SSTV.org.uk

Robot mode

Robot 24

Robot 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, 26.311 s.

R24 SSTV BBC-style colour test card
R24 test card, 160 x 120

Mode spec

Short nameR24
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.
Duration24.002 s
Frame160 x 120
Data lines120
Public VISVIS 4 (0x04)
Standard VIS code0x04 (4)
Extended/N-VISNo
Color modelYCrCb
Component sequenceY-RY-BY
Line rate299.981 lpm
Public timing profileNo implementation-grade public line timing was found in checked sources; app implementation fields are listed separately.
App duration24.002 s
App frame160 x 120
App raw VIS0x84 (132)
App timing profileApp RX line fields: sync 6 ms; front porch 0.1 ms; back porch 3 ms; separator/blank 4.5 ms; video tones 1500-2300 Hz around 1900 Hz.
App RX sync6 ms
App RX front porch0.1 ms
App RX back porch3 ms
App RX separator/blank4.5 ms
App subcarrier1900 Hz
App deviation400 Hz
App tone range1500-2300 Hz

Strengths

  • R24 is a fast compact Robot mode: 24.002 s, 160 x 120, YCrCb.
  • R24 uses Y-RY-BY colour-difference scanning; the VIS 4 (0x04) row keeps luminance separate from alternating chroma information for Robot-family compatibility.
  • R24 has explicit app timing fields: 6 ms sync, 0.1 ms front porch, 3 ms back porch, 4.5 ms separator/blank, and 1500-2300 Hz around 1900 Hz video tones.
  • R24 is documented from the app timing row; the line fields are explicit even where checked public sources do not publish every porch value.

Tradeoffs

  • R24's 24.002 s airtime is practical for casual contacts, while the 160 x 120 frame still gives less margin than the longer high-detail modes.
  • R24 colour-difference coding can preserve useful luminance detail, but chroma edges may look softer than full-rate RGB modes after weak-path reception.

Source notes

Public VIS/timing labels are normalized from checked SSTV references where available. App raw VIS 0x84 and app timing fields are generated from sstv/sstv/sstv/sstvparam.swift during the website build.