Handheld facsimile and alphanumeric message transceiver operating over telephone or wireless networks

• US 5,249,220 A
• Filed: 04/18/1991
• Issued: 09/28/1993
• Est. Priority Date: 04/18/1991
• Status: Expired due to Fees

• Current Assignee: RTS Electronics, Inc.
• Original Assignee: RTS Electronics, Inc.
• Inventors: Moskowitz, Jay, Squillante, Peter, Kravitz, Spencer, Karron, Abraham
• Primary Examiner(s): Dwyer, James L.
• Assistant Examiner(s): Chan, Jason
• Application Number:
  US07/687,380
• Time in Patent Office: 894 Days
• Field of Search: 379/100, 379/93, 379/96, 379/97, 379/98, 379/52, 358/470, 358/427, 358/261.4, 341/106, 341/65, 341/90, 341/67, 178/18, 375/67, 375/56
• US Class Current: 379/93.19
• CPC Class Codes: H03M 7/40 Conversion to or from variable length codes, e.g. Shannon-Fano code, Huffman code, Morse code
• CPC Class Codes: H03M 7/42 using table look-up for the coding or decoding process, e.g. using read-only memory H03M7/4006 takes precedence
• CPC Class Codes: H04N 1/00281 with a telecommunication apparatus, e.g. a switched network of teleprinters for the distribution of text-based information, a selective call terminal details of transmission H04N1/00095; establishing a communication with one of a facsimile machine or another apparatus sharing a single line H04N1/32704; interfacing cordless telephone terminals with an accessory to increase the functionality of user interface H04M1/72409
• CPC Class Codes: H04N 1/0031 with a selective call apparatus, e.g. a paging device selective call receivers H04W88/022; selective call encoders H04W88/185
• CPC Class Codes: H04N 2201/0046 Software interface details, e.g. interaction of operating systems
• CPC Class Codes: H04N 2201/0065 Converting image data to a format usable by the connected apparatus or vice versa
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: Y10S 379/906 Touchtone message transmission

Abstract

According to the present invention, a hand-held portable transmitter is provided which is capable of communicating with a variety of different message receiving hosts. The transmitter is provided with a technique for generating waveforms to communicate with foreign message receivers over a communication channel by using a lookup table and software implementation in combination with a telephone interface circuit. Also provided is a versatile encoding protocol in which a message is optionally converted to a four-bit, five-bit, or six-bit sequence, or to a sequence of variable-length bit-strings, the converted message is queued and regrouped as four-bit nibbles, and the nibbles are communicated by DTMF tones.

Claims

1. A portable hand held message transmitter for use in selecting a destination device capable of receiving synthesized waveforms over a switched network from a plurality of destination devices, said portable hand held message transmitter comprising:

input means for receiving alphanumeric characters and commands from a user and for generating signals indicative thereof;

display means for displaying characters indicative of signals provided thereto;

destination selection means responsive to signals generated by the input means for selecting the destination device from said plurality of destination devices, for establishing a transmission path in the switched network, and for determining a data type for the selected destination device, said data type being one of at least two predetermined data types;

message holding means responsive to signals generated by the input means for holding words of binary data indicative of a message from the user, each word associated with a particular character in the message;

waveform synthesis means responsive to the data type being a first one of the at least two predetermined data types, for deriving pixel-map data indicative of rows of the perceived shape of the characters associated with the words of binary data, for producing bit streams indicative of the pixel-map data, and for synthesizing differential phase-shift key waveforms corresponding to the bit streams, whereby the waveforms may be received by a first device type from said plurality of destination devices capable of recognizing said differential phase-shift key waveforms;

said waveform synthesis means further responsive to the data type being a second one of the at least two predetermined data types, for deriving and queuing binary-coded signals associated with the words of binary data, for providing the signals in nibbles composed of fewer bits than the number of bits in the binary-coded signals, and for synthesizing dual-tone multifrequency waveforms indicative of the nibbles, whereby the waveforms may be received by a second device type from said plurality of destination devices which is capable of recognizing said synthesized dual tone multi-frequency waveforms; and

coupling means for coupling said synthesized waveforms to a transmission line.

2. The message transmitter of claim 1 wherein the input means comprises a keyboard.

3. The message transmitter of claim 1 wherein the input means comprises a writing tablet.

4. The message transmitter of claim 1 wherein the nibbles are four bits in length.

5. The message transmitter of claim 4 wherein the higher of the dual tones is selected from one of four predetermined frequencies and wherein the lower of the dual tones is selected from one of four predetermined frequencies.

6. The message transmitter of claim 1 wherein the waveform synthesis means is further responsive to the said data type being a third one of the at least two predetermined data types, for queuing the words of binary data, for generating a serial bit stream of the words of binary data, and for synthesizing frequency-shift keyed signals indicative of the bit stream.

7. A portable hand held message transmitter for use in selecting a destination device from a plurality of destination devices, said selected device capable of receiving synthesized waveforms over a switched network, said portable hand held message transmitter comprising:

input means for receiving alphanumeric characters and commands from a user and for generating signals indicative thereof;

display means for displaying characters indicative of signals provided thereto;

destination selection means responsive to signals generated by the input means for selecting the destination device from among the plurality of destination devices, for establishing a transmission path in the switched network, and for determining a data type for the selected destination device, said data type being one of at least two predetermined data types;

message holding means responsive to signals generated by the input means for holding words of binary data indicative of a message from the user, each word associated with a particular character in the message;

waveform synthesis means responsive to a first one of the at least two predetermined data types, for deriving pixel-map data indicative of rows of the perceived shape of the characters associated with the words of binary data, for producing bit streams indicative of the pixel-map data and for synthesizing differential phase-shift key waveforms corresponding to the bit streams by controlling a differential phase-shift key waveform generator for transmission to a first device type capable of recognizing said differential phase-shift key waveforms,

said differential phase-shift key waveform generator comprising

sinusoidal generation means responsive to a predetermined command generated by the input means for scanning a table having a predetermined number of equally spaced apart entries corresponding to different amplitudes values of a sinusoidal wave with an index pointer, the amplitude of the established signal selected resulting from the scanning of different table entries by the index pointer, thereby generating a sinusoidal carrier frequency,

phase shift means responsive to the contents of the bit stream for changing the index pointer sufficiently to change the phase of the sinusoidal signal delivered to the selected destination;

said waveform synthesis means further responsive to the said data type being a second one of the at least two predetermined data types, for deriving and queuing binary-coded signals associated with the words of binary data, for providing the signals in nibbles composed of fewer bits than the number of bits in the binary-coded signals, and for synthesizing dual-tone multifrequency waveforms indicative of the nibbles, whereby the waveforms may be received by a second device type from said plurality of destination devices, which is capable of recognizing said synthesized dual tone multi-frequency waveforms; and

coupling means for coupling said synthesized waveforms to a transmission line.

8. A portable hand held transmitter as described in claim 7, wherein the switched network is a public switched telephone network.

9. A portable hand held transmitter as described in claim 7, wherein the sinusoidal carrier frequency is 1800 Hz.

10. A transmitter for communicating characters comprising:

input means for receiving characters from a user and for generating corresponding binary-coded character signals indicative of the received characters, said character signals comprising a number of bits sufficient to permit a unique signal for each character receivable by the input means;

lookup means with respect to a lookup table having a plurality of rows associated with binary-coded row numbers and two column-pairs associated with a plurality of respective groups, each column-pair comprising two columns each associated with one case of an upper case and a lower case, wherein the intersections of ones of the plurality of rows and ones of the two columns are associated with ones of the character signals, said lookup means responsive to ones of the character signals indicative of the received characters for determining the row and column associated therewith, for determining the binary-coded row number associated with the row, and for determining the case and group associated with the column;

group encoding means having an initial group state and an initial case state, said group encoding means responsive to receipt of an one of the character signals indicative of the received characters for providing the one of the character signals indicative of the received characters to the lookup means and receiving the group and case and binary-coded row number associated with the one of the character signals indicative of the received characters, said group encoding means further responsive to receipt of the group associated with the one of the character signals indicative of the received characters for comparing said group with the previous group state and generating a change-of-group signal in the event of a difference therebetween, said group encoding means further responsive to receipt of the case associated with the one of the character signals indicative of the received characters for comparing said case with the previous case state and generating a change-of-case signal in the event of a difference therebetween, and for generating a row signal associated with the binary-coded row number, the change-of-case and change-of-group signals having the same number of bits as the binary-coded row numbers,

queuing means for receiving and queuing the generated signals and for providing the signals in nibbles composed of fewer bits than the number of bits in the binary-coded row numbers, and

analog means for receiving the nibbles, for producing analog signals indicative thereof, and for coupling said analog signals to a communication channel.

11. The system of claim 10 wherein the input means comprises a keyboard and the communication channel is a transmission line.

12. The system of claim 10 wherein the input means comprises a writing tablet and the communication channel is a transmission line.

13. The system of claim 10 wherein the input means comprises a telephone transmission line and the communication channel is a radio frequency broadcast system.

14. The system of claim 10 wherein the input means comprises a keyboard and the communication channel is a radio frequency broadcast system.

15. The system of claim 10 wherein the nibbles are four bits in length, and wherein the analog signals are dual-tone multifrequency signals.

16. The system of claim 15 wherein the higher of the dual tones is selected from one of four predetermined frequencies and wherein the lower of the dual tones is selected from one of four predetermined frequencies.

17. The system of claim 10 wherein the characters include letters from an alphabet having upper and lower case letters, and wherein the lookup table assigns each pair of corresponding upper and lower case letters to a particular row and to a particular column-pair.

18. The system of claim 10 wherein the characters include letters from the Roman alphabet and the number of bits of the binary-coded row numbers is five.

19. The system of claim 10 wherein the characters include letters from the Roman alphabet and the number of bits of the binary-coded row numbers is six.

20. The system of claim 10 wherein the lookup means, the group encoding means, and the queuing means each comprise a processor and a memory, the processor executing a stored program in the memory, whereby the processor receives characters from the user and provides nibbles to the analog means.

21. The system of claim 20 wherein the nibbles are four bits in length, and wherein the analog signals are dual-tone multifrequency signals, whereby the dual-tone multifrequency signals communicate the characters from the user.

22. The system of claim 21 wherein the higher of the dual tones is selected from one of four predetermined frequencies and wherein the lower of the dual tones is selected from one of four predetermined frequencies.

23. The system of claim 10 wherein the number of bits of the binary-coded row number is four.

24. A transmitter for communicating characters comprising:

input means for receiving characters from a user and for generating corresponding binary-coded character signals indicative of the received characters, said character signals comprising a number of bits sufficient to permit a unique signal for each character receivable by the input means and to be indicative of a character case associated with each of the received characters;

lookup means with respect to a lookup table having a binary bit representation for selected character signals, wherein the binary bit representation provides relatively shorter unique binary bit representation for frequently used characters and relatively longer binary bit representations for less frequently used characters;

group encoding means having an initial previous character case state, said group encoding means responsive to receipt of an one of the character signals indicative of the received characters for providing the one of the character signals indicative of the received characters to the lookup means and receiving the binary bit representation associated with the one of the character signals indicative of the received characters, said group encoding means further responsive to receipt of the binary bit representation associated with the one of the character signals indicative of the received characters for comparing the character case of the character signals indicative of the received characters with the previous character case state of the group encoding means and generating a change-of-case signal and an update previous character case state signal in the event of a different therebetween,

queuing means for receiving and queuing the generated binary bit representations and for providing the representations in nibbles composed of different number bits than the number of bits in the Huffman binary bit representation, and

analog means for receiving the nibbles, for producing analog signals indicative thereof, and for coupling said analog signals to a communication channel.

25. The system of claim 24 wherein the input means comprises a keyboard and the communication channel is a transmission line.

26. The system of claim 24 wherein the input means comprises a writing tablet and the communication channel is a transmission line.

27. The system of claim 24 wherein the input means comprises a telephone transmission line and the communication channel is a radio frequency broadcast system.

28. The system of claim 24 wherein input means comprises a keyboard and the communication channel is a radio frequency broadcast system.

29. The system of claim 24 wherein the nibbles are four bits in length, and wherein the analog signals are dual-tone multifrequency signals.

30. The system of claim 29 wherein the higher of the dual tones is selected from one of four predetermined frequencies and wherein the lower of the dual tones is selected from one of four predetermined frequencies.

31. The system of claim 24 wherein the characters include letters from an alphabet having upper and lower case letters.

32. The system of claim 24 wherein the characters include letters from the Roman alphabet and the number of bits of the Huffman representation varies from two to twenty-two.

33. The system of claim 24 wherein the lookup means, the group encoding means, and the queuing means each comprise a processor and a memory, the processor executing a stored program in the memory, whereby the processor receives characters from the user and provides nibbles to the analog means.

34. The system of claim 33 wherein the nibbles are four bits in length, and wherein the analog signals are dual-tone multifrequency signals, whereby the dual-tone multifrequency signals communicate the characters from the user.

35. The system of claim 34 wherein the higher of the dual tones is selected from one of four predetermined frequencies and wherein the lower of the dual tones is selected from one of four predetermined frequencies.

36. A portable hand held transmitter for communicating characters according to one of a plurality of encoding schemes, said transmitter comprising:

input means for receiving characters from a user and for generating corresponding binary-coded signals indicative of the received characters, said binary-coded character signals comprising a number of bits sufficient to permit a unique signal for each character receivable by the input means;

lookup means for generating at least one corresponding binary bit representation for each of the binary-coded character signals generated by the input means, said lookup means including a lookup table including a plurality of binary bit representations for a select group of characters receivable by the input means wherein one of said plurality of binary bit representations includes a four bit binary representation for each of the select group of characters receivable by the input means

group encoding means responsive to receipt of the binary coded character signals from the input means for determining which of the plurality of encoding schemes to transmit the received characters from the input means, for providing the received binary coded character signals to the lookup means and for receiving the corresponding binary bit representations from the lookup means for the binary coded character signals received; and

analog means for receiving the binary bit representations from the group encoding means, for producing analog signals indicative thereof, and for coupling said analog signals to a communication channel.

37. The system of claim 36 wherein the input means comprises a keyboard and the communication channel is a transmission line.

38. The system of claim 36 wherein the input means comprises a writing tablet and the communication channel is a transmission line.

39. The system of claim 36 wherein the input means comprises a telephone transmission line and the communication channel is a radio frequency broadcast system.

40. The system of claim 36 wherein the input means comprises a keyboard and the communication channel is a radio frequency broadcast system.

41. A portable hand held message transmitter for use in selecting a destination device from a plurality of destination devices, said selected device are capable of receiving synthesized waveforms over a switched network, said portable hand held message transmitter comprising:

input means for receiving alphanumeric characters and commands from a user and for generating signals indicative thereof;

display means for displaying characters indicative of signals provided thereto;

destination selection means responsive to signals generated by the input means for selecting the destination device from said plurality of destination devices, for establishing a transmission path in the switched network, and for determining a data type for the selected destination device, said data type being one of at least two predetermined data types;

message holding means responsive to signals generated by the input means for holding words of binary data indicative of a message from the user, each word associated with a particular character in the message;

waveform synthesis means responsive to the data type being a first one of the at least two predetermined data types, for deriving pixel-map data indicative of rows of the perceived shape of the characters associated with the words of binary data, for producing bit streams indicative of the pixel-map data, and for synthesizing differential phase-shift key waveforms corresponding to the bit streams, whereby the waveforms may be received by a first device type capable of recognizing said differential phase-shift key waveforms;

said waveform synthesis means further responsive to the said data type being a second one of the at least two predetermined data types, for queuing the words of binary data, for generating a serial bit stream of the words of binary data, and for synthesizing frequency-shift keyed signals indicative of the bit stream whereby the waveforms may be received by a second device type which is capable of recognizing said synthesized frequency-shift keyed signals; and

coupling means for coupling said synthesized waveforms to a transmission line.

42. The message transmitter of claim 41 wherein the input means comprises a keyboard.

43. The message transmitter of claim 41 wherein the input means comprises a writing tablet.

44. A portable message transmitter for use in selecting a destination device from a plurality of destination devices, said selected device capable of receiving synthesized waveforms over a switched network, said portable hand held message transmitter comprising:

input means for receiving alphanumeric characters and commands from a user and for generating signals indicative thereof;

display means for displaying characters indicative of signals provided thereto;

destination selection means responsive to signals generated by the input means for selecting the destination device from among a plurality of destination devices, for establishing a transmission path in the switched network, and for determining a data type for the selected destination, said data type being one of at least two predetermined data types;

message holding means responsive to signals generated by the input means for holding words of binary data indicative of a message from the user, each word associated with a particular character in the message;

waveform synthesis means responsive to the data type being a first one of the at least two predetermined data types, said waveform synthesis means responsive to the destination selection means for deriving pixel-map data indicative of rows of the perceived shape of the characters associated with the words of binary data, for producing bit streams indicative of the pixel-map data, and for synthesizing differential phase-shift key waveforms corresponding to the bit streams by controlling a differential phase-shift key waveform generator, said differential phase-shift key waveform generator comprising

sinusoidal generation means responsive to a predetermined command generated by the input means for scanning a table having a predetermined number of equally spaced apart entries corresponding to different amplitudes values of a sinusoidal wave with an index pointer, the amplitude of the established signal selected resulting from the scanning of different table entries by the index pointer, thereby generating a sinusoidal carrier frequency,

phase shift means responsive to the contents of the bit stream for changing the index pointer sufficiently to change the phase of the sinusoidal signal delivered to the selected destination; and

coupling means for coupling said synthesized waveforms to a transmission line,

whereby the waveforms may be received a first device type from said plurality of destination devices capable of recognizing said differential phase-shift key waveforms;

said waveform synthesis means further responsive to the said data type being a second one of the at least two predetermined data types, for queuing the words of binary data, for generating a serial bit stream of the words of binary data, and for synthesizing frequency-shift keyed signals indicative of the bit stream; and

coupling means for coupling said synthesized waveforms to a transmission line.

45. A message receiver for receiving alphanumeric characters from message transmitter over a communication channel, said message transmitter providing analog output signals representing nibbles of a binary representation of characters in an alphanumeric message, said message receiver comprising:

input means responsive to reception of analog signals from the message transmitter for receiving the analog signals over the communication channel and for converting the analog signals to binary bit nibbles;

queuing means responsive to reception of the binary bit nibbles for queuing the binary bit nibbles as a serial binary bit stream and for converting the serial binary bit stream to binary coded row numbers, each of the binary coded row numbers comprising a predetermined number of bits from said serial binary bit stream;

lookup means having an initial case state and an initial group state with respect to a lookup table having a plurality of rows associated with binary-coded row numbers and two column-pairs associated with a plurality of respective groups, each column-pair comprising two columns each associated with one case of an upper case and a lower case, wherein the intersections of ones of the plurality of rows and ones to the two columns are associated with ones of character signals in a preselected case of a preselected group, said lookup means responsive to the receipt of a binary coded row number for selecting the intersection of the row associated with the binary coded row number and said preselected case of said preselected group, said preselected case of said preselected group initially corresponding to the initial case state and initial group state, said lookup means further responsive to the receipt of a change-case signal from the selected intersection for changing the preselected case for subsequent selection of intersections, said lookup means further responsive to receipt of a change-group signal from the selected intersection for changing the preselected group for subsequent selection of intersections; and

character output means responsive to the receipt a character signal from the intersection of selected rows and columns in the lookup means for converting said character signals to user accessible representations.

46. The message receiver of claim 45 wherein the communication channel is a switched network and the message receiver is a message receiving host.

47. The message receiver of claim 45 wherein the communication channel is a radio frequency broadcast system and the message receiver is a portable battery powered device.

48. The message receiver of claim 45 wherein the binary coded row number comprises 5 bits.

49. The message receiver of claim 45 wherein the binary coded row number comprises 6 bits.

50. The message receiver of claim 45 wherein the binary coded row numbers may be one of at least two predetermined bit lengths and wherein said input means further comprises a binary row bit length decoding means responsive to the reception of said binary bit nibbles for determining the binary bit length of the binary coded row numbers.

51. The message receiver of claim 45 further characterized in that each of the binary bit nibbles is provided by the message transmitter as a respective analog dual-tone multifrequency tone, and wherein the message receiver converts each of said respective analog dual-tone multifrequency tones to the respective binary bit nibble.

52. The message receiver of claim 45 further characterizes in that each of the binary bit nibbles is provided by the message transmitter as a serial sequence of a plurality of analog signals each representative of a corresponding bit of the binary bit nibble, and wherein the message receiver converts each such analog dual-tone to the respective binary bit nibble.

53. The message receiver of claim 45 wherein the binary-coded row numbers comprises 4 bits.

54. A message receiver for receiving alphanumeric characters from message transmitter over a communication channel, said message transmitter providing analog output signals representing nibbles of a binary representation of characters in an alphanumeric message, said message receiver comprising:

input means responsive to reception of analog signals from the message transmitter for receiving the analog signals over the communication channel and for converting the analog signals to binary bit nibbles;

queuing means responsive to reception of the binary bit nibbles for queuing the binary bit nibbles as a serial binary bit stream;

lookup means with respect to a plurality of lookup tables having binary bit representations for respective selected character signals, wherein the binary bit representation in at least one of said plurality of lookup tables provides relatively shorter unique binary bit representation for frequently used characters and relatively longer binary bit representations for less frequently used characters, the binary bit representation being no shorter than a predetermined shortest length and no longer than a predetermined greatest length, said lookup means comprising means to receive binary bit nibbles from the queuing means for selecting one of the plurality of lookup tables for evaluating a series of binary bit data and for receiving a sequence of binary bit nibbles of a length corresponding to the shortest unique binary bit representation within the selected one of the plurality of lookup tables, said lookup means further comprising first means for determining whether the sequence of bits matches that of one of the binary bit representation of a length equal to that of the sequence of bits within the selected lookup table, and for generating the character signal corresponding to the matching bit representation, said lookup means further comprising second means responsive to the absence of a match and the selection of one of the plurality of lookup tables which provides for relatively shorter unique binary bit representation for frequently used characters and relatively longer binary bit representation for less frequently used characters for receiving from the queuing means and for appending at least one additional bit to the sequence of bits, said sequence of bits being provided to the first means; and

character output means responsive to the receipt of a character signal from the lookup mans for converting said character signals to user accessible representations.

55. The message receiver of claim 54 wherein the communication channel is a switched network and the message receiver is a message receiving host.

56. The message receiver of claim 54 wherein the communication channel is a radio frequency broadcast system and the message receiver is a portable battery powered device.

57. The message receiver of claim 54 further characterized in that each of the binary bit nibbles is provided by the message transmitter as a respective analog dual-tone multifrequency tone, and wherein the message receiver converts each such analog dual-tone multifrequency tone to the respective binary bit nibble.

58. The message receiver of claim 54 further characterizes in that each of the binary bit nibbles is provided by the message transmitter as a serial sequence of a plurality of analog signals each representative of a corresponding bit of the binary bit nibble, and wherein the message receiving host converts each such analog dual-tone to the respective binary bit nibble.