LRPT
Page: Sats.LRPT - Last Modified : Sun, 19 Jun 11
(redirected from Misc.LRPT)
Meteor M1 LRPT downlink
| OLD MODULATION FORMAT |
| |
| Frequency: | 137.100 MHz |
| Modulation: | QPSK |
| Rate: | 72000 sym/s |
| Interleaving: | None |
| Coding: | Viterbi 1/2 + Reed Solomon |
| Scrambling: | 255byte sequence |
| Syncword: | 0x1ACFFC1D |
| S/C ID: | 0 |
| |
| Signal spectrum (click for full image): |
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|
| NEW MODULATION FORMAT |
| |
| Frequency: | 137.100 MHz |
| Modulation: | QPSK |
| Rate: | 80000 sym/s |
| Interleaving: | 36/2048 (~8 seconds) |
| Coding: | Viterbi 1/2 + Reed Solomon |
| Scrambling: | 255byte sequence |
| Syncword: | 0x1ACFFC1D |
| S/C ID: | 0 |
| |
| Signal spectrum (click for full image): |
 |
|
UPDATE 2010-01-15
Meteor-M1 is back to the old modulation format as specified above with no RS problems. Currently with channels 67 and 68, both with good IR imagery. Decoded images are below (20100115 1853z pass).
UPDATE 2010-01-13
After weeks of no IR imagery, passes on 2010-01-12 had channel 68 with some nice images - all still with non-CCSDS compatible RS.
However on both passes on 2010-01-13 evening, all AC coefficients were zero for both 64 and 68 channels. This changes the signal spectrum slightly as it's sending a lot of zeroes. Also all frames still with bad RS.
UPDATE 2010-01-01
After two passes with with just added interleaver, Reed solomon encoder probably failed completely or was switched to some non-standard mode. RS block is still 128bytes at end of frame, non protected data are still same and can be decoded (with errors).
Possibilities are:
- RS encoder failed - possible as there was problem with it before
- switched to dual-basis mode as in CCSDS spefification - tried this, doesn't match
- something with encoder order - like scrambling just input data, not RS checksum
- wrong bit order somewhere in decoder
- RS encoder use some different polynome and interleaving - unlikely
I have tried all combinations of scrambling before/after, dual-basis vs. normal mode, bit order swap before/after RS. Haven't found any way how to decode it properly. As first passes were using same RS as old format, I suspect is is failed RS encoder, not some new format of RS ECC.
UPDATE 2009-12-26
MERRY CHRISTMAS AND HAPPY NEW YEAR 2010
Downlink LRPT format changed and it's not 100% according to Metop LRPT specification. Scrambler seems to be working perfectly, spreading errors over few seconds and helping Viterbi to reconstruct more frames.
Format of actual frames is still same, so links below are still relevant.
Archive with raw decoded frames
I have uploaded archive with raw decoded frames (entire CCSDS 1024Byte frame, starting with SYNC) from last 3 passes (exact time & data is in file name):
Download: meteor-lrpt.rar (4MB) (raw received frames, no decoded images and no readable text inside)
List of PIDs active on all decoded passes:
| Date | Time | vis | vis | IR | IR | vis | ctl | Notes |
|---|
| 20091103 | 1748z | 64 | 65 | 66 | -- | -- | 70 | Vis only/black@night. |
| 20091103 | 1928z | 64 | 65 | 66 | -- | -- | 70 | Vis only/black@night. |
| 20091104 | 1730z | 64 | 65 | 66 | -- | -- | 70 | Vis only/black@night. |
| 20091104 | 1907z | 64 | 65 | 66 | -- | -- | 70 | Vis only/black@night. |
| 20091105 | 1848z | 64 | 65 | 66 | -- | -- | 70 | Vis only/black@night. |
| 20091105 | 2028z | 64 | 65 | 66 | -- | -- | 70 | Vis only/black@night. |
| 20091106 | 1826z | 64 | 65 | 66 | -- | -- | 70 | Vis only/black@night. |
| 20091106 | 2004z | 64 | 65 | 66 | -- | -- | 70 | Vis only/black@night. |
| 20091108 | 1745z | 64 | 65 | 66 | -- | -- | 70 | Vis only/black@night. |
| 20091108 | 1929z | 64 | 65 | 66 | -- | -- | 70 | Vis only/black@night. |
| 20091109 | 1904z | 64 | -- | -- | 67 | 68 | 70 | 64,68=black@night 67=good |
| 20091110 | 1842z | 64 | -- | -- | 67 | 68 | 70 | 64,68=black@night 67=good |
| 20091110 | 2021z | 64 | -- | -- | 67 | 68 | 70 | 64,68=black@night 67=good |
| 20091111 | 1821z | 64 | -- | -- | 67 | 68 | 70 | 64,68=black@night 67=good |
| 20091119 | 1854z | 64 | -- | -- | 67 | 68 | 70 | 64,68=black@night 67=good |
| 20091120 | 1653z | 64 | -- | -- | 67 | 68 | 70 | 64,68=black@night 67=good |
| 20091120 | 1833z | 64 | -- | -- | 67 | 68 | 70 | 64,68=black@night 67=good |
| 20091120 | 2010z | 64 | -- | -- | 67 | 68 | 70 | 64,68=black@night 67=good |
| 20091121 | 1811z | 64 | -- | -- | 67 | 68 | 70 | 64,68=black@night 67=good |
| 20091121 | 1949z | 64 | -- | -- | 67 | 68 | 70 | 64,68=black@night 67=good |
| 20091122 | 1933z | 64 | -- | -- | 67 | 68 | 70 | 64,68=black@night 67=good |
| 20091123 | 1728z | 64 | -- | -- | 67 | 68 | 70 | 64,68=black@night 67=good |
| 20091123 | 1908z | 64 | -- | -- | 67 | 68 | 70 | 64,68=black@night 67=good |
| 20091123 | 2051z | 64 | -- | -- | 67 | 68 | 70 | 64,68=black@night 67=good |
| 20091124 | 1849z | 64 | -- | -- | 67 | 68 | 70 | 64,68=black@night 67=good |
| 20091125 | 1827z | -- | -- | -- | 67 | 68 | 70 | 68=bad/low contrast 67=good |
| 20091126 | 0959z | -- | -- | -- | 67 | 68 | 70 | 68=bad/low contrast 67=good |
| 20091128 | 1903z | -- | -- | -- | 67 | 68 | 70 | 68=bad/low contrast 67=good |
| 20091130 | 1822z | -- | -- | -- | 67 | 68 | 70 | 68=bad/low contrast 67=good |
| 20091130 | 2000z | -- | -- | -- | 67 | 68 | 70 | 68=bad/low contrast 67=good |
| 20091202 | 0747z | -- | -- | -- | 67 | 68 | 70 | GRAYSCALE TEST PATTERN |
| 20091202 | 0931z | -- | -- | -- | 67 | 68 | 70 | GRAYSCALE TEST PATTERN |
| 20091202 | 1742z | -- | -- | -- | 67 | 68 | 70 | GRAYSCALE TEST PATTERN |
| 20091202 | 1918z | -- | -- | -- | 67 | 68 | 70 | GRAYSCALE TEST PATTERN |
| 20091203 | 1051z | 64 | 65 | 66 | -- | -- | 70 | encoder resets/long idle periods |
| 20091203 | 1717z | 64 | 65 | 66 | -- | -- | 70 | Vis only/black@night. |
| 20091203 | 1858z | 64 | 65 | 66 | -- | -- | 70 | Vis only/black@night. |
| 20091203 | 2034z | 64 | 65 | 66 | -- | -- | 70 | Vis only/black@night. |
| 20091204 | 1838z | 64 | -- | -- | -- | 68 | 70 | Vis only/black@night. |
| 20091204 | 2015z | 64 | -- | -- | -- | 68 | 70 | Vis only/black@night. |
| 20091205 | 1955z | 64 | -- | -- | -- | 68 | 70 | Vis only/black@night. |
| 20091208 | 1848z | -- | 65 | -- | -- | 68 | 70 | Vis only/black@night. |
| 20091209 | 1827z | -- | -- | 66 | -- | 68 | 70 | Vis only/black@night. |
| 20091209 | 2007z | -- | -- | 66 | -- | 68 | 70 | Vis only/black@night. |
| 20091211 | 0758z | 64 | -- | -- | 67 | -- | 70 | encoder resets/long idle periods |
| 20091211 | 0938z | 64 | -- | -- | 67 | -- | 70 | encoder resets/long idle periods |
| 20091211 | 1746z | 64 | -- | -- | 67 | -- | 70 | 64=black@night. 67=good |
| 20091211 | 1925z | 64 | -- | -- | 67 | -- | 70 | 64=black@night. 67=good |
| 20091212 | 1904z | 64 | -- | -- | 67 | -- | 70 | 64=black@night. 67=good |
| 20091213 | 1843z | 64 | -- | -- | 67 | -- | 70 | 64=black@night. 67=good |
| 20091214 | 1822z | -- | 65 | -- | 67 | -- | 70 | 64=black@night. 67=good |
| 20091217 | 1859z | 64 | -- | 66 | 67 | -- | 70 | RS Encoder block #4 error |
| 20091217 | 2044z | -- | -- | 66 | 67 | -- | 70 | RS Encoder block #4 error |
| 20091218 | 1838z | 64 | 65 | -- | -- | 68 | 70 | Vis only/black@night. |
| 20091218 | 2023z | 64 | 65 | -- | -- | 68 | 70 | Vis only/black@night. |
| 20091219 | 1817z | 64 | 65 | -- | -- | 68 | 70 | Vis only/black@night. |
| 20091219 | 2001z | 64 | 65 | -- | -- | 68 | 70 | Vis only/black@night. |
| 20091220 | 1939z | 64 | 65 | -- | -- | 68 | 70 | Vis only/black@night. |
| 20091222 | 0727z | 64 | 65 | -- | 67 | -- | 70 | encoder resets/long idle periods |
| 20091222 | 0907z | 64 | 65 | -- | 67 | -- | 70 | encoder resets/long idle periods |
| 20091222 | 1853z | 64 | 65 | -- | 67 | -- | 70 | 64=black@night. 67=good |
| 20091223 | 1833z | 64 | 65 | -- | 67 | -- | 70 | 64=black@night. 67=good |
| 20091223 | 2013z | 64 | 65 | -- | 67 | -- | 70 | 64=black@night. 67=good |
| NEW DOWNLINK FORMAT |
| 20091226 | 1853z | 64 | -- | -- | -- | 68 | 70 | No imagery. |
| 20091226 | 1909z | 64 | -- | -- | -- | 68 | 70 | No imagery. |
| 20091226 | 1735z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20091226 | 1909z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20091228 | 2008z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20091229 | 1807z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20091229 | 1950z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20091230 | 1750z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20091230 | 1929z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20091231 | 1909z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20100101 | 1847z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20100102 | 1823z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20100103 | 1802z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20100104 | 1744z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20100104 | 1920z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20100105 | 1729z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20100105 | 1905z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20100106 | 1842z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20100107 | 1818z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20100108 | 1757z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20100108 | 1936z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20100109 | 1739z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20100109 | 1919z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20100110 | 1859z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. No imagery. |
| 20100112 | 1817z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. |
| 20100112 | 1956z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. |
| 20100113 | 1756z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. All AC = zero |
| 20100113 | 1935z | 64 | -- | -- | -- | 68 | 70 | Unknown RS used. All AC = zero |
| OLD DOWNLINK FORMAT AGAIN |
| 20100115 | 1853z | -- | -- | -- | 67 | 68 | 70 | Good imagery. |
| 20100116 | 1658z | -- | -- | -- | 67 | 68 | 70 | Good imagery. |
| 20100116 | 1834z | -- | -- | -- | 67 | 68 | 70 | Good imagery. |
| 20100117 | 1812z | -- | -- | -- | 67 | 68 | 70 | Good imagery. |
| 20100117 | 1954z | -- | -- | -- | 67 | 68 | 70 | Good imagery. |
| 20100118 | 1752z | -- | -- | -- | 67 | 68 | 70 | Good imagery. |
| 20100118 | 1930z | -- | -- | -- | 67 | 68 | 70 | Good imagery. |
| 20100119 | 1910z | -- | -- | -- | 67 | 68 | 70 | Good imagery. 137.9MHz |
| 20100120 | 1850z | -- | -- | -- | 67 | 68 | 70 | Good imagery. 137.9MHz |
| 20100121 | 1830z | -- | -- | -- | 67 | 68 | 70 | Good imagery. |
| 20100121 | 2005z | -- | -- | -- | 67 | 68 | 70 | Good imagery. |
| 20100125 | 1708z | -- | -- | -- | 67 | 68 | 70 | Good imagery. |
| 20100125 | 1845z | -- | -- | -- | 67 | 68 | 70 | Good imagery. |
| 20100125 | 2026z | -- | -- | -- | 67 | 68 | 70 | Good imagery. |
| 20100126 | 1823z | -- | -- | -- | 67 | 68 | 70 | Good imagery. |
| 20100126 | 1958z | -- | -- | -- | 67 | 68 | 70 | Good imagery. |
| 20100127 | 1804z | -- | -- | -- | 67 | 68 | 70 | No imagery. |
| 20100127 | 1948z | -- | -- | -- | 67 | 68 | 70 | No imagery. |
| 20100128 | 1740z | 64 | 65 | 66 | -- | -- | 70 | Vis only/black@night. |
|
Sample images:
| PID 64 |
|---|
| (no good images so far) |
| |
| PID 65 |
|---|
| (no good images so far) |
| |
| PID 66 |
|---|
| (no good images so far) |
| |
| PID 67 |
|---|
20091119 1854z
Eastern Europe/Russia
(enh/gamma 0.5/inv)
20091222 1853z
Nice pass over Europe
(enh/gamma 0.4/inv)
20100115 1853z
Pass over central Europe
(enh/gamma 0.4/inv)
|
| |
| PID 68 |
|---|
20091202 1918z
Test pattern
20100115 1853z
Pass over central Europe
(enh/gamma 0.4/inv)
|
| |
| PID 70 |
|---|
| (data only) |
| |
(click thumbnails for full resolution images)
|
