Motorola Oncore GT User Manual

QUICK START GUIDE

MOTOROLA Oncore™ GT
GPS Module for Embedded OEM

A rugged and reliable eight-channel receiver, the Oncore™ GT provides position and velocity
data anywhere on Earth, at any time of day, in any weather. It also provides accurate time. A
one-pulse-per-second signal output is synchronized to UTC within a nominal accuracy of five
hundred nanoseconds—ideal for multi-site synchronization and time-distribution applications.

Features

• 8-channel parallel receiver, 8 simultaneous satellite vehicles, L1 1575.42 MHz

• Code plus carrier tracking (carrier-aided tracking)

• Velocity: 1000 knots (515 m/s); > 1000 knots at altitudes < 60,000 ft.

• Position filtering

• Antenna current sense circuit

• Operates from +5 Vdc regulated power

• TTL interface to host equipment

• 3-dimensional positioning within 25 meters, SEP (without Selective Availability [SA])

• Latitude, longitude, height, velocity, heading, time, and satellite status information output either
continuously (once per second) or polled

• Differential GPS with Motorola binary corrections

• RTCM SC-104 differential GPS correction input on second comm port

• Motorola binary protocol at 9600 baud

• NMEA 0183 output at 4800 baud: GGA, GLL, GSA, GSV, RMC, VTG, ZDA sentences

• Velocity filtering

• 1PPS output (+/- 500 ns accuracy)

Time To First Fix (TTFF)

• < 15 s typical TTFF-hot (with current almanac, position, time and ephemeris)

• < 45 s typical TTFF-warm (with current almanac, position and time)

• < 90 s typical TTFF-cold

Oncore™ Operation Voltage and Current Ranges

5VDC Main power
Voltage: 4.75 V to 5.25 V
50 mV peak-to-peak ripple
Current: < 0.9 W at 5 V at 25°C with active antenna drawing 20 mA

BATTERY (Externally applied backup power)
Voltage: 2.5 V to 5.25 V
Current: 5 µA typical @ 2.5 V
100 µA typical @ 5.0 V

IMPORTANT NOTICE: The information presented in this document is presented “AS-IS” and
no warranty or guarantee is offered or implied. Nor is any liability assumed for any damages,
either actual or punitive incurred by the use or misuse of the information contained in this
document.

ONCORE™ USER’S GUIDE

The complete Oncore™ User’s Guide is available in Acrobat .pdf file format at the Motorola GPS
products website:

http://www.motorola.com/ies/GPS/products/manual.html

ELECTRICAL CONNECTIONS

The Oncore™ receives electrical power and receives/transmits I/O signals through a 10-pin power & data
connector mounted on the Oncore™. Refer to Figure 1 for pin numbering.

The following table lists the assigned signal connections of the Oncore™ receiver’s power and data
connector.

Pin # Name Description
1
2
3
4
5
6
7
8
9
10

BATTERY Externally applied backup power ( +2.5V to + 5V)
+5V PWR +5 VDC regulated
GROUND Ground (receiver)
VPP Flash memory programming voltage
RTCM IN RTCM input
1PPS One pulse per second signal
1PPS RTN One pulse per second return
TTL TXD Transmit Data 5V logic
TTL RXD Receive Data 5V logic
TTL RTN Transmit/receive return

Table 1 – 10-pin Header Receiver and RS-232 Interface Signals.

Figure 1 - Oncore™ GPS 10 Pin Connector Pinout

ADAPTING THE OSX ANTENNA CONNECTOR

The OSX antenna connector used on the Oncore™ GPS board will normally need to be adapted to an
SMB or BNC connector to match connectors commonly found on GPS antennas. An adapter can easily be
made using a short piece of RG-174 coaxial cable with the desired antenna connector.

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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

1PPS SIGNAL

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 time­distribution 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)

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