1. Solid State Recorder
Liu Dahai
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2. Abstraction
SSR is a storage device of payload system. BC and PLRT transfer data packets to SSR via 1553B bus. When satellite flies over receive station the data packets saved in SSR are sent to HRM and then to downlink.
SSR short for Solid State Recorder
BC short for Bus Controller
PLRT short for Payload Remote Terminal
HRM short for High Rate Multiplexer
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3. EM’s Parameter
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4. SSR’s Struction CSSAR A prime recorder and a cold redundant recorder
Prime Memory
Prime CPU
I/O
Redundant CPU
Redundant Memory
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5. Capacity and Organization
Capacity: 2,147,483,648 bits
The total output time is hours at the rate of 16 Kbps.
Organization : pages x 4096 bytes.
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6. Record CSSAR SSR receive data packets from 1553B bus.
One packet contains 512 bytes and one page consists of 8 packets.
When the SSR is full, new data will be placed on the first page and replace old data.
Data for a given instrument will be added to SSR only when the instrument is active.
Packet
508 bytes
4 bytes
Information Symbols
RS Check Symbols
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7. Record
When writing the first packet of one page, SSR will take the current time as a time mark of the page.
Time 0
Page 0
Time 1
Page 1
Time 65534
Page 65534
Time 65535
Page 65535
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8. Output
During flying over receive station, SSR output recorded data after receiving request signal from HRM.
SSR stop outputting if no request signal is received.
If receiving request signal once more SSR continues outputting data.
After outputting the data stored in the last page SSR will output the data in the first page.
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9. Memory Load Command CSSAR
The memory load command can be used to select start location to be output.
If there is no memory load command given, that is the default mode, SSR will output from the location at which last output stopped.
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10. Memory Load Command CSSAR Execute Time Output Loacation event
An event tell SSR to set the start output location to “Output Location” at the “Execute Time”.
The precision of Execute Time is second.
The “Output Location” is a time value at which the data was record. It’s precision is second.
One memory load command can include 7 events at the most.
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11. Data Protection CSSAR RS(256,252 ) is used to correct errors.
Hardware completes RS encoding when SSR recording;
Software repeats decoding to correct error which appeared in data saved in SSR.
Examine the Validity of storage unit.
A page is set as invalid page and will be bypassed
if more than 32-word units are invalid in the page.
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12. House keeping CSSAR Include the information of SSR, such as:
page being written;
page being read;
how many memory load commands are received and executed;
how many pages are invalid;
…...
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13. Thank you !
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