A wireless telemetry link for a robot
Range, bandwidth and latency pull in opposite directions. This guide matches the radio to the job and lists the parts for each option.
BeginnerTarget budget €120.00From €30.33 with the cheapest option at every step
1.Wi-Fi for indoor video and ROS traffic
Enough bandwidth for a video stream and a full middleware, and it stops at the walls of the building. Range indoors is a matter of tens of metres and drops fast through concrete. A module with an external antenna connector is worth the small extra cost, since the antenna does more for range than the radio does.
Assembly
- Choose a module with an external antenna connector rather than a PCB trace antenna if range matters.
- Keep the antenna away from motors and power wiring, which are the loudest noise sources on the robot.
- Fix the robot's address, since a telemetry link that moves after every reboot is not usable.
2.LoRa for kilometres of range at low rate
Several kilometres in the open with a few hundred bytes per second. That is enough for position, battery state and commands, and far from enough for video. Duty cycle limits apply in Europe and constrain how often you may transmit.
3.Bluetooth for the configuration link
Ten metres, a phone at the other end and no infrastructure. It suits tuning a parameter or reading a log at the bench, and it is the wrong tool for continuous telemetry.
MouserIn stock
Nessie Circuits RIOTEE_MODULE_10 — Bluetooth Modules - 802.15.1 Battery-free BLE module with a Cortex M4 and support for energy harvesting, energy storage, and power management
€50.74
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NewarkIn stock
RENESAS - DA14586-00F02AT2 - Bluetooth Module, BLE 5.0, Class 2/2.4GHz, -93dBm, 0.9-3.3V, I2C/I2S/SPI/UART, 0.197"x0.197"x0.035"
€5.61$6.47
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4.Antennas
The antenna is the cheapest part of the link and the one that changes the result most. Match the frequency band exactly, keep the connector type consistent, and mount it vertically and clear of metal.
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