SSTV.org.uk

Monochrome mode

B/W 12

Short black-and-white image transmission and compatibility testing.

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, 14.311 s.

BW12 SSTV BBC-style colour test card
BW12 test card, 160 x 120

Mode spec

Short nameBW12
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.
Duration12.001 s
Frame160 x 120
Data lines120
Public VISVIS 6 (0x06; green BW component, public component set 5/6/7)
Standard VIS code0x06 (6)
Extended/N-VISNo
Color modelBW
Component sequenceY
Line rate599.95 lpm
Public timing profileNo implementation-grade public line timing was found in checked sources; app implementation fields are listed separately.
App duration12.001 s
App frame160 x 120
App raw VIS0x86 (134)
App timing profileApp RX line fields: sync 6 ms; front porch 0.5 ms; back porch 1.5 ms; separator/blank 0 ms; video tones 1500-2300 Hz around 1900 Hz.
App RX sync6 ms
App RX front porch0.5 ms
App RX back porch1.5 ms
App RX separator/blank0 ms
App subcarrier1900 Hz
App deviation400 Hz
App tone range1500-2300 Hz

Strengths

  • BW12 is a very fast compact Monochrome mode: 12.001 s, 160 x 120, BW.
  • BW12 uses a single Y luminance channel, so the VIS 6 (0x06; green BW component, public component set 5/6/7) entry can be decoded as a compact monochrome image without colour registration concerns.
  • BW12 has explicit app timing fields: 6 ms sync, 0.5 ms front porch, 1.5 ms back porch, 0 ms separator/blank, and 1500-2300 Hz around 1900 Hz video tones.
  • BW12 is documented from the app timing row; the line fields are explicit even where checked public sources do not publish every porch value.

Tradeoffs

  • BW12's 12.001 s pass is quick, but the 160 x 120 frame leaves little scan time for fine detail or noisy channels.
  • BW12 is deliberately monochrome; it is efficient for tone and sync checks, but it cannot preserve colour information.

Source notes

Public VIS/timing labels are normalized from checked SSTV references where available. App raw VIS 0x86 and app timing fields are generated from sstv/sstv/sstv/sstvparam.swift during the website build.