Introduction

A lot of very good information on the GPS system is already available on the net, and is not repeated here.  For more see the list with links on this site.

Some time ago i managed to get some GPS receiver modules.  This is the brains of a GPS receiver.  Such a module accepts an antenna on the input side, and produces a serial data stream on the output side.  This serial output contains information on the position and speed of the antenna, the exact time, and more details like what satellites it receives etc.

These Rockwell Jupiter GPS modules were unused and meant to become part of a truck fleet management system.  Despite the fact that these modules were stocked for about 3 years, they are still very potent and quite up-to-date receivers with the following characteristics:

• 12 channel parallel receiver.  The module receives and tracks a maximum of 12 satellites simultaneously.
• 1 PPS output.  This means 1 puls per second.  This pulse starts exactly at the UTS second transition.
• 10 kHz output.  An extremely accurate frequency source, for examply to lock an oscillator as to produce a frequency standard.
• NMEA 0183 v.2.01 serial data output with several configuration possibility's, compatible with all familiar navigation and route planner applications, APRS etc.
• Sensitive enough to be used with a passive antenna, for example a home-brew antenna.
• Separate power supply input for an active antenna.
• Antenna connector is a standard MCX (OSX) connector, which is often used in commercial GPS receivers.  Antenna's with this connector are readily available.
• Extremely well documented. (see downloads)

Some special properties of this GPS module are:

• The interface connector is a somewhat exotic 2mm pitch 20-pin connector.
• There is no backup battery for the real-time clock and memory.  There is a place for a super-capacitor.
• The serial signals are on TTL levels and need to be converted to RS232 levels to be compatible with a serial port of a PC

Because of these properties we designed a support kit.  This kit contains a PCB with components, and has the following specifications:

• Size: 7cm * 11cm, height 2cm incl. GPS module
• Switching power supply to convert 10-25V input to 5V.
• Power supply extensively filtered and protected against overvoltage, pulses and reverse polarity
• Various options jumpers: direct 5V supply or 10-25V unregulated, active/passive GPS antenna, NMEA mode or Rockwell binary mode, 1PPS on RS232 port etc.
• Place for 3.6V NiCd battery for long-term clock&memory backup, or 0,22F supercap on module for approx 48 hours backup.

The PCB fits in a standard Strapu case (125 * 74 * 27 mm) which is also available.

The Rockwell Jupiter GPS module which can be placed on this PCB is also available separately, with a supercap and the 20p 2mm connector.

There is also an active GPS antenna available that can be connected on this kit.

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