DXpatrol GPSDO 2.0 User Manual
- June 6, 2024
- DXpatrol
Table of Contents
10 000 000Hz GPSDO 2.0 Reference from DXPatrol
fig 1: front panel
This is our new issue, a low-cost GPSDO developed for the most rigorous and
demanding microwave enthusiasts.
The DXpatrol GPSDO uses an internal GPS reference original U-Blox 7N
controlling a 10Mhz CTI – OCXO 0,05ppb * Square wave Oscillator
Features:
- New Oled Display data presentation
- Ultra-High accurate UTC Clock
- Local GPS coordinates the presentation
- Number of satellites in range
- Wait/Lock indication.
- GPS, Galileo, Glonass receiver
- 4 ( 3+1) Outputs 10MHz 1.5vpp
- 3 Sine Wave outputs A+B+C ~ 7dBm
- 1 Square Wave output sqr
- Duty cycle 50%
- Phase Noise @ 1Hz -80dBc/Hz
- Phase Noise @ 10Hz -120dBc/Hz
- Phase Noise @ 1KHz -145dBc/Hz
- Phase Noise @ 10KHz – 150dBc/Hz
- Second harmonic < 51dBs
- Third harmonic < 56dBs
- Turn ON time ~ 5 minutes
- Working Temperature range 0ºC to 75ºC
- Operating Temperature ~50º C (OCXO)
- Supply voltage 8V to 14V
- Current 600mA first minute, 270mA after lock
- Dimensions metal case : 84mm/71mm/25mm
fig 2: back panel.
Fig 3: Sin Wave outputs ABC
fig 4: Square Wave output
How it works.
New version 2.0 Dxpatrol GPSDO has an internal ATMega microprocessor
programmed to communicate with the Ublox module and present several GPS-NMEA
pieces of information on an Oled display.
Useful information as your local geographic coordinates, UTC high precision
time
Clock and the number of satellites in range.
The U-Blox GPS receiver is instructed by Atmega to generate a 1000PPS
frequency on its output.
( Due to the very high Jitter these modules produce, the signal sharpness was
highly improved with a Schmitt Trigger to get a clean 1kHz square wave.)
The OCXO 10Mhz passes through a chain of dividers so we had a 1000Hz to
compare on a Phase Lock loop CD4046.
Fig 5: starting ON, no GPS received or no antenna connected.
Fig 6: UTC time clock detected, waiting for more satellites.
Fig 7: 6 satellites in range, clock and coordinates detected. OCXO warming up.
Fig 8 : Lock complete, ready to use
Fig 9 schematic
Operating
This GPSDO is programmed in Hotstart mode. This means, even without an antenna
or any GPS signal received, the GPSDO will yet have a fair and accurate 10Mhz
signal on its outputs.
However, as we are using an internal OCXO, Oven Controlled Oscillator, the
internal heater will take about 5 minutes to achieve the operating temperature
– 50ºC ( this means you will feel the box a bit warm. That is normal )
After connecting the supply, the display will show the logo Dxpatrol for 2
seconds.
If any satellite is detected, UTC time will be shown, usually after 5 seconds.
Acquiring position will be displayed until valid coordination is received from
GPS.
OCXO Oven Oscillator will be in warming period for a few minutes and Wait to
flash will be shown.
After a few minutes, a Lock indication will take place and GPSDO is ready to
use.
Fig 10: SA signal reading @ 100Khz span.
Fig 11 Second harmonic -43dBm
Fig 12 Third harmonic -49dBm
Fig 13 Frequency accurate
FIG 13 ON0EME reception using Dxpatrol GPSDO as reference.
António Matias
www.dxpatrol.pt technical mails
[email protected] or commercial
[email protected]