General Description
The SkySweeper HFDL decoder supports ARINC 635 specification uplink and downlink message types. The radio receiver should be in USB reception mode. The decoder frequency is always tuned to the fixed 1440 Hz frequency and it cannot be changed by the user. The SkySweeper HFDL decoder uses cellular type of adaptive multipath channel equaliser to handle difficult channel conditions. CRC error check is performed to every messages and it can be selected are CRC failed messages printed or not. Also automatic frequency correction (AFC) is used to correct Doppler and other frequency error sources. AFC can be stopped (not recommended in the normal case) by pressing ‘Lock’. ‘Reset’ resets the decoder and the received text can be saved using ‘Save’.
Configuration
Pressing the Config button opens the following configuration dialog.
Parameters
Console Plot OptionsThe console plot options are used to define the output format of the received HFDL message. The same message can be plotted in many different formats. The following options are available:
Raw Binary Data
If selected the received message is printed as binary format without any message decoding
Raw Hex Data
If selected the received message is printed as hexa decimal format without any message decoding
Raw Decimal Data
If selected the received message is printed as decimal format without any message decoding
Full Decoding
If selected HFDL PDUs are decoded into readable format according to the ARINC 635-3 specification.
Print CRC Failed PDUs
If selected PDUs which have been received but CRC has been failed are printed into console.
Print Time Stamps
If selected time of day and message number is printed at the beginning of the message.
HFDL Print Format
Message parser number print format selection.
Decimal
Numbers are printed as decimal format
Hexadecimal
Numbers are printed as hexadecimal format
ACARS Protocol Configuration
HFDL protocol is able to carry ACARS data blocks. The SkySweeper includes ACARS message parser which decodes encapsulated ACARS messages.
Decode ACARS Blocks
If selected ACARS data blocks in the unnumbered acknowledged data lpdu are decoded.
ACARS Configuration
If ACARS block decoding is selected the push button opens the ACARS Message Parser DialogHELP_FILTER_TYPE_ACARS
FFT
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
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 be also saved into file or sent into socket.
Lock
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.
Reset
The reset button resets the decoder and clears the text window.
