Alert radio repeater automated backup, failover, recovery David Leader HydroLynx Systems

Alert radio repeaters are critical points in a flood warning system telemetry network. A single repeater failure can lead to major data loss during a flood warning event. – System design redundancy is needed to prevent data loss. Increased data loading can overwhelm a repeater – Data distribution over several repeater is needed to prevent repeater overloading. HydroLynx worked with Washoe County, NV telemetry network manager to address these issues to – Provide redundancy. – Distribute radio channel use.

Washoe County, NV upgraded two Alert repeaters to automated failover. Two repeaters in Washoe County receive Alert data on frequency f1 and repeat data on frequency f2. – Peavine Peak – Slide Mountain One base station receives the repeated Alert data on frequency f2. – National Weather Service Office in Reno, NV Upgrade repeaters to with automated failover.

Peavine Peak Slide Mountain NWS Reno NV

Simple Solution - Paired Repeaters Pass the Same Remote Data. Two repeaters receive all remote station data. – Repeaters have the same pass/block list. – Data received from sensor in list is repeated. – Base station receives the same data from both repeaters. Advantages – If one repeater fails, data is received from surviving repeater. Disadvantages – Base station incoming radio channel use is doubled.

Repeater Pass the Same Remote Data. Alert Base Station Alert Decoder Alert Receiver Peavine Peak Slide Mountain NWS Reno, NV Remote sites f2 f1 f2 f1

Data Load Distributed Between Paired Repeaters Using Pass/Block Lists. Two repeaters receive all remote station data. – Each repeater has a separate pass/block list. – Data received from sensor in list is repeated. – Base station receives separate data from both repeaters. Advantages – Base station incoming radio channel use is halved. Disadvantages – If one repeater fails, half of remote data is lost.

Repeater Distributed Remote Data Load. Alert Base Station Alert Decoder Alert Receiver Peavine Peak Slide Mountain NWS Reno, NV Remote sites f2 f1 f2 f1

Manual remote repeater failover controls repeat function and pass/block lists. Two repeaters receive all remote station data. – Each repeater has a separate pass/block list. – Data received from sensor in list is repeated. – Base station receives separate data from both repeaters. Advantages – If one repeater fails, control sent to surviving repeater to repeat all data. Disadvantages – Operator action required to send remote control failover command.

Repeater Distributed Load Normal Alert Base Station Alert Decoder Alert Receiver Peavine Peak Slide Mountain NWS Reno, NV Remote sites f2 f1 f2 f1

Single Repeater in Failover by Manual Control Passes all Remote Data. Alert Base Station Alert Decoder Alert Receiver Peavine Peak Slide Mountain NWS Reno, NV Remote sites f2 f1 f2 X f1 f2 f1 Transmit failover control to repeater

Automated local repeater failover was the next step in repeater control. Two repeaters receive all remote station data. – Each repeater has a separate pass/block list. – Data received from sensor in list is repeated. – Base station receives separate data from both repeaters. Advantages – If one repeater fails, surviving repeater takes local control and repeats all data. – No operator action required to execute local failover command.

Teamed repeaters continuously check each others health. Health check must use radio. – Test receiver on other repeater. – Test transmitter on other repeater. Multiple check-in failure required for failover – Transmit check-in every 15 minutes. – Execute failover if no check-in for 1 hour. Repeater check-in not repeated. – Base station does not receive repeater check-in reports.

Repeater Health Radio Check-in Repeater 1 transmits a check-in ID. – Check-in ID (903) transmitted every 15 minutes. – Repeater 2 responds by transmitting a check-in received response ID (904) back to repeater 1. – Repeater 1 resets the failover timeout counter. Repeater 2 transmits a check-in ID. – Check-in ID (913) transmitted every 15 minutes. – Repeater 1 responds by transmitting a check-in received response ID (914) back to repeater 2. – Repeater 2 resets the failover timeout counter.

Repeater Distributed Load with Automated Check-in. Alert Base Station Alert Decoder Alert Receiver Peavine Peak Slide Mountain NWS Reno, NV Remote sites f2 f1 f2 f1 Check-in

Repeater Failover Failover repeater on check-in timeout (1 hour) – Load failover configuration. – Failover state ID (902) transmitted to base station. – Failover configuration repeats all sensor data. Monitor other repeater check-in for recovery. – Increment recovery count for each check-in. – After 4 check-in reports received, restore repeater teaming. – After timeout on check-in report, reset restore count.

Single Repeater in Failover by Automated Control Passes all Remote Data. Alert Base Station Alert Decoder Alert Receiver Peavine Peak Slide Mountain NWS Reno, NV Remote sites f1 f2 f1 Check-in Failed X X

Repeater Recovery Repeater recovery after 4 check-ins succeed. – Load normal configuration. – Repeater status set to normal. – Repeater status transmit to base station. – Normal configuration repeats selected sensor data. Restart repeater health radio check-in. – Transmit check-in every 15 minutes. – Execute failover if no check-in response after 1 hour.

Repeater Distributed Load Restored after Automated Check-in Recovery Alert Base Station Alert Decoder Alert Receiver Peavine Peak Slide Mountain NWS Reno, NV Remote sites f2 f1 f2 f1 Check-in Restored

Repeater Radio Check-in Control Repeaters have two radios and two antennas. – Receive on omni radio antenna using frequency f1. – Transmit on directional antenna using frequency f2. Repeater check-in on receive frequency. – Repeater 1 transmits check-in on receive radio using frequency f1. – Repeater 2 responds to check-in on receive radio using frequency f1. Repeater receive radio control. – Use repeater digital output to switch transmit to receive radio.

Future Enhancements Planned Repeaters are Alert2 ready – Use Alert2 protocol to transmit repeated data to base station. – When low power Alert2 receiver available, switch remote transmitters and repeater receive protocol to Alert2.

Other Enhancements Possible Add wired or wireless internet access to repeaters. – Provide an alternate communication pathway to the base station. – Allow remote repeater testing and configuration programming. – Retrieve received data logged in repeater.

Thank you You can download this presentation from: HydroLynx Systems, Inc. 950 Riverside Pkwy., #10 West Sacramento, CA