STANAG 4285 Decoder




SkySweeper STD : NO

SkySweeper STD+ : YES

SkySweeper PRO : YES


General description

STANAG 4285 is the NATO standard for HF communication. It consists of several sub modes (75-2400 bps) and two different interleaving options (short and long). The receiver should be in USB mode and provide flat frequency response from 600 Hz to 3000 Hz. The center frequency is set to1800Hz and cannot be changed. The decoder has two main operational modes: ‘Slot Mode’ and ‘Message Mode’. In the Slot Mode the decoder prints every STANAG slot (length 0.1067 sec) it receives. In the Message Mode the whole STANAG4285 message (several slots) is printed at the same time. The STANAG5066 message decoder can only be activated in Message Mode. STANAG4285 doesn’t provide any information about the used mode, so the ‘Auto’ mode means that the decoder searches the correct mode sequentially by changing the receive mode after given time period (typically 5-10 sec). The automatic mode detection can take long time, so it is strongly recommended to set the correct mode manually (if known). If the decoder load seems to be too high for your system, please de-activate the high performance equalizer and reduce the ‘Max Freq Error’ value.



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







This selects the mode based on the net bit rate. ‘Auto’ means the automatic mode search.



This selects the used interleaver (short/long).


Message Mode

Selects the operational mode. If the ‘Message Mode’ is activated the decoder prints STANAG4285 messages (multiple slots) otherwise every received slot is printed.


Enable Equalizer

This activates the high performance channel equalizer. The improved equalizer will be released in the future versions.


Auto Scan Time

This sets the scan time per mode in automatic mode search.


Max Freq Error

This is the maximum frequency error (+-) which is handled by the decoder. The decoder load can be dropped by reducing this number.


Enable STANAG 5066 Parser

If check box selected enables STANAG 5066 Message Parser, which can be configure by pressing configure button. Parser can be used only in Message Mode.


Print Time Stamps



RX Modem Data Print Options

These are the decoder print options. The data can be printed in the binary, hexadecimal, decimal or string format.



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



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



In the HFDL pressing ‘Lock’ stops the AFC (automatic frequency correction) and the decoder is tuned to fixed 1440 Hz frequency. Please Note! Stopping AFC is not recommended in normal cases because the decoder loses it capability to handle frequency error. Push ‘Unlock’ button to activate AFC again.



The reset button resets the decoder and clears the text window.