computer monitor that has control access to the various channels of the GOES-TAP system. GOES-TAP users may be connected to one of several  satellite  field  distribution  facilities  or  be connected to another user. When connected to a distribution hub, the user may select several different channels of imagery sig- nals. There are several hubs located at various National Weather  Service  (NWS)  forecasts  offices,  such  San Francisco, Miami, and Kansas City, to name a few. If the user is not connected directly to a hub, but connected to another user, this arrangement is appro- priately called a slave connection. The secondary user has no direct choice of incoming imagery signal and only receives the data on the channel selected by the primary user. Several Navy and Marine Corps weather stations are connected as slaves. Slaved GOES-TAP users  must  coordinate  with  the  primary  user  if  a different channel of imagery is desired. Each  channel  of  GOES-TAP  is  a  separate broadcast of imagery. One channel, for example, may contain only alternating visual and infrared GOES satellite images of the full disk (hemisphere) of the earth. Another channel may contain visual and infrared GOES images of only the southeastern United States. A  third  channel  may  contain  imagery  from  the European METEOSAT. Yet another channel may contain  high-resolution  picture  transmission  (HRPT) imagery from a NOAA satellite. Enhanced infrared imagery from GOES is also routinely available via GOES-TAP. Most GOES-TAP data is processed and analyzed by  using  a  desktop  computer  with  a  color  video monitor. The monitor is used to display both the imagery   and   the   control   menus.   Initial   issue equipment  was  the  GOES-TAP  Imaging  System (GTIS), which used a Unisys 80386 desktop computer. Most of these systems have been replaced by the Meteorology and Oceanography (METOC) Integrated Data Display System (MIDDS). A laser printer may be connected to either system to provide hard copy prints of the imagery. Although hard copies of selected images may be made, hard copy quality is a function of the printer or imagery connected to the system.  Similar equipment  called  the  Naval  Satellite  Display  System- Enhanced   (or   NSDS-E)   is   used   at   most NAVMETOCCOM  centers.  This  system  has  the additional capability of copying NOAA polar-orbiter and DMSP imagery. Further changes to GOES-TAP processing equipment are very likely in the future. Almost  all  satellite  imagery  processors  have looper capability. The primary application of any looper  system  is  to  store  and  display  a  series  of geostationary satellite images of the same area in a sequence that shows the movement of clouds and weather systems. Individual satellite images may also be  displayed  and  studied.  The  various  other  display options,  such  as  map  overlay  and  enhancement,  are menu-driven for both the GTIS and the MIDDS as is the channel selection. Instructions for using GTIS are contained  in  the  User’s  Manual  provided  with  each installation. The MIDDS has a colorized custom enhancement function and a few systems have the additional capa- bility  of  obtaining  satellite  images  via  WEFAX broadcast,  HF  radio,  or  Automatic  Picture Transmission  (APT)  receiver.  Instructions  for  obtain- ing satellite information via MIDDS is contained in the Meteorology and Oceanography (METOC) Integrated Data Display System (MIDDS) User’s Guide. DIRECT-READOUT  SERVICE Direct-readout  service  is  an  image-data transmission designed to be received by user-operated satellite receiver stations, such as the AN/SMQ-11 satellite  terminal  and  the  Interim  Mobile Oceanography  Support  System  (IMOSS)  satellite module. The raw satellite signals are converted to an image by the receiver station. Direct-readout service is available   from   all   polar-orbiting   meteorological satellites. This service is generally not available from geostationary  satellites,  although  a  few  weather activities  have  acquired  geostationary  direct-readout systems  from  commercial  contractors. One type of direct-readout service that is provided by  the  NOAA  satellites  is  the  Automatic  Picture Transmission (APT) service. APT service provides a continuous  transmission  of  both  visual  and  infrared satellite imagery. The NOAA satellites transmit a pair of images, one visual and one infrared, over sunlight portions  of  the  earth,  and  two  different  infrared channels over the dark side of the earth. The scan rate is 120 lines per minute at 4-kilometer resolution. The amount of data received by a station depends on the location  of  the  satellite  subpoint;  the  further  the subpoint falls from the station, the smaller the area of coverage  becomes. The received APT images are  ungridded—no latitude/longitude lines nor land/water or geographical boundaries are added to the image (fig. 1-21). APT service  is  also  available  from  foreign  polar-orbiting 1-22