APT

Automatic Picture Transmission
(APT) system
(and WEFAX, and APT-like antennas)


This page contains philatelic information on the Automatic Picture Transmission (APT) system, Weather Facsimile (WEFAX), and APT-like antennas. Catalog numbers, years of issue, and notes on the satellites 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.

APT is a low-resolution analog transmission of 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. Reference: http://www.ncdc.noaa.gov/oa/pod-guide/ncdc/docs/klm/html/c4/sec4-2.htm

WEFAX is a method to transmit weather satellite images via facsimile. The intended recipients are ships and aircraft, most of which receive WEFAX via satellite radio links.

The necessary equipment for APT has been placed aboard various satellites:

  1. US TIROS/ESSA weather satellites (beginning with TIROS-8 launched in December 1963)
  2. US Nimbus weather satellites (Nimbus-1 and Nimbus-2 only, launched in August 1964 and May 1966, respectively)
  3. US 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)

In the future, the analog signal of APT systems will be replaced by a digital signal of Low Rate Picture Transmission (LRPT) systems.

Launch covers
(including anniversary-of-launch covers, and launch-related event covers)
(farther below)
Other postal items
(stamps, souvenir sheets, aerogrammes, postal cards, etc.)
(immediately below)
APT
WEFAX6
APT images1
APT antennas2
Multiple-helix tracking antennas3 Multiple-helix tracking antennas3
Multiple-Yagi tracking antennas4 Multiple-Yagi tracking antennas4


Below is a list of APT system on postal items (stamps, souvenir sheets, aerogrammes, postal cards, etc.).

CountryCatalog NumberType of ItemYear of IssueNotes on Content
Automatic Picture Transmission (APT) images
Dominica359 (Mi359)1973APT-like (filmstrip1) image
Dominica354-360 fdcOne of seven stamps on FDC
Dominica354-360 proofs1Proof sheet
Dominica354-360 proofs2Proof sheet (different)
Dominica360a (BL17)MS2 (359-360)
Dominica360a fdcMS2 on FDC
Grenada496 (Mi522)1973APT-like (filmstrip1) image
Hungary2019 (Mi2580A)
i2019 (Mi2580B)

Imperforate
1970APT-like image
Hungary2019 fdc
i2019 fdc
Stamp on FDC
Imperforate stamp on FDC
Automatic Picture Transmission (APT) antennas2
Argentina977 cover (Mi1127 cover)Cachet on cover1972Crossed-Yagi APT antenna; Inauguration in 1972 of the APT reception station (in cachet in Spanish text)
ArgentinaC133 cover (Mi1076 cover)Cachet (same) on cover (different)
Argentina977 cover (Mi1127 cover)Cachet (same) on cover (different)1973Crossed-Yagi APT antenna; Inauguration in 1972 of the APT reception station (in cachet in Spanish text)
ArgentinaNoneCachet (same) on aerogramme, also back1973Crossed-Yagi APT antenna; Inauguration in 1972 of the APT reception station (in cachet in Spanish text)
Argentina1017 cover (Mi1170 cover)Cachet on FDC1977Helical APT antenna
ArgentinaNone(Purple) cachet on cover, or in more detail in this black version1993Vicecomodoro Marambaio APT Receiving Station (in Spanish text)
Belgium836 (Mi1714)
i836

Imperforate
1973Helical APT antenna
Belgium836 fdc1Stamp and cancel and cachet on FDC
Belgium836 fdc2Stamp and cancel (same) and cachet (different) on FDC
Belgium836 fdc3Stamp and cachet (same) on FDC
Belgium836 fdc4Stamp and cachet (different) on FDC
Belgium836 fdc5Stamp on FDC
Belgium836 fdc6Stamp on FDC (different)
Belgium836 cardStamp and cancel and cachet on FDC card
Belgium836 sc1Souvenir card
Belgium836 sc2Souvenir card (different)
Belgium836 sc3Souvenir card (different)
Belgium836 sc4Souvenir card (different)
Belgium836 maxiMaxicard
Belgium836 cardStamp on card1980Helical APT antenna
BelgiumUnknown ms (Mi?)On one stamp of MS5 (a-e)2013(possible) APT antenna on building
BelgiumUnknown fdcOne of five stamps on FDC
Czechoslovakia1718-1719 fdc (Mi1972-1973 fdc)(Printed) cachet on FDC1970(possible) APT antenna
France1903 fdc (Mi2416 fdc)('FDC') cachet on FDC1983Helical APT antenna
French Southern and Antarctic TerritoriesNone(Annotated) cachet on cover1986(possible) APT-antenna
Germany (East)983 (Mi1344)
i983
One of strip of 3 (984a (982-984)) (Mi1343-1345)
One of imperforate strip of 3 (i984a)
1968Helical APT antenna
Germany (East)984a fdcOne of three stamps on FDC
Germany (East)1363 (BL35)SS11972(possible) APT antenna
Germany (East)1363 fdc1SS1 on FDC
Germany (East)1363 fdc2SS1 on FDC (different cancel)
Hungary2019 (Mi2580A)
i2019 (Mi2580B)

Imperforate
1970Helical APT antenna
Hungary2019 fdc
i2019 fdc
Stamp and cachet on FDC
Imperforate stamp and cachet on FDC
JapanNoneCancel on cover1985(possible) APT antenna
Kenya, Uganda, and Tanzania262 (Mi250)1973Helical APT antenna
Kenya, Uganda, and Tanzania259-262 fdc1One of four stamps on FDC (Dar-es-Salaam, Tanzania cancel)
Kenya, Uganda, and Tanzania259-262 fdc2One of four stamps on FDC (Kampala, Uganda cancel)
Kenya, Uganda, and Tanzania259-262 cardPresentation card
Maldive Islands467 (Mi482)
i467

Imperforate
1974Helical APT antenna (note: mis-spelling of "metereological" instead of "meteorological")
MongoliaC35 (Mi773)1973Helical APT antenna
Qatar327 (Mi524)1972Helical APT antenna
Russia (USSR)NoneCachet on stamped envelope1982Helical APT antenna
Russia (USSR)5246 cover (Mi5376 cover)Cachet on cover1986Helical APT antenna
Russia (USSR)5246 cover (Mi5376 cover)Cachet (same) on cover (different)1987Helical APT antenna
Russia6575a (BL30)In (lower-right) margin of MS5 (6571-6575 + label)2000Helical APT antenna
Russia6577 (BL31)SS12000Helical APT antenna
Russia6577 fdc1SS1 on FDC
Russia6577 fdc2SS1 on FDC (different)
RussiaNone(Photo) cachet on cover2007Helical APT antenna
Tunisia653 (Mi860)1975Helical APT antenna
Tunisia653 fdcStamp on FDC
United Nations188 fdc (Mi204 fdc)(Schering) cachet on FDC1968Helical APT antenna
United StatesNone(Schering) cachet on PPO postcard1968Helical APT antenna
United States
Fort Myers FL (USA)
1501 fdc
local fdc
(Blue rubber-stamp) cachet on dual-cancel FDC1973
1973
Helical APT antenna: "automatic measurement & transmission of data by radio from space vehicles to a receiving station for recording & analysis"
Vietnam (South)447 (Mi525)1973Crossed-Yagi APT antenna
Vietnam (South)447 fdc1Stamp on FDC
Vietnam (South)447 fdc2Stamp on FDC (different)
Vietnam (South)447 fdc3Stamp on FDC (different)
Vietnam (South)447 fdc4Stamp on FDC (different)
Vietnam (South)447 fdc5Stamp on FDC (different)
Vietnam (South)447 fdc6Stamp on FDC (different)
Vietnam (South)447 fdc7Stamp on FDC (different)
Vietnam (South)447 fdc8Stamp on FDC (different)
Vietnam (South)447 fdc9Stamp on FDC (different)
Vietnam (South)447 fdc10Stamp on FDC (different)
Vietnam (South)447 fdc11Stamp on FDC (different)
Vietnam (South)447 folder1FDC folder, also inside
Vietnam (South)447 folder2FDC folder (different color)
Vietnam (South)447 folder3FDC folder (different)
Vietnam (South)447 folder4FDC folder (different)
Vietnam (South)447 scSouvenir card
Vietnam (South)497 (Mi575)447 overprinted new currency1974Crossed-Yagi APT antenna
Multiple-helix tracking antennas3
Andorra (French Admin.)167 (Mi193)19654-helix
Andorra (French Admin.)167 fdcStamp on FDC ('FDC' cachet)
Andorra (French Admin.)167 maxiMaxicard
France1047 (Mi1413)19624-helix; (see also Reunion 343)
France1047 maxi1Maxicard
France1047 maxi2Maxicard (different)
France1047 maxi3Maxicard (different)
France1047 fdc1Stamp and (PAC) cachet on FDC
France1047 fdc2Stamp and (PJ no.437) cachet on FDC
France1047 fdc3Stamp and (Combet?) cachet on FDC
France1047 dsDeluxe sheet (1047)
France1047 proofsTrial color proofs
France1047-1048 ms2On one of MS2 (1047-1048)19624-helix
France1047 cover1Stamp and cancel on cover1962-10-194-helix
France1047 cover2Stamp and cancel (different) and (Lollini) cachet on cover1962-11-034-helix
France1047 cover3Stamp and cancel (same as first) and (PJ) cachet on cover1962-11-194-helix
France1047 cover4Stamp on cover1962-11-204-helix
France1048 cover1 (Mi1414 cover1)Cancel on cover1962-10-194-helix
France1048 cover2 (Mi1414 cover2)Cancel (different) on cover1962-11-104-helix
France1048 cover3 (Mi1414 cover3)Cancel (same as first) on cover1962-11-194-helix
France1048 cover4 (Mi1414 cover4)Cancel (with reproduction of France 1047) on cover1962-12-15/164-helix
France1048 maxi1 (Mi1414 maxi1)Cancel on maxicard19624-helix
France1048 maxi2 (Mi1414 maxi2)Cancel (different) on maxicard
France1047 cover (Mi1413 cover)Stamp on cover1963-09-124-helix
France1067 fdc (Mi1443 fdc)Cachet (with reproduction of France 1047) on FDC19634-helix
France1100 (Mi1480)
i1100
From MS8 (1100a (8x 1100 + 8 labels))
From imperforate MS8 (i1100a (8x i1100 + 8 labels))
19644-helix; see also Hungary 2367
France1100 maxiMaxicard
France1100_half fdc1100a half-sheet on FDC
France1100+label cover (Mi1480+label cover)Stamp on cover (PJ cachet)19644-helix; see also Hungary 2367
France1122 (Mi1520)
i1122

Imperforate
19654-helix
France1122 proofsTrial-color proofs
France1122 fdc1Stamp and ('FDC') cachet on FDC
France1122 fdc2Stamp and (PJ no.532) cachet on FDC
France1122 maxi1Maxicard
France1122 maxi2Maxicard (different)
France1122 maxi3Maxicard (different)
France1122 ms4MS4 (4x 1122)
FranceNone(Blue printed) cachet on cover19733 or 4-helix (bottom-right)
Germany (West)NoneCancel and cachet on cover19693 or 4-helix
Hungary2367+lab (Mi3043)Stamp (stamp-on-stamp: France 1100) and label19754-helix
Monaco609 (Mi802)19654-helix
Monaco609 maxiMaxicard
Monaco609 fdc1Stamp on FDC (PJ no.129 cachet)
Monaco609 fdc2Stamp on FDC ('FDC' cachet)
Monaco609 fdc3Stamp on FDC (? cachet)
Monaco605-610 fdcOne of six stamps on FDC (B. Minne cachet)
Monaco876 (Mi1082)19734-helix
Monaco873+875-876+878 spOne of four stamps and center of souvenir page (873+875-876+878)
Reunion343 (Mi423)France 1047 overprinted19634-helix
Reunion343 dsDeluxe sheet (343)
Reunion343-344 fdcOne of two stamps on FDC
Reunion343 coverFour stamps (France 1047 overprinted) on cover1963-06-124-helix
Russia (USSR)5296 fdc (Mi5438 fdc)Cachet on FDC19843-helix
Russia (USSR)5299 (BL176)In (right) margin of SS119843-helix
Russia (USSR)5299 fdcSS1 and cachet on FDC
Multiple-Yagi tracking antennas4
Albania1210 (Mi1338)19694 Yagis
Albania1208-1210 fdcOne of three stamps on FDC
Chad440B (BL151)
i440B
In (left) margin of SS1, gold foil
In (left) margin of imperforate SS1, gold foil
19834 Yagis
Congo (Republic)C37 (Mi93)
iC37

Imperforate
19668 crossed-Yagis
Congo (Republic)C37 fdcStamp on FDC
Cuba964 (Mi1026)19654 booms5
Cuba964-968 fdcOne of five stamps on FDC
Czechoslovakia2307 (Mi2562)19806 crossed-Yagis (3 each of 2 different sizes)
Czechoslovakia2304+2307 fdcOne of two stamps and cachet on FDC
Czechoslovakia2304+2307 cardFDC card
France1835 (Mi2335A)
i1835 (Mi2335B)

Imperforate
19825 crossed-Yagis
France1835 fdc1Stamp on FDC (CEF cachet)
France1835 fdc2Stamp on FDC (different)
France1835 fdc3Stamp on FDC (different)
France1835 fdc4Stamp and ('FDC') cachet on FDC
France1835 fdc5Stamp on FDC (different)
France1835 scStamp on souvenir card
France1835 maxiMaxicard
Great BritainNone(Maia, The Band private advertising) cinderella20124 Yagis; design similar to Russia 2235
Hungary1659 (Mi2101)
i1659

Imperforate
19654 Yagis
Hungary1659+1661+1666-1667 fdc
i1659+i1661+i1666-i1667 fdc
One of four stamps on FDC
One of four imperforate stamps on FDC
India655 fdc1 (Mi624 fdc1)Cachet on FDC (New Delhi cancel)19758 crossed-Yagis
India655 fdc2 (Mi624 fdc2)Cachet (same) on FDC (Lucknow cancel)
India655 cover1 (Mi624 cover1)Cancel on cover19768 crossed-Yagis
India655 cover2 (Mi624 cover2)Cancel (same) on cover (different)19768 crossed-Yagis
RomaniaNoneCachet on stamped envelope19844 Yagis
Russia (USSR)2091 (Mi2104)19584 Yagis
Russia (USSR)2091 cover (Mi2104 cover)Stamp on cover19584 Yagis; also International Geophysical Year (IGY)
Russia (USSR)2235 (Mi2261)19594 Yagis; see also Great Britain cinderella 2012
Russia (USSR)3110 (Mi3129)19654 Yagis
Russia (USSR)3700 (Mi3728)19704 Yagis
Russia (USSR)NoneCachet on stamped envelope19795 crossed-Yagis
Russia (USSR)4898 (Mi5029)19814 Yagis
Russia (USSR)4898 fdcStamp on FDC
Russia (USSR)NoneCachet on cover19814 Yagis
Russia (USSR)NoneCachet on stamped envelope19854 Yagis
Russia (USSR)5462 (Mi5611)19865 Yagis?
Russia (USSR)NonePostal card19873 Yagis
Russia (USSR)NonePostal card (with different cancel)19873 Yagis
Rwanda815 (Mi879)
i815

Imperforate
19774 crossed-Yagis
SyriaC452 (Mi1097)19702 Yagis and dish
SyriaC453 (Mi1098)
Upper VoltaC29 (Mi187)
iC29

Imperforate
19668 crossed-Yagis
Upper VoltaC29 proofSigned proof (red)
Upper VoltaC29 fdcStamp and (Éditions So.Ge.Im.) cachet on FDC
Wallis and Futuna IslandsC153 (Mi528)19874 crossed-Yagis
Wallis and Futuna IslandsC153 proofSigned proof (brown-black)
Wallis and Futuna IslandsC153 fdcStamp and cachet (design like stamp) on FDC

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.

CountryCancel DateCancel LocationType of ItemNotes on Content
Automatic Picture Transmission (APT)
United States1963-12-21Cape Canaveral FL(Printed) cachet on TIROS-8 launch cover, also (newspaper clippings and hand-written) insert"Automatic Picture Transmission"
United States1963-12-21Cape Canaveral FL (hand cancel)(Centennial) cachet on TIROS-8 launch cover"Automatic Picture Transmission"
United States1963-12-21Cape Canaveral FL (machine cancel)(Centennial) cachet on TIROS-8 launch cover
United States1963-12-21Cape Canaveral FL(SpaceCraft/Swanson) insert or insert variation (slightly different line lengths) from TIROS-8 launch cover, also front"Automatic Picture Transmission"
United States1963-12-21Patrick AFB, FL(SpaceCraft/Swanson) insert or insert variation (slightly different line lengths) from TIROS-8 launch cover, also front
United States1963-12-21Cape Canaveral FL(Astro Covers) cachet on TIROS-8 launch cover"Automatic Picture Tranmissior System"
United States1963-12-21Cape Canaveral FL(Rank velvet, brown) cachet on TIROS-8 launch cover"APT"
United States1963-12-21Cape Canaveral FL(Rank velvet, red-brown) cachet on TIROS-8 launch cover
United States1966-02-28Cape Canaveral FL(SpaceCraft/Swanson) cachet on ESSA-2 launch cover, also insert"Instant weather watcher" (in text), APT antenna and facsimile machine (on insert)
United States1966-02-28Patrick AFB, FL (machine cancel)(SpaceCraft/Swanson) cachet on ESSA-2 launch cover, also insert
United States1966-02-28Patrick AFB, FL (hand cancel)(SpaceCraft/Swanson) cachet on ESSA-2 launch cover, also insert
United States1966-05-15Vandenberg AFB, CA(Sarzin?) cachet on Nimbus-2 launch cover"simple inexpensive ground equipment" (in text), referring to APT receiving equipment
United States1967-01-26Vandenberg AFB, CA(Sarzin) cachet on ESSA-4 launch cover"Its two cameras will…send pictures immediately to ground stations around the world" (in text), referring to APT receiving equipment
United States1967-01-26Vandenberg AFB, CA(Orbit Covers) cachet on ESSA-4 launch cover"'Instant Weather' photos" (in text), referring to APT receiving equipment
United States1967-04-20Vandenberg AFB, CA(Orbit Covers) cachet on ESSA-5 launch cover"'Instant Weather' photos" (in text), referring to APT receiving equipment
United States1967-11-10Vandenberg AFB, CA(SpaceCraft/Swanson) cachet on ESSA-6 launch cover, also insert1 and insert2 and insert2 back"Up-to-the-moment weather pictures direct from space" (in text), referring to APT receiving equipment
United States1967-11-10Lompoc CA(Orbit Covers) cachet on ESSA-6 launch cover"'Instant Weather' photos" (in text), referring to APT receiving equipment
United States1968-12-15Vandenberg AFB, CA(SpaceCraft/Swanson) cachet on ESSA-8 launch cover"Automatic Picture Transmission"
United States1968-12-15Vandenberg AFB, CA(Orbit Covers) cachet on ESSA-8 launch cover"two APT"
United States1969-02-26Kennedy Space Center FL(SpaceCraft/Swanson) cachet on ESSA-9 launch cover, also insert1 or insert1 variation (slightly different line lenghts) and insert2 and insert2 back"Instant Weather" photos (in text), referring to APT equipment
United States1969-02-26Patrick AFB, FL (hand cancel)(SpaceCraft/Swanson) cachet on ESSA-9 launch cover, also insert1 or insert1 variation (slightly different line lenghts) and insert2 and insert2 back
United States1969-02-26Patrick AFB, FL (machine cancel)(SpaceCraft/Swanson) cachet on ESSA-9 launch cover, also insert1 or insert1 variation (slightly different line lenghts) and insert2 and insert2 back
United States1969-02-26Cape Canaveral FL (hand cancel)(SpaceCraft/Swanson) cachet on ESSA-9 launch cover, also insert1 or insert1 variation (slightly different line lenghts) and insert2 and insert2 back
United States1969-02-26Cape Canaveral FL (machine cancel)(SpaceCraft/Swanson) cachet on ESSA-9 launch cover, also insert1 or insert1 variation (slightly different line lenghts) and insert2 and insert2 back
United States1969-02-26Vandenberg AFB, CA(Orbit Covers) cachet on ESSA-9 launch cover"Instant Weather" photos (in text), referring to APT equipment
United States1970-01-23Vandenberg AFB, CA(Orbit Covers) cachet on TIROS-M and OSCAR-5 launch cover"two APT"
United States1970-12-11Lompoc CA, Vandenberg AFB(Space Voyage) insert from NOAA-1 and CEP-1 launch cover, also front"Automatic Picture Transmission (APT) camera systems"; "APT pictures will be taken and transmitted every 260 seconds"; the "photographs will be received by some 500 specially-equipped ground stations around the globe for issuing local weather forecasts and warnings"
United States1970-12-11Lompoc CA, Vandenberg AFB(Solar Covers no.7) insert from NOAA-1 and CEP-1 launch cover"Automatic Picture Transmission (APT)" system
United States1971-10-21Lompoc CA, Vandenberg AFB(Space Voyage) cachet on ITOS-B [failed] launch cover, also insert"transmit instant pictures of weather to small stations around the world" (in text), referring to APT receiving equipment; "Cameras were to transmit the scenes they were viewing at any given time directly to one-man receiving stations" (known as APT (Automatic Picture Transmission) receiving stations). "More than 500 [such] ground stations now are in operation in more than 50 countries around the globe in the ITOS system". (in insert text)
Russia (USSR)1972-03-30Moscow International PO(Swanson) cachet on Meteor-1-11 launch cover"Automatic Picture Transmission"
United States1972-10-15Lompoc CA, Vandenberg AFB(Polar Covers) insert from NOAA-2 and OSCAR-6 launch cover, also insert back and front and back"SR data is transmitted in real time to the local APT stations"
United States1972-10-15Lompoc CA(Polar Covers) insert from NOAA-2 and OSCAR-6 launch cover, also insert back and front and back
Russia (USSR)1972-10-26Moscow International PO(Swanson) cachet on Meteor-1-13 launch cover"Automatic Picture Transmission"
Russia (USSR)1973-05-29Moscow International PO(W. Anklam) cachet on Meteor-1-15 launch cover"Automatic Picture Transmission"
Weather Facsimile (WEFAX)6
United States1974-05-17Kennedy Space Center FL(Space Voyage) cachet on SMS-1 launch cover"relay weather data to thousands of receiving stations" (WEFAX implied)
United States1974-05-17Cape Canaveral FL(InterSpace Cover) cachet on SMS-1 launch cover
United States1974-05-17Cape Canaveral FL(Orbit Covers) cachet on SMS-1 launch cover"transmits weather pictures and data to hundreds of small stations" (WEFAX implied)
United States1975-02-06Cape Canaveral FL(Orbit Covers) cachet on SMS-2 launch cover"transmits weather pictures and data to hundreds of small stations" (WEFAX implied
United States2009-06-27Cape Canaveral FL(Mission 57) cachet on GOES-14 launch cover, also front"digital Weather Facsimile (WEFAX)"6 (in text)
United States2010-03-04Cape Canaveral FL(Mission 57) cachet on GOES-15 launch cover, also front"digital Weather Facsimile (WEFAX)"6 (in text)
Multiple-helix tracking antennas3
United States1962-08-20Andover ME (hand cancel)(Sarzin) cachet on Telstar-1 launch cover4-helix
United States1962-08-20Andover ME (machine cancel)(Sarzin) cachet on Telstar-1 launch cover4-helix
Multiple-Yagi tracking antennas4
India1976-04-20Sri Hari Kota Launch RangeCancel on Aryabhata anniversary cover8 crossed-Yagis
Russia (USSR)1979-06-07Moscow(Printed) cachet on Bhaskara launch cover (stamped envelope)5 crossed-Yagis

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.
6Digital Weather Facsimile (WEFAX) refers to the digital replacement for analog WEFAX transmissions. That service is called Low Rate Information Transmission (LRIT). At some point it is expected the NOAA's GOES satellites will transmit only digital LRIT. The transmission frequency for LRIT will remain 1691 MHz, but will require changes to present receivers and the decoding and display software to accommodate a digital data stream. The advantage of a digital signal will be improved resolution or visual quality of the images and the additional data in the transmission.


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