SSTV.org.uk

MMSSTV mode

MMSSTV MP73-Narrow

Software-era analog SSTV operation and MMSSTV compatibility.

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, 75.927 s.

MP73-N SSTV BBC-style colour test card
MP73-N test card, 320 x 256

Mode spec

Short nameMP73-N
Support statusSupported in app
Spec statusSupported in app; public VIS and timing summary are separated from the app raw timing fields.
Duration72.966 s
Frame320 x 256
Data lines128
Public VISN-VIS 0x02 (2; MMSSTV narrow-band code)
Standard VIS codeNot applicable or not published in checked sources
Extended/N-VISN-VIS 0x02 (2)
Color modelYCrCb
Component sequenceY-RY-BY
Line rate210.508 lpm
Public timing profileMMSSTV MP-N timing: narrow-band color-difference mode with 9.000 ms sync, 1.000 ms separator at the lower narrow tone, Y odd, R-Y, B-Y, Y even; scan signals occupy the 2044-2300 Hz span.
App duration72.966 s
App frame320 x 256
App raw VIS0x5C256D (6038893)
App timing profileApp RX line fields: sync 9 ms; front porch 0 ms; back porch 1 ms; separator/blank 0 ms; video tones 2044-2300 Hz around 2172 Hz.
App RX sync9 ms
App RX front porch0 ms
App RX back porch1 ms
App RX separator/blank0 ms
App subcarrier2172 Hz
App deviation128 Hz
App tone range2044-2300 Hz

Strengths

  • MP73-N is a medium-length standard colour MMSSTV mode: 72.966 s, 320 x 256, YCrCb.
  • MP73-N identifies through N-VIS 0x02 (2; MMSSTV narrow-band code), separating MMSSTV-era modes from the 7-bit VIS space used by older analog families.
  • MP73-N has explicit app timing fields: 9 ms sync, 0 ms front porch, 1 ms back porch, 0 ms separator/blank, and 2044-2300 Hz around 2172 Hz video tones.
  • MP73-N has a checked public timing summary plus app timing fields, so the public spec and implementation timing can be compared line by line.

Tradeoffs

  • MP73-N's 72.966 s airtime is practical for casual contacts, while the 320 x 256 frame still gives less margin than the longer high-detail modes.
  • MP73-N depends on N-VIS 0x02 (2) and the narrow 2044-2300 Hz around 2172 Hz span; older receivers that only watch standard VIS may need manual mode selection.

Source notes

Public VIS/timing labels are normalized from checked SSTV references where available. App raw VIS 0x5C256D and app timing fields are generated from sstv/sstv/sstv/sstvparam.swift during the website build. Public MMSSTV VIS 0x02 differs from app raw 0x5C256D; both values are shown.