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digital_mode [2026/10/02 16:22] – Organise Wikiham as an encyclopedia of individual articles 127.0.0.1digital_mode [2026/10/02 21:06] (current) – Add technical encyclopedia coverage, formulas, examples and primary references admin
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 ====== Digital mode ====== ====== Digital mode ======
  
-Digital modes encode information so a receiver or computer can decode it. They range from keyboard conversations to packet networks, image transmission and short weak-signal messages.+A **digital radio mode** represents information using discrete symbols that a receiver can decode. Modes differ in modulation, message format, error handling, occupied bandwidth and purpose. A narrow waterfall trace alone does not identify its protocol.
  
-===== A typical station =====+===== Modulation and information rate =====
  
-Many computer-assisted modes use a transceiver, a computer and an audio or data interface. Important setup details include audio levels, transmit control, frequency settings and the time synchronisation required by the selected mode.+Frequency-shift keying (FSK) selects between frequency states. Phase-shift keying (PSK) represents information through phase changes. Some modes combine modulation with pulse shaping, coding and synchronisation sequences. 
 + 
 +For M distinguishable symbol states, a basic uncoded mapping can carry log2(M) bits per symbol: 
 + 
 +<code> 
 +Raw mapped bit rate = symbol rate × log2(M) 
 +</code> 
 + 
 +For example, a four-state alphabet can represent two bits per symbol. Actual useful throughput is lower when synchronisation, error correction, headers or acknowledgements consume capacity. Baud counts symbols per second; it is not automatically the number of useful bits per second. 
 + 
 +===== Modes and applications ===== 
 + 
 +^ Mode or system ^ Main purpose ^ Key characteristic ^ 
 +| [[ft8|FT8]] | Structured weak-signal contacts | 15-second slots; 8-tone GFSK | 
 +| [[ft4|FT4]] | Faster structured contacts | 7.5-second slots; 4-tone GFSK | 
 +| [[wspr|WSPR]] | Propagation reporting | Very narrow beacon transmissions | 
 +| [[psk31|PSK31]] | Live keyboard conversation | Phase modulation and Varicode | 
 +| [[rtty|RTTY]] | Teleprinter-style conversation | Mark/space frequency states | 
 +| [[packet_radio|Packet radio]] | Framed data and networking | Protocol-defined packets | 
 +| [[aprs|APRS]] | Positions, messages and telemetry | Reporting system often over AX.25 | 
 + 
 +APRS is an application system, and packet radio is a broader transport concept. They are included here because they use digital radio links, not because they are each one unique modulation waveform. 
 + 
 +===== A typical station =====
  
-===== Examples =====+Many modes use a computer, transceiver and audio/data interface. Audio levels, PTT or CAT control, dial reference, sideband and clock synchronisation must match the chosen mode. [[single_sideband|SSB]] can translate generated audio tones into RF; other systems use FM or direct modem inputs.
  
-  * [[ft8|FT8]] and **FT4:** structured, short-message modes provided by WSJT-X. +Error detection can identify damaged data. Forward error correction adds redundancy to recover some errors without retransmission. A protocol may also acknowledge and repeat frames. These mechanisms solve different problems and do not guarantee reception under all conditions.
-  * **WSPR:** weak-signal beacon reporting, used to observe propagation paths. +
-  * **RTTY and PSK:** families of keyboard communication modes. +
-  * [[packet_radio|Packet radio]]: data communication organised into packets, used for several amateur applications.+
  
-Digital modes have different purposes and operating conventions. Document the exact software version, settings and mode when describing a result.+[[wsjt_cb|WSJT-CB]] adapts a software workflow for CB identifiers while retaining established weak-signal modes. Software support and radio-service authorisation are separate questions.
  
-===== Further reading =====+===== References =====
  
-  * [[https://wsjt.sourceforge.io/wsjtx.html|WSJT-X project and user documentation]]. +  * [[https://wsjt.sourceforge.io/wsjtx.html|WSJT-X project documentation]]. 
-  * [[https://www.aprs.org/|APRS information]].+  * [[https://www.w1hkj.org/FldigiHelp/|Fldigi modem documentation]]. 
 +  * [[https://web.tapr.org/tech_docs/AX25/AX25.2.2.pdf|TAPR: AX.25 version 2.2 specification]].