Splitter for analog telephone signal and digital data
View Patent ↗In a telephone system where frequency multiplexed analog telephone signals and digital data signals are transmitted over a line, incoming calls are announced to the customer installation by a ringing indication signal having an amplitude between 1 and 30 V RMS, which is much less than the regular ringing and therefore easier to be generated, and moreover having a smoother shape than a rectangular shape. Upon receiving the ringing indication signal, the customer installation locally generates and provides a full ringing signal to a telephone. The amplitude of this local ringing signal is higher than the amplitude of the ringing indication signal, but the line with the digital data signal is isolated from the customer telephone equipment at the time the ringing signal is generated, so as to avoid disturbance of the digital data transmission by the ringing current, which is a source of impulsive noise.
1. A telephone system wherein analog telephone signals are frequency multiplexed with digital data signals for transmission over a line, wherein at a receiver at a customer premise, a standard POTS ringing signal is generated upon the detection of a ringing indication signal having a voltage amplitude less than 30 V RMS and comprising a spectrum that lacks detectable components in a frequency band that is used for digital data signals at a time when the ringing indication signal announces an incoming telephone call.
2. The telephone system of claim 1 , wherein said ringing indication signal has a voltage amplitude less than 20 V RMS.
3. The telephone system of claim 1 , wherein said ringing indication signal has a voltage amplitude higher than 1 V RMS.
4. The telephone system of claim 1 , wherein said ringing indication signal has a voltage amplitude higher than 10 V RMS.
5. The telephone system of claim 1 , wherein the ringing indication signal has a frequency lower than the frequency of analog telephone signals.
6. The telephone system of claim 1 , wherein the ringing indication signal has a frequency that is one frequency of a set of available data carriers for digital signals, said digital data signals being transmitted using data carriers above said one frequency.
7. A central office installation for transmitting and receiving frequency multiplexed analog telephone signals and digital data signals over a line, wherein the installation comprises:
a splitter for demultiplexing and multiplexing analog telephone signals and digital data signals,
a digital data signals device connected to the splitter for transmitting and receiving digital data signals, and
an analog telephone signals device connected to the splitter for transmitting and receiving analog data signals, wherein the analog telephone signals device generates a standard POTS ringing signal when a ringing indication signal is detected, the ringing indication signal having a voltage amplitude less than 30 V RMS and comprising a spectrum that lacks detectable components in a frequency band that is used for digital data signals at a time when the ringing indication signal announces an incoming telephone call.
8. The installation of claim 7 , wherein said ringing indication signal has a voltage amplitude less than 20 V RMS.
9. The installation of claim 7 , wherein said ringing indication signal has a voltage amplitude higher than 1 V RMS.
10. The installation of claim 7 , wherein said ringing indication signal has a voltage amplitude higher than 10 V RMS.
11. The installation of claim 7 , wherein the ringing indication signal has a frequency lower than the frequency of analog telephone signals.
12. The installation of claim 7 , wherein the ringing indication signal has a frequency that is a frequency of a data carrier for the digital signals.
13. The installation of claim 7 , wherein the analog telephone signals device transmits a ringing signal for announcing an incoming telephone call when said digital data signals device does not receive digital data signals, said ringing signal having a voltage amplitude higher than said ringing indication signal.
14. The installation of claim 7 , wherein said splitter comprises a low pass filter for filtering analog telephone signals, and a high pass filter for filtering digital data signals, and wherein the order of said low pass and high pass filters is less than 5.
15. A splitter for transmitting and receiving frequency multiplexed analog telephone signals and digital data signals over a line port, said splitter comprising:
means for demultiplexing and multiplexing analog telephone signals and digital data signals,
a telephone port for transmitting and receiving analog telephone signals to and from said demultiplexing and multiplexing means, and
ringing signal generation means for generating a ringing signal applied to the telephone port when a ringing indication signal is received over said line port, wherein the ringing indication signal has a voltage amplitude less than 30 V RMS and a spectrum that lacks detectable components in a frequency band for digital data signals at a time when the ringing indication signal announces an incoming telephone call.
16. The splitter according to claim 15 , wherein said ringing indication signal has a voltage amplitude less than 30 V RMS.
17. The splitter of claim 15 , wherein said ringing indication signal has a voltage amplitude less than 20 V RMS.
18. The splitter of claim 15 , wherein said ringing indication signal has a voltage amplitude higher than 1 V RMS.
19. The splitter of claim 15 , wherein said ringing indication signal has a voltage amplitude higher than 10 V RMS.
20. The splitter of claim 15 , wherein the ringing indication signal has a frequency lower than the frequency of analog telephone signals.
21. The splitter of claim 15 , wherein the ringing indication signal has a frequency that is the frequency of a data carrier for the digital signals and the ringing signal has a voltage amplitude higher than the ringing indication signal.
22. The splitter of claim 15 , further comprising switching means for isolating said telephone port from said line port when a ringing signal is generated and applied to said telephone port.
23. The splitter of claim 15 , wherein said demultiplexing and multiplexing means comprise a low pass filter for filtering analog telephone signals, and a high pass filter for filtering digital data signals, and wherein the order of said low pass and high pass filters is less than 5.
24. The splitter of claim 15 , further comprising a digital data signals port for transmitting and receiving digital data signals to and from said demultiplexing and multiplexing means, switching means between said digital data signals port and said line port, and power detection means for detecting improper power supply to the splitter and for opening said switching means when improper power supply is detected.
25. A central office installation for transmitting and receiving frequency multiplexed analog telephone signals and digital data signals over a line, wherein the installation comprises:
a splitter for demultiplexing and multiplexing analog telephone signals and digital data signals,
a digital data signals device connected to the splitter for transmitting and receiving digital data signals, and
an analog telephone signals device connected to the splitter for transmitting and receiving analog data signals, wherein the analog telephone signals device transmits a ringing indication signal for announcing an incoming telephone call, the ringing indication signal having a voltage amplitude less than 30 V RMS, wherein the analog telephone signals device transmits a ringing signal for announcing an incoming telephone call when the digital data signals device does not receive digital data signals and the ringing signal has a voltage amplitude higher than the ringing indication signal.