AVHRR Acquisition System
Design Document

Dave Lloyd, Tim Baltzer
Computer Services Branch
Software Engineering Department

Mar 08, 2001



Signatures

Prepared by: Dave Lloyd - Tim Baltzer
  Software Engineer,
  Raytheon, ITSS
Concurred by: Carla Damme
  Technical Area Lead, CSB/SED
  Raytheon, ITSS
Approved by: Mike Benson
  Project Manager,
  Raytheon, ITSS

Document History

Number Date and Sections            Notes                                                                                        
1 Mar 08, 2001 Document Created
2 Jul 22, 2002 Changed design of ACQUMAN to a non-X-windows application, also to not start SHOACQU. All communication between ACQUMAN and SHOACQU is now via sockets.
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Contents

Introduction

Functional Summary

The AVHRR Acquisition System is responsible for all of the live reception of NOAA Tiros-N data at the EROS Data Center.

Comments

None.

Background

The AVHRR acquisition system is an existing system running on old unsupported equipment. It was decided that portions of the system should be upgraded. A new frame synchronizer replaces the existing one and an Intel based Linux server replaces the vax 3800. All other hardware remains in place. Existing hardware consists of: antenna and antenna subsystems, antenna control unit, receiver, and bit synchronizer. A new interface exists between the bit synchronizer and new frame synchronizer. An Ethernet interface exists between the frame synchronizer and Linux server. There is a serial connection between the Linux server and the receiver. The Linux server is connected to the ADAPS production system through a local area network. Figure 1 depicts the AVHRR acquisition system.

Figure 1 -- AVHRR Acquisition System

Scope/Limitations

This document only covers the software components located on the Linux server of the AVHRR acquisition system.

Overall design

The software for the ADAPS Acquisition system will be comprised of three main modules: an acquisition manager, a acquisition display, and a frame synchronizer interface. There will also be several ancillary modules that interface with the ADAPS production system (push data to it).

The acquisition manager, ACQUMAN, controls the operation of the acquisition display, SHOACQU, and the frame synchronizer interface, ACQUIRE. ACQUMAN determines when scheduled passes are to be acquired by reading the AVHRR master schedule in ADAPSTABLES. SHOACQU is a moving window display that gives the user a visual depiction of the scene as it is acquired and also a line of text with the next acquisition time. ACQUIRE communicates with the frame synchronizer, downloads data and stores it in an output file.

PUSHACQU is an ancillary module that transfers all acquired images, 'modsid' files, and time correction files to the ADAPS production system. 'modsid' files contain data to update the master schedule file (modify-by-scene-id), and are part of the legacy AVHRR scheduling system.


Figure 2 -- AVHRR Acquisition System Software

In this design the following conventions are used:

Flow diagrams

Module Design

1. Acquman

2. Acquire

3. Shoacqu

4. Pushacqu