NOAA KLM User's Guide

Section 1.2.6

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1.2.6 Data Handling Subsystem

The functions of the Data Handling Subsystem (DHS) are to collect, format, average, and store baseband data from other satellite subsystems; to output baseband data to other satellite subsystems; and to provide synchronous signals and clocks to other satellite subsystems. Tables 1.2.6-1 and 1.2.6-2 list the subsystem data inputs and data outputs, respectively.

Table 1.2.6-1. NOAA KLM Data Handling Subsystem Data Inputs.
Name of Data Source of Data First Component Receiving the data Data Characteristics
Analog Telemetry All active electronic components on the satellite - 512 separate channels TIP Analog health-monitor voltage on a dedicated wire per quantity.
Digital-B Telemetry Same as above, but 352 separate channels. TIP Bi-level status voltage on a dedicated wire per quantity.
Central Processing Unit (CPU) Telemetry-Boost Mode Same as above, but 352 separate channels. TIP NRZ-L data per a specified hand-shake. 8000 bps.
CPU Telemetry - Orbit Mode CIU TIP Same as above, but at 960 bps.
Command Verification Data CIU TIP NRZ-L data per a specified hand-shake. One 16-word per 0.05 second (Boost Mode) or 0.1 second (Orbit Mode).
Digital-A Data All Government-furnished instruments except AVHRR, SARR, SARP and AMSU.(16 channels, 4 used). TIP NRZ-L data per a specified hand-shake. In multiples of 8 bits per 0.1 second: not accepted in TIP Boost or Dwell Modes.
AVHRR Data AVHRR MIRP NRZ-L data per a specified hand-shake. In bursts at 1.9968 Mbps, averaging to 0.6213 Mbps.
AMSU Data AMSU-A1, A2, B and MHS AIP NRZ-L data per a specified hand-shake. 25 8-bit words from AMSU-A1, 13 8-bit words from AMSU-A2, and 50 8-bit words from AMSU-B per 0.1 second. Not intended for TIP Boost or Dwell Modes.

Table 1.2.6-2. NOAA KLM Data Handling Subsystem Data Outputs.
Name of Data Real-Time or Playback Destination Conditions Data Characteristics
TIP Orbit Real-Time Both Beacon Transmitters (BTX's) TIP in Orbit Mode 8320 bps split phase
TIP Orbit Real-Time STX-2

STX-4

TIP in Orbit Mode Command to XSU Command to AIP 8320 bps split phase
TIP Boost Real-Time STX-2

STX-4

(PRIMARY)

TIP in Boost Mode Command to XSU Command to AIP 16640 bps split phase
HRPT Real-Time STX-1, -2, or -3 MIRP On Command to XSU 665.4 kbps split phase
APT Real-Time Both VHF Real-time Transmitters (VTX's) MIRP On Amplitude-modulated 2400-Hz subcarrier
TIP Orbit Playback STX-1, -2, or -3 Command to XSU 332.7 kbps split phase
TIP Boost Playback STX-1, -2,or -3 Command to XSU 332.7 kbps split phase
GAC Playback STX-1, -2, or -3 and STX-4 MIRP on Command to XSU 2.6616 Mbps NRZ or 1.3308 Mbps split phase
LAC Playback STX-1, -2, or -3 and STX-4 MIRP on Command to XSU 2.6616 Mbps NRZ or 1.3308 Mbps split phase
TIP Subcom Data Real-Time CIU CIU responds to handshake 64 bits per TIP minor frame-in bursts
AIP Playback STX-1, -2, or -3 and STX-4 AIP in Data Mode TIP in Orbit Mode Command to XSU 332.7 kbps split phase
AIP Real-Time STX-1, -2 or -3 AIP in Data Mode TIP in Orbit Mode Command to XSU 16640 bps split phase
STX-4 Command to AIP

The MIRP generates the four formats (GAC, LAC, HRPT and APT) described earlier. It incorporates algorithms for data processing and data compression and contains large multi-access buffer stores, which time-average the intermittent AVHRR Earth-scan input (thereby achieving a bandwidth reduction) and manipulates the AVHRR signals together with TIP and AIP data into the desired digital formats.

Data storage is provided by five identical Digital Tape Recorders (DTR). Each DTR consists of one Electronic Unit (EU) and two tape Transport Units (TU's) with the EU switchable to either of the TU's. Each TU has a record capacity of 225 min of TIP data, 113 min of GAC data or 11.3 min of LAC data. Normal operational playback time for GAC or LAC data is 3 min, but a one-half speed (6 min) GAC or LAC playback can also be commanded. The DTRs are identical to provide flexibility and redundancy at a minimum cost. The spacecraft XSU during record provides the selected record mode command (TIP, GAC, or LAC) clock, and record input data to any of the five DTRs. During playback, the XSU provides the selected playback mode command (TIP, GAC, or LAC) and clock to any of the five DTRs, as well as playback output data from any of the five DTRs to any of four S-band transmitters.


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