Browse Prior Art Database

Digital Data Communication Over Twisted Pair Voice Telephone Wiring

IP.com Disclosure Number: IPCOM000050795D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 4 page(s) / 68K

Publishing Venue

IBM

Related People

Kuhar, E: AUTHOR

Abstract

The illustrated time division switching network sustains voice telephone and data communications concurrently over twisted pair conductors ordinarily used only for voice telephone traffic. Consequently, this scheme permits telephone system customers to use existing wiring facilities for both voice telephone and data communications with associated cost savings.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 43% of the total text.

Page 1 of 4

Digital Data Communication Over Twisted Pair Voice Telephone Wiring

The illustrated time division switching network sustains voice telephone and data communications concurrently over twisted pair conductors ordinarily used only for voice telephone traffic. Consequently, this scheme permits telephone system customers to use existing wiring facilities for both voice telephone and data communications with associated cost savings.

Time division switch 1 (Fig. 1) has 256 input ports 2 and 256 output ports 3. The input and output ports are connected in pairs to digital voice telephone instruments, such as 4, and digital data work stations, such as 5 (which in the illustrated network operate through digital telephone instruments). Each port/instrument connection includes at least one twisted pair input conductor 6 and one output twisted pair conductor 7; for instance, the connection to the representatively illustrated instrument 4 includes input twisted pair 6a and output twisted pair 7a.

Each telephone instrument connection requires electronic adaptation equipment (not shown) for converting voice and tone signals between analog and digital forms and for presenting digital form (7-bit PCM) signals to the switch in synchronism with time division operations of the switch. Each data work station requires adaptation equipment (also not shown) for interfacing with the respective telephone instrument and exchanging data therewith in a format, and at a rate, commensurate with switch operations.

Microprocessor 10, operating under the direction of host processor 11, controls operations of switch 1. The microprocessor has bus connections 12a, 12b and 12c with switch 1 and bus connections 14 with host system 11 via that system's I/O channel 15. Buses 12a permit microprocessor 10 to exchange data with the ports 6, 7. Buses 12b and 12c allow the microprocessor to vary time slot interchange switching associations (i.e., connections) between input and output ports. Bus 14 allows the microprocessor to exchange port traffic data and control information with host processor 11.

Outgoing voice signals at the telephone instruments are sampled at a rate of 8,000 samples per second in synchronism with operations of the switch. Each sample is quantized as a 7-bit PCM (pulse code modulated) character, and combined with an eighth bit signalling function used for control functions (indicating on hook, off hook and hook flash states, dialing number information, etc.). Information transferred from the switch to the telephone circuits is similarly quantized in 7-bit PCM format and combined with eighth bits representing synchronizing functions and progress tones (dial tones, busy tones, ringing tones, etc.) , the latter synthesized by the microprocessor under direction of the host. Digital data workstations operate through the telephone station, adapting circuits to gain access to assigned time intervals of the switch.

The switch operates in character transfer frames...