This product is no longer available and has been replaced by: RF452.
RF451 900 MHz 1 W Spread-Spectrum Radio
Services Available
Repair Yes
Free Support Yes


The RF451 is a powerful 900 MHz serial radio that is well suited for wireless networking with PakBus data loggers that are located miles apart. The RF451 is a 902 to 928 MHz frequency-hopping spread-spectrum radio. The radio features high noise immunity, fast serial data transfer speeds, and the maximum transmit power allowed by the FCC in an effort to provide reliable, hassle-free operation.

Constructing a network using RF451 radios is a simple, easy-to-do configuration process. To construct a network, connect one radio to a PC and configure it as the gateway radio. Then connect a second radio to a data logger. The link can be treated as a high-speed, multi-drop serial connection.

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Benefits and Features

  • Does not require individual operational license in several regions around the world
  • Long-distance, high-speed, serial communication with battery-operated stations
  • Each radio capable of performing gateway, remote, or repeater role
  • Remote diagnostics and setup possible with diagnostics cable and software
  • Compatible with existing RF450 and FreeWave FGR radio networks


RF451 front tilt view
RF451 front tilt view
RF451 front tilt view
RF451 front tilt view
RF451 front tilt view
RF451 front/top view
RF451 front view
RF451 back view
RF451 left view
RF451 right view
RF451 top view
RF451 bottom view

Detailed Description

The RF451 is a frequency-hopping spread-spectrum radio, capable of operating between 902 to 928 MHz and transmitting up to 1 Watt (30 dBm). The specific frequencies used may be selected when operating outside the US and Canada to meet local regulations. Additionally, the RF power output may be adjusted to as low as 10 mW via software.

Typical communication distances are greater than 4 miles with up to 60 miles achievable under ideal conditions. Extended communication distances are possible using repeaters. 

The operating frequency band of this radio modem may be shared with other non-licensed services such as cordless telephones and with licensed services including emergency broadcast and air-traffic control.

The RF451 consists of a radio module manufactured by FreeWave Technologies and a Campbell Scientific interface board. It reduces susceptibility to RF interference from other spread-spectrum devices by providing user-selectable frequency hopping patterns. Spread-spectrum radios spread the normally narrowband information signal over a relatively wide band of frequencies. This process allows communications to be more immune to noise and other interference.

RF451 radios, like all FCC Part 15 devices, are not allowed to cause harmful interference to licensed radio communications and must accept any interference that they receive. Most Campbell Scientific users operate in open or remote locations where interference is unlikely. If there is a problem, interference can be reduced using methods such as moving the device, reorienting or using a different type of antenna, or adding RF shielding.

Powering the Radio

At least two radios are required to create a link. The radio may be powered through the dc barrel connector or via a CS I/O connection. When ac power is available, the 15966 wall charger is commonly used. At remote sites, the RF451 typically is powered through the CS I/O or the 14291 field cable.


Campbell Scientific offers a variety of antennas for this radio. The 14204 is a 0 dBd, 1/2 wave omnidirectional whip antenna that connects directly to the radio (no cable required) and can transmit short distances (up to 1 mile). The 15970 dipole antenna includes adhesive for window or wall mounting and a cable for connecting to the radio.

Our higher gain 14221 omnidirectional and 14205 Yagi antennas require a cable to connect them to the radio. The 31314 surge protector is available for radios susceptible to lightning or electrostatic buildup or when the cable length needs to be longer than 3 m (10 ft), as measured between the transceiver and the antenna.


Radio Type Frequency Hopping Spread Spectrum (FHSS)
Frequency 902 to 928 MHz
Country Used In US, Canada, Australia
Power Output 10 to 1,000 mW (user-selectable)
Transmission Distance
  • -Note- Transmission distance assumes line-of-sight and appropriate antenna. Line-of-sight obstructions, RF interference, and antenna type will affect transmission distance.
  • 20.92 to 96.56 km (13 to 60 mi) depending on antenna and line-of-sight
Modulation 2 level GFSK
RF Data Rate 115.2 or 153.6 kbps (selectable speeds)
Occupied Bandwidth 142 kHz (applicable to FCC ID KNYAMM0921TT)
Hopping Patterns 15 per band, 105 total (user-selectable)
Hopping Channels 50 to 111 (user-selectable) applicable to FCC ID KNYAMM0921TT
Frequency Zones 16
Receiver Sensitivity
  • -108 dBm at 115.2 kbps (for 10-4 BER)
  • -103 dBm at 153.6 kbps (for 10-4 BER)
IF Selectivity 40 dB (at fc ± 230 kHz)
Receiver Selectivity 50 dB (at 896 MHz, 935 MHz)
Error Detection 32-bit CRC (retransmit on error)
Data Encryption proprietary spread-spectrum technology
Link Throughput 115.2 kbps (maximum)
RF Connector Reverse Polarity SMA (RPSMA) jack (external antenna required)
CS I/O DB9 M, SDC 7/8/10/11 device
RS-232 DB9 F, DCE
Operating Temperature Range -40° to +85°C
Relative Humidity 0 to 95% RH (non-condensing)
Compliance Information
  • 2329B-AMM0921TT (Industry Canada ([IC])
Average Current Drain (@ 12 Vdc)
  • 650 mA (transmit)
  • 40 mA (receive)
  • 15 mA (idle)
  • 6 mA (sleep)
Communication Ports
  • RS-232 9 pin D female
  • CS I/O 9 pin D male
  • USB Type B jack
Service Requirements Shares frequency with other devices. Must not cause harmful interference to licensed radios. Requires line-of-sight.
Dimensions 13.61 x 2.74 x 7.01 cm (5.36 x 1.08 x 2.76 in.)
Weight 0.18 kg (0.4 lb)


Input Voltage 7 to 28 Vdc
Powered Over CS I/O or barrel plug
Connector Barrel plug, center positive 12 V (used to connect the 14291 Field Power Cable or 15966 ac adapter)


-NOTE- Used for connection to computer for network communications or device configuration. Does not supply enough power for normal operation; RF451 must be powered through dc barrel plug or CS I/O.
Type USB standard B (device only)


Note: The following shows notable compatibility information. It is not a comprehensive list of all compatible or incompatible products.

Data Loggers

Product Compatible Note
CR1000 (retired)
CR10X (retired) -PB option
CR200X (retired)
CR206X (retired) Connects via RS-232; disable internal 900 MHz radio
CR211X (retired) Connects via RS-232; disable internal 900 MHz radio.
CR216X (retired)
CR23X (retired) -PB option
CR295X (retired)
CR300 Connects via RS-232; use a 18663 null modem cable.
CR3000 (retired)
CR350 Connects via RS-232; use a 18663 null modem cable.
CR510 (retired) -PB option
CR6 To integrate the CR6 with the RF451, order the CR6-RF451 option on the CR6 product page.
CR800 (retired)
CR850 (retired)

Additional Compatibility Information

Data Logger Considerations

For non-PakBus data loggers, there is typically only one data logger on the network, as they cannot be uniquely addressed by LoggerNet. The RF451 does not support Modem Enable devices over CS I/O. An RF451 may be connected to a mixed-array data logger (for example, CR10, CR10X) by using an SC932A or SC105 between the data logger's CS I/O port and the RF451's RS-232 port.

Spread-Spectrum Radio Considerations

The RF451 can be used in networks containing RF450 and FreeWave FGR radios. Campbell Scientific does not recommend using the RF451 next to an RF400, RF410, RF401, RF411, RF401A, RF411A, CR205, CR210, CR206(X), CR211(X), AVW206, or AVW211, as it may cause interference that will adversely affect device performance.


RF45x Operating System v.3 (429 KB) 06-16-2023

Current RF451 / RF452 operating system. The Device Configuration Utility is used to update the firmware.

View Update History

Device Configuration Utility v.2.29 (54 MB) 11-15-2023

A software utility used to download operating systems and set up Campbell Scientific hardware. Also will update PakBus Graph and the Network Planner if they have been installed previously by another Campbell Scientific software package.

Supported Operating Systems:

Windows 11 or 10 (Both 32 and 64 bit)

View Update History

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