Difference between revisions of "GPS Frequency Standard"
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** [https://github.com/land-boards/QT-Py/blob/main/CircuitPython/Seeed_XIAO_RP2040/GPS_004.py CircuitPython code] fits into [[QT Py (SAMD based)]] but a [[QT Py (RP2040 based)]] could be used | ** [https://github.com/land-boards/QT-Py/blob/main/CircuitPython/Seeed_XIAO_RP2040/GPS_004.py CircuitPython code] fits into [[QT Py (SAMD based)]] but a [[QT Py (RP2040 based)]] could be used | ||
** 3.3V, 40 MHz | ** 3.3V, 40 MHz | ||
− | * Modified [[PulseGen]] | + | * Modified [[PulseGen]] card |
− | ** | + | ** Oscillator circuit removed (not used as pulse generator) |
− | ** Receives input from GPS output and | + | ** Receives input from GPS output and drives 50 Ohm output on BNC |
* Status LED | * Status LED | ||
** Blinks in for 1 second at power up | ** Blinks in for 1 second at power up | ||
− | ** | + | ** Goes off until serial communications are working |
− | ** Blinks on-off while waiting for Satellite | + | ** Blinks on-off as data is received from GPS while waiting for Satellite signal lock |
− | ** | + | ** LED is on solid once output is enabled |
* Fits into Aluminum Project Box Enclosure DIY 100*76*35mm - [https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=100*76*35mm+aluminum&_sacat=0&LH_TitleDesc=0&_odkw=100*76*35mm+Aluminum+PCB+Instrument+Box+Enclosure+Electronic+Project+Case+Set&_id=174408274566 ebay search] | * Fits into Aluminum Project Box Enclosure DIY 100*76*35mm - [https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=100*76*35mm+aluminum&_sacat=0&LH_TitleDesc=0&_odkw=100*76*35mm+Aluminum+PCB+Instrument+Box+Enclosure+Electronic+Project+Case+Set&_id=174408274566 ebay search] | ||
* [http://www.scullcom.uk/design-build-a-gps-locked-frequency-standard-part-4/ Inspired by] | * [http://www.scullcom.uk/design-build-a-gps-locked-frequency-standard-part-4/ Inspired by] |
Revision as of 19:17, 26 June 2022
Build V2
Stand-alone design does not require PC. Generates a 10 MHz output after satellite lock.
- NEO-7M GPS
- QTPy49 card
- CircuitPython code fits into QT Py (SAMD based) but a QT Py (RP2040 based) could be used
- 3.3V, 40 MHz
- Modified PulseGen card
- Oscillator circuit removed (not used as pulse generator)
- Receives input from GPS output and drives 50 Ohm output on BNC
- Status LED
- Blinks in for 1 second at power up
- Goes off until serial communications are working
- Blinks on-off as data is received from GPS while waiting for Satellite signal lock
- LED is on solid once output is enabled
- Fits into Aluminum Project Box Enclosure DIY 100*76*35mm - ebay search
- Inspired by
Wiring
# Wiring # Signal Color From To # GND Black QTPy49 J4-1 GPS pin 4 # VCC Red QTPy49 J4-2 GPS pin 5 # QTPy>GPS Blue QTPy49 J4-3 GPS pin 2 # GPS>QTPy White QTPy49 J4-4 GPS pin 3 # GND Black QTPy49 J5-1 PulseGen GND # VCC Red QTPy49 J5-2 PulseGen VCC # PPS Purple GPU pin 1 PulseGen In # LED-VCC Red QTPy49 J9-3 D0 # LED-GND Black QTPy49 J9-1 GND
Code
- GPS_004.py - Final working code
- Saved as code.py to auto-run
- GPS_003.py - Capture data from GPS module a line at a time - helpful for debugging
- GPS_002.py - Read 32 bytes at a time
- GPS_001.py - Formatted stings output
Build V1
Requires PC running ublox software on PC to set output.
- NEO-7M GPS
- FTDI-49MM card set to 3.3V signal levels
- PulseGen modified to receive output from GPS and drive 50 Ohm output out of the box
- Fits into Aluminum Project Box Enclosure DIY 100*76*35mm - ebay search
GPS
- GPS Satellite Positioning Module NEO7M UBLOX
- Specifications:
- Working Voltage: 3.3v-5.0v
- Color: As Picture Shown
- Description:
- With micro USB interface, you can debug GPS module with ordinary phone data cable, no longer need to use USB-TTL and other tools.
- TTL interface is reserved to facilitate the use of USB-TTL or external microcontroller to control and receive GPS information.
- Ceramic antenna on module board, no GPS external antenna can be used to search for stars.
- Reserved SMA antenna interface, can use external antenna, star search ability is stronger.
Reference Materials
- Design & Build a GPS locked Frequency Standard- Scullcom
- SIMPLE 10 MHZ GPS FREQUENCY STANDARD AND RF GENERATOR
- uses Arduino Nano as FTDI replacement
- An Arduino-based GPS Disciplined Oscillator
- An Arduino Version of Brooks Shera's GPSDO
- Simulating the Brooks Shera (W5OJM) GPSDO Algorithm
Videos