• Inserts the EMWIN service into LRIT with minimal service latency and minimal bandwidth overhead

• Complies with CGMS & CCSDS and supports NOAA LRIT VC priority scheme

• Allows re-use of existing EMWIN S/W or new TCP/IP based EMWIN S/W

  • D6 S/W supports simultaneous RS-232 & TCP/IP interfaces

  • TCP/IP Socket (internal & external) output for newer S/W

  • RS232 to support legacy EMWIN user S/W

NOAA LRIT System Architecture

CGMS Communication Model

LRIT Domain 4 Existing Design

Domain 4 Context

Communication Processor

• Monitors arrival of LRIT files received from Preprocessor via FTP.

• Implements Session, Transport, Network, and partial Datalink CGMS layers.

• Sends CADUs to Uplink Processor via IPDU interface.

• Uplink Processor implements remainder of Datalink layer as well as physical layer

Domain 4 Architecture

Domain 5 Uplink Processor (No Changes)

LRIT Domain 5

• Domain 5 Functional Specification

  • Receive IPDU Encapsulated VCDU + ASM

  • RS Encode, Randomize, Optional Differential Encode (NRZ-M), Optional Convolution Encode

  • Insert Fill VCDUs (VC63) to maintain constant uplink rate (IOC=146.942 kbps, FOC=293.884 kbps)

  • IPDU > LRIT VCDU + Non-LRIT VCDU > CVCDU > Serialize (constant rate)
    

Domain 5 Context

Domain 5 Specification

Domain 5 Architecture

LRIT Domain 6 Existing Design

LRIT Domain 6 Context

Domain 6 Software Context

Domain 6 Transfer Application

• DLLs implemented as in-process COM Servers

• Data flow roughly follows layer model

• Log / Error logging object

EMWIN - LRIT Insertion

• Carry EMWIN as a bit-stream, but inside a simple file encapsulation

• Use MPDU + Application Packet (AP)+ LRIT File Headers

• Use CGMS File Type for mission specific use (128…255). Assign EMWIN: LRIT file type 214 (0xD6).

• Group EMWIN RS-232 bits into fixed length bit-stream segments

• Insert each EMWIN bit-stream segment after the LRIT File Header

• 1 VCDU per EMWIN bit-stream file

• D6 groups file segments, extracts & concatenates, then outputs serially

• Preserves minimum latency & low overhead bandwidth feature of bit-stream

• LRIT rate = 17.9 frames / sec ; EMWIN rate @ 9.6 = 1.14 frames/sec

• D6 Output compatible with RS-232 COTS EMWIN S/W (i.e. RealEmwin)

EMWIN Bit-Stream VCDU Format

• For preservation of bandwidth and minimal latency, received EMWIN Bitstream is segmented into fixed length segments (836 bytes)

• File creation latency = 836 bytes * input baud rate; file complete prior to queueing

• Fixed length segments are encapsulated per CGMS MPDU/AP/LRIT-File Headers, and sequentially output

• LRIT File Types 128…255 available for mission specific use

CGMS CCSDS VCDU Header

D4 Communication Processor Upgrades for New Design

H/W

• Allow configuration of two RS-232 ports

• Both ports are installed and active
  

S/W

• New Config file S/W monitors config file and implements VC(Priority), COM port settings (speed, parity, stop/start)

• Create S/W for receiving bit-stream data (strip start/stop bits) over RS-232

• Create S/W for encapsulating bitstream in sequential fixed length files

• S/W uses configuration file to select valid data source port
  

LRIT D4 EMWIN Upgrade

D6 User Terminal Upgrades

H/W

• Allow configuration of multiple RS-232 ports for multiple output

S/W

• Create S/W for concatenating EMWIN File Type data

• Output concatenated data as serial stream to sockets

• Allow routing of received bit-stream data to RS-232 port(s)

• Allow routing of received bit-stream data to TCP/IP port(s)

Domain 6 Transfer Application

• LRIT session layer modifiec to support EMWIN

• EMWIN oputputs: file / RS-232 / TCP-IP