Design of Comms Plugin: RF

A project log for Robot Communications Module

Communicate with your robot over long-ranges using a variety of plugins (RF/cellular/laser)

neil-k-sheridanNeil K. Sheridan 03/30/2018 at 18:320 Comments



I've decided the RF plugin should use 433Mhz for serial communication: in order to transmit control commands from base station to robot, and transmit telemetry (GPS, temperature, battery voltage, etc.) from robot to the base station. This is fairly simple, so I won't list the modules.

The RF plugin should use ~2.4Ghz for video transmission from robot to base station. Unfortunately, there is a lot of stuff using 2.4Ghz so there will be interference depending on area. 

I was thinking to try the Synapse RF266PC1 first. This comes with Synapse SNAP network operating system [pdf], an embedded Python virtual machine . So you don't need an MCU on the module. Here's the SNAP SNAPcore firmware primer [pdf]. BUT this has been discontinued! So, instead, I will try the Synapse RF220SU-EU instead. This seems even better! With 4.8km LOS range giving 250Kbps. 

I doubt we are going to get much of range in urban environment at 500Kbps non-LOS! But let's not be put-off, because we would likely have 4G there instead! The RF comms is going to be used in environments that don't have 3G/4G/5G! So probably not many buildings in these places, which means we might even have LOS. And nothing else using 2.4Ghz either!

2.4Ghz Modules

Here are some of the 2.4Ghz modules I've found as candidates for this!

Synapse RF220SU-EU

4.8km range [this is actually LOS outdoors at 250Kbps]

2.4Ghz band operation

250Kbps, 500Kbps, 1Mbps, 2Mbps data rates

Transmit power: +20 dBm

150mA TX at +20 dBm 

22mA RX

U.FL Connector / rp-sma connector for antenna


Nordic Semiconductors nRF24L01+ Single Chip 2.4GHz Transceiver

100m range 

2.4GHz ISM band operation

 250kbps, 1Mbps and 2Mbps on air data

11.3mA TX at 0dBm output power

13.5mA RX at 2Mbps air data rate


[there are supposedly lots of fakes for this chip!]

Synapse RF266PC1 - 2.4GHz (chip antenna)

1200m range (at 250kbps)

so I assume we can get to 2Mbps at shorter ranges

2.4GHz ISM band operation

250kbps, 1Mbps and 2Mbps on air data

Transmit Current (Typ@3.3V) 130mA [TX]
Idle/Receive Current (Typ@3.3V) 25mA [RX]


[possibly discontinued - see the latest modules here ]


1km range 

2.4Ghz ISM band operation

250Kbps / 1Mbps / 2Mbps  data rates

Transmit  100mW (+20dBm) Maximum Transmit Power


MRF24WB0MB/RM -  RF Transceiver Radio Module, 802.11B, U.Fl Connection, 2.483 GHz

[IEEE 802.11 compliant WiFi transceiver module]

400m range

2.483GHz operation

1Mbps/2Mbps data rates

Designed for use with PIC18, PIC24, dsPIC33, and PIC32 MCU's with downloadable TCP/IP stack


 As you can see, we won't be able to transmit HD video over long-distances (1km+) using 2.4GHz. There is nothing to stop us implementing repeater stations however! Exploration robots could deposit their own repeaters as they progress I suppose! All of these modules are low-cost (<£30).