Fraud control for radio fleets in a land mobile radio system

• US 5,625,870 A
• Filed: 06/10/1994
• Issued: 04/29/1997
• Est. Priority Date: 06/10/1994
• Status: Expired due to Fees

• Current Assignee: Uniden America Corporation (Cornwall Capital Management LP)
• Original Assignee: Uniden America Corporation (Cornwall Capital Management LP)
• Inventors: Moon, Billy G.
• Primary Examiner(s): URBAN, EDWARD F
• Application Number:
  US08/258,237
• Time in Patent Office: 1,054 Days
• Field of Search: 455/9, 455/15, 455/17, 455/33.1, 455/34.1, 455/34.2, 455/54.1, 455/54.2, 455/67.1, 379/58, 379/63, 379/59, 340/825.31, 340/825.34
• US Class Current: 455/411
• CPC Class Codes: H04W 4/10 Push-to-Talk [PTT] or Push-On-Call services
• CPC Class Codes: H04W 76/45 for Push-to-Talk [PTT] or Push-to-Talk over cellular [PoC] services
• CPC Class Codes: H04W 84/08 Trunked mobile radio systems

Abstract

A land mobile radio communication system has a plurality of cell sites, each of which typically has a plurality of repeaters. The over-the-air radio communications between the cell site repeaters and the mobile radios in the system include both a voice component and a data component. The data component is carried as low-frequency subaudible information. Communication channels are provided between the radio users at each site as well as between users at different sites and between mobile radio users and the public telephone network. Within a cell site, the transmitted and received communicatios are digitized and passed through serial buses in a time multiplex fashion. The digitized voice is transferred between time slots to provide the required switching function. The system includes operational software to provide direct inward dial telephone number recognition, automatic voice prompts for a user entering a new cell, call priority override, fraud control for radio fleets and a dynamic control channel.

Claims

1. A method for preventing unauthorized use of communication equipment in a land mobile radio system which has a cell with a plurality of repeaters, each repeater having a transmitter and a receiver, the method comprising the steps of:

receiving at a repeater receiver in the cell a first identification code transmitted by a first radio,

after receipt of said first identification code from said first radio, establishing a link between said repeater receiver and its corresponding transmitter to set up a retransmission channel,

starting a timer following receipt of said first identification code from said first radio, said timer having a predetermined time-out period, and

terminating said link if a second identification code is not received from said first radio before said timer completes said predetermined time-out period.

2. A method for preventing unauthorized use of communication equipment in a land mobile radio system which has a cell with a plurality of repeaters, each repeater having a transmitter and a receiver, the method comprising the steps of:

receiving at a repeater receiver in the cell a first identification code transmitted by a first radio,

after receipt of said first identification code from said first radio, establishing a link between said repeater receiver and its corresponding transmitter to set up a retransmission channel,

starting a timer following receipt of said first identification code from said first radio, said timer having a predetermined time-out period, and

stopping said timer if a second identification code is received from said first radio before said timer completes said predetermined time-out period.