DGPS Decoder

General Description

The Marine Differential GPS (DGPS) system provides the correction values to GPS decoders. SkySweeper DGPS decoder decodes the DGPS message types which will contain the ID, frequency or location information of the transmitting station. The speeds of 100 and 200 bauds are supported. DGPS is based on MSK modulation. The automatic frequency locking is not supported. The frequency can be set by double clicking the mouse on the required frequency position or by setting the default carrier value in the DGPS configuration dialog.

‘Reset’ resets the decoder. Received text can be saved using ‘Save’.

SkySweeper supports both FFT and waterfall display modes for the decoder tuning. The Decoder Spectrum Dialog chapter gives more information about the spectrum display options.

Parameters can be modified by pressing the ‘Config’ button. Note: you can install several decoders in one configuration, if required.

 

Configuration

Pressing the ‘Config’ button opens the following Configuration dialog box.

 

 

Parameters

 

Speed

The modulation speed is selected here. SkySweeper supports 100 baud and 200 baud DGPS decoding.

 

Default Carrier

The modulation center frequency can be predefined here. It can be then changed by mouse, if needed.

 

Raw Binary Data

If this option is selected, the received data is printed in binary format.

 

Raw Hex Data

If this option is selected, the received data is printed in hexadecimal format.

 

Raw Decimal Data

If this option is selected, the received data is printed in decimal format.

 

Message Decoding

If this option is selected, the received data is printed in message format.

 

Print CRC Failed Messages

If this option is selected, the messages which CRC (error checking) has failed will also be printed.

 

Print Time Stamps

If this option is selected, a timestamp is printed before the actual message.

 

Message Print Format

The numeric values in a message can be printed in either decimal or hexadecimal format.

 

FFT

The ‘FFT’ button opens and closes the power spectrum window. You can, for example, close the power spectrum window when the decoder has been locked onto the correct frequency in order to get more space for the text window.

 

Save

The ‘Save’ button opens the log file control Dialog, which is used to open or close a log file. The detector text window can also be saved into a file or sent into a socket.

 

Lock

The ‘Lock’ button locks or unlocks the decoder frequency. Decoders have the ‘automatic frequency tracking’ feature. Push the ‘Lock’ button when you want to lock the decoder onto the selected frequency. Push the ‘Unlock’ button when you want to release frequency locking.

 

Reset

The ‘Reset’ button resets the decoder and clears the text window.