15 August 2015

Rohde & Schwarz ALIS



This is the Rohde & Schwarz proprietary standard "ALIS" (Automatic Link Setup) selective call, an adaptive ALE procedure based on FSK modem and ALIS processor. 
The signal  (http://signals.radioscanner.ru/base/signal104/) has been heard today afternoon at 1620z on 12270.5 KHz on USB. The waveform is an FSK 228.6Bd/170 (normal FSK modulation, ALIS basic feature) using PRP as automatic error correction, ACF value of ~376 mS. By using the SA "scan raster" method is visible the feature called "diagonal bit" that can be used to recognize the signal.


 

About the ALIS version I do not know if this signal is probably an ALIS variant, as shown in the decoding below. What I can say is that the ACF value is different than the two diagrams reported in radioscanner.ru: these diagrams exhibit the values 399.3 and 494.7 mSec respectively for ALIS-1 and ALIS-2 versions whereas my diagram - as said above - exhibits a value of 376.2 mSec.


Processing the two ALIS samples provided in the above radioscanner.ru link, decoder k500 says "ALIS-2000" for version-1 and "Probable ALIS variant 50" for version-2 and these values do not match my results ("Probable ALIS variant: 40").
 
Below some decodings  from which you can see some some ALIS features and the called addresses.

[ Averaging over 14 bursts ]
Called address: 40
Pool size: 8
ALIS 2000: No
Ack: true
Followon type: External modem
ECC: PRP
Spectral diversity: Adaptive
Data rate: Fast
Data encryption: No (clear)
Rephase: false
Sending counter: 1
Probable ALIS variant: 40

[ Averaging over 2 bursts ]
Called address: 8488
Pool size: 8
ALIS 2000: No
Ack: true
Followon type: Morse
ECC: PRP
Spectral diversity: Adaptive
Data rate: Fast
Data encryption: No (clear)
Rephase: false
Sending counter: 1
Parity error in above information.
Probable ALIS variant: 40


More informations can be downloaded from this link: http://www.radioscanner.ru/uploader/2009/alis.zip
As usual, the recordered signal is available for your anaylsis: ask me by email o leave a comment below.

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