1pps signal – Motorola Oncore GT User Manual

Page 3

background image

Refer to Figure 2 for the following instructions.

1. Attach the desired antenna connector (typically SMB or BNC female) to one end of the RG-174.
2. On the end of the cable that will connect to the Oncore™ GPS receiver, remove the outside jacket to

approximately 0.75” (2 cm) from the end. Carefully separate the braid of the RG-174 to one side.

3. Remove 1/16” (1.5mm) of the insulator from the center conductor and tin with solder.
4. Twist the braid strands together and cover with shrink tubing, leaving 1/16” (1.5mm) exposed at the

end. Tin the exposed end with solder.

5. Solder the center conductor to the center conductor of the OSX connector as shown in the illustration.
6. Solder the shield of the RG-174 to one of the four shield connections of the OSX connector.

Note: The Oncore™ GPS RF Connector is a M/A-COM #5864-5002-10 (OSX) sub-miniature snap-on.

Figure 2 - Antenna Adapter Connection


If you are really serious about time, a very accurate clock synchronization option is provided by the
constellation of Global Positioning System (GPS) satellites. Each Block II/IIA satellite contains two
cesium (Cs) and two rubidium (Rb) atomic clocks. Each Block IIR satellite contains three Rb atomic
clocks. In addition to helping people on the ground get their navigational fixes, the satellites transmit
precise time pulses synchronized to the on-board atomic clocks.

A one-pulse-per-second signal output by the Oncore™ GPS receiver is synchronized to UTC within a
nominal accuracy of five-hundred nanoseconds—ideal for multi-site synchronization and time-
distribution applications. The accompanying suggested interface schematic includes optional circuitry to
interface the 1PPS pulse to a PC for highly accurate time synchronization of the PC clock.

1PPS Pulse Characteristics:

• 0 to 5 V TTL level pulse
• 1 PPS time mark is synchronous with the mid point of the rising edge of the pulse rising from 0-5 V.
• Rise time is approximately 20 to 30 ns
• 5 V pulse width is approximately 200 ms ± 1 ms
• The falling edge will occur approximately 200 ms after the rising edge
• Accurate to < 500 ns (1 sigma) in stand alone mode (with SA on)

QUICK-START GUIDE, MOTOROLA Oncore™ GT - GPS Module for Embedded OEM