Dial pulse selection

• US 4,924,501 A
• Filed: 03/30/1989
• Issued: 05/08/1990
• Est. Priority Date: 11/25/1985
• Status: Expired due to Term

• Current Assignee: Michael Paul Ziaylek, Theodore Ziaylek Jr
• Original Assignee: British Telecommunications PLC (BT Group PLC)
• Inventors: Cheeseman, David S., Wright, Arthur J.
• Primary Examiner(s): BROWN, THOMAS
• Application Number:
  US07/331,030
• Time in Patent Office: 404 Days
• Field of Search: 379/286, 379/287, 379/386, 379/372, 379/31, 379/342, 379/105, 379/238, 379/237, 379/236, 375/94, 399/280, 399/201, 399/233
• US Class Current: 379/286
• CPC Class Codes: H04Q 1/32 using trains of dc pulses H04Q1/39 takes precedence

Abstract

A dial pulse detection system 20 has an analogue input buffer 22, an analogue to digital converter (ADC) 24, a processor 25, and an output buffer 26. Processor 25 operates on the digitally encoded samples produced by ADC 24 from the received signal to achieve detection of the dial pulse signalling data in the received signal. This detection process involves a training process and a recognition process. The training process extracts amplitude and timing characteristics of a first part of the received signal from a dialling instrument. These characteristics are then used to form a template for recognition of subsequent dialled digits. Detected digits are then made available at output buffer 26. Processor 25 includes a facility for sending an error signal to the user to indicate that dialled digits have not been correctly received.

Claims

1. A method of detecting dial pulse signalling data in a received signal comprising the steps of:

performing a training process to train a dial pulse detector by processing a known dialled signal to extract information relating to the timing of the dialled pulses in a known dialled digit; and

performing a recognition process by using said information to assist said detector in detecting dial pulse signalling data in the received signal, wherein said information includes measured values for a maximum make pulse level, a maximum break pulse level, a make period, a break period, and a total dial pulse period.

2. A method of detecting dial pulse signalling data as claimed in claim 1, wherein the training process is re-started if a value obtained for the total dial pulse period is outside of a given tolerance.

3. A method of detecting dial pulse signalling data as claimed in claim 1, wherein the recognition process comprises measuring the maximum make pulse level of received signals during time periods spaced according to the measured spacing of pulses during the training process.

4. A method of detecting dial pulse signalling data as claimed in claim 3, wherein said time periods are less than 25 milliseconds.

5. A method of detecting dial pulse signalling data as claimed in claim 3, wherein the recognition process includes comparing the level of received signals during said time periods with the pulse levels derived from the training process to detect the presence or absence of valid dial pulses.

6. A method of detecting dial pulse signalling data as claimed in claim 5, wherein the recognition process includes storing information upon the detection of the presence or absence of valid dial pulses for each time period in respective locations of a data store.

7. A method of detecting dial pulse signalling data as claimed in claim 3, wherein said recognition process is terminated and/or re-started according to a count of pulse absences.

8. A method of detecting dial pulse signalling data as claimed in claim 7, wherein said count of pulse absences is reset by subsequent detection of the presence of at least two consecutively valid dial pulses.

9. A method of detecting dial pulse signalling data as claimed in claim 6, wherein said recognition process derives a detected value of a dialled digit by examination of the information stored in the locations of the data store representing at least two consecutively valid dial pulses.

10. A method of detecting dial pulse signalling data in a received signal comprising the steps of:

performing a training process to train a dial pulse detector by processing a signal known to be a dialled signal;

said step of performing a training process including the steps of extracting timing information relating to the dialled pulses in a dialled digit in said dialled signal and processing said timing information; and

performing a recognition process by using said processed timing information to assist said detector in detecting dial pulse signalling data in the received signal.

11. A method of detecting dial pulse signalling data as claimed in claim 10, wherein if the training process fails to extract said timing information from said received signal, the training process will transmit a failure message.

12. A method of detecting dial pulse signalling data as claimed in claim 10, wherein said recognition process includes transmitting a message to indicate the detected dial pulse signalling data.

13. A method of detecting dial pulse signalling data as claimed in claim 10, wherein the received signal comprises digitally encoded representations of telephone dial pulses.

14. A method of detecting dial pulse signalling data as claimed in claim 13 wherein said received signal processed by the training process comprises representations of at least four dial pulses.

15. A method of detecting dial pulse signalling data as claimed in claim 10, wherein said step of performing a training process includes the step of measuring time intervals between successive peak signals and storing time information relating thereto.

16. A method of detecting dial pulse signalling data as claimed in claim 15, wherein said step of performing a training process includes the step of measuring an amplitude relating to the peak of the signals and storing amplitude information relating thereto.

17. A method of detecting dial pulse signalling data as claimed in claim 15, wherein the step of performing a training process includes the steps of detecting the presence of erroneous signalling information from the stored time information, erasing the stored time information, and restarting the training process using further received signals.

18. A method of detecting dial pulse signalling data as claimed in claim 15, further including the step of providing a series of analysis windows computed from the stored information for use in the recognition process.

19. A method of detecting dial pulse signalling data as claimed in claim 18, further including the step of determining during each analysis window whether a signal has been received corresponding to that anticipated as a result of the training process and if so storing an indication thereof.

20. A detector for dial pulse signalling data comprising:

means for processing a received signal including training means and recognition means, said training means including means for processing a signal known to be a dialled signal to extract and process timing information relating to the dialled pulses in a dialled digit in said dialled signal, and said recognition means including means for operating on said processed timing information to assist in detecting dial pulse signalling data in the received signal.

21. Interactive terminal equipment comprising a detector for detecting dialled digits comprising means for processing a received signal including training means and recognition means, said training means comprising means for processing a signal known to be a dialled signal to extract timing information relating to the dialled pulses in a dialled digit in said dialled signal, said recognition means including means for using said timing information to assist in detecting dial pulse signalling data in dialled digits, and including means to transmit messages to a user inviting the user to dial digits according to the user'"'"'s requirements and to provide a service to the user dependent on the digits dialled.

22. Interactive terminal equipment as claimed in claim 21, wherein the equipment is associated with an exchange to provide an automatic operator service so that an outside exchange line user is able to dial any extension on the exchange.