GENERIC DECODER EXAMPLE (PRO ONLY)

The generic decoders in SkySweeper Professional are universal tools to decode the bits of known and unknown transmissions. There are generic decoders for FSK, MFSK, MPSK (multi-tone-PSK), MSK, PAM (pulse-amplitude-modulation) and PSK. The decoder can be configured to decode the signal with given parameters like baud rate, tone number, frequency shift etc. The generic decoder produces the raw bit stream. The decoder output is then analyzed with SkySweeper’s very sophisticated bit domain analysis tools. Bit domain tools will then display the decoded bit stream in the selected format. The supported number formats are binary, hexadecimal, octal and decimal. The supported character sets are (ASCII 7 bit, ASCII 7+1 bit, ASCII 8 bit, Baudot (ITA2), ITU 342-3 (ITA3), ITU 476-5 (SITOR), ARQ-E and BCD. The bits can be also shown as defined message format.

It is possible to use the bit analyzer tool in online or offline mode. In the online mode the bits are decoded and displayed in real time like in any other decoder. In the offline mode the decoded bits are first saved into a log file, which can be analyzed afterwards with the offline bit tool. The different modes and are shown in the pictures below.

DGPS EXAMPLE

The DGPS signal for example can easily be decoded by using the generic MSK decoder configured for 100 bauds. The bit tool is configured as message mode (sync word is ‘01100110’). If needed, the bit stream output can be then displayed in different formats like BCD.

ONLINE MODE:

In online mode, the input signal is from radio unit. The signal is decoded as bits, using any generic decoder. The synchronization block finds the bit synchronization from the bit stream. The interleaver is used to change the bit order. The display block prints to the screen in the chosen format.

 

The bit stream can be saved into a bit log file after the decoder, synchronization or the interleaver.

 

OFFLINE MODE:

 

The offline mode reads bits from a bit log file, which is recorded by the online bit analyzer. Because data is stored in a file, it can be scrolled back and forth without any limitations.