Link 11

Technical characteristics

Link 11 is a half-duplex, netted link that normally operates by roll call from a data net control station (DNCS). Link 11 can also operate in the broadcast mode. The roll call mode of operation used in the Link 11 interface requires that each participating unit (PU) respond in turn while all other stations are receiving. A DNCS initiates the roll call by addressing and transmitting an interrogation message to a specific PU that then responds by transmitting its data. The DNCS then interrogates the next PU in the prescribed roll call. Link 11 can be transmitted on high frequency (HF) and/or Ultra High Frequency (UHF) bands. Data speed can be selected from bit rates of 2250 or 1364 bits per second. Dual sideband diversity operation and Doppler shift correction features improve reliability and accuracy of data exchange. Link 11 operates on HF (2-30 MHz) and/or UHF (line of sight (LOS)) (225-400 MHz). Some data terminal sets (DTS) provide the option to select either the conventional Link 11 waveform (CLEW) or the single tone Link 11 Waveform (SLEW). SLEW and CLEW are not compatible waveforms. SLEW, among other enhancements, provides increased propagation and a more powerful error detection and correction (EDAC) algorithm. While the option exists to operate in either CLEW or SLEW, all participants in a given Link 11 net must select the same waveform to achieve connectivity between units. Link 11 is defined in military standard (MIL STD) 6011, Tactical Data Link (TDL) A/B Message Standard.