SSTV.org.uk

Martin mode

Martin 2

Martin family analog SSTV operation and compatibility reference.

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, 60.374 s.

M2 SSTV BBC-style colour test card
M2 test card, 320 x 256

Mode spec

Short nameM2
Support statusSupported in app
Spec statusSupported in app; public VIS and timing summary are separated from the app raw timing fields.
Duration58.064 s
Frame320 x 256
Data lines256
Public VISVIS 40 (0x28)
Standard VIS code0x28 (40)
Extended/N-VISNo
Color modelRGB
Component sequenceG-B-R
Line rate264.536 lpm
Public timing profilePublic Martin M2 timing: VIS 40; 256 lines; same Martin line order as M1 with 4.862 ms sync, 0.572 ms porch/separators, and 73.216 ms color scans.
App duration58.064 s
App frame320 x 256
App raw VIS0x28 (40)
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

  • M2 is a medium-length standard colour Martin mode: 58.064 s, 320 x 256, RGB.
  • M2 keeps the classic Martin G-B-R RGB order, which makes colour order predictable for receivers expecting VIS 40 (0x28).
  • M2 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.
  • M2 has a checked public timing summary plus app timing fields, so the public spec and implementation timing can be compared line by line.

Tradeoffs

  • M2's 58.064 s airtime is practical for casual contacts, while the 320 x 256 frame still gives less margin than the longer high-detail modes.
  • M2 sends colour sequentially in RGB; sync drift can appear as colour fringing before the whole frame becomes unreadable.

Source notes

Public VIS/timing labels are normalized from checked SSTV references where available. App raw VIS 0x28 and app timing fields are generated from sstv/sstv/sstv/sstvparam.swift during the website build.