SEQUENTIAL TONE SIGNALLING SYSTEM

• US 3,766,523 A
• Filed: 10/04/1972
• Issued: 10/16/1973
• Est. Priority Date: 10/04/1972
• Status: Expired due to Term

• Current Assignee: Jerry R. Powell, John R. Brocker, Paul Jacobs, Robert L. Peay, Ronald C. Johnson, Ronald H. Chapman
• Original Assignee: Jerry R. Powell, John R. Brocker, Paul Jacobs, Robert L. Peay, Ronald C. Johnson, Ronald H. Chapman
• Inventors: Chapman, Ronald H., Brocker, John R., Jacobs, Paul, Johnson, Ronald C., Powell, Jerry R., Peay, Robert L.
• Primary Examiner(s): Yusko, Donald J.
• Application Number:
  US05/295,074
• Time in Patent Office: 377 Days
• Field of Search: 340/171R,171PF
• US Class Current: 340/4.35
• CPC Class Codes: G08G 1/202 Dispatching vehicles on the basis of a location, e.g. taxi dispatching
• CPC Class Codes: H04L 1/00 Arrangements for detecting or preventing errors in the information received correcting synchronisation H04L7/00
• CPC Class Codes: H04W 84/025 with acknowledge back capability

Abstract

A selective calling sequential tone signalling system for transmitting and receiving predetermined coded messages. A base station and at least one mobile station is provided, and message, status, automatic status and identification codes comprising predetermined format sequences having seven tones each are transmitted therebetween. Automatic message acknowledgment is provided for message receipt verification, and apparatus is provided for substantially eliminating false reception of signals having an improper format.

Claims

1. A sequential tone signalling system including in combination:

tone signal receiving means;

tone detecting means for providing a pulse signal in response to a tone signal applied thereto;

variable frequency filter means adapted to be connected to said tone signal receiving means and to said tone detecting means for passing predetermined frequency tone signals from said tone signal receiving means to said tone detecting means;

filter program means for storing information representative of a particular sequence of tone frequencies connected to said variable frequency filter means;

pulse responsive switching means connected to said filter program means for changing the frequency of said variable frequency filter means in the particular sequence determined by said filter program means in response to pulses applied to said frequency switching means to select the frequencies of the tone sequence passed by said variable frequency filter means;

data entry means connected to said program means for applying frequency representative information to said filter program means;

feedback means adapted to be connected to said variable frequency filter means, said feedback means and said variable frequency filter means cooperating when connected together to generate oscillations;

pulse producing clock means coupled to said filter frequency switching means; and

function selector means connected to said variable frequency filter means having means for selectively connecting said variable frequency filter means to at least one of said tone signal receiving means, said tone detecting means, and said feedback means, said function selector means being switchable to a first encoding and a second decoding mode, wherein said variable frequency filter means is connected to said feedback means in the first encoding mode to generate a variable frequency tone sequence in accordance with the frequency representative information in said program means in response to pulses from said clock means, and wherein said variable frequency filter means is connected to said tone signal receiving means and to said detector means in said second decoding mode to cause said system to respond to a predetermined tone sequence represented by said frequency representative information in said filter program means.

2. A system as recited in claim 1 wherein said filter program means include means for storing first frequency representative data therein when said function selector is in said second decoding mode, and means for storing second frequency representative data therein when said function selector is in said first encoding mode, said programming means further including means for retaining said second frequency representative data in said filter program means after said function selector means is switched from said first encoding mode to said second decoding mode.

3. A system as recited in claim 2 further including means for reentering said first frequency representative data into said filter program means after said system has responded to the tone sequence represented by said second frequency representative data.

4. A system as recited in claim 3 further including automatic switching means for switching said function selector means from said second decoding mode to said first encoding mode to regenerate said second tone sequence if said system has not responded to said second tone sequence within a predetermined time interval following the generation thereof.

5. A system as recited in claim 4 further including means for reentering said first frequency representative data into said filter program means after said second tone sequence has been regenerated a predetermined number of times.

6. A system as recited in claim 5 wherein said data entry means includes means for altering said second frequency representative data.

7. A system as recited in claim 6 wherein said altering means includes a pushbutton.

8. A system as recited in claim 6 wherein said altering means includes means for automatically altering said second frequency representative data.

9. A system as recited in claim 8 wherein said automatic altering means includes a status sensor means.

10. A system as recited in claim 9 wherein said status sensor means includes means for altering said second frequency representative data only when there is a change in status.

11. A system as recited in claim 6 wherein said automatic switching means includes means for maintaining said function selector means in said second decoding mode, and further includes means for automatically switching said system to said first encoding mode to generate said second tone sequence when said second frequency representative data is altered.

12. A system as recited in claim 1 further including discharge means connected to said variable frequency filter means for discharging the energy therein between changes in frequency thereof.

13. A system as recited in claim 1 further including signal monitoring means connected to said tone signal receiving means for providing clear signals in response to an absence of signals received by said receiving means, random clock means for generating pulses, and inhibiting means connected to said signal monitoring means and to said random clock means for inhibiting the generation of the variable frequency tone sequence unless both the clear signal and a pulse from said clock are applied thereto.

14. A sequential tone signalling system including in combination:

a first station for receiving and transmitting sequential tone signals, said first station including first signal receiving means, a plurality of filters connected to said first signal receiving means for passing predetermined frequency tone signals from said receiving means therethrough, detecting means connected to each of said filters for receiving and detecting the predetermined frequency tone signals, decoding means connected to said detecting means and responsive thereto to provide a decoded signal representative of a predetermined received tone sequence, storage means connected to said decoding means for receiving and storing said decoded signal, programming means connected to said storage means for applying a predetermined coded signal representative of a tone sequence thereto, tone generating means coupled to said storage means and responsive thereto for generating a tone sequence in response to signals therefrom, and switching means connected to said storage means for causing said tone generating means to generate a tone sequence representative of one of said decoded and coded signals; and

a second station for receiving and transmitting sequential tone signals, said second station including second signal receiving means, variable frequency filter means switchably connected to said second signal receiving means for passing a predetermined frequency tone signal therethrough, detecting means connected to said variable frequency filter means for receiving and detecting tone signals, filter program means, filter frequency switching means coupled to said filter means, said filter program means, and said detector means for varying the frequency of said filter means in a sequence determined by said filter program means in response to signals from said detecting means, tone generating means for providing tone signals switchably connected to said variable frequency filter means for varying the frequency of the tone signals from said tone generating means in response to the frequency of said variable filTer means, data entry means connected to said filter program means for causing said filter program means to vary the frequency sequence of said variable filter means, and means for connecting said variable frequency filter means to said second signal receiving means for receiving a predetermined tone sequence determined by said filter program means, and to said tone generating means for causing said tone generating means to generate a tone sequence in response to said filter program means.

15. A signalling system as recited in claim 14 wherein said first station further includes means for automatically regenerating tone sequences received thereby.

16. A signalling system as recited in claim 15 wherein said second station further includes means for automatically regenerating a particular tone sequence initially generated thereby if a sequence substantially the same as the particular sequence is not received by said second station within a predetermined time interval following the generation thereof.

17. A signalling system as recited in claim 16 wherein said second station further includes means for inhibiting the generation of a tone sequence when any signal is being received by said second signal receiving means.

18. A signalling system as recited in claim 17 wherein said second station further includes means for enabling the generation of a tone sequence after a random time interval within a predetermined range of time intervals following the termination of a signal received by said second signal receiving means.

19. A sequential tone signalling system including in combination:

means for generating a predetermined group of tones representative of a plurality of information digits;

means for generating a separation tone different from the information digit representative tones;

means for transmitting the tones generated by said generating means;

control means connected to said generating means and said transmitting means and cooperating therewith for causing said transmitting means to sequentially transmit an initial tone selected from the group of information digit representative tones, a first plurality of tones representative of a predetermined message selected from the group of information digit representative tones, wherein each tone is further selected to be different than the tones immediately preceding and following it, the separation tone, and a second plurality of tones selected from the group of information digit representative tones, wherein each tone is further selected to be different than the tone immediately preceding it.

20. A system as recited in claim 19 including means for transmitting said separation tone after one of said information digit representative tones to indicate a repeat of the information digit represented thereby.

21. A system as recited in claim 20 wherein said control means includes means for providing a seven tone sequence.

22. A system as recited in claim 19 further including means for receiving tone sequences, wherein said receiving means includes means responsive to the information digits represented by the tone sequences.

23. The method of transferring a sequential tone signal from a first station to a second station comprising the steps of:

transmitting a system tone having a predetermined frequency and time duration from said first station for receipt by said second station responsive to tones having said predetermined frequency to enable said second station to receive subsequently transmitted tones;

transmitting a plurality of tones representative of a predetermined message from said first station, wherein each tone has a fixed time duration and a frequency equal to one of several predetermined frequencies, and wherein each tone has a frequency different than the frequency of the tone immediately preceding it;

transmitting a separation tone having a frequency different than the frequency of any preceding tone; and

transmitting a plurality of identification tOnes representative of digits for identifying one of said stations, wherein no two successive identifying tones have the same frequency, and wherein said separation tone is transmitted to indicate that a digit is to be repeated.

24. The method recited in claim 23 further comprising the steps of:

receiving at said second station the sequential tone signal transmitted by said first station;

re-transmitting said sequential tone signal from said second station to said first station for receipt thereby;

applying the tones of the sequential tone signal received by said first station to an input terminal of a variable frequency bandpass filter tuned to pass signals having a frequency equal to the frequency of the first tone in said sequence to an output terminal thereof;

detecting the presence of the first tone at the output terminal of the bandpass filter;

adjusting the variable frequency bandpass filter to pass signals having a frequency equal to the frequency of the second tone in said sequence upon detection of the first tone;

detecting the presence of the second tone at the output of the bandpass filter;

readjusting the variable frequency bandpass filter after each detection to pass signals having a frequency equal to the frequency of the tone sequentially following the last detected tone until the last tone of the sequence has been detected; and

providing a signal indicative of the detection of the last tone.

25. The method recited in claim 24 further including the step of re-transmitting said sequential tone signal from said first station when said sequential tone signal is not received thereby within a predetermined time interval following transmission of said sequential tone signal by said first station.