RTK module - cm precision and heading for less than $250

[Sergei Grichine]

RTK becomes more affordable - not so with u-blox X20 yet.

Dual-band antennas are less than $70 each, the module - $106. 

Same from Holybro - in a case and more expensive

I am not sure how good is NMEA protocol (vs u-blox UBX) - but that's manageable, I guess.

There is a configuration tool - Uprecise for Windows

Don't forget a base station or access to an RTK corrections (RTCM) provider ;-)

https://witmotion-sensor.com/products/rtk-gps-gnss-modules-centimeter-level-um982-um980-um960?variant=42873258279109

Best Regards,

-- Sergei

[Chris Albertson]

I’ve been looking at the polar opposite of this.  Rather than asking “Where am I?”  the robot asks "Where is my human?”

This question doesn’t need cm-level answers and I don’t want to spend even $50.     My thoughts are that a robot, to be useful, needs to be as smart as a dog.   I don’t need an AI chatbot because my wristwatch has that built in.  But a robot that is literally “dumber than a dog” can’t do much.   After all, we’d like to say “Hey Robbie, come here” and not “Hey Robbie(navigate(robot,kitchen7));”

So to that end, I found that in their normal operation, all WiFi devices report the WiFi signal strength, and as people move about, they affect the WiFi signals.   If you are smart enough, you can monitor this and track humans by how they affect the WiFi.     I’m not that smart and never would have thought of this, but I found a project where someone got it to work using < $10 microcontrollers.  There are some commercial products too.  Philips calls theirs “motion sense,” and they use a n exiting Zigbee mesh network to track,   It helps that humans are to a first order of approximation, bags of water that walk.  It can turn on lights where you are, and turn them off where you aren’t.   Philips did this literally for free with a firmware upgrade to an existing product. 

On Apr 21, 2026, at 9:17 AM, Sergei Grichine <vital...@gmail.com> wrote:

RTK becomes more affordable - not so with u-blox X20 yet.

Dual-band antennas are less than $70 each, the module - $106. 

Same from Holybro - in a case and more expensive

<image.png>

I am not sure how good is NMEA protocol (vs u-blox UBX) - but that's manageable, I guess.

There is a configuration tool - Uprecise for Windows

Don't forget a base station or access to an RTK corrections (RTCM) provider ;-)

https://witmotion-sensor.com/products/rtk-gps-gnss-modules-centimeter-level-um982-um980-um960?variant=42873258279109

<image.png>

Best Regards,

-- Sergei

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