Frequency agile GPS reference for less than $30
- Slightly off-topic perhaps, but many Softrocks owners are challenged to get and stay on frequency. Two modules from eBay can be easily and simply configured to produce a GPS disciplined oscillator that can output any fundamental frequency from 0.25 Hz to 10 MHz with GPS precision. Strong harmonics from the square wave output are useful well into the GHZ range. The module can be configured via the USB interface with downloaded software from u-Blox, the module manufacturer. The configuration is saved in battery backed up RAM so the USB interface can be disconnected once programmed.
An incredible value to have GPS precision in the shack.
The modules can be found on eBay here and the attached picture shows my configuration. A really cheap, fun, and useful project!
I finally got my GPS reference in a case. I've added a lithium coin battery for config backup and battery power when not plugged into USB. I used a LE50 LDO regulator for 5v supply which is disabled when USB power is applied. I removed the onboard LED and attached an external one.
I also removed the UART connector and replaced it with a USB cable.
Attached is a few pics and a schematic.