Cellular telephone signalling circuit operable with different cellular telephone systems

• US 5,396,653 A
• Filed: 06/05/1992
• Issued: 03/07/1995
• Est. Priority Date: 06/05/1992
• Status: Expired due to Term

• Current Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Kivari, Raimo, Pikkarainen, Juha
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): WISLER, MARK
• Application Number:
  US07/893,769
• Time in Patent Office: 1,005 Days
• Field of Search: 455/33.1, 455/33.4, 455/88, 455/38.3, 455/68, 455/70, 455/54.1, 455/56.1, 375/38, 379/59
• US Class Current: 455/88
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

Apparatus operable with different cellular telephone systems and signalling protocols is described. Signalling messages, both data messages and supervisory related signals between a cellular telephone microcontroller (4) and a base station are transferred via a baseband signalling circuit (10). The baseband signalling circuit is operable to employ different signalling protocols, the protocol being selected by control bits provided from the microcontroller to the signalling circuit. In a preferred embodiment, the signalling protocol selection is made between an AMPS/TACS signalling protocol and a NAMPS/NTACS subaudible signalling protocol.

Claims

1. A baseband signalling circuit for use with a cellular telephone that comprises a cellular telephone control means for selectively setting a state of a control signal line as a function of a received cellular communications system signalling protocol, said baseband signalling circuit being responsive to a first state of said control signal line for operating in accordance with a first cellular communications system signalling protocol that employs a signalling frequency that is greater than one kilo-Hertz, said baseband signalling circuit further being responsive to a second state of said control signal line for operating in accordance with a second cellular communications system signalling protocol that employs a signalling frequency that is less than one kilo-Hertz, said baseband signalling circuit further comprising means for recovering data bits from a received signal, said recovering means being responsive to the first state of said control signal line for sampling the received signal at a first sampling rate, said recovering means being responsive to the second state of said control signal line for sampling the received signal at a second sampling rate, wherein said first sampling rate is at least an order of magnitude greater than said second sampling rate.

2. A baseband signalling circuit as set forth in claim 1 wherein the first signalling protocol is selected from Advanced Mobile Phone Services (AMPS) and Total Access Communication System (TACS) signalling protocols, and wherein the second signalling protocol is selected from Narrowband Advanced Mobile Phone Services (NAMPS) and Narrowband Total Access Communication System (NTACS) signalling protocols.

3. A baseband signalling circuit as set forth in claim 1 and further including clock generator means that is responsive to said control signal line for generating clock signals having first frequencies for the first state of said control signal line and clock frequencies having second frequencies for the second state of said control signal line, and wherein said first frequencies are greater than said second frequencies.

7. A baseband signalling circuit as set forth in claim 2 and further comprising circuit means for processing received signals associated with said AMPS and TACS signalling protocols, and wherein said baseband signalling circuit is responsive to the second state of said control signal line for setting said circuit means in a low power mode of operation.

4. A baseband signalling circuit for use with a cellular telephone that comprises a cellular telephone control means for selectively setting a state of a control signal line as a function of a received cellular communications system signalling protocol, said baseband signalling circuit being responsive to a first state of said control signal line for operating in accordance with a first cellular communications system signalling protocol that employs a continuous signalling frequency that is greater than one kilo-Hertz, said baseband signalling circuit further being responsive to a second state of said control signal line for operating in accordance with a second cellular communications system signalling protocol that employs a signalling frequency that is less than one kilo-Hertz, wherein the first cellular communications system signalling protocol is selected from Advance Mobile Phone Services (AMPS) and Total Access Communication System (TACS) signalling protocols, and wherein the second cellular communications system signalling protocol is selected from narrowband Advanced Mobile Phone Services (NAMPS) and Narrowband Total Access Communication System (NTACS) signalling protocols;

said baseband signalling circuit further including decoder means, responsive to the first state of said control signal line, for operating as a Manchester decoder for decoding received AMPS/TACS data that is input into said baseband signalling circuit, said decoder means being responsive to the second state of said control signal line for operating as a one bit integrator for decoding received NAMPS/NTACS data that is input into said baseband signalling circuit.

5. A baseband signalling circuit as set forth in claim 4 and further including means, responsive to a first state of a second control signal that is generated by said control means, for generating an interrupt signal that indicates to said cellular telephone control means that eight bits of the received data has been decoded, said generating means being responsive to a second state of the second control signal for generating the interrupt signal to indicate that one bit of the received data has been decoded.

6. A baseband signalling circuit as set forth in claim 5 and further including means for storing one or more of the decoded bits prior to the decoded bits being output to the control means.

8. A baseband signalling circuit as set forth in claim 4 wherein said decoder means, when operating as a one bit integrator, operates with a weighting function h(n) of integration wherein:

h(n)=0, when n=1,2,3,4,5,6,7,34,35,36,37,38,39,40;

h(n)=1, when n=8,9,10,11,12,13,28,29,30,31,32,33; and

h(n)=2, when n=14,15,16,17,18,19,20,21,22,23,24, 25,26,27; and

wherein

a decided data bit y(k) is given by;

##EQU2## where x is a sample of the input NAMPS/NTACS data.

9. A baseband signalling circuit for use with a cellular telephone, said baseband signalling circuit including first means for interfacing to a cellular telephone control means and second means for interfacing to a radio frequency reception and transmission means, said baseband signalling circuit being responsive to a first state of a control signal line for operating in accordance with Advanced Mobile Phone Services (AMPS)/Total Access Communication System (TACS) signalling protocols, said baseband signalling circuit further being responsive to a second state of said control signal line for operating in accordance with Narrowband Advanced Mobile Phone Services (NAMPS)/Narrowband Total Access Communication System (NTACS) subaudible signalling protocols, wherein the state of the control signal line is selectively controlled by said cellular telephone control means as a function of a received cellular communications system signalling protocol, wherein said first interface means includes a multi-bit data bus and an interrupt signal line that is coupled between said baseband signalling circuit and said cellular telephone control means, and wherein said baseband signalling circuit is responsive to information written over said data bus by said cellular telephone control means for selectively generating said interrupt signal on an occurrence of a reception of eight data bits from said second interface means or on an occurrence of a reception of one bit from said second interface means.

10. A baseband signalling circuit for use with a cellular telephone, said baseband signalling circuit including first means for interfacing to a cellular telephone control means and second means for interfacing to a radio frequency reception and transmission means, said baseband signalling circuit being responsive to a first state of a control signal line for operating in accordance with Advanced Mobile Phone Services (AMPS)/Total Access Communication System (TACS) signalling protocols, said baseband signalling circuit further being responsive to a second state of said control signal line for operating in accordance with Narrowband Advanced Mobile Phone Services (NAMPS)/Narrowband Total Access Communication System (NTACS) subaudible signalling protocols, wherein the state of the control signal line is selectively controlled by said cellular telephone control means as a function of a received cellular communications system signalling protocol, said baseband signalling circuit further comprising decoder means, responsive to the first state of said control signal line, for operating as a Manchester decoder for decoding AMPS/TACS data that is received from said radio frequency receiving means, said decoder means being responsive to the second state of said control signal line for operating as a one bit integrator for decoding NAMPS/NTACS Digital Supervisory Audio Tone (DSAT), Word Synchronization (WSYNC), and DATA WORD information that is received from said radio frequency receiving means.

11. A baseband signalling circuit as set forth in claim 10 wherein said decoder means, when operating as a one bit integrator, operates with a weighting function h(n) of integration wherein:

h(n)=0, when n=1,2,3,4,5,6,7,34,35,36,37,38,39,40;

h(n)=1, when n=8,9,10,11,12,13,28,29,30,31,32,33; and

h(n)=2, when n=14,15,16,17,18,19,20,21,22,23,24, 25,26,27; and

wherein

a decided data bit y(k) is given by;

##EQU3## where x is a sample of the input NAMPS/NTACS data.

12. A baseband signalling circuit as set forth in claim 10 wherein said second interface means includes means, responsive to information received from said cellular telephone control means, for varying a deviation of a radio frequency signal that is transmitted by said radio frequency transmitter means, wherein the information that is received from said cellular telephone control means includes the state of said control signal line and a state of a second control signal that indicates if a discontinuous transmission DTX mode of operation is in effect, and wherein the transmitted deviation is given as one of the group consisting of

13. A baseband signalling circuit for use with a cellular telephone, said baseband signalling circuit including first means for interfacing to a cellular telephone control means and second means for interfacing to a radio frequency reception and transmission means, said baseband signalling circuit being responsive to a first state of a control signal line for operating in accordance with Advanced Mobile Phone Services (AMPS)/Total Access Communication System (TACS) signalling protocols, said baseband signalling circuit further being responsive to a second state of said control signal line for operating in accordance with Narrowband Advanced Mobile Phone Services (NAMPS)/Narrowband Total Access Communication System (NTACS) subaudible signalling protocols, wherein the state of the control signal line is selectively controlled by said cellular telephone control means as a function of a received cellular communications system signalling protocol, and wherein said baseband signalling circuit is further comprised of means for recovering data bits from a signal received from said second interface means, said recovering means being responsive to the first state of said control signal line for sampling the received signal at a first sampling rate, said recovering means being responsive to the second state of said control signal line for sampling the received signal at a second sampling rate, wherein said first sampling rate is at least an order of magnitude greater than said second sampling rate.

14. A baseband signalling circuit as set forth in claim 13 and further comprising digital phase lock loop (DPLL) means that is responsive to information received from said cellular telephone control means for varying a locking range about a center frequency of said DPLL means.

15. A baseband signalling circuit as set forth in claim 13 wherein said second interface means includes means, responsive to information received from said cellular telephone control means, for varying a deviation of a radio frequency signal that is transmitted by said radio frequency transmitter means.

16. A baseband signalling circuit as set forth in claim 15 wherein the information received from said cellular telephone control means includes the state of said control signal line and a state of a second control signal that indicates if a discontinuous transmission DTX mode of operation is in effect.

17. A baseband signalling circuit as set forth in claim 13 wherein said first interface means further comprises means for Manchester encoding information that is received from said cellular telephone control means prior to the information being applied to said second interface means for transmission by said radio frequency transmitter means.

18. A baseband signalling circuit as set forth in claim 17 and further including means, responsive to the second state of said control signal line, for bypassing said Manchester encoding means and for receiving Manchester encoded data from said cellular telephone control means through said first interface means.