Radio trunking fault detection system with power output monitoring and on-air monitoring

• US 5,086,506 A
• Filed: 11/28/1989
• Issued: 02/04/1992
• Est. Priority Date: 08/14/1987
• Status: Expired due to Term

• Current Assignee: Com-Net Ericsson Canada Corp. (TE Connectivity Limited), Com-Net Ericsson Critical Radio Systems, Inc. (TE Connectivity Limited)
• Original Assignee: General Electric Company
• Inventors: Hall, Nancy L., Hattey, David L.
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): FAILE, ANDREW I
• Application Number:
  US07/442,319
• Time in Patent Office: 798 Days
• Field of Search: 455/8-9, 455/11, 455/13, 455/15-16, 455/17, 455/34, 455/67, 375/3, 375/3.1, 375/4, 370/13.1, 370/13, 371/5.1, 371/20.2, 371/20.4
• US Class Current: 455/8
• CPC Class Codes: H04L 1/1607 Details of the supervisory signal
• CPC Class Codes: H04L 1/1877 for semi-reliable protocols, e.g. for less sensitive applications like streaming video buffer level management for video bitstream control arrangements H04N21/44004
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 4/10 Push-to-Talk [PTT] or Push-On-Call services
• CPC Class Codes: H04W 52/0232 according to average transmission signal activity
• CPC Class Codes: H04W 74/06 using polling
• 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
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A trunked radio frequency (RF) repeater system for public service trunking (PST) or the like includes a fault detection system having an RF output power monitoring, over-the-air RF monitoring and other repeater transceiver testing capabilities. An over-the-air monitor continually tests the digital signalling transmitted by different transceivers within the repeater system. The site controller automatically removes transceivers that test faulty, and does not permit tested faulty transceivers to go back on line until they have passed poll response, power output and RF digital signalling tests.

Claims

1. A radio frequency repeater system including:

a plurality of radio frequency repeater stations each capable of transmitting RF signals;

site controller means coupled to said repeater stations for controlling said stations, and for periodically polling said stations and receiving poll responses generated by said stations in response to said polling;

RF output power monitor means coupled to said site controller means and said plurality of radio frequency repeater stations for monitoring the RF power output level of active ones of said stations and for indicating to said site controller if any said monitored power level falls below a predetermined level; and

testing means connected to said site controller means for monitoring RF digital signalling produced by active repeater stations and for notifying said site controller means of errors detected in said signalling,

wherein said site controller means automatically removes a repeater station from operation without human intervention whenever the station (a) fails to respond to polls, (b) has low RF power output level as detected by said RF output power monitor means, or (c) produces erroneous signalling as detected by said testing means, and restores removed repeater stations from service only when all three of said failure conditions (a), (b) and (c) are not present.

2. A digitally trunked radio frequency communication system of the type having an RF control channel and plural RF working channels, said system transmitting and receiving RF signals over said RF control and working channels, said working channels being temporarily assigned for RF communications by radio units in response to digital control signals passed over said control channel, said system comprising:

plural radio frequency repeaters each transmitting RF signals on a respective associated RF channel;

plural discrete processing means, operatively connected to and corresponding with said plural radio repeaters, for controlling said corresponding repeaters and for periodically generating poll response messages;

RF output power monitoring means for monitoring RF power output of said radio repeaters;

RF testing means for testing RF signals transmitted by said radio repeaters for digital signal content; and

site controller means, connected to said processing means, said RF output power monitoring means and said RF testing means, for automatically removing a radio repeater from service when any of the following occurs;

(1) the processing means associated with said radio repeater fails to generate poll response messages,

(2) the radio repeater power output monitored by said power monitoring means falls to below a preset level, and

(3) the testing performed by said RF testing means reveals errors in the digital signal content of RF signals transmitted by said radio repeater.

3. A system as in claim 2 wherein:

said site controller means periodically applies poll messages to said processing means;

said processing means generate said poll response messages in response to poll messages applied thereto; and

said site controller means continues to apply poll messages to the processing means associated with radio repeaters which have been removed from service.

4. A system as in claim 3 wherein said site controller means provides poll messages to processing means associated with radio repeaters which have been removed from service at a lower frequency than the frequency at which it provides poll messages to processing means associated with radio repeaters that have not been removed from service.

5. A system as in claim 2 wherein said site controller means includes means for determining the number of consecutive poll responses generated by processing means associated with radio repeaters taken out of service.

6. In a digitally trunked radio frequency communications system of the type having an RF control channel and plural RF working channels, said RF working channels being temporarily assigned for communication by radio units in response to digital control messages passed over said RF control channel, said control messages including embedded synchronization signals and being protected by error-checking signals, a method of testing the operation of said system comprising:

(a) continually monitoring said RF control channel and receiving and demodulating digital RF control messages passed over said control channel;

(b) testing for the presence of recurring digital synchronization signals within said monitored messages;

(c) performing error-checking analysis on error-checking signals within said monitored messages; and

(d) generating a fault indication whenever said testing step (b) reveals said recurring synchronization signals are not present and/or whenever said performing step (c) reveals the presence of errors in said messages.

7. A method as in claim 6 wherein:

said performing step (c) comprises determining whether a plurality N of received messages contain errors in response to said error-checking signals contained therein; and

said generating step (d) includes generating a notification whenever said determining step determines a preset number K less then N of consecutive messages contain errors.

8. A method as in claim 6 wherein said testing step (b) includes determining whether Barker codes are present within messages passed over said RF control channel.

9. A method as in claim 6 further including:

(e) testing for the presence of a preset code in said control messages indicating said communications system is operating in failsoft mode; and

(f) generating a notification whenever said testing step (e) reveals said system is operating in said failsoft mode.

10. A method as in claim 6 wherein said generating step (d) includes generating a digital control channel fail message having the following form:

a bit which is set whenever no control channel messages are received;

a further bit which is set whenever said testing step (b) reveals said recurring digital synchronization signals are absent; and

a still further bit which is set whenever said performing step (c) reveals a preset number of messages passed consecutively over said control channel are undecodable due to errors contained therein.

11. A method as in claim 10 wherein:

said method further includes decoding a site identification code contained within said monitored messages and comparing said decoding site identification code with a preprogrammed code; and

said sending step further includes sending a first bit in said control channel fail message indicating if no site identification code is decoded by said decoding step, and sending a different bit which is set if the comparison reveals said decoded site identification code and said preprogrammed code do not match.

12. A method as in claim 11 further including sending plural bits in said control channel fail message identifying the control channel monitored by said monitoring step (a).

13. In digitally trunked radio frequency repeater system, a radio frequency testing/monitoring apparatus connected via a digital signal link to a digitally trunked radio repeater system site controller, said apparatus including RF transceiver circuitry which is capable of transmitting and receiving RF signals, said RF transceiver including:

(a) a first arrangement which continually monitors RF digital signalling passed over an RF control channel and generates messages indicating control channel signalling status for application to said site controller over said link;

(b) a second arrangement which provides for user calls by transmitting RF signals to and receiving RF signals from said trunked radio frequency repeater system in response to manual user control; and

a third arrangement which provides RF digital test calls by automatically transmitting digital RF signals to and receiving digital RF signals from said system in response to digital test call commands originated by said site controller and passed to said apparatus via said digital signal link.

14. Apparatus as in claim 13 wherein said apparatus is preprogrammed to perform the following functions:

(1) continually monitor digital control messages passed over said control channel;

(2) test for the presence of recurring digital synchronization signals within said monitored messages;

(3) perform error-checking analysis on said monitored messages in response to receipt of said error-checking signalling embedded within said messages; and

(4) notify said site controller whenever said testing reveals said recurring synchronization signals are not present and whenever said analysis reveals the presence of errors in said monitored messages.

15. Apparatus as in claim 13 wherein said apparatus is preprogrammed to perform the following functions:

(1) test for the presence of a preset code in said control signalling indicating said system is operating in failsoft mode; and

(2) notify said site controller whenever said system is operating in said failsoft mode.

16. Apparatus as in claim 13 wherein said apparatus is programmed to perform the following functions:

(1) in response to receipt of a test call message passed over said link, transmit a digital RF call message over said control channel;

(2) receive a working channel assignment message passed over said control channel;

(3) monitor high-speed digital signalling passed over said assigned RF working channel;

(4) transmit low-speed digital RF signalling over said working channel;

(5) monitor low-speed RF signalling passed over said working channel;

(6) receive a drop channel digital signal message passed over said control channel; and

(7) apply a call results message to said site controller over said link.

17. A digitally trunked radio frequency communication system which transmits and receives radio frequency signals over plural radio frequency channels, said system comprising:

plural radio frequency repeaters which transmit digitally encoded radio frequency signals over corresponding said plural RF channels;

processing means, operatively connected to said plural radio repeaters, for controlling said repeaters and for periodically generating poll response messages corresponding to different ones of said radio repeaters;

RF output power monitoring means for monitoring the RF power outputs of said radio repeaters;

RF testing means for receiving said demodulating radio frequency signals transmitted by said radio repeaters and for testing digital signalling encoded thereon; and

means, connected to said RF output power monitoring means and said RF testing means, for automatically removing a radio repeater from service when any of the following events occur;

(1) the absence of poll response messages associated with said radio repeater,

(2) the radio repeater RF power output falls below an acceptable level, and

(3) the testing performed by said RF testing means reveals the digital signalling produced by said radio repeater is erroneous, and

for restoring to service a radio repeater previously removed from service whenever all of the following events occur;

(1) poll response messages associated with said radio repeater are present,

(2) the radio repeater RF power output monitored by said power monitor means is above said acceptable level, and

(3) the testing performed by said RF testing means reveals the digital signalling produced by said radio repeater is acceptable.

18. A system as in claim 17 wherein said RF testing means operates alternately in the following states:

(a) a monitor state wherein said monitoring means continuously monitors digital signalling passed over said control channel and generates messages indicating control channel signalling status for application to said site controller means;

(b) a user call state wherein said RF transmitting means and said monitoring means together transmit RF signals to and receive RF signals from at least one of said plural radio repeaters in response to manual user control; and

(c) a test call state wherein said RF transmitting means and said monitoring means automatically transmit digital RF signals to and receive digital Rf signals from at least one of said plural RF repeaters in response to digital test call command originated by said site controller means.

19. A digitally trunked radio frequency repeater system including:

at least one radio frequency repeater which transmits digitally encoded radio frequency signals;

a radio frequency signal testing arrangement which tests the digital encoding content of said radio frequency signals transmitted by said repeater;

a digital signal response testing arrangement coupled to said repeater, said digital control signal response testing arrangement testing response by said repeater to digital signals applied to said repeater;

an RF power output testing arrangement coupled to said repeater, said RF power output testing arrangement testing the RF power output of said repeater; and

a controller coupled to said repeater, said radio frequency signal testing arrangement, said digital signal response testing arrangement, and said RF power output testing arrangement, said controller automatically taking and/or keeping said repeater out of service unless tests with favorable outcomes are performed by each of said radio frequency signal testing arrangement, said digital signal response testing arrangement, and said RF power output testing arrangement.