2, they are fully compensated and the reception path signal is not received in the transmission path.

权利要求:
Claims (1)
[1]
A DIGITAL DIFFERENTIAL SYSTEM comprising a first adder connected to a two-wire line, a second adder, the output of which is connected to a transmission path of a four-wire line, and an analog filter connected to the other input of the first adder, and a digital filter, the output of which is connected to the input of the second adder, characterized in that, in order to increase the transient attenuation between the receiving and transmitting paths of the four-wire line, an analog-to-digital converter, a digital-to-analog converter, and additional digital filter, the output of which is connected to the subtracting input of the second adder, and the input of the additional digital filter is connected to the receiving path of the four-wire line and the input of the digital-to-analog converter, the output of which is connected to the input of the analog filter, while the output of the first adder through the analog-to-digital converter connected to the input of a digital filter.
1 1191001

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法律状态:

优先权:

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申请号 | 申请日 | 专利标题

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US77371377A| true| 1977-03-02|1977-03-02|

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