Improved Automatic Link Set-up (ALIS-2)
Automatic Link Set-up (ALIS) - Improved Automatic Link Set-up (ALIS-2)
ALIS-2, also known as RS-ARQAutomatic Repeat reQuestAutomatic Repeat Query, RS ARQAutomatic Repeat reQuestAutomatic Repeat Query 240, and MERLIN, is an improvement of the original ALIS system. ALIS-2 is used in the Rohde & Schwarz MERLIN modem. This mode has been used most frequently by Turkish, German and Italian diplomatic stations. The Italian diplomatic stations seem to favor the 5 bit (ITA2) mode. Turkish diplomatic stations have been found using the 8 bit mode for all traffic.
ALIS-2 is described in the "Report of the CCIRComité Consultatif International pour la Radio (Predecessor of the ITU-R) 1990, Fixed Service at Frequencies below about 30 MHzMegaHertz (MHz) 10^6 Hz" of the ITU.
ALIS-2 was developed by Rohde & Schwarz, the same company that developed the original ALIS. ALIS-2 uses an 8-FSKFrequency-Shift Keying burst mode running at 240.82Bd (720 bits/sBits per second (bps)). The spacing between tones is 240Hz. Each tone has a duration of 4.15254 msmilliseconds (.001 of a second) every burst.
When the system is found in the 7 tone mode it is in ISSInformation Sending Station in an ARQ link (The station sending information to the recipient). Usually the signal that's longer in duration than the short RQ (Repeat Request) bursts from the IRS. mode, the IRSInformation Receiving Station in an ARQ link (The station receiving information from the ISS. Will send RQ's (Repeat Request) to let the ISS know the information was received successfully. mode uses an 8 tone signal.
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