Z code

Z Code (like Q Code and X Code) is a set of operating signals used in CW, TTY and RTTY radio communication.

Distinct versions There are at least three sets of Z codes. {| |- style="vertical-align:top;" | 1. | One set of codes was originally developed by Cable & Wireless Ltd. (the Cable & Wireless Service Z code) for commercial communications in the early days of wire and radio communications.

Many of the old C&W codes are derived from mnemonics (ZAL = alter wavelength,ZAP = ack please,ZSF = send faster, etc.)

The old C&W Z codes are not widely used today. |- style="vertical-align:top;" | 2. | APCO also developed a system of Z codes. |- style="vertical-align:top;" | 3. | NATO forces independently developed a later set of Z codes for military use and inter-language needs. The NATO Z codes are still in use, and are published in the unclassified document ACP-131.

There are other sets of codes internally used by Russia's military and other operating agencies.

Examples {| class="wikitable" |+ |- ! Code ! Meaning ! Source

| I am closing down (until ...) | C&W |- | ZAP ... | Work ... 1. Simplex;2. Duplex; 3. Diplex; 4. Multiplex; 5. Single sideband; 6. With automatic error correction system; 7. Without automatic error correction system. 8. With time and frequency diversity modem | C&W |- | ZBK | Are you receiving my traffic clear? | NATO |- | ZBK 1 | I am receiving your traffic clear | NATO |- | ZBK 2 | I am receiving your traffic garbled | NATO |- | ZBM 2 | Place a competent operator on this circuit | C&W |- | ZBW ... | Change to backup frequency ... | C&W |- | ZBZ ... | Measure of printability 1=Garbled / unreadable, up to 5=Perfect | C&W |- | ZLD 2 | I cannot transmit pictures | C&W

| Switch off ... (except ...) 1. IFF;2. IFF sets for 10 minutes in area denoted except for ships with the following | C&W |- | ZUJ | Stand by. | NATO

Z code

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