FSK Speed Analyzer

 

General description

FSK Speed Analyzer (FSA) is a tool for the FSK baud rate analyzing. It provides a decoder part similar to the other SkySweeper FSK based decoders. Also, there is the baud rate histogram display as well as the text window for printing out the analysis results in text format.

 

The FSA decoder searches the transmission within the given frequency boundaries. Also you can set the lower FSK frequency by double clicking mouse on the required frequency position, and then SkySweeper allows you to set a second (=higher) frequency just by a mouse click. The values of the frequencies and the frequency offset are also shown on the screen.

 

When a transmission has been detected within the given range, the decoder will then lock itself to that frequency. When locked, the decoder draws a bold blue line on the spectrum display at the currently locked frequency. If the decoder is not locked, then the blue line is not shown as bold.

 

In the non-locked state, the carrier frequencies are automatically monitored within the given frequency boundaries. If the carrier frequency changes, then the decoder moves to a new frequency. If 'Lock' is pressed in the user interface, then the decoder will not automatically change the frequency. ‘Reset’ resets the decoder and the results can be saved using ‘Save’. The parameters can be modified pressing the ‘Config’ button.

 

The received text can be saved with ‘Save’. ‘Reset’ resets the decoder and ‘Config’ is used to set the parameters.

 

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

 

Configuration

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

 

 

 

 

Parameters

 

Tone Scan Area

The FSK transmission has two tones - Mark and Space. The scanned frequency range for Mark and Space will be given with two values, namely ‘low’ and ‘high’. The Mark and Space tones are searched for only inside this frequency window

 

Fixed Offset

If the Fixed Offset check box is selected, the user can enter the fixed frequency offset between the Mark and Space carrier frequencies. The fixed frequency offset is used in automatic scanning mode.

 

Mode

This selects the scale which is used to present the analyzed results. There are two choices for the scale (Baud Rate or symbol length (ms)).

 

Line Colors

The sets the histogram line colors for Mark and Space symbols.

 

Line Draw Mode

The Space and Mark histograms can be drawn to the same scale (overlapped mode) or a different scale (when the Mark scale is negative). This is called ‘Mirror’ mode.

 

AVG Filter Length

This is the Average filter length measured in milliseconds. If the baud rate is low, then a longer average filter gives better analyzing performance.

 

Print statistics into text window

If this switch is selected, the analyzed results (bit lengths) will be printed into the text window.

Time stamp

If this switch is selected, the time stamp is added to the text. This works only if ‘Print statistics into text window’ is selected.