SSTV.org.uk

PD mode

PD290

Higher-resolution color work where longer transmission time is acceptable.

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, 291.014 s.

PD290 SSTV BBC-style colour test card
PD290 test card, 800 x 616

Mode spec

Short namePD290
Support statusSupported in app
Spec statusSupported in app; public VIS and timing summary are separated from the app raw timing fields.
Duration288.702 s
Frame800 x 616
Data lines308
Public VISVIS 94 (0x5E)
Standard VIS code0x5E (94)
Extended/N-VISNo
Color modelYCrCb
Component sequenceY-RY-BY-Y
Line rate128.021 lpm
Public timing profilePublic PD timing: 20.000 ms sync, 2.080 ms porch, odd-line Y, averaged R-Y, averaged B-Y, even-line Y; repeat pairs until the mode-specific line count is complete.
App duration288.702 s
App frame800 x 616
App raw VIS0xDE (222)
App timing profileApp RX line fields: sync 20 ms; front porch 0 ms; back porch 2 ms; separator/blank 0 ms; video tones 1500-2300 Hz around 1900 Hz.
App RX sync20 ms
App RX front porch0 ms
App RX back porch2 ms
App RX separator/blank0 ms
App subcarrier1900 Hz
App deviation400 Hz
App tone range1500-2300 Hz

Strengths

  • PD290 is a extended high-detail PD mode: 288.702 s, 800 x 616, YCrCb.
  • PD290 uses Y-RY-BY-Y pair-line colour-difference scanning, giving two luma passes around shared chroma samples in the PD family.
  • PD290 has explicit app timing fields: 20 ms sync, 0 ms front porch, 2 ms back porch, 0 ms separator/blank, and 1500-2300 Hz around 1900 Hz video tones.
  • PD290 has a checked public timing summary plus app timing fields, so the public spec and implementation timing can be compared line by line.

Tradeoffs

  • PD290's 288.702 s transfer can carry more picture detail, but it occupies the channel longer and is less forgiving of fades across the 800 x 616 frame.
  • PD290 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 0xDE and app timing fields are generated from sstv/sstv/sstv/sstvparam.swift during the website build.