Lost call detection display pager with repeat call discrimination capability

• US 5,572,197 A
• Filed: 04/26/1994
• Issued: 11/05/1996
• Est. Priority Date: 04/26/1993
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Matsumoto, Mariko
• Primary Examiner(s): Horabik, Michael
• Assistant Examiner(s): MERZ, EDWARD W
• Application Number:
  US08/233,521
• Time in Patent Office: 924 Days
• Field of Search: 340/825.44, 340/825.47, 340/825.48, 340/311.1, 455/38.4
• US Class Current: 340/7.58
• CPC Class Codes: G08B 5/227 with call or message storage means

Abstract

From a paging station a radio display pager receives a sequence of repeat calls and non-repeat calls. Each of the repeat and non-repeat calls contains a message and a message number identifying the message, the same message numbers being repeated for the repeat calls of the sequence. The message numbers of received calls are stored in a first memory. A currently received call is compared with each of the previously stored calls to detect a mismatch. Upon detection of the mismatch, a lost call detector determines the message number of a lost call which may exist between the currently received call and a call stored last in the first memory. The determined message number is stored into a second memory as a lost message number. The stored lost message number is erased if a call bearing the same message number is received. The lost message number that remains in the second memory is put on display to allow the owner of the pager to inform the system center of the lost message number to obtain the lost message.

Claims

1. A radio display pager comprising:

receiver means for receiving from a paging station a sequence of repeat calls and non-repeat calls addressed to the radio pager, each of said repeat and non-repeat calls containing a message and a message number identifying the message, the message numbers of repeat calls containing identical messages being equal to each other;

first memory means for storing the message numbers of calls received by the receiver means;

second memory means;

mismatch detector means for comparing a call currently received by the receiver means with each of the calls previously stored in the first memory means for detecting a mismatch therebetween;

lost call detector means responsive to the detection of a mismatch by the mismatch detector means for detecting the message number of a lost call which may exist between a call currently received by the receiver means and a call stored last in the first memory means storing the detected message number into the second memory means as a lost message number, and removing from the second memory means the lost message number when a call having the same message number is received by the receiver means; and

display means for displaying the message number which remains in said second memory means.

2. A radio display pager as claimed in claim 1, wherein said lost call detector means comprises:

first detector means responsive to the detection of a mismatch by the mismatch detector means for detecting the presence of a lost call when there is a difference of at least one between the message number of a call currently received by the receiver means and the message number of a call stored last in the first memory means;

second detector means responsive to the detection of a lost call by the first detector means for detecting a mismatch between the message number of the currently received message and a message number stored in the second memory means; and

third detector means responsive to the detection of a lost call by the second detector means for determining a message number which exists between the message number of the currently received call and the message number of the call last stored in the first memory means and storing the determined message number into the second memory means as said lost message number, and responsive to the detection of a match by the second detector means for removing from the second memory means said lost message number which is equal to the message number of a call received by the receiver means.

3. A radio display pager as claimed in claim 1, wherein said lost call detector means comprises:

first means, responsive to the detection of a mismatch by the mismatch detector means, for detecting a match or a mismatch between the message number of the currently received call and a lost message number stored in the second memory means when the message number of a call currently received by the receiver means is not equal to the message number of a call stored last in the first memory means plus one; and

second means, responsive to the detection of said mismatch by the first means, storing every sequential number residing between the message number of the currently received call and the message number of the call last stored in the first memory means into the second memory means as said lost message number, and responsive to the detection of said match by the first means for removing from the second memory means a lost message number which is equal to the message number of a call received by the receiver means.

4. A radio display pager as claimed in claim 1, wherein said lost call detector means is a microprocessor programmed to perform the steps comprising:

(a) detecting a mismatch when the message number of a call currently received by the receiver means is not equal to the message number of a call stored last in the first memory means plus one in response to the detection of a mismatch by the mismatch detector means;

(b) detecting a match or a mismatch between the message number of the currently received call and a lost message number stored in the second memory means, in response to the detection of said mismatch by the step (a); and

(c) storing every sequential number residing between the message number of the currently received call and the message number of the call last stored in the first memory means into the second memory means as said lost message number in response to the detection of said mismatch by step (b), and removing from the second memory means a lost message number which is equal to the message number of a call received by the receiver means in response to the detection of said mismatch by step (b).

5. A radio pager receiving messages having associated message numbers and storing the received messages and the associated message numbers in a memory, said radio pager comprising a microprocessor programmed to perform the functions comprising:

determining whether a match exists between an associated message number of a currently received message and associated message numbers previously stored in the memory;

when no match is found, deciding that a message has not been lost when the associated message number of the currently received message equals a reference number defined as an associated message number of a last previously stored message plus one, and deciding that a message has been lost otherwise;

storing as a lost message number every sequential number residing between the associated message number of the currently received message and the reference number.

6. The radio pager of claim 5, wherein said microprocessor is programmed to further perform the following functions:

determining whether a match exists between the associated message number of the currently received message and a previously stored lost message number, and deleting the previously stored lost message number when a match exists.

7. The radio pager of claim 6, wherein said microprocessor is programmed to further perform the following functions:

starting a timer when it is determined that a lost message number is stored in the memory and, when the timer has counted a predetermined period, displaying the lost message number which is still stored in the memory.

8. A method for detecting and managing lost messages in a radio pager receiving messages having associated message numbers, comprising the steps of:

comparing the associated message number of a presently received message with associated message numbers of previously received and stored messages;

storing as a lost message number any consecutive number residing between the associated message number of the currently received message and a reference number defined by a last previously stored associated message number plus one;

erasing a stored lost message number that is equal to the associated message number of the presently received message.

9. The method according to claim 8, further comprising the steps of:

starting a timer when it is detected that a lost message number is stored in a memory of said radio pager;

alerting the user that a lost message number exists if it is determined that a lost message number is stored in the memory after the timer has reached a predetermined count.