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Transmission Modes WAVECOM Decoder W74PC, W-PCI/e, W-CODE, W-CLOUD Manual V9.1.0
ALE, Broadcast/Simplex FEC
ALF-RDS
ALF-RDS (Accurate positioning by Low Frequencies) is a German system for the transmission of DGPS in-
formation on low frequencies (in this case 123, 7 kHz). Data is transmitted in RDS format. RDS (Radio Da-
ta System) is a one-way data transmission system used by FM broadcasters worldwide to broadcast pro-
gram, time and traffic information on a 57 kHz BPSK DSB sub carrier with suppressed carrier and a bit
rate of 1187.5 bps. In the case of ALF-RDS, the transmission is made in SSB with a decreased level pilot
carrier to reduce bandwidth.
The basic RDS data unit is a group which consists of four blocks, each having 16 data bits and 10 error
detection and correction bits. Groups are divided into type A and B, each containing 16 different groups.
In the upper window, a Display Mode can be selected. The default display mode is All Blocks, which dis-
plays the information of each block. Binary will display the contents of a group in binary format.
In the lower window, other information like flags, time, program information and transmitted text is dis-
played.
ALIS
ALIS (Automatic Link Set-up) is a simplex ARQ system and operates at a Symbol rate of 228.66 Baud on
the radio link.
ALIS is described in report 551-2 of the ITU "Reports of the CCIR 1990 - Fixed Services at Frequencies be-
low about 30 MHz".
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