Difference between revisions of "Frequency Calibration via GPS"
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* Used modified [[PulseGen]] card to drive 50 Ohms, 5V level output | * Used modified [[PulseGen]] card to drive 50 Ohms, 5V level output | ||
| − | ** Remove oscillator circuit | + | ** Remove oscillator circuit parts (R/C) |
| − | ** 5 parallel 74AC14 outputs with 249 ohm resistors on each output | + | ** 5 parallel 74AC14 outputs with 249 ohm series resistors on each output |
* Able to drive long 50 ohm coax | * Able to drive long 50 ohm coax | ||
* Square wave output | * Square wave output | ||
Revision as of 11:23, 22 December 2020
Inexpensive Frequency Standard with output synchronized to GPS satellites,
Contents
Features
- Generates very accurate frequency output
- U-Blox NEO-7M GPS Module
- Remote Amplified GPS Antenna
- FTDI-49MM
- 50 Ohm Output
- Metal enclosure
Parts
GPS
- U-Blox NEO-7M GPS Module
- Programmable frequency from USB
- SMA Female connector
- 5V operation
U-Center Programming Software
- TP5 sets PPS output to "any" frequency
- U-Blox website
- Set to 8 MHz on GPS PPS pin when locked
- Other frequencies have some "jitter" but are still GPS accurate
- Set to 2 Hz on GPS PPS pin when not locked
FTDI
- FTDI-49MM USB to serial interface
- U-Center communicates with the GPS over this interface
- Tx/Rx LEDs
- 49x49mm
50 Ohm Driver (Not Required - nice to have)
- Used modified PulseGen card to drive 50 Ohms, 5V level output
- Remove oscillator circuit parts (R/C)
- 5 parallel 74AC14 outputs with 249 ohm series resistors on each output
- Able to drive long 50 ohm coax
- Square wave output
- Very fast edges
Videos
- This is the approach I followed
- GPSDO vs Rubidium Frequency Standard
