SSTV.org.uk

Scottie mode

Scottie 1

Scottie 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, 111.944 s.

S1 SSTV BBC-style colour test card
S1 test card, 320 x 256

Mode spec

Short nameS1
Support statusSupported in app
Spec statusSupported in app; public VIS and timing summary are separated from the app raw timing fields.
Duration109.632 s
Frame320 x 256
Data lines256
Public VISVIS 60 (0x3C)
Standard VIS code0x3C (60)
Extended/N-VISNo
Color modelRGB
Component sequenceG-B-R
Line rate140.104 lpm
Public timing profilePublic Scottie S1 timing: VIS 60; 256 lines; first line begins with a 9.0 ms starting sync, then Green, Blue, sync between Blue and Red, 1.5 ms separator/porch pulses, and a 138.240 ms color scan.
App duration109.632 s
App frame320 x 256
App raw VIS0x3C (60)
App timing profileApp RX line fields: sync 9 ms; front porch 0.1 ms; back porch 1.25 ms; separator/blank 1.25 ms; video tones 1500-2300 Hz around 1900 Hz.
App RX sync9 ms
App RX front porch0.1 ms
App RX back porch1.25 ms
App RX separator/blank1.25 ms
App subcarrier1900 Hz
App deviation400 Hz
App tone range1500-2300 Hz

Strengths

  • S1 is a standard-length standard colour Scottie mode: 109.632 s, 320 x 256, RGB.
  • S1 keeps the classic Scottie G-B-R RGB order, which makes colour order predictable for receivers expecting VIS 60 (0x3C).
  • S1 has explicit app timing fields: 9 ms sync, 0.1 ms front porch, 1.25 ms back porch, 1.25 ms separator/blank, and 1500-2300 Hz around 1900 Hz video tones.
  • S1 has a checked public timing summary plus app timing fields, so the public spec and implementation timing can be compared line by line.

Tradeoffs

  • S1's 109.632 s frame is a balanced choice, but it still needs a stable path for the full 320 x 256 scan.
  • S1 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 0x3C and app timing fields are generated from sstv/sstv/sstv/sstvparam.swift during the website build.