GPS is an amazing technology and this board lets you harness it to have a very accurate clock (frequency reference) in your own house.
I liked this device in particular because simply by recompiling the firmware I could select the exact RF frequency in Hz. So I've used it as a frequency reference for a 1960s frequency meter (1MHz), a 1970s quartz watch tester (4.32MHz), and even to create a test signal for said watch tester (1Hz, 5Hz, 360Hz). It is very satisfying to re-tune these old devices' OCXOs.
The author has been responsive to my questions, including when I had some early trouble due to my choice of USB-Serial dongle. Beware that the power requirements of this board are too great to be met by certain "3.3V" USB-Serial adapters, which may not be able to supply a full 70mA of current to the device. When this happens, it appears that the microcontroller repeatedly enters "brown out" mode and not work properly or reprogram from within the Arduino environment. If the green "GPS Power" LED blinks this may be happening to you. In my case, a "5V" USB-serial adapter worked great. (contrary to what another reviewer stated, a USB-serial adapter was not included in my order. The adapters I tried are FTDI-based adapters sold by SparkFun probably 5-8 years ago)
Fast shipment, outstanding support. High quality product, well designed and manufactured. Good versatility, easily integrated in larger projects. Very good price-quality trade-off (so far the most affordable high-stability frequency reference available to my knowledge).
The products arrived fast and well packaged. Functionality is consistent with description. Support is really outstanding - customizing the code and a free USB interface were included in the package. Documentation and schematics updated and well organized. Highly recommended maker!
The ARB on my bench can only output 5 MHz (20 MHz sine waves.) So I needed something that could provide a higher frequency output. My current scope is limited to a couple hundred megahertz. The signal quality at 100MHz is on-part with my expectations and works for my use. I really like the Serial interface. It simplifies the control. I'm interested in I2C for automation, but for now, simple ASCII commands works for me.
Great job on the board, thanks!