CG2-SHANTY • CompactPCI GPS Receiver/Clock
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EKF Elektronik GmbH • Philipp-Reis-Str. 4 • 59065 HAMM • Germany
Tel. +49 (0)2381/6890-0 • Fax. +49 (0)2381/6890-90 • E-Mail [email protected] • Internet www.ekf.com
The CG2-SHANTY incorporates a highly
integrated digital GPS receiver, which uses
the SiRFstarII chipset and is accommodated
on a miniature daughter board as an
exchangeable mezzanine sub-assembly. The
12-channel architecture provides rapid Time-
To-First-Fix (TTFF) under all startup
conditions. The receiver decodes and
processes signals from all visible GPS
satellites, thereby producing a highly
accurate and robust navigation solution. In a
typical situation, a horizontal accuracy better
than 3m can be achieved. The external GPS
antenna connects to the front panel
mounted SMB style jack and must have
reasonable visibility of the sky. For best
performance, use an active antenna (+5V or
+3.3V selectable power), in particular for a
cable length of 3m and beyond.
Under certain conditions, differential RTCM
SC-104 data capability can further enhance
the positioning accuracy. For that, the CG2-
SHANTY is equipped with an additional serial
port for communication with an external
DGPS (Differential GPS) receiver.
With respect to the CompactPCI bus, the
CG2-SHANTY appears as a quad serial
adapter card, based on 16C550 compatible
PCI UARTs (which are also known as COM-
ports in a typical PC). The first serial port of
the CG2-SHANTY is for on-board use only. It
serves as the communications interface to
the GPS receiver. Commands and data can
be sent to and received from the GPS
daughter board according to the
NMEA-0183 standard protocol. When
operated in NMEA ASCII mode, the
moderate transmission rate of 4800bps cares
for low interrupt load of the system host. As
an option, the SiRF binary raw data protocol
allows much higher throughput.
The second serial port is intended either as
external DGPS interface (read only), or as a
general purpose RS-232E communications
channel. The wiring of the front panel
mounted 9-pin male D-SUB connector is
identical to desktop PC COM ports. When
receiving differential DGPS data at 9600bps
according to the RTCM SC-104 standard, the
GPS daughter module uses this information
for its internal calculations to sharpen the
positioning data. The second serial interface
is also directly readable by the system host.
Programs as LabMon can process DGPS data
in parallel to the GPS receiver data for
presentation.
The remaining two serial ports are currently
not in use. However, the CG2-SHANTY can
be optionally equipped with connectors
suitable for attachment of external PHY
transceiver modules (EKF CU-series, e.g. CU7-
RS485).
The CG2-SHANTY provides a pulse output
(1pps) with better than 1us timing accuracy,
which can be used to generate interrupts in
order to synchronize processes.
Available by download, the EKF utility
WinGPS displays the GPS data and allows to
synchronize the system clock with the UTC
(Universal Time Coordinated). In addition,
the Internet is full of GPS shareware tools.
The common basis of most applications is
the NMEA-0183 protocol, so that they
should be usable with the CG2-SHANTY
without any modification. Furthermore, there
are various commercial GPS application
programs available, mostly allowing
comfortable cartographical visualization.
