Line-of-Sight Radio Series (H-4400)

WaterLOG Line-of-Sight Radio Series (H-4400)

Using modern spread spectrum technology, the Line-of-Sight Radio series (H-4400) provides highly secure frequency with interference immunity. Specifically designed for transparent SDI-12 compliant communication, the Radio link is compatible with any WaterLOG data logger at one or more remote sites. And, to make things even better, each remote site can also have multiple SDI-12 sensors. With ten models to choose from, each offering a master to slave option, prefered frequency and location are taken into account to fit your unique site application.

  • Features
  • Specifications

The Line-of-Sight Radio Series (H-4400) combines ruggedness and reliability in radio bridges that are capable of communicating via radio link or repeating radio receiver.

  • Easy to use radio link
  • Compatible with all WaterLOG data loggers
  • Each remote site can have multiple SDI-12 sensors
  • Uses modern frequency hopping spread spectrum telemetry radios
  • Provides transparent SDI-12 compliant communication between you data recorder and one or more remote sites

> Learn more about our SDI-12 Interfaces.

Quick SpecsRS-232SDI MasterSDI Slave

250 mW (24 dBM)

1 Watt


H-424-MS Yes Yes Yes
H-424-MS-2.4 Yes Yes Yes
H-4401-M Yes Yes
H-4401-S Yes Yes
H-4402-M Yes Yes
H-4402-S Yes Yes
H-4410-M Yes Yes Yes
H-4410-S Yes Yes Yes
H-4411-M Yes Yes Yes
H-4411-S Yes Yes Yes
Master SDI-12
Slave SDI-12
Type Transparent SDI-12 works with all SDI-12 commands including extended and V1.2 commands
Requirements Data logger must support multiple (3/3) SDI-12 breaks with retries. One SDI-12 address must be assigned to the H-424 itself (facilitates awakening the master and slaves low power sleep)
Input Range 902.5 to 927.5 MHz
2.4 GHz (H-424-MS-2.4 model only)
Line of Sight 5+ miles (depending on antenna and site conditions)
Modulation Type Direct sequence spread spectrum
Enclosure Size 8 in. W x 6 in. L x 4 in. H
Enclosure Material Fiberglass NEMA 4 Hinged screw cover
Input Voltage 9.6 to 18 V DC
Transmission 100 mW (=20dBM)
Control Remote station uses programmable sleep / wake to detect carrier
H-424 Connection Switchcraft EN3P4M (4-pin male)
Mate Connection Switchcraft EN3C4F (4-pin female)
RF Connector Reverse Type -TNC
Receive Sensitivity -110 dBM
Standby Current 200 µa (sleep)
Receive Current 30 mA (vary with model)
Transmit Current 60 mA (vary with model)
Average Current Less than 2.0 mA
SDI-12 Output
Baud Rate 1200
Protocol SDI-12, 7-bit even parity, 1 stop bit (H-424-MS models and -S versions of H-4400 Series models only)
Voltage Levels

Minimum high 3.5 V

Maximum low 0.8 V

General Specifications
Operating Temperature -40 ° to +60 ° C
Storage Temperature -50 ° to 70 ° C
Humidity 0 to 100% non-condensing
Type Frequency hopping spread spectrum transceiver
Warranty The WaterLOG® H-4400 Line-of-Sight Series is warranted against defects in materials and workmanship for twenty-four months from date of shipment.

Options & Accessories


Antenna - OMNI - Whip


Antenna - OMNI High Gain Whip, 5 Watt


Antenna - OMNI - Whip w/Mount & 15 ft. (4.6 m) cable


Antenna - Yagi, 6dB


Antenna - Yagi High Gain, 13dB


Cable - 15 ft. (4.6 m), Reverse TNC/Reverse TNC

H-440-C-1 (-50, -75)

Cable - 50 ft. (15.2 m), Reverse TNC/Reverse TNC;

Cable - 75 ft. (22.9 m), Reverse TNC/Reverse TNC


Cable - 15 ft. (4.6 m), Reverse TNC to N Female

H-440-C-1-5 (-50, -75)

Cable - 50 ft. (15.2 m), Reverse TNC to N Female;

Cable - 75 ft. (22.9 m), Reverse TNC to N Female


Cable - 15 ft. (4.6 m), Reverse TNC/N Male

H-440-C-2 (-50, -75)

Cable - 50 ft. (15.2 m), Reverse TNC/N Male;

Cable - 75 ft. (22.9 m), Reverse TNC/N Male