Method and apparatus for providing priority channel scan in a radio

• US 4,776,037 A
• Filed: 08/03/1987
• Issued: 10/04/1988
• Est. Priority Date: 08/03/1987
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Rozanski, Walter J. Jr.
• Primary Examiner(s): Blum, Theodore M.
• Assistant Examiner(s): Barron, Jr., Gilberto
• Application Number:
  US07/082,719
• Time in Patent Office: 428 Days
• Field of Search: 455/166, 455/58, 455/35, 455/38, 455/185, 455/186, 340/825.04, 340/825.44, 340/825.5, 340/825.51, 340/825.1
• US Class Current: 455/166.2
• CPC Class Codes: H03J 1/0058 provided with channel identification means arrangements for monitoring the use made of broadcast services H04H60/31
• CPC Class Codes: H04B 1/40 Circuits

Abstract

A priority channel scan for use in radios capable for receiving at least two channels, wherein one of the channels is a priority communications channel. The radio periodically interrupts communications on the non-priority channel for very brief moments to allow monitoring of the priority channel for the presence of digital code word segments. These digital code word segments are stored until the complete code word can be reconstructed and compared against stored code words. When a match occurs, the radio switches to the priority channel to allow reception of a priority message occurring thereon.

Claims

1. Priority channel scan for use in a radio having:

receiver means for receiving, selectively, at least a first and second channel, wherein said first channel comprises a priority channel;

code detection means for detecting and decoding a code word received on said first channel;

said priority channel scan comprising;

(A) first control means for causing said receiver means, when said receiver means is receiving said second channel, to periodically receive said first channel for a predetermined period of time to allow said code detection means to detect a word segment of said code word if said code word is then being transmitted on said first channel, wherein said predetermined period of time is not adequate to allow said code word to be completely received;

(B) memory means for storing said word segments as said word segments are periodically received;

(C) second control means for comparing said word segments, when reconstructed into a complete word, against at least one predetermined code word, and for causing said receiver means to receive said first channel when said complete word matches said at least one predetermined code word.

2. The priority channel scan of claim 1 wherein said predetermined period of time does not exceed 40 milliseconds.

3. The priority channel scan of claim 1 wherein said complete word comprises 23 bits.

4. A method of providing priority channel scan in a radio having:

receiver means for receiving, selectively, at least a first and second channel, wherein said first channel comprises a priority channel; and

code detection means for detecting a code word received on said first channel;

wherein said method comprises the steps of;

(A) when receiving said second channel, momentarily receiving for a first predetermined period of time said first channel, which first predetermined period of time is inadequate to allow reception of a complete code word;

(B) storing a code word segment as may be received when momentarily receiving said first channel and receiving said second channel again;

(C) until a sufficient number of code word segments have been consecutively stored, repeating from step (A) following a second predetermined period of time;

(D) when a sufficient number of code word segments have been consecutively stored, using said code word segments to reconstruct a complete code word;

(E) comparing said complete code word against at least one stored code word;

(F) if said complete code word does not match said at least one stored code word, repeating from step (A);

(G) if said complete code word does match said at least one stored code word, causing said receiver means to receive said first channel to allow reception of a priority message being transmitted thereon.

5. The method of claim 4 wherein said first predetermined period of time does not exceed 40 msec.

6. The method of claim 4 wherein said first predetermined period of time equals 34.2 msec.

7. The method of claim 4 wherein step (G) further includes the step of receiving and decoding said code word as a whole, and of matching said code word against said at least one stored code word prior to rendering said priority message audible.