Advanced Features

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Star Sync GPS Receiver
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ClockWatch Star Sync GPS
Advanced Features

Testing Features
Satellite View
Map Current Location
GPS Setup Features
Run-Time Options
Back-up Timeserver

GPS Test Screen

ClockWatch Star Sync allows you to test to see if the program is able to communicate with a GPS receiver’s data port through the computer’s serial port. After the connection to the GPS is opened, the test screen shows the raw data coming from the GPS, displays the information parsed from the raw data, and shows current satellite activity.

The GPS test is useful in verifying that 1) the GPS is working, 2) the cabling is correct, and 3) the software setup is correct.


Data window: when the connection to the GPS is opened, the test screen shows the raw data strings output by the GPS.

Send field: sends a command to the GPS; after the connection is made, commands can be sent to the GPS to enable/disable options.

Read delay: to slow down the test screens sampling rate of the GPS, slide the control to the right.

Type: NMEA data message type (GSV, RMC, GLL, etc.) last sent by the GPS.

Time: time from the GPS (in UTC).

Date: date from the GPS (at UTC).

Lat: latitude in degrees N/S.

Long: longitude in degrees E/W.

Status: current GPS status when connection is open; status message includes “OPENING PORT,” “AWAITING FIX,” “SATS OK,” etc.

Speed: speed over land as reported by GPS (in miles per hour).

Alt: altitude as reported by GPS (in feet).

Track: track made good, course over ground, degrees true.


Map Current Location  

Star Sync can map the current location over the web (U.S. only). The current location will be mapped using the latitude and longitude output by the GPS on U.S. Census maps and display the map in your web browser.

Satellite View

Star Sync shows a polar view chart of current satellite activity. North is in the 12 o’clock position, East at 3 o’clock, etc. More on satellites...

Satellite PRN number
Elevation over horizon, degrees, 90 degree maximum
Azimuth, degrees True, 000 to 359
- Strength, (C/No) 00-99dB, 0 when not tracking

GPS Setup


The Setup screen lets you configure the GPS to work with the Star Sync software.


Model Number: Choose the model number of the GPS connected to the serial port. If the GPS you are using is not in the list, then you can enter the settings manually.


Serial Port: Select the number of the serial port (or COM port) connected to the GPS.


Baud Rate: Baud rate in bits per second (use 4800). Enter the baud rate as a number. Note: Most GPSs use 4800 baud as a data rate.


Handshaking Options
Handshaking refers to the internal communications protocol implemented in the computer hardware by which data is transferred from the communications port to the GPS.

DSR pulse: Determines whether to have Star Sync wait for a pulse on the DSR line before making a time fix. Pulse-per-second outputs are options on some GPS receivers such as the Gamin 16. This feature requires a custom interface cable between the GPS and PC. Contact Beagle Software for more information.

DTR Enable: Determines whether to enable the Data Terminal Ready (DTR) line during communications. Typically, the Data Terminal Ready signal is sent by a computer to the GPS to indicate that the computer is ready to accept incoming transmission.

Type Handshake: A handshaking protocol is used so data is not lost when it arrives at the communications port.

None: No handshaking.

RTS: RTS/CTS (Request To Send/Clear To Send) handshaking.

Initialization Strings: The initialization strings are optional strings that are sent to the GPS each time ClockWatch starts and before the first time setting is made. The strings can be used to configure the GPS or modify the NMEA strings that are outputted by the receiver. Both strings are optional.

Minimum Time change: Enter the number of milliseconds for the smallest time change for which the clock will be set. This value should be set slightly above the accuracy of the GPS receiver. Set the value high enough so that the clock will not be changed constantly by a small value.

Run-Time Options 

The GPS tab in ClockWatch Options allows you to set how often the computer’s clock is updated from the GPS.

Enable GPS as time base

Checks to use GPS as a time source. This will cause ClockWatch to set the operating system time to the GPS time at the interval specified.

It allows you to specify the Refresh time in minutes, the number of minutes between GPS time readings.


Use external time server as a backup when GPS is unavailable
For the times that the GPS is unavailable, Star Sync can connect to an external time server to synchronize clocks using the settings in the Timeserver tab for which time server to use and how to connect to it. Use the warning settings to determine when the backup time server should be contacted.

  • You can choose to use either an Internet-based time server or contact the NIST directly via a directly dialing modem.
  • You can set time to wait before the backup time server is contacted. For example, you can set Star Sync to contact an external timeserver 1 hour after the last synchronization with GPS.

Don't ever set the clock time back
When checked, this feature allows the computer clock to be set ahead but never back in time. It is intended to accommodate certain applications that rely on a precise chronological order, such as video monitoring or certain database transactions. Note that the vast majority of computer clocks run slow and not fast, making the exercising of this option infrequent.


Activity Logging
Logging allows you to create a permanent record of all time settings made through the GPS.

When selected, the logging of time settings is to the named file. The log shows the results of each reading, regardless if the clock is changed or not. When logging is enabled, the status of each attempt is also shown in the timeserver log window (bottom of 3 windows) on the main ClockWatch screen.


Sample Log file


Synchronization Log          9/6/2001 4:01:06 PM

Date     Time      Difference Accuracy  Status Server

-----    ----      ---------- --------  ------ ------

01-09-06 10:01:06   0         0.0        12    GPS

01-09-06 10:29:03   0.42      0.0        5     GPS

01-09-06 10:30:02   0.47      0.0        5     GPS
01-09-06 10:31:03   0.65      0.0        0     GPS

 explanation of log file columns and status values

For more information

Star Sync Product Information
  Advanced Features
  Star Sync GPS Receiver
    Installation InformationInstallation Video
    Antenna Mounting Options
  Frequently Asked Questions about GPS

Star Sync Main Page
Star Sync Site Index


For more information on Star Sync, please complete the information request form  or call us toll-free at 1-877-845-2549.

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