1. TRT ROD Data Compression
TRT Overview Meeting
25 June 2013
Paul T. Keener

2. Outline Compression status Validity gate Next steps Paul T. Keener
TRT Overview 25 June 2015

3. Compression Status Huffman compression is still working well
Run : 50ns, L=7.5x1033, μ≈35, Occ=37%
Total compression: 4.45 bits/straw (16.5%)
Non-zero compression: 10.3 bits/straw (εNZ=0.32)
Run : 25ns, L=0.57x1033, μ≈10, Occ=26%
Total compression: 3.43 bits/straw (12.7%)
Non-zero compression: 10.5 bits/straw (εNZ=0.33)
Paul T. Keener
TRT Overview 25 June 2015

4. Stability
Compare the non-zero compression for these runs using Table 6 and tables generated from these runs:
Compress with Table
Run
Table 6
209109
216432
10.34 bits/straw
10.30 bits/straw
10.44 bits/straw
10.51 bits/straw
10.49 bits/straw
10.32 bits/straw
Everything is within 2%.
Expect 25ns run to be worse
Patterns should be different!
Paul T. Keener
TRT Overview 25 June 2015

5. Validity Gate
Suppress most info for straw that do not have LT hits in some gate
Avoid compression lookups in ROD
Reduce ROD->ROS bandwidth
Paul T. Keener
TRT Overview 25 June 2015

6. V-Gate Preliminary Results
Run , 50ns 7.5x1033
Gate (LT bitmaps, early -> late)
Bar:
EC :
Total occupancy: 37.0%
Non-valid straw words: 14.8%
Top valid pattern: 11th most frequent, 0.37%
Total Compression: 3.7 bits/straw (13.8%)
Non-Zero Compression: 8.3 bits/straw (εNZ=0.26)
Paul T. Keener
TRT Overview 25 June 2015

7. V-Gate Preliminary Results (2)
Run , 50ns 7.5x1033, reduced readout
Same gate as Full Readout mode
Total occupancy: 27.3%
Non-valid straw words: 5.5%
Top valid pattern: 9th most frequent, 0.43%
Total Compression: 3.4 bits/straw (12.4%)
Non-Zero Compression: 8.2 bits/straw (εNZ=0.26)
Paul T. Keener
TRT Overview 25 June 2015

8. What to do about non-valid straws
There is value in preserving the non-empty status of non-valid straws
Encode with special pattern that means “non-empty, non-valid”
Gives us a better view of status of detector
Monitoring
Debugging
Other?
Cost: 1 bit for ~ 15% of straws (plus a little…)
Paul T. Keener
TRT Overview 25 June 2015

9. Non-valid Straws with HT
Useful to preserve this information as well
Unique encoding
Tiny rate
Paul T. Keener
TRT Overview 25 June 2015

10. Symbol Generation
With full data, the relative rates of non-valid hit patterns can be calculated
Appropriate symbol length can be determined and fixed
Paul T. Keener
TRT Overview 25 June 2015

11. Next Steps Look at realistic high μ, 25ns datasets
Characterize compression scheme in general
Reduced ReadOut Mode
Validity Gate
Check effect of Ar vs Xe.
Look at possibility of running multiple tables
Supported in ByteStream Converter
Need to add to DAQ and DB
Paul T. Keener
TRT Overview 25 June 2015

12. Summary Compression is working well
Appear to be in good shape for 100 KHz L1A
Paul T. Keener
TRT Overview 25 June 2015