EP0238972A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Call meter signal receiver for subscriber's private metering of telephone system
Assignee: Fujitsu Ltd
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Filing: 1987-03-17
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Granted: —
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Expires: 2007-03-17
Abstract
Abstract A call meter signal receiver for subscriber's private metering (SPM) system operated by a call meter signal sent from a central office (CO). The receiver is operable both by common mode and normal mode signals. The receiver is so small in size that it can be installed in a central office trunk (COT) of the Private Branch Exchange (PBX). The call meter signal receiver composed of a frequency tuned receiver (44) comprising two buffer circuits (41, 42), the first one (41) for receiving the common mode and the second one (42) for receiving the normal mode signal. The first buffer circuit (41) is connected to the input side of a hybrid circuit (23) of the COT and has a high impedance, while the second buffer circuit (42) is connected to one of the output terminals of the hybrid circuit (23) for receiving the normal mode signal and has high impedance for voice signals. The outputs of these buffer circuits (41, 42) are fed to the frequency tuned receiver (44) composed of a phase locked loop (PLL) of which frequency is tuned to 50 Hz, 12 kHz or 16 kHz by switching externally attached circuit composed of capacitor and resistors. The call meter signal receiver is so small sized that it can be installed in a central office trunk (COT) provided in a private branch exchange (PBX) equipment.
Inventors
- 👤 Kazuhiro Sato
- 👤 Yoshimi Iijima
- 👤 Hiroyoshi Mori
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 14:15
CPC Classifications
H; H04; H04M; H04M15/00; H04M15/34
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
97 words
A call meter signal receiver for subscriber's private metering (SPM) system which is installed in a central office trunk (COT) provided in a private branch exchange (PBX) equipment and is operated by a call meter signal sent from a central office (CO), said call meter signal receiver comprising: plurality of buffer circuits (41, 42) for respectively receiving a predetermined type of call meter signals sent from a central office (CO); and a frequency tuned receiver (44) for detecting said call meter signal, said frequency tuned receiver (44) being tuned to the frequency of said call meter signals.
Claim 2
Dependent Claim
97 words
A call meter signal receiver for subscriber's private metering (SPM) system which is installed in a central office trunk (COT) provided in a private branch exchange (PBX) equipment and is operated by a call meter signal sent from a central office (CO), said call meter signal receiver comprising: plurality of buffer circuits (41, 42) for respectively receiving a predetermined type of call meter signals sent from a central office (CO); and a frequency tuned receiver (44) for detecting said call meter signal, said frequency tuned receiver (44) being tuned to the frequency of said call meter signals.
Claim 3
Dependent Claim
37 words
A call meter signal receiver as set forth in claim 1, further comprising a switching means for switching the tuning frequency of said frequency tuned receiver (44) to one of predetermined frequency of said call meter signals.
Claim 4
Dependent Claim
53 words
A call meter signal receiver as set forth in claim 1, wherein said frequency tuned receiver comprises a phase locked loop (PLL) circuit for stabilizing the receiving frequency, and said receiving frequency is tuned to the frequency of call meter signal by choosing an externally attached circuit composed of a capacitor and resistors.
Claim 5
Dependent Claim
43 words
A call meter signal receiver as set forth in claim 1, wherein said buffer circuits (41, 42) are composed of: a first buffer circuit (41) for receiving a common mode signal; and a second buffer circuit (42) for receiving a normal mode signal.
Claim 6
Dependent Claim
76 words
A call meter signal receiver as set forth in claim 4, wherein said COT comprises a hybrid circuit (23) for converting 2-wire signal to 4-wire signal, said first buffer circuit (41) is connected to an input side of said hybrid circuit (23), and said second buffer circuit (42) is connected to an out side of said hybrid circuit (23), and both outputs of said buffer circuits (41, 42) are fed to said frequency tuned receiver (44).
Claim 7
Dependent Claim
68 words
A call meter signal receiver as set forth in claim 5, wherein said first buffer circuit (41) being connected to a junction point of two resistors (R6, R7), and the other ends of said resistors (R6, R7) are respectively connected to opposite input terminals of said hybrid circuit (23), and said second buffer circuit (42) is connected to one of the output terminals of said hybrid circuit (23).
Claim 8
Dependent Claim
36 words
A call meter signal receiver as set forth in claim 5, wherein said first buffer circuit (41) has a high input impedance, and said second buffer circuit (42) has a high input impedance for voice signals.
Claim 9
Dependent Claim
127 words
A call meter signal receiver for subscriber's private metering (SPM) system which is installed in a central office trunk (COT) provided in a private branch exchange (PBX) equipment and is operated by a call meter signal sent from a central office (CO), said call meter signal receiver comprising: a first frequency tuned receiver for receiving common mode call meter signal, and being connected to a junction point of two resistors (R6, R7) of which other ends being respectively connected to opposite terminals of the two input terminals of a hybrid circuit (23) provided in said COT; and a second frequency tuned receiver for receiving normal mode call meter signal, said second frequency tuned meter being connected to one of output terminals (43) of said hybrid circuit (23).
Claim 10
Dependent Claim
127 words
A call meter signal receiver for subscriber's private metering (SPM) system which is installed in a central office trunk (COT) provided in a private branch exchange (PBX) equipment and is operated by a call meter signal sent from a central office (CO), said call meter signal receiver comprising: a first frequency tuned receiver for receiving common mode call meter signal, and being connected to a junction point of two resistors (R6, R7) of which other ends being respectively connected to opposite terminals of the two input terminals of a hybrid circuit (23) provided in said COT; and a second frequency tuned receiver for receiving normal mode call meter signal, said second frequency tuned meter being connected to one of output terminals (43) of said hybrid circuit (23).
Claim 11
Dependent Claim
46 words
A call meter signal receiver as set forth in claim 8, wherein said first frequency tuned receiver is tuned to the frequency of common mode call meter signal, and said second frequency tuned receiver is tuned to the frequency of a normal mode call meter signal.
Claim 12
Dependent Claim
56 words
A call meter signal receiver as set forth in claim 9, wherein the receiving frequency of said frequency tuned amplifiers are stabilized by a phase locked loop circuit, and said receiving frequency is tunable to the frequency of call meter signals sent from central office (CO) by varying externally attached circuit of a capacitor and resistors.
References Cited (Backward Citations)
No citation records indexed.
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