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AVT mode

Amiga Video Transceiver AVT94

Historical Amiga Video Transceiver compatibility and reference decoding.

Supported in app

Mode sample

BBC-style colour test card and app-generated audio

The image is generated locally for this mode's raster. For supported modes, the audio sample is encoded from that image with the SSTV Signal Desk transmitter code, then published as lossless FLAC for static playback.

FLAC, 48 kHz, 16-bit mono, 96.223 s.

AVT94 SSTV BBC-style colour test card
AVT94 test card, 320 x 200

Mode spec

Short nameAVT94
Support statusSupported in app
Spec statusSupported in app; public line-level timing was not found in checked sources, so app timing fields are labeled separately.
Duration93.750 s
Frame320 x 200
Data lines200
Public VISVIS 72 (0x48; AVT normal code from public 72/73/74/75 set)
Standard VIS code0x48 (72)
Extended/N-VISNo
Color modelRGB
Component sequenceR-G-B
Line rate128 lpm
Public timing profileNo implementation-grade public line timing was found in checked sources; app implementation fields are listed separately.
App duration93.750 s
App frame320 x 200
App raw VIS0x48 (72)
App timing profileApp RX line fields: sync 5 ms; front porch 0.8 ms; back porch 0.5 ms; separator/blank 0.5 ms; video tones 1500-2300 Hz around 1900 Hz.
App RX sync5 ms
App RX front porch0.8 ms
App RX back porch0.5 ms
App RX separator/blank0.5 ms
App subcarrier1900 Hz
App deviation400 Hz
App tone range1500-2300 Hz

Strengths

  • AVT94 is a standard-length compact AVT mode: 93.750 s, 320 x 200, RGB.
  • AVT94 preserves AVT R-G-B RGB ordering while publishing the normal-code label VIS 72 (0x48; AVT normal code from public 72/73/74/75 set) separately from the app raw VIS value.
  • AVT94 has explicit app timing fields: 5 ms sync, 0.8 ms front porch, 0.5 ms back porch, 0.5 ms separator/blank, and 1500-2300 Hz around 1900 Hz video tones.
  • AVT94 is documented from the app timing row; the line fields are explicit even where checked public sources do not publish every porch value.

Tradeoffs

  • AVT94's 93.750 s frame is a balanced choice, but it still needs a stable path for the full 320 x 200 scan.
  • AVT94 AVT public tables vary by source; use the app-generated sample audio when checking exact receive timing.

Source notes

AVT public mode tables vary and Dayton N7CXI excludes AVT timing because it did not have solid author data. This row presents the app-supported implementation with the public normal VIS label where available. App raw VIS 0x48 and app timing fields are generated from sstv/sstv/sstv/sstvparam.swift during the website build.