ATIS is an abbreviation of "Automatic Transmitter Identification System". ATIS is used in the VHF-UHF radio systems on the river Rhine and automatically generates the identification signal at the end of each period of speech transmission. In case of lengthy transmissions, the ATIS signal is required to be transmitted at least once every five minutes.

ATIS conforms in certain aspects to the CCITT Recommendation 493-3. The specifications are directed at all river Rhine nautical radio installations, fixed as well as mobile stations and has been in use there since 1994 and from 1995 also internationally.

The ATIS signal sequence is transmitted using the FSK with space and mark frequencies of 1300 Hz and 2100 Hz and a modulation rate of 1200 Baud. The higher frequency corresponds to the B-state of the signal and the lower to the Y-state.

The ATIS sequence consists of a country identifier and a four digit call-sign, e.g., PE 1234 for a Dutch vessel or HB 6235 for a Swiss vessel.

All sequences are transmitted twice (DX and RX positions). A 10-bit code is used in this synchronous system. Bits 8, 9 and 10 are a binary representation of the number of bits in the B-state. The error check character corresponds to a modulo-2 sum of the corresponding information bits.

ATIS Country Identification Code