L ow R ate I nformation T ransmission

Low Rate Information TransmissionProduct Suite

Satellite Direct Readout Conference for the Americas in Miami, Florida December 9-13, 2002 1

Charles Vance [email protected]

L R I T

Sometimes referred to as:• Digital WEFAX• High Speed WEFAX• Next Generation WEFAX

LRIT is more than WEFAX


01:00 17Z 72Hr MSLP/1000-500 THK 01:05 17Z 72Hr 500MB HT PA33 W502 01:10 GOES-8 2345Z NE IR 01:14 GOES-8 2345Z SE IR 01:18 GOES-8 2345Z NW IR 01:22 GOES-8 2345Z SW IR 01:26 GOES-8 2345Z 4KM US IR 01:30 GOES-8 2345Z 16KM FD IR 01:34 GOES-8 2345Z NH WV 01:38 GOES-8 2345Z NE WV 01:42 GOES-8 2345Z SE WV 01:46 GOES-8 2345Z NH WV 01:50 GOES-8 2345Z SW WV 01:54 GOES-8 0045Z NH IR 01:58 GOES-8 2345Z 16KM FD WV

WEFAX(Weather Facsimile)

Transmits only images using low rate facsimile, 24 hours a day on a fixed schedule of 4 and 5

minute time slotsPRODUCTS

GOES EAST GOES WEST

135 GOES 132 GOES

59 NWS Charts 58 NWS Charts

44 NOAA Polar 44 NOAA Polar

2 TBUS 3 msg files 2 TBUS 3 msg files

67 Meteosat 7 Meteosat

40 GMS


L R I T(More than WEFAX)

Integrated Stream of Digital Products that can be Transmitted Asynchronously

Improved Image Resolution

Can Utilize Compression

Diverse Product Suite

Digital Text Messages!Satellite Direct Readout Conference for the Americas in Miami, Florida December 9-13, 2002 4

Initial LRIT Product Suite• Used WEFAX as a Baseline and

– Reduced latency– Increased resolution– Improved user flexibility

• Also added other services such as– NWS messages including EMWIN– DCS

• Evolving Capabilities and Products


Geostationary Satellite Data Polar Satellite Data

GOES Data Collection Service

NWS Data (including)• Models/Charts• EMWIN

L R I TL R I T Integrated Stream of Digital Products

Text and Administrative Messages


GOES Imagery Example WEFAX Limitations

• Resolution Limitations– Pixel Area limited by 2.4KHz modulation– Pixel Depth (brightness) roughly 6.5 bits

• Latency– One Daytime GOES Full Disk Ingest generating

14 WEFAX image products takes 56 minutes to transmit

– Initial processing delays of 25 minutes– Scheduling – images sent one after another


14 WEFAX PRODUCTS FROM 1 DAYTIME FULL DISK8 KM Northern Hemisphere and Quadrants

16 KM Full Disk 4 KM CONUS

IR WV IR VIS

IR

WV

IR IR

IR IR

VIS

VISVIS

VIS


LRIT Transmits Full Disk in near real time segments for improved reliability and less latency

User can generate sectors for areas of interest

Missing segment does not negate

entire transmission

Total Transmission time of approximately 20-25 minutesSlightly longer than normal GVAR transmission


LRIT Viewer Screen ShotGOES-10 8 Km IR


LRIT Viewer Screen ShotGOES-10 8 Km IR Missing Segment w Overlays


LRIT Viewer Screen ShotGOES-10 8 Km IR Missing Segment w Zoom


LRIT Viewer Screen ShotGOES-8 8 Km IR


LRIT Viewer Screen ShotGOES-8 8 Km IR with Zoom and Overlay


GOES Imagery Example LRIT Improvements

• Resolution– Pixels per line variable and ‘unlimited’– Pixel Depth of 8 bits (generally)

• Latency– Initial processing delays minimized– One Daytime GOES Full Disk Ingest sent in

segments taking 20 – 25 minutes to transmit– Scheduling – multiple products sent

‘simultaneously’


LRIT Viewer Screen Shot(Compressed) GMS with ZOOM (Embedded Overlays)


LRIT Receiver Screen Shot


Time Share of WEFAX and LRIT During Transition

0500

30

50

154540

5510

202535

Reduced Product Suite for Each ServiceAlternates Each

HourWEFAX

GOES Images

NWS Charts

GMS

Meteosat?

LRIT

GOES

NWS products• Models/Charts• EMWIN

GMS

GOES DCS channel?Satellite Direct Readout Conference for the Americas in Miami, Florida December 9-13, 2002 18

Summery

• LRIT is an Integrated Stream of Diverse Digital Products that can be Transmitted Asynchronously and has Reduced Latency, Improved User Flexibility, Increased Resolution, and Increased Reliability compared to WEFAX

• The LRIT Product Suite is User Driven


Are you ready?

• Email: [email protected]

• http://www.osdpd.noaa.gov/COB/COB.html

• http://noaasis.noaa.gov/WEFAX/ ( /LRIT/ ? )

• http://www.nws.noaa.gov/datamgmt/doc/lrit.html


L ow R ate I nformation T ransmission

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