Method for preventing an unauthorized device from operating in an 800 MHz trunked radio communications system using channels 559 to 320

• US 7,536,196 B1
• Filed: 08/30/2005
• Issued: 05/19/2009
• Est. Priority Date: 08/30/2005
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Cassidy, Marc W., McDonald, Daniel J., Mills, David R., Trandai, Tanhoa, Gilbert, John M., Griffis, Donald R.
• Primary Examiner(s): Nguyen; Duc
• Assistant Examiner(s): YOUSSEF, ADEL Y
• Application Number:
  US11/214,595
• Time in Patent Office: 1,358 Days
• Field of Search: 455/520, 455/426.1, 455/426.2
• US Class Current: 455/520
• CPC Class Codes: H04W 12/08 Access security
• CPC Class Codes: H04W 48/02 Access restriction performed under specific conditions
• CPC Class Codes: H04W 84/08 Trunked mobile radio systems

Abstract

A receiving device in a trunked radio communications system determines a transmit frequency, wherein the transmit frequency is calculated by subtracting a voice channel number from 559, multiplying by a channel spacing and adding a base frequency to yield the transmit frequency, if the voice channel number is between 559 and 320. The receiving device determines a receive frequency by 851.0250 MHz+[(559−a voice channel number)*12,500 Hz], if the voice channel number is between 559 and 320. In any case, the voice channel number is communicated in an outbound signaling message defined by Motorola'"'"'s 3600-baud radio trunking protocol.

Claims

1. In a trunked radio communications system operating in the 800 MHz spectrum wherein the trunked radio communications system comprises at least one site, at least one control channel, at least one voice channel, and a plurality of receiving devices, a method for preventing an unauthorized device from operating in the trunked radio communications system, the method comprising the steps of:

at a receiving device in the trunked radio communications system;

determining a transmit frequency, wherein the transmit frequency is calculated by subtracting a voice channel number from 559, multiplying by a channel spacing and adding a base frequency to yield the transmit frequency, if the voice channel number is between 559 and 320,

wherein the voice channel number is communicated in an outbound signaling message defined by Motorola'"'"'s 3600-baud radio trunking protocol.

2. The method of claim 1 wherein at least one of a) a formula for the transmit frequency, b) the base frequency, c) the voice channel number, and d) the channel spacing is entered into the receiving device by a user programmable interface.

3. The method of claim 1 wherein the base frequency relates to a value of 806.0125 MHz.

4. The method of claim 1 wherein the channel spacing relates to a value of 12.5 kHz.

5. The method of claim 1 further comprising receiving at a receive frequency which is 45 MHz from the transmit frequency.

6. In a trunked radio communications system operating in the 800 MHz spectrum wherein the trunked radio communications system comprises at least one site, at least one control channel, at least one voice channel, and a plurality of receiving devices, a method for preventing an unauthorized device from operating in the trunked radio communications system, the method comprising the steps of:

at a receiving device in the trunked radio communications system;

requesting a voice channel for a communication;

receiving an outbound signaling message on a control channel comprising a voice channel number for the receiving device to utilize for the communication on the voice channel, wherein the outbound signaling message is defined by Motorola'"'"'s 3600-baud radio trunking protocol; and

tuning to about a transmit frequency, wherein the transmit frequency is determined by subtracting the voice channel number from 559, multiplying by a channel spacing and adding a base frequency to yield the transmit frequency, if the voice channel number is between 559 and 320.

7. The method of claim 6 further comprising:

modulating the communication to about the transmit frequency; and

transmitting the modulated communication with a transmit deviation that relates to a maximum of 4 kHz.

8. The method of claim 6 wherein the receiving device is at least one of a subscriber, a subscriber unit, a radio, a mobile, a portable, a receiver, a scanner, and a scanner device.

9. The method of claim 6 wherein the base frequency is calculated by performing mathematical operations to arrive at 806.0125 MHz.

10. The method of claim 6 wherein the base frequency is stored in hexadecimal format.

11. The method of claim 6 wherein the channel spacing is calculated by performing mathematical operations to arrive at 12.5 kHz.

12. The method of claim 6 further comprising receiving at a receive frequency which is 45 MHz from the transmit frequency.

13. The method of claim 6 wherein the receive frequency is calculated by adding 45 MHz to the transmit frequency.

14. In a trunked radio communications system operating in the 800 MHz spectrum wherein the trunked radio communications system comprises at least one site, at least one control channel, at least one voice channel, and a plurality of receiving devices, a method for preventing an unauthorized device from operating in the trunked radio communications system, the method comprising the steps of:

at a receiving device in the trunked radio communications system;

determining a receive frequency, wherein the receive frequency is determined by 851.0125 MHz+[(559−

a voice channel number)*12,500 Hz], if the voice channel number is between 559 and 320,

wherein the voice channel number is communicated in an outbound signaling message defined by Motorola'"'"'s 3600-baud radio trunking protocol.

15. The method of claim 14 wherein the receiving device is at least one of a subscriber, a subscriber unit, a radio, a mobile, a portable, a receiver, a scanner, and a scanner device.

16. The method of claim 14 wherein at least one of a) a formula for the receive formula and b) the voice channel number is entered into the receiving device by a user programmable interface.

17. The method of claim 14 further comprising performing mathematical operations to arrive at a value of 851.0125 to the 851.0125 MHz.

18. The method of claim 14 further comprising performing mathematical operations to arrive at a value of 12,500 to the 12,500 Hz.

19. The method of claim 14 further comprising tuning to about the receive frequency to receive communications of the trunked radio communications system.

20. The method of claim 14 wherein the base frequency is stored in hexadecimal format.