Automatic Picture Transmission (APT) (and other APT-like antennas)

Below is a checklist of Automatic Picture Transmission (APT) system postal items (stamps, souvenir sheets, aerogrammes, postal cards, etc.). Catalog numbers, years of issue, and notes on the items featured are given when available. If readers know of additional information or images, please contact the authors using the e-mail addresses at the bottom of this page.

Farther below is a list of APT system on satellite launch covers.

The necessary receivers for APT have been placed aboard various satellites:

1. U.S. TIROS/ESSA weather satellites (beginning with TIROS-8 launched in December 1963),
2. U.S. Nimbus weather satellites (Nimbus-1 and Nimbus-2 only, launched in August 1964 and May 1966, respectively), and
3. U.S. ITOS/TIROS-N/ATN (NOAA) weather satellites (beginning with TIROS-M launched in January 1970).
4. Russian Meteor weather satellites (beginning with Meteor-1-11 launched in March 1972).

Reference: http://www2.ncdc.noaa.gov/docs/klm/html/c4/sec4-2.htm

APT is a low-resolution analog transmission of Advanced Very High Resolution Radiometer (AVHRR) data from polar-orbiting satellites. Two channels of reduced-resolution (4 km) data are continuously transmitted using analog VHF signals (137 MHz) at reduced rates (120 lines per minute), allowing use of simple, low-cost ground station equipment for APT reception.

• APT images
• APT antennas²
• Multiple-Helix Tracking Antennas³
• Multiple-Yagi Tracking Antennas⁴

^*Scott catalog number, unless prefixed with Mi or BL for Michel.
^**FDC = first day cover; PPO = printed to private order; SS# = souvenir sheet, MS# = miniature sheet, where # = number of stamps in sheet, and the numbers in parentheses are the catalog numbers of the stamps in the sheet.

¹The "35-mm filmstrip" satellite images on these items are likely low-resolution APT images.
²A helical or crossed-Yagi antenna is required for (right-hand) circular-polarized APT signals. (A helical antenna consists of a conducting wire wound in the form of a helix, usually mounted over a ground plane; a Yagi is a directional antenna consisting of an array of a dipole and additional closely-coupled parasitic elements, usually a reflector and one or more directors. The Yagi antenna, or more-properly the Yagi-Uda antenna, is named after Hidetsugu Yagi and Shintaro Uda of Japan, who jointly invented it in 1926.)
³APT-like multiple-helix tracking antennas, similar to the single helix on most APT antennas.
⁴APT-like multiple-Yagi tracking antennas, many of which are associated with weather balloons/radiosondes.
⁵The image of the antenna on this item is so small, that only the four (4) booms and no helix or Yagi elements can be seen.

Below is a list of APT system on satellite launch covers.

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