Methods and apparatus for encoding and decoding data transmitted over telephone lines

• US 6,236,724 B1
• Filed: 07/24/1997
• Issued: 05/22/2001
• Est. Priority Date: 10/04/1994
• Status: Expired due to Term

• Current Assignee: Cidway Technologies, Ltd.
• Original Assignee: Encotone Ltd.
• Inventors: Kelly, Michael K., Labaton, Isaac J.
• Primary Examiner(s): Chan, Wing F.
• Application Number:
  US08/809,886
• Time in Patent Office: 1,398 Days
• Field of Search: 379/352, 379/361, 379/386, 379/283, 379/93.18, 379/93.23, 379/93.26, 379/93.27, 379/399, 340/825.44, 379/353, 379/368, 379/444, 379/355
• US Class Current: 379/357.03
• CPC Class Codes: H04M 1/2155 Acoustic coupling
• CPC Class Codes: H04M 1/275 implemented by means of portable electronic directories
• CPC Class Codes: H04M 11/066 Telephone sets adapted for data transmision

Abstract

A method of generation and detection of acoustic signals carrying alpha-numeric data for reducing the effects of noise and thereby improving signal transmission without the need to boost the power of the signal. In accordance with one aspect of the invention, a special DTMF acoustic signal consisting of a combination of two frequencies will be generated for the representation of a particular alpha-numeric character that will be similar to the standard DTMF tone. The difference between the amplitudes of both frequencies varies during the time of generation of the DTMF tone in such a way that both signals will arrive at a final destination detector, i.e., an interactive voice response board, at least for a portion of the generation time, at a relatively similar amplitude, thereby substantially increasing the probabilities of being recognized as a DTMF signal.

Claims

1. A method for encoding and decoding data carried by a plurality of signals transmitted from a portable acoustic signal generator to a destination unit through the use of transmission equipment, wherein the signals are acoustical for at least a portion of the transmission path, the method comprising the steps of:

generating, via the signal generator, a plurality of time ordered acoustic signals spaced apart in a pre-determined time window sequence, wherein the plurality of time ordered acoustic signals comprises at least two data characters acoustically encoded;

removably coupling the signal generator to a microphone associated with the transmission equipment such that the plurality of acoustic signals is received by the microphone;

transmitting the plurality of signals over the transmission equipment;

detecting, by the destination unit, the plurality of signals;

determining, by the destination unit, a plurality of time ordered time slots for each of the signals; and

analyzing, by the destination unit, each of the time ordered time slots to derive the data character originally encoded in the acoustical signal generator.

2. The method of claim 1 further comprising the step of generating, via the signal generator, a pre-determined specific signal at the beginning of the plurality of time ordered acoustic signals.

3. The method of claim 1 further comprising the steps of:

generating, via the signal generator, a pre-determined baseline signal that is included with the plurality of time ordered acoustic signals; and

computing, by the destination unit, a transmission complex frequency response characteristic from the baseline signal.

4. The method of claim 1, wherein each of the data characters is represented by two different frequencies.

5. The method of claim 1, wherein the two different frequencies vary in amplitude as a function of time.

6. The method of claim 1, wherein each of the data characters is represented by three different frequencies out of a pre-determined set of frequencies.

7. The method of claim 1, wherein the generating step further comprises adding at least one error correction character to the data to be encoded into the plurality of the time ordered acoustic signals.

8. The method of claim 1, wherein the acoustical signal generator comprises a substantially planar, credit card-sized module with embedded electronic components and a speaker which generates the acoustic signal.

9. The method of claim 1, wherein the acoustical signal generator further includes a standard PCMCIA connector configured to allow compatibility with any PCMCIA compatible device.

10. The method of claim 1, wherein the acoustical signal generator has a standard chip card slot configured to receive a smart chip card.