Radio telephone apparatus

• US 5,134,708 A
• Filed: 02/25/1991
• Issued: 07/28/1992
• Est. Priority Date: 09/29/1987
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Hattori, Kiyoshi, Marui, Kuniyoshi
• Primary Examiner(s): Esienzopf, Reinhard J.
• Assistant Examiner(s): CHAROUEL, LISA
• Application Number:
  US07/660,555
• Time in Patent Office: 519 Days
• Field of Search: 455/33, 455/34, 455/53, 455/54, 455/67, 455/62, 455/68, 455/69, 455/154, 455/156, 379/59, 379/60, 379/61, 379/63
• US Class Current: 455/421
• CPC Class Codes: H04M 1/72516 with means for out-of-range alerting
• CPC Class Codes: H04W 52/0241 where no transmission is received, e.g. out of range of the transmitter
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Radio telephone apparatus for use in a cellular mobile telephone system includes an alarm to inform a user of a drop in signal strength of radio frequency signals received over an established communication link. Such a drop occurs, for example, when the user is approaching the boundary of a service area. Further, the mobile unit detect the presence or strength of a tone signal modulated on at least one of the received radio signals. The mobile unit disconnects the telephone link and returns to the standby mode if the tone signal is lost or becomes too weak.

Claims

1. A cellular radiotelephone unit for use in a cellular radiotelephone system for serving one or more geographic areas formed of a plurality of cellular zones, the cellular radiotelephone unit comprising:

receiving means for receiving radio signals transmitted over a speech radio channel or a control radio channel;

measuring means, coupled to the receiving means, for measuring the strength of the radio signals received by the receiving means;

tone signal measuring means, coupled to the receiving means, for measuring the strength of a tone signal modulated on at least one of said received signals;

alarming means for alarming at least the user of the cellular mobile radiotelephone unit in response to the detection of a signal strength measured by the measuring means at or below a first criterion after a communication link with a second party using a speech radio channel is established; and

control means for controlling the receiving means to receive radio signals transmitted over the control radio channel, instead of the speech radio channel, in response to the detection of a tone signal strength measured by the tone signal measuring means at or below a second criterion.

2. The cellular radiotelephone unit of claim 1 wherein the alarming means comprising means for generating sounds and a related sound signal.

3. The cellular radiotelephone unit of claim 2 further comprising means for broadcasting the generated sound signal over the communication link with a second party.

4. The cellular radiotelephone unit of claim 2 wherein the sound generating means comprises speech synthesis means for synthesizing predetermined speech patterns.

5. The cellular radiotelephone unit of claim 2 wherein the generated sounds and related sound signal comprise a periodic signal of less than one second duration in which short periods of tone are interleaved with shorter period of silence.

6. The cellular radiotelephone unit of claim 4 wherein the predetermined speech patterns simulate the voice of the user of the unit.

7. The cellular radiotelephone unit of claim 1 wherein the alarming means comprises a visual display unit.

8. A cellular radiotelephone unit for use in a cellular radio-telephone system for serving one or more geographic areas formed of a plurality of cellular zones, the cellular radiotelephone unit comprising:

receiving means for receiving radio signals transmitted over a reverse radio channel;

broadcasting means for broadcasting radio signals to be transmitted over a forward radio channel;

measuring means, coupled to the receiving means, for measuring the strength of the radio signals received by the receiving means;

tone signal measuring means, coupled to the receiving means, for measuring the strength of a tone signal modulated on at least one of said received signals;

alarming means for alarming at least the user of the cellular mobile radiotelephone unit in response to a detection of a signal strength measured by the measuring means at or below a first criterion after a communication link with a second party using the forward and reverse radio channels is established; and

control means for controlling the broadcasting means to terminate broadcasting radio signals over the forward radio channel in response to a detection of tone signal strength measured by said tone signal measuring means at or below a second criterion;

the receiving means continuing to receive radio signals transmitted over the reverse radio channel after termination of the signal broadcast over the forward radio channel.

9. The cellular radiotelephone unit of claim 8 wherein the alarming means comprising means for generating sounds and a related sound signal.

10. The cellular radiotelephone unit of claim 9 wherein the sound generating means comprises speech synthesis means for synthesizing predetermined speech patterns.

11. The cellular radiotelephone unit of claim 9 wherein the generated sounds and related sound signal comprise a periodic signal of less than one second duration in which short periods of tone are interleaved with shorter period of silence.

12. The cellular radiotelephone unit of claim 10 wherein the predetermined speech patterns simulate the voice of the user of the unit.

13. The cellular radiotelephone unit of claim 8 wherein the alarming means comprises a visual display unit.

14. A cellular radiotelephone unit for use in a cellular radiotelephone system serving one or more geographic areas formed of a plurality of cellular zones, the cellular radiotelephone unit comprising:

receiving means for receiving radio signals transmitted over a reverse radio channel;

broadcast means for broadcasting signals to be transmitted over a reverse radio channel;

measuring means, coupled to the receiving means, for measuring the strength of the signals received by the receiving means;

tone signal measuring means, coupled to the receiving means, for measuring the strength of a tone signal modulated on at least one of said received signals;

sound generating means for generating sounds and a related sound signal;

means for providing the sound signal generated by the sound generating means to the broadcasting means so that the sounds are transmitted to a second party connected to the user of the unit over a communication link using the forward and reverse radio channels in response to the detection of a signal strength measured by the measuring means at or below a first criterion after the communication link is established; and

controlling means for controlling the broadcasting means to terminate broadcasting radio signals over the forward radio channel in response to the detection of a tone signal strength measured by the tone signal measuring means at or below a second criterion.

15. The cellular radiotelephone unit of claim 14 wherein the sound generating means comprises speech synthesis means for synthesizing predetermined speech patterns.

16. The cellular radiotelephone unit of claim 14 further comprising display means for providing a visual display indicating the return of the signal strength above the first criterion after the signal strength measured by the measuring means is at or below the first criterion.

17. A method for alarming a user and a second party connected together over a radio communication link, the method for use in a cellular radiotelephone unit, the method comprising the steps of:

receiving radio signals transmitted over a control radio and a speech radio channel;

broadcasting radio signals to be transmitted over the speech radio channel;

measuring the strength of the received radio signals;

measuring the strength of a tone signal modulated on at least one of the received radio signals;

providing sounds and a related sound signal, the related sound signal being transmitted to the second party in response to the detection of a signal strength below a first criterion after the communication link using the speech radio channel is established;

controlling the cellular radiotelephone unit to terminate broadcasting radio signals and to receive signals transmitted over the control radio channel instead of the speech radio channel in response to the detection of a tone signal strength at or below a second criterion.

18. The method of claim 17 further comprising the step of visually displaying an indication when the received signal returns to a level above the first criterion.

19. The method of claim 17 wherein the sounds and related sound signals comprise synthesized speech.

20. Radio telephone apparatus comprising:

receiving means for receiving signals transmitted over a radio channel;

measuring means coupled to the receiving means for measuring the strength of the received signals;

tone signal measuring means coupled to the receiving means for measuring the strength of a tone signal modulated on at least one of the received signals;

signal generating means coupled to the measuring means and the tone signal measuring means, and in the event that a communication link using the channel has been established, the signal generating means generating a first signal in response to the detection of a signal strength measured by the measuring means at or below a first criterion and for generating a second signal in response to the detection of a tone signal strength measured by said tone signal measuring means at or below a second criterion;

alarming means responsive to the first signal for alarming at least one user of the apparatus; and

control means responsive to the second signal for causing a disconnection of the communication link.

21. The apparatus of claim 20 wherein the alarming means comprises means for generating sounds.

22. The apparatus of claim 21 further comprising means for broadcasting the generated sounds over the communication link.

23. The apparatus of claim 21 wherein the sound generating means comprises speech synthesis means for synthesizing predetermined speech patterns.

24. The apparatus of claim 21 wherein the sounds comprise a periodic signal of less than one second duration in which short periods of tone are interleaved with shorter periods of silence.

25. The apparatus of claim 23 wherein the predetermined speech patterns simulate the voice of a user of the apparatus.

26. The apparatus of claim 20 wherein the alarming means comprises a visual display unit.

27. Radio telephone apparatus comprising:

receiving means for receiving signals transmitted over a radio channel;

measuring means coupled to the receiving means for measuring the strength of the received signals;

tone signal detection means coupled to the receiving means for detecting a tone signal modulated on at least one of the received signals;

signal generating means coupled to the measuring means and the tone signal detection means, and in the event that a communication link using the channel has been established, the generating means generating a first signal in response to the detection of a signal strength measured by the measuring means below a first criterion and for generating a second signal in response to a failure to detect a tone signal by the tone signal detection means;

alarming means responsive to the first signal for alarming at least one user of the apparatus; and

control means responsive to the second signal for causing a disconnection of the communication link.

28. The apparatus of claim 27 wherein the alarming means comprises means for generating sounds.

29. The apparatus of claim 28 further comprising means for broadcasting the generated sounds over the communication link.

30. The apparatus of claim 28 wherein the sound generating means comprises speech synthesis means for synthesizing predetermined speech patterns.

31. The apparatus of claim 28 wherein the sounds comprise a periodic signal of less than one second duration in which short periods of tone are interleaved with shorter periods of silence.

32. The apparatus of claim 30 wherein the predetermined speech patterns simulate the voice of a user of the apparatus.

33. The apparatus of claim 27 wherein the alarming means comprises a visual display unit.

34. The apparatus of claim 27 wherein the frequency of said tone signal is one of 5970 Hz., 6000 Hz., or 6030 Hz.

35. A cellular radiotelephone unit for use in a cellular radiotelephone system for serving one or more geographic areas formed of a plurality of cellular zones, the cellular radiotelephone unit comprising:

receiving means for receiving radio signals transmitted over a speech radio channel or a control radio channel;

measuring means, coupled to the receiving means, for measuring the strength of the radio signals received by the receiving means;

tone signal measuring means, coupled to the receiving means, for measuring the strength of a tone signal modulated on at least one of said received signals;

alarming means for alarming at least the user of the cellular mobile radiotelephone unit in response to the detection of a signal strength measured by the measuring means at or below a first criterion after a communication link with a second party using a speech radio channel is established; and

control means for controlling the receiving means to receive radio signals transmitted over the control radio channel, instead of the speech radio channel, in response to the detection of a tone signal strength measured by the tone signal measuring means at or below a second criterion.

36. The cellular radiotelephone unit of claim 35 wherein the alarming means comprising means for generating sounds and a related sound signal.

37. The cellular radiotelephone unit of claim 36 further comprising means for broadcasting the generated sound signal over the communication link with a second party.

38. The cellular radiotelephone unit of claim 36 wherein the sound generating means comprises speech synthesis means for synthesizing predetermined speech patterns.

39. The cellular radiotelephone unit of claim 36 wherein the generated sounds and related sound signal comprise a periodic signal of less than one second duration in which short periods of tone are interleaved with shorter period of silence.

40. The cellular radiotelephone unit of claim 38 wherein the predetermined speech patterns simulate the voice of the user of the unit.

41. The cellular radiotelephone unit of claim 35 wherein the alarming means comprises a visual display unit.

42. A communication method for use with a cellular radiotelephone system including a base station and at least one mobile unit by means of radio signals, the method comprising:

transmitting a control signal from the base station to a given mobile station to indicate the frequency of a tone signal that will be transmitted by the base station to indicate the establishment of a communication link;

configuring the mobile unit to detect a tone signal of the frequency indicated by the control signal;

transmitting a tone signal from the base unit to the mobile unit to indicate an attempted establishment of a communication link;

controlling the mobile unit to complete establishment of the communication link;

monitoring the signals received by the mobile unit to determine the strength of the received signals and the strength of the tone signal;

alarming at least one user of the communication system if the signal strength determined by the monitoring step is at or below a first criterion;

disconnecting the communication link if the tone signal strength determined by the monitoring step is at or below a second criterion.

43. A communication method for use with a cellular radiotelephone system including a base station and at least one mobile unit by means of radio signals, the method comprising:

transmitting a control signal from the base station to a given mobile station to indicate the frequency of a tone signal that will be transmitted by the base station to indicate the establishment of a communication link;

configuring the mobile unit to detect a tone signal of the frequency indicated by the control signal;

transmitting a tone signal from the base unit to the mobile unit to indicate an attempted establishment of a communication link;

controlling the mobile unit to complete establishment of the communication link;

monitoring the signals received by the mobile unit to determine the strength of the received signals and the presence of the tone signal

alarming at least one user of the communication system if the signal strength determined by the monitoring step is at or below a first criterion;

disconnecting the communication link if the monitoring step indicates that the tone signal is absent.