Review on 🌐 High Sensitivity GPS Module Receiver NEO-6M for Arduino GPS, Drone Microcontroller, GPS Receiver, Compatible with STM32, Arduino UNO R3, with Antenna; Navigation Satellite Positioning by Issac Smart

I bought this GPS receiver module to use as a time reference in my digital clock. It catches the satellite perfectly while I'm in my house. I didn't have to change any settings of the GPS module itself. I hooked it up to a NodeMCU esp8266 controller and it worked as expected with the NTP GPS server from the Tasmota firmware. Tasmota does not use the PPS (Pulse Per Second) signal available from this module, so this configuration is not a high-fidelity NTP server. But that is not due to the GPS module. This is the result of Tasmota interacting with the GPS module. I connected it to a Raspberry Pi 3B+ and a Zero W. It worked with both and achieved nanosecond accuracy when using a PPS signal. The Pi 3B+ was more accurate. I believe that's because it has a quad-core processor and can devote one processor entirely to PPS signal monitoring. I only tested the accuracy on the Pis themselves. I haven't tested how accurate NTP clients connecting to the Pi's NTP server can get. I used GPSd and Chrony on Linux to interact with the GPS module. Chrony is an NTP server and can directly access the PPS suite of GPS modules through the /dev/pps0 device provided by the Linux kernel. This only provides an impulse that marks the beginning of the second, but does not indicate the time of day. You need a secondary time source to get the calendar date and time. The GPSd daemon supplies the calendar date and time from the serial port of the GPS modules to the Chrony NTP software. You can configure GPSd to access the /dev/pps0 device, but I don't see any advantage in doing so since Chrony can access it directly. Adding another programming layer between pps and chrony seems like a bad idea. Linux utilities I've found useful to get the GPS module to talk to Chrony and GPSd: ppswatch - make sure /dev/pps0 provides PPS heart rate information - displays info provided by the serial GPS interface can be provided. cgps - Displays information provided by the GPS serial port. ntpshmmon - Shows which SHM ranges are provided by GPSd. This information is used when setting up Chrony.