Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B3/00—Line transmission systems
  • H04B3/54—Systems for transmission via power distribution lines
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04M—TELEPHONIC COMMUNICATION
  • H04M1/00—Substation equipment, e.g. for use by subscribers
  • H04M1/71—Substation extension arrangements
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B2203/00—Indexing scheme relating to line transmission systems
  • H04B2203/54—Aspects of powerline communications not already covered by H04B3/54 and its subgroups
  • H04B2203/5429—Applications for powerline communications
  • H04B2203/5437—Wired telephone

Definitions

• Patent No. 3,949,172 is not immune to eavesdropping by others who have access to the same AC power line. It is another object to provide protection against such eavesdropping.
• the subscriber's premises has a telephone line 1 which usually consists of four wires (not shown) called the tip line, the ring line, earth ground and a fourth line for special party line ringing circuits.
• the ring line is usually red
• the tip line is green
• the earth ground is black
• the fourth line is yellow.
• three of these lines, the tip, ring and ground connect to "on line" conventional telephones at the premises and also connect to telephone line wall jacks 2.
• This incoming call can be answered by any of the system telephones, or all can simultaneously engage the incoming call and communicate with each other.
• the incoming caller and all the system telephones can conference together.
• the incoming call is not terminated at the subscriber's location until all of the system telephones are on hook (cradled) .
• any of the system telephone can place a call to the telephone line, just as any conventional phone places a call, by the phone going off hook and signalling the call number by using the phone's key pad (buttons) ; and before, during or after this signaling, the other phones of the system can go off hook and join in the call.
• the main TX-RX computer 31 processes all system signals between the main and extension phones. More particularl , it processes all initiating and terminating signals from the telephone line including ring signals, processes all signals from the system extension telephones, processes the main telephone hook switch signal derived from hook switch 23, processes all signals from the main key pad 32, controls the subset (SS) relay switch 33, the carrier (C) relay switch 34 and the hold (H) relay switch 35, (all in the telephone line interface 21) , turns the main transmitter 25 on and off, adds CODE to the analog VOICE transmitted by the main transmitter and controls the system dual tone multi-frequency (DTMF) generator 36, depending on coded key pad signals received at the main from an extension.
• DTMF system dual tone multi-frequency
• the main telephone computer may store twelve additional numbers with a maximum of 160 digits, the last number dialed at the main being included among these digits.
• the numbers that are stored in the main telephone computer are entered into storage in the main computer by the operator thereof as follows: first coming off-hook; then pressing the S button; then the "#" button; then one of the twelve buttons in the top three rows of the key pad (see Figure 14A) ; and then pressing the specific telephone number to be entered by pressing that number in the sequence of keys of the pad. Entry of the stored number can be stopped by either the main phone going on-hook or by pressing any of the feature buttons I, H, P or S.
• the response at E2 is to receive RXm, detect the CD2 (for BUZ) and activate E2 ring drive 47 with a BUZ signal and so E2 is buzzed for an intercom communication;
• E2 - Off Hk When E2 goes Off Hk, it turns on TX2, transmitting CD (for E2 - Off Hk) R @ M The response at M is to receive RX2, detect the CD (for E2 - Off Hk) which causes TXm to send CD2 (addressed to
• Hybd are deactivated and relay SS is deactivated so that the outputs of MRX1 and MRX2, combined at 340 are fed directly through Hybd 27 as RX to the input of MTXM and El and E2 remain in intercom; and so El + E2 - I Routine status is achieved.
• the main phone power supply, regulator 32 provides all operating power for the main phone except power derived from the telephone line for operating parts of the telephone line interface system 21 and for operating the main DTMF 37 as already described.
• the power supply 32 produces 12 volts and 5 volts DC for operating the systems and subsystems in the main phone.
• Power to regulator 32 comes from transformer 72M in the adaptor plug.
• the primary side 73M of that transformer connects directly across the power line and the secondary has a center tap that is carried by cord 6a to terminal 3 in the main phone that provides the main phone ground while the two ends of the secondary are connected together via diodes 75M, as shown, providing rectified positive voltage that is carried by cord 6a to terminal 1 in the
• the keypad outputs are designated by their row and column symbol rather than the pin and the pin designation is described only with reference to these figures.
• the pin designation is not carried through in the descriptions of operations of the keypad system elsewhere herein.
• the electrical connections between the extension keypad 53 and the extension computer 44 and extension address set switches 54 is described more fully hereinbelow with reference to Fig. 17.
• dial tones are coupled by transformer actions to the secondary 22e, which is across the tip and ring

Applications Claiming Priority (8)

Publications (1)

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• 1983
  • 1983-09-29 WO PCT/US1983/001518 patent/WO1984001481A1/en not_active Application Discontinuation
  • 1983-09-29 EP EP83903636A patent/EP0120959A1/de not_active Withdrawn

Non-Patent Citations (1)

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