ALERT Serial Interface (H-264)

WaterLOG ALERT Serial Interface (H-264)

The ALERT Serial Interface (H-264) is field friendly, with its user selectable ALERT transmission preamble length (from 101 to 665 milliseconds) allowing system design for maximum channel capacity with and without a repeater. Its ultra low power consumption will provide absolute minimum drain from the battery to get you through, no problem. And to add to its efficiency, the hardware watchdog timer guards against the transmitter being on too long. To sum it all up, this device controls power, audio and PTT lines of an attached transmitter, to send a standard ALERT binary format transmission while maintaining impressive power supply usage.

  • Features
  • Specifications

The ALERT Serial Interface (H-264) accepts ALERT ID and data information and automatically buffers, parses, and converts them to 300 baud FSK audio signals in binary ALERT format. Combine this product with any XL Series product to convert ASCII ALERT format input to binary ALERT transmission.

other features

  • User selectable serial input
  • Double buffered serial interface
  • Each buffer accepts up to 10 serial input ALERT messages for conversion and transmittion in a single ALERT transmission
  • Robust ESD and over-voltage protection on serial and battery supply
  • 12-second duty cycle timer protects transmitter and ensures no single unit saturates a channel
Serial Input
RS-232 Level (negative logic) 2 wire input (Data & Gnd)
Baud Rate DIP switch selectable: 300, 1200 or 4800

Data bits, no parity bit, 1 stop bit.

Input Message Format ASCII ALERT format (8 bytes for each ID+Data message)
Binary ALERT Format 4 bytes for each ID+Data message
ESD Protection +/- 15kV - Human Body Model; +/- 8kV – IEC1000-4-2, Contact Discharge; +/- 15kV – IEC 1000-4-2, Air Gap Discharge.
Test Switch Input (forces test transmission)
Contact Closure 2 wire input switch interface; transmission on contact "break"
Open Time Minimum open time 2 milliseconds; RC & Schmitt trigger debounced.
Over-Voltage Protection 100 ohm + 10V bidirectional 400 mW zener diode
EDS Protection Exceeds JESD 22: 2000-V Human Body Model (A114-A); 200-V Machine Model (A115-A); 1000-V Charged Device Model (C101).
Size 10.0 cm x 6.20 cm
Mounting Holes 4, (0.381 cm diameter, designed for M3x0.5mm mounting screw clearance)
2 located 0.40 cm from top edge and 0.40 cm from the right side
2 located 0.40 cm from bottom edge and 2.00 cm from the left side

Connectors Screw terminal connector rated 125 V DC, 6 A, wire size AWG 28-16, 3.5 mm spacing, 5.5 mm wire strip length
2 pin battery input (left edge),
4 pin transmitter I/O (left edge),
4 pin serial input (right edge)
0.025" gold plate square post, 0.1" on centers; rated 500 V DC, 2.5 A

2 pin test switch input header (right edge)
4 pin AuxRS232 header (right edge)

Reset Switch Momentary, 6.5mm x 6.5 mm, tactile switch
Supply Current
Idle (waiting for serial input) 9 uA TDB
Buffer Message Conversion 320 uA TDB
High speed processing (ADC) 2.8 mA TDB
ALERT transmission (with LEDs & audio filter on) 10 mA TDB
(Supply Current ASI only, with nominal 12 V DC input)
ALERT Transmitter Interface
4 Wire Interface Switched Battery Power, Gnd, Push To Talk, and Audio)
Switched Battery Power

Low dropout high side power switch: typically < 0.05 V drop (1 A), max TBD.

High current rating: min 2 A at 18 V continuous without additional heat sink.

High breakdown voltage rating: 30 V.

PTT Output

Open collector NPN output, no pull up; on ("current sink) for "Push to Talk".

200 mA max current; V(CE) typically 0.3 V at 50 mA.

Audio Tone Output AC coupled (non-polarized 1 uF capacitive coupling).
200 mV RMS, +/- TBD%; (factory settable for 50 - 707 mV RMS).
FSK tones: Mark - 2140 Hz, Space - 1920 Hz, +/- 0.05%.
3 pole low pass FSK filter: typical: 3rd harmonics attenuated 30 dB, min TBD
No spurious transitions at bit period transitions
All Outputs RF attenuated for noise control (in line ferrite bead, nominal 100 ohms series resistance at 100 MHz – 500 MHz).
Transmission Indicators Green LED on Switched Battery Power output
Red LED on "Push to Talk" output.
General Specifications
Operating Temperature -40 ° to +85 ° C
Relative Humidity 10% to 95% non-condensing
Warranty The WaterLOG® H-264 is warranted against defects in materials and workmanship for twenty-four months from date of shipment.

Options & Accessories


Antenna cable. BNC Male/N Male. 20 ft. (6.1 m)


168-174 MHz ALERT Antenna