Telephone line monitoring apparatus and method

• US 5,553,116 A
• Filed: 06/13/1994
• Issued: 09/03/1996
• Est. Priority Date: 09/06/1990
• Status: Expired due to Fees

• Current Assignee: Teletron, Inc.
• Original Assignee: Teletron, Inc.
• Inventors: Avni, Shlomo
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): LOOMIS, PAUL A
• Application Number:
  US08/259,305
• Time in Patent Office: 813 Days
• Field of Search: 379/377, 379/7, 379/35, 379/164, 379/165, 379/34, 379/1
• US Class Current: 379/32.04
• CPC Class Codes: G01R 19/003 Measuring mean values of current or voltage during a given time interval
• CPC Class Codes: G01R 19/16528 using digital techniques or performing arithmetic operations using digital techniques to measure a voltage or a current, see G01R19/25
• CPC Class Codes: G01R 19/25 using digital measurement techniques
• CPC Class Codes: G01R 27/16 Measuring impedance of element or network through which a current is passing from another source, e.g. cable, power line
• CPC Class Codes: H04M 1/82 Line monitoring circuits for call progress or status discrimination for detecting caller identity H04M1/573
• CPC Class Codes: H04N 1/00 Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
• CPC Class Codes: H04N 1/00002 Diagnosis, testing or measuring; Detecting, analysing or monitoring not otherwise provided for error detection, error correction or monitoring in digital computers or digital computer components G06F11/00
• CPC Class Codes: H04N 1/0001 Transmission systems or arrangements
• CPC Class Codes: H04N 1/00039 Analysis, i.e. separating and studying components of a greater whole
• CPC Class Codes: H04N 1/00042 Monitoring, i.e. observation H04N1/00029 - H04N1/00039 take precedence
• CPC Class Codes: H04N 1/0009 Storage
• CPC Class Codes: H04Q 1/32 using trains of dc pulses H04Q1/39 takes precedence
• CPC Class Codes: Y10S 379/908 Multimedia

Abstract

A fax monitoring apparatus includes one or more line interface circuits to simultaneously detect and analyze audio signals produced on any given telephone line by two connected fax machines, analyzing circuitry to analyze and interpret the audio signals to form a compressed fax image, expansion circuitry, to expand the compressed fax image into a bit-mapped image, memory, to store the compressed fax image and/or the bit-mapped image, and display to display the bit-mapped image of the original fax transmission. A method for monitoring and analyzing the activity of a telephone line includes the steps of sampling the voltage of the telephone line to be monitored, calculating the mean value of the voltage from the samplings, comparing the mean value of the voltage with a reference voltage defined as the mean voltage obtained during the previous time interval, replacing the value of the reference voltage with the mean value, and upon activation, recording the activity of the telephone line.

Claims

1. A method for monitoring and analyzing an activity of a telephone line, comprising:

continuously sampling a voltage of the telephone line to be monitored;

calculating a mean value of the voltage from a plurality of samplings taken during a given time interval;

comparing the mean value of the voltage with a reference voltage defined as a mean voltage obtained during a previous time interval;

replacing a value of the reference voltage with the mean value;

if a difference between a last calculated mean value and the reference value exceeds a predetermined value;

stopping replacement of the reference voltage with the calculated mean value of the voltage;

activating signal recording means to record signals transmitted through the telephone line; and

continuously comparing the calculated mean value with the reference value; and

if the difference between the two compared values is below a predetermined minimal value;

deactivating the signal recording means; and

resuming the replacement of the value of the reference voltage with the calculated mean value of the voltage, and the subsequent steps.

2. A method according to claim 1, further comprising recording and analyzing a telephone number dialed by a monitored telephone line by the steps of:

identifying dialing beginning by comparing the calculated mean value of the voltage and the reference voltage, and determining whether the difference is below a predetermined maximal value;

counting number of pulses of high voltage occurring within about 0.1 second from one another, to determine a dialed digit;

identifying an end of the dialed digit by identifying a low-voltage interval of a length exceeding about 0.1 second;

recording the pulses of high voltage or equivalent digits of a dialed number in the signal recording means.

3. A method according to claim 2, further comprising providing tone-detecting means to identify and record tone-modulated codes and/or digits.

4. A method according to claim 1, wherein recording is initiated when the calculated mean value is equal to or less than 80-85% of the reference voltage.

5. A method according to claim 1, wherein the calculated mean value of the voltage is an arithmetic mean of 200 to 5,000 samplings, preferably about 1000 samplings taken during a time interval of about 1 second.

6. A method according to claim 1, wherein the recording means comprise digital recording apparatus.