Cellular telephone unit with prioritized frequency acquisition

• US 4,916,728 A
• Filed: 07/25/1988
• Issued: 04/10/1990
• Est. Priority Date: 07/25/1988
• Status: Expired due to Term

• Current Assignee: GTE Mobilnet Incorporated (Verizon Communications Inc.)
• Original Assignee: GTE Mobilnet Incorporated (Verizon Communications Inc.)
• Inventors: Blair, Kevin B.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US07/223,865
• Time in Patent Office: 624 Days
• Field of Search: 379/62, 379/59, 379/60, 379/63, 455/33
• US Class Current: 455/455
• CPC Class Codes: H04W 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
• CPC Class Codes: H04W 48/18 Selecting a network or a communication service
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 76/50 for emergency connections

Abstract

A cellular telephone unit includes selective carrier signal acquisition. Priority of acquisition is given to carrier signals associated with home system identification codes (SIDs), then to any carrier signal associated with a non-excluded SID. Any attempt to dial an emergency call (e.g., a 911 call) overrides any lockout of excluded SIDs. A display such as "roam" and "no service" lights is used selectively to indicate to the user the availability of home and/or non-excluded carrier signals.

Claims

1. A cellular telephone unit with control logic circuit means including:

scanning means for scanning a plurality of frequencies to identify a home SID signal,

means responsive to said scanning means, in the absence of a home SID signal, for alternatively scanning for any nonnegative SID,

means for acquiring a carrier signal corresponding to an SID signal found by said scanning means, and

means for activating a display indicating the availability of any SID so found.

2. A cellular telephone unit including:

scanning means for sequentially monitoring a plurality of frequencies;

detection means for detecting any SID that is present on any said frequency that is monitored by said scanning means;

frequency selection means for selecting as a working frequency the frequency corresponding to a home SID if said home SID is detected by said detection means, and for selecting as a working frequency the frequency corresponding to a nonhome, nonnegative SID if such an SID is detected by said detection means and a home SID is not detected by said detection means; and

display means for displaying a frequency selection status corresponding to any said frequency selected by said frequency selection means.

3. A cellular telephone unit comprising:

scanning means for sequentially monitoring a plurality of frequencies and for detecting any SID corresponding to any said frequency;

frequency selection means for selecting a working frequency from among said plurality of frequencies;

a roam status indicator and a no-service status indicator;

frequency selection control means for controlling the selection by said frequency selection means of a working frequency,

said working frequency being a frequency corresponding to a home SID if said home SID is detected by said scanning means, and

said working frequency being a frequency corresponding to a nonnegative SID if such an SID is detected by said scanning means and a home SID is not detected by said scanning means, and

said working frequency being a frequency corresponding to a negative SID if no nonnegative SID is detected by said scanning means; and

display control means for controlling said roam status indicator and said no-service status indicator, whereby;

if said frequency selection control means selects a working frequency that corresponds to a home SID, neither of said status indicators is activated,

if said frequency selection control means selects a working frequency that corresponds to a nonnegative, nonhome SID and that is a home frequency, said roam status indicator is continuously activated,

if said frequency selection control means selects a working frequency that corresponds to a nonnegative, nonhome SID and that is a nonhome frequency, said roam status indicator is intermittently activated, and

if said frequency selection control means selects a working frequency corresponding to a negative SID, neither of said status indicators is activated.

4. Logic circuitry for control of a cellular telephone unit, said telephone unit including:

scanning means for sequentially monitoring a plurality of frequencies and for detecting any SID corresponding to any said frequency,

frequency selection means for selecting a working frequency from among said plurality of frequencies,

a roam status indicator and a no-service status indicator,

said logic circuitry comprising;

frequency selection control means for controlling the selection by said frequency selection means of a working frequency,

said working frequency being a frequency corresponding to a home SID if said home SID is detected by said scanning means, and

said working frequency being a frequency corresponding to a nonnegative SID if such an SID is detected by said scanning means and a home SID is not detected by said scanning means, and

said working frequency being a frequency corresponding to a negative SID if no nonnegative SID is detected by said scanning means; and

display control means for controlling said roam status indicator and said no-service status indicator, whereby;

if said frequency selection control means selects a working frequency that corresponds to a home SID, neither of said status indicators is activated,

if said frequency selection control means selects a working frequency that corresponds to a nonnegative, nonhome SID and that is a home frequency, said roam status indicator is continuously activated,

if said frequency selection control means selects a working frequency that corresponds to a nonnegative, nonhome SID and that is a nonhome frequency, said roam status indicator is intermittently activated, and

if said frequency selection control means selects a working frequency corresponding to a negative SID, neither of said status indicators is activated.

5. A method for displaying the availability of carrier signals associated respectively with a home SID, a nonhome, nonnegative SID on a home frequency, a nonhome, nonnegative SID on a nonhome frequency, and a negative SID, comprising the steps of:

if a carrier signal is available that corresponds to a home SID, then activating neither a roam status indicator nor a no-service indicator;

else if a carrier signal is available that corresponds to a nonhome, nonnegative SID on a home frequency, then continuously activating said roam status indicator;

else if a carrier signal is available that corresponds to a nonhome, nonnegative SID on a nonhome frequency, then intermittently activating said roam status indicator;

else if a carrier signal is available that corresponds to to a negative SID, then activating said no-service indicator.

6. A cellular telephone unit comprising:

scanning means for sequentially monitoring a plurality of frequencies and for detecting any SID corresponding to any said frequency;

frequency selection means for selecting a working frequency from among said plurality of frequencies;

frequency selection control means for controlling the selection by said frequency selection means of a working frequency;

said working frequency being a frequency corresponding to a home SID if said home SID is detected by said scanning means, and

said working frequency being a frequency corresponding to a nonnegative SID if such an SID is detected by said scanning means and a home SID is not detected by said scanning means, and

said working frequency being a frequency corresponding to a negative SID if;

(i) no home SID is detected by said scanning means, and

(ii) no nonnegative SID is detected by said scanning means, and

(iii) a user dials a predetermined number.

7. A cellular telephone unit as defined in claim 6 wherein the predetermined number is an emergency number.