Novatel SMART ANTENNA - Manual (Page 21)

Operation Chapter 3
SMART ANTENNA User Manual Rev 6 21
3.1 Communications with the Receiver
Communication with the receiver is straightforward, and consists of issuing commands through the
communication ports from an external serial communications device. This could be either a terminal or a PC
that is directly connected to the COM1 serial port of the receiver using a straight serial cable. If you are using
an RS-232 communications device such as a radio modem, connect it to the receiver’s COM2 (DGPS IN) port
by means of a radio serial cable. For information about input and output messages that are useful for basic
operation of the receiver, refer to the SUPERSTAR II Firmware Reference Manual. See also the StarView
examples in Section 3.2, Getting Started starting on Page 21.
3.1.1 Serial Port Default Settings
The receiver communicates with your PC or terminal through a serial port. For communication to occur, both
the receiver and the operator interface have to be configured properly. The receiver’s COM1 and COM2
(DGPS IN) default port settings are as follows:
• 9600 bps, no parity, 8 data bits, 1 stop bit, no handshaking, echo off
Changing the default baud setting requires using Message ID# 110, Configure COM1 Port Mode, which is
described in the SUPERSTAR II Firmware Reference Manual. It is recommended that you become thoroughly
familiar with the input and output messages detailed in the above reference manual to ensure maximum
utilization of the receiver’s capabilities.
The default data transfer rate is 9600 bps unless your receiver has Carrier Phase Output (CP) capability
with 19200 bps as the default. A list of models may be found in Appendix A of the SUPERSTAR II
Firmware Reference Manual, see Reference [6] on Page 12.
The data transfer rate you choose determines how fast information is transmitted. Take for example a message
whose byte count is 96. The default port settings allow 10 bits/byte. It therefore takes 960 bits per message. To
get 10 messages per second then requires 9600 bps. Please also remember that even if you set the bps to 9600
the actual data transfer rate will be less and depends on the number of satellites being tracked, filters in use, and
idle time. It is therefore suggested that you leave yourself a margin when choosing a data rate.
CAUTION: Although the receiver can operate at data transfer rates as low as 300 bps, this is not
desirable. For example, if several data messages are active (that is, a significant amount of
information needs to be transmitted every second) but the bit rate is set too low, data will
overflow the serial port buffers, cause an error condition in the receiver status and result in
lost data.
3.2 Getting Started
Included with your receiver is NovAtel’s StarView program. StarView is a Windows-based graphical user
interface which allows you to access the receiver's many features without struggling with communications
protocol or writing special software. The information is displayed in windows accessed from the Window
menu. For example, to show details of the GPS satellites being tracked, select Satellites | Status from the
Window menu. Select Navigation | LLH Solution from the Window menu to display the position of the receiver
in LLH (latitude, longitude and height) coordinates.
WARNING: If you are using StarView, ensure the Power Settings on your PC are not set to go into
Hibernate or Standby modes. Data will be lost if one of these modes occurs during a
logging session.