Universal Clock Generator Based on GPS

Figure 1 

Building a universal clock generator would provide extremely accurate timing for GPS satellites and GPS Ground Segment in order for GPS users to be aware of their Earth position.

The types of clock generators could be Rubidium or Cesium which are used for generating and synchronizing the signals that the navigator obtains from the orbiting GPS satellites. Time marks and high frequency clock references are extracted by many commercial systems using the same GPS signals.

A 1pps output is being provided by almost all commercially available GPS modules while synchronized with GPS time. Accurate high frequency clocks could be generated using the pulse as reference. However, the short-term jitter affecting the 1pps signal has to be addressed by a special design. The higher frequency synchronization signal is used an alternate and simpler solution. The device can be completed by n ideal use of a PLL frequency multiplier with a loop bandwidth in the range of 50-100MHz.

The NMEA sentences from GPS module is received by the PIC16F628 microcontroller and displays them on the LCD screen. A more graphical interpretation of NMEA can be obtained by providing an RS232 connection to a PC.

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