Plain answers about flood-warning systems

ALERT (Automated Local Evaluation in Real Time) is the radio protocol that flood-warning networks in North America have used since the 1970s: field stations transmit short data bursts the moment something happens — a bucket tip, a level change — so operators see conditions in real time.

ALERT2 is its modern successor and the standard adopted by the National Hydrologic Warning Council. It adds GPS-synchronized TDMA time slots (so two stations never talk over each other), forward error correction (so data survives weak or noisy radio paths), and up to 4800 bps — sixteen times legacy ALERT's 300 baud.

New networks should be ALERT2 — it's the current standard and what receivers, software and federal guidance are built around. If you're adding stations to an existing legacy ALERT network, we build every model in both versions: the legacy model number joins your network as-is, and the /A2 version is the same station with the ALERT2 encoder and GPS receiver.

You can also run mixed during a migration: legacy stations keep reporting to your existing decoder while new ALERT2 stations report to a 5052RD-K-H.

Everything the site needs: the standpipe enclosure, the sensor for that station type, the transmitter with data logging, the radio, the antenna and cable, a 22 Ah gel-cell battery, and a solar panel with regulator. You provide the site, the foundation, and your licensed frequency. The station arrives configured and tested as one unit.

ALERT networks operate on licensed VHF/UHF frequencies, and the radio in your station is factory-tuned to yours — that's why every order asks you to specify it. If your agency already runs a flood-warning network, your radio shop or the network operator will know the frequency.

If you're starting from scratch, frequencies are licensed through the FCC (often with a frequency coordinator's help). Hydrologic warning channels also exist in some regions. Our engineers can point you in the right direction — and if radio licensing isn't practical for your site, stations can report by cellular OP21, Iridium satellite OP22, Wi-Fi OP23 or IP network OP14 instead.

Direction. The 50386 is a one-way reporter: it transmits on events and timed schedules, which is all most flood-warning sites need. The 50388 adds a return path — from the office you can poll the station on demand, change its configuration, and operate control outputs (gates, pumps, signs). Station families follow the platform: 53xx models (5354, 5390, 5381, 5391) are one-way; 58xx models (5854, 5890, 5881, 5891) are two-way.

The transducer measures the water column above it, so the range needs to cover the maximum depth you expect — with headroom for flood stage. As a rule of thumb, 1 PSI is about 2.31 feet of water: a 0–5 PSIG sensor covers roughly 11 ft, 0–15 PSIG about 34 ft, and so on up to 0–300 PSIG. Don't oversize wildly: accuracy is a percentage of full scale, so a sensor matched to your actual stage range gives better resolution. Accuracy classes from ±0.10% to ±1.0% FSO are available — your choice depends on how the data will be used.

Yes — that's the point of the upgrade kits. The 5096/A2 firmware upgrade and 50386/A2-UP kit (ALERT2 encoder, GPS antenna/receiver, lynx386 v2 software) install in the field on existing 50386 transmitters. We recommend refreshing power at the same time with a 5033-0.6B solar panel and 5031-18 battery. Your standpipes, sensors and site work all carry forward.

For most stations the Multi-Sensor Report (MSR3 English or MSR4 metric) is the right answer: compact, preconfigured, efficient. Rain stations can use the Tipping-Bucket Report to capture every individual tip, though on busy repeater networks small buckets in intense rain lengthen messages. The General Sensor Report handles unusual sensors but is easiest to misconfigure. Repeater airtime is shared, so shorter messages help everyone. Your station arrives configured, and we review report types during system design — see configuring stations well for the details.

Three layers: field stations that measure (rain, level, weather), a radio path to get the data home — direct, or through one or more hilltop repeaters 50386P/A2 — and a base station: a receiver/decoder 5052RD-K-H feeding software such as NovaStar5 or your SCADA system. The Product Selector can specify each piece.

Standard tipping buckets only measure liquid. For frozen precipitation you have two options: the 5045 all-weather gauge weighs the catch on a load cell — an antifreeze charge melts snow, sleet and hail as it lands, so every form of precipitation registers — or the 2500E heated tipping bucket melts frozen precipitation with a 120 Vac heater where line power is available. Either way, a 2526 wind screen improves catch accuracy at exposed sites — there's a standpipe mounting kit 2526MK-S for packaged stations.

They're designed for years of unattended operation, but a simple routine keeps data trustworthy: keep the funnel and screen clear of debris, verify gauge accuracy with a 2595 calibrator, inspect the battery and solar panel, and confirm radio reporting at the base. Many agencies do this once or twice a year per site. Options like the slide-in access door 5054SD make frequent service easier.

Pricing is by quote, because nearly every order has site-specific items — radio, frequency, transducer range, options. Build a worksheet with the Product Selector (or just describe your project) and send it to sales@hydrolynx.com, submit the Request Information form, or call 1-916-374-1800. We'll confirm the configuration and return pricing and lead times.

ALERT2 is an open standard, so decoded data feeds NovaStar5 5073NS-5, flood-monitoring software 5073FMD Pro, or your existing SCADA system. Two-way 50388 stations integrate with SCADA for supervisory control. Station setup uses the Toolbox configuration software 5073TBX.