Dual Source GPS/DCF77 NTP-Server with AIS and ADS-B receivers: Unterschied zwischen den Versionen

Version vom 10. Dezember 2016, 14:09 Uhr

1 Scope

This project is a continuation of my stream of experiments with the NTP protocol and GPS-disciplined clock models. I need to reference the past projects before we go into details:

• NTP-Server with Raspberry Pi and Trimble Resolution SMT
• NTP-Server with Raspberry Pi and Sure Electronics GPS Eval board

These past projects raised the question, how precise a DCF-77 clock would be. And this project here also needs to be seen in the context of an April 1st joke of Rainer DF2NU, who proposed that DCF-77 can be switched off now because the GPS system is there and it is much more precise. So I started to collect ideas to investigate how less precise a DCF-77 disciplined clock model would be compared to the GPS Pulse Per Second.

In addition to the clock question I was thinking of setting up a pair of receivers for the AIS frames broadcasted around Regensburg by the shipd on the danube and I wanted to receove ADS-B frames. Even though slowly navigating ships allow for some frame processing delay, and in case the delay is a couple of seconds, one would still consider such an application a real time application. A jet plane however travels quite distance in a couple of seconds, so a positioning application would need to add some timestamping logic in order to allow for a realistic position information, particularly if received by multiple receivers.

For this reason it makes perfect sense to add a precise clock to a position frame receiver setup.

2 List of components

• The chassis: http://shop.meconet.de/Gehaeuse/Outdoor/Chassis-Outdoor-CA-OTU-RB-433-RB-435-RB-493-RB-800-3-LAN-4-N-Type-large::111356.html - 72 €
• A Raspberry Pi 3: https://www.amazon.de/Raspberry-Pi-3-Model-B/dp/B01CEFWQFA - 35 €
• SanDisk 32GB MicroSD Card: https://www.amazon.de/SanDisk-Android-microSDHC-Speicherkarte-SD-Adapter/dp/B013UDL5RU/ref=sr_1_1 - 10 €
• GUDE Expert Mouse Clock 0107: https://www.amazon.de/VALUE-Funkuhr-Expert-mouseCLOCK-Kabel/dp/B0049K3ZI6 116 €
• FlightAware Pro Stick USB ADS-B Receiver: https://www.amazon.de/FlightAware-Pro-Stick-ADS-B-Empf%C3%A4nger/dp/B01D1ZAP3C/ref=sr_1_cc_2 - 17 €
• FlightAware ADS-B 1090MHz Band-pass SMA Filter: https://www.amazon.de/ADS-B-1090MHz-Band-pass-SMA-Filter/dp/B010GBQXK8/ref=sr_1_1 20 €
• FlightAware 1090MHz ADS-B Antenne - 66cm / 26in: https://www.amazon.de/1090MHz-ADS-B-Antenne-66cm-26in/dp/B00WZL6WPO/ref=sr_1_cc_1 - 45 €
• Pigtail N - SMA - 3 €
• USB A Extension Male/Female - 3 €
• Passive POE Injector: https://www.amazon.de/PoE-Passiv-Injector-PowerOverEthernet-Spannungsversorgung-WRAP-Boards/dp/B00FXOH4C0/ref=sr_1_24 - 3 €
• DC/DC converter: 3 €
• Ferrite cores: 2 €
• diverse standoff headers, screws: 5 €
• Sparkfun USB2serial 3,3V: https://www.sparkfun.com/products/9873 - 10 €
• Adafruit Ultimate GPS Breakout (66 channel w/10 Hz): http://www.watterott.com/de/Adafruit-Ultimate-GPS-Breakout-66-channel - 45 €
• BMP180 temperature and air pressure sensor: http://www.ebay.de/itm/BMP180-Temperatur-Druck-Modul-/291751659851?hash=item43edc1094b:g:TWoAAOSwc1FXZJQU - 5 €
• MMCX 10cm: 10 €
• FL Pigtail 25cm: 10 €
• AISspotter USB stick: http://busse-yachtshop.de/s/AIS-Empfaenger-im-USB-Stick-Gehaeuse - 99 €
• 2x N/N cable 2m with H155: 10 €
• Marineband radio antenna: 35 €
• diverse PCBs and pin headers: 2 €

~ 560 Euro

The prices are partly a bit over the market, roundet up, so that there are no surprises.

3 Configuration

4 Results

5 Integration

6 Images