Communication system and device having unit locating feature

• US 6,002,342 A
• Filed: 11/21/1997
• Issued: 12/14/1999
• Est. Priority Date: 11/21/1997
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Leitch, Clifford Dana
• Primary Examiner(s): Le, Amanda T.
• Assistant Examiner(s): HA, DAC V
• Application Number:
  US08/976,044
• Time in Patent Office: 753 Days
• Field of Search: 375/356, 375/358, 375/359, 375/371, 375/377, 340/825.44, 340/825.49, 340/825.54, 342/398, 342/442, 342/367
• US Class Current: 342/147
• CPC Class Codes: G01S 2205/008 using a mobile telephone network
• CPC Class Codes: G01S 3/14 Systems for determining direction or deviation from predetermined direction aerial arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00; combinations of different interacting aerial units for giving a desired directional characteristic H01Q21/29; aerials or aerial systems providing at least two radiation patterns H01Q25/00
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308
• CPC Class Codes: H04B 7/084 Equal gain combining, only phase adjustments antenna beam scanning or forming by phase or amplitude control H01Q3/26, e.g. phased arrays

Abstract

A communication system (700) comprises a plurality of base sites (702-708) which include a first antenna (712) for transmitting a synchronous communication protocol such as a paging protocol and a second antenna (714) for transmitting a rotating phase signal. A communication device (250) takes the synchronous communication protocol and develops a reference signal (220) from the received protocol. The communication device (250) takes the reference signal (220) and the received rotating phase signal (214) and uses a phase detector (216) to produce a phase difference signal (232) which is substantially equal to the angle of the communication device (250) with respect to the particular base site (702-708) which transmitted the signals. In order to determine the location of the communication device at least two such phase difference signals (232), one phase difference signal from at least two different base sites is determined. In the preferred embodiment, the phase difference signals (232) are transmitted by the communication device (250) to a paging system controller (710) for calculation of the proximate location of the communication device (250).

Claims

1. A communication system, comprising:

a base site having a first antenna for transmitting a synchronous communication protocol and a second antenna for transmitting a rotating phase signal; and

a portable communication device including;

`a receiver section for receiving the synchronous communication protocol from the base site and generating a reference signal, the receiver section also receives the rotating phase signal from the base site; and

a receiver section for receiving the synchronous communication protocol from the base site and generating a reference signal, the receiver section also receives the rotating phase signal from the base site; and

a phase detector coupled to the receiver section for calculating the phase difference between the reference signal and the rotating phase signal and producing an output signal (θ

).

2. A communication system as defined in claim 1, wherein the synchronous communication protocol transmitted by the base site comprise a paging protocol.

3. A communication system as defined in claim 1, wherein the second antenna comprises a rotating antenna.

4. A communication system as defined in claim 1, wherein the output signal (θ

) is substantially equal to the angle between the portable communication device and the base site.

5. A communication system as defined in claim 4, further comprising a system controller coupled to the base site, and the portable communication device further comprises a transmitter coupled to the phase detector for transmitting the output signal (θ

) to the system controller.

6. A communication system as defined in claim 1, wherein the rotating phase signal is transmitted using a single sideband (SSB) signal which includes a pilot carrier which serves as a gain and phase reference for the portable communication device.

7. A communication system as defined in claim 1, wherein the rotating phase signal is transmitted using a quadrature amplitude modulated (QAM) signal which includes a pilot carrier which serves as a gain and phase reference for the portable communication device.

8. A portable communication device which receives a synchronous communication protocol and a rotating phase signal transmitted by a remote base site, comprising:

a receiver section for receiving the synchronous communication protocol and generating a reference signal from said synchronous communication protocol;

an amplitude modulation detector responsive to the received rotating phase signal for providing an amplitude modulated (AM) signal; and

a phase detector responsive to the reference signal and the AM signal calculates a phase difference between the reference signal and the AM signal and produces a phase difference signal (θ

) which is substantially equal to the angle between the portable communication device and the remote base site.

9. A portable communication device as defined in claim 8, wherein the portable communication device comprises a pager and the synchronous communication protocol comprises a paging protocol having frame sync signals.

10. A portable communication device as defined in claim 9, wherein the receiver section further comprises:

a frame synchronizer coupled to the receiver section which synchronizes to the frame sync signals and provides a frame synch reference signal; and

a phase-locked-loop which in response to the frame synch reference signal generates the reference signal.

11. A portable communication device as defined in claim 9, wherein the pager further comprises a transmitter for transmitting the phase difference signal (θ

).