Scottie mode

Scottie 3

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, 57.122 s.

S3 SSTV BBC-style colour test card — S3 source card, 320 x 128

S3 SSTV round-trip decoded test card — Receiver decoded S3 from the FLAC-restored WAV, 128 lines.

Round-trip decode evidence

Encoded, compressed losslessly, restored, then decoded.

The published FLAC is restored to WAV and passed through the SSTV Signal Desk receiver sample harness. The receiver decoded S3 from the FLAC-restored WAV and wrote 128 image lines for this S3 test card.

Open the generated decode report

Mode spec

Short name	S3
Support status	Supported in app
Spec status	Supported in app; public line-level timing was not found in checked sources, so app timing fields are labeled separately.
Duration	54.812 s
Frame	320 x 128
Data lines	128
Public VIS	VIS 52 (0x34)
Standard VIS code	0x34 (52)
Extended/N-VIS	No
Color model	RGB
Component sequence	G-B-R
Line rate	140.115 lpm
Public timing profile	No implementation-grade public line timing was found in checked sources; app implementation fields are listed separately.
App duration	54.812 s
App frame	320 x 128
App raw VIS	0xB4 (180)
App timing profile	App RX line fields: sync 9 ms; front porch 0 ms; back porch 1.5 ms; separator/blank 1.5 ms; video tones 1500-2300 Hz around 1900 Hz.
App RX sync	9 ms
App RX front porch	0 ms
App RX back porch	1.5 ms
App RX separator/blank	1.5 ms
App subcarrier	1900 Hz
App deviation	400 Hz
App tone range	1500-2300 Hz

Strengths

S3 is a medium-length compact Scottie mode: 54.812 s, 320 x 128, RGB.
S3 keeps the classic Scottie G-B-R RGB order, which makes colour order predictable for receivers expecting VIS 52 (0x34).
S3 has explicit app timing fields: 9 ms sync, 0 ms front porch, 1.5 ms back porch, 1.5 ms separator/blank, and 1500-2300 Hz around 1900 Hz video tones.
S3 is documented from the app timing row; the line fields are explicit even where checked public sources do not publish every porch value.

Tradeoffs

S3's 54.812 s airtime is practical for casual contacts, while the 320 x 128 frame still gives less margin than the longer high-detail modes.
S3 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 0xB4 and app timing fields are generated from sstv/sstv/sstv/sstvparam.swift during the website build.

SSTV Signal Desk SSTVTableSSTV Signal Desk - accessed 2026-08-24Authority for app-supported mode names and app timing parameters.
SSTV Handbook Chapter 5: List of SSTV modesSSTV Handbook - accessed 2026-08-24Reference for analog SSTV mode names, VIS codes, durations, line counts, column counts, and line rates.