SSTV.org.uk

Martin mode

Martin HQ4

Martin HQ4 is listed as a 51 s, 320 x 144 YCrCb high-quality Martin-family mode, but the checked table does not publish its VIS code.

Needs verification

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.

No app-generated audio sample is published for this needs-verification mode because no matching transmitter entry exists in the app code.

HQ4 SSTV BBC-style colour test card
HQ4 test card, 320 x 144

Mode spec

Short nameHQ4
Support statusNeeds verification
Spec statusReference timing row from the OK2MNM SSTV mode-list PDF.
Duration51 s
Frame320 x 144
Data lines144
Public VISVIS unknown in OK2MNM table
Standard VIS codeNot applicable or not published in checked sources
Extended/N-VISNo
Color modelYCrCb
Component sequenceY-RY-BY
Line rate170.099 lpm
Public timing profileMode-list row gives 51 s total duration, 144 scan lines, 320 columns, and 170.099 lpm; line-level porch timing is not part of this catalog row.

Strengths

  • HQ4 has a concrete catalogue row: 51 s, 320 x 144, YCrCb, VIS unknown in OK2MNM table.
  • HQ4's Y-RY-BY component order and 170.099 lpm line rate make it useful for comparing airtime, raster, and colour structure against related modes.

Tradeoffs

  • HQ4 is not app-supported yet, so the 51 s / 320 x 144 row should be treated as reference data rather than a verified transmit preset.
  • HQ4 still needs implementation-grade porch, sync, and pixel timing before an app-generated WAV/FLAC sample can be published with the same confidence as supported modes.

Source notes

OK2MNM SSTV Handbook chapter 5 lists HQ4 as YCrCb, VIS unknown in OK2MNM table, 51 s, 144 lines, 320 columns, 170.099 lpm. Martin high-quality variant listed in the OK2MNM mode table without a confirmed VIS code.