NOAA KLM User's GuideSection 1.2.6 |
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.
| 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. |
| 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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