GPS Frequency Standard

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GPS Freq Std P18490-720px.jpg

Build V2 Features[edit]

Stand-alone design does not require PC. Generates a 10 MHz output after satellite lock.

Hardware[edit]

QTPy49 Card[edit]

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GPS Card[edit]

  • GPS Satellite Positioning Module NEO7M UBLOX Module
  • 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.

GPS NEO-7M-03.PNG

50 Ohm Driver Card[edit]

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DRIVE50 P1080480-720PX.jpg

  • Uses DRIVE50 50 Ohm Driver
    • Able to drive long 50 ohm coax
    • 5 parallel 74AC14 outputs with 249 ohm series resistors on each output
    • Square wave output
    • Very fast edges
    • BNC is high quality (Amphenol) connector

Alternate (Previous) Driver Design[edit]

  • Previous design used modified PulseGen card to drive 50 Ohms at 3.3V level output
    • Remove oscillator circuit parts (R/C)
    • Only 1 BNC high quality (Amphenol) connector
    • Wire from GPS PPS pin attached as below
    • Use 1x2 pin header for power instead of 5MM Terminal Blocks

PulseGen Mod P18338-720px.jpg

  • Schematic

PulseGen Mods.PNG

Wiring[edit]

  • Dupont headers
    • GPS = 5-pin
    • LED = 3-pin
    • UART = 4-pin
    • DRIVE50 = 3-pin
Signal From To Color
GND QTPy49 J4-1 GPS pin 4 Black
VCC QTPy49 J4-2 GPS pin 5 Red
QTPy>GPS QTPy49 J4-3 GPS pin 2 Blue
GPS>QTPy QTPy49 J4-4 GPS pin 3 White
GND QTPy49 J5-1 DRIVE50 J1-3 GND Black
VCC QTPy49 J5-2 DRIVE50 J1-2 VCC Red
PPS GPU pin 1 DRIVE50 J1-1 In Purple
LED-VCC QTPy49 J9-3 D0 Red
LED-GND QTPy49 J9-1 GND Black

Build V1[edit]

Software[edit]

Enclosure[edit]

  • Fits into Aluminum Project Box Enclosure DIY 100*76*35mm - ebay search
  • White-on-Black P-Touch labels

PulseGen P1080344-720px.jpg

Reference Materials[edit]

Videos[edit]