This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.
>From: Robb Kambic <address@hidden> >Organization: UCAR/Unidata >Keywords: 200011291843.eATIhJp06962 IDD NIDZ floater Robb, Last week, you sent the following: >I saved some of the floaters products on zero, ~ldm/data/radar. These >products have 2 extras nulls at the end so they have different md5 >checksums. >ie. >... >... >0102220 327 020 W 347 020 W 027 \0 310 l 233 372 \r \r \n 003 >0102240 \0 \0 > >Hopefully your decoder can handle the extra chars. Also are the file >names in a usable format? First, the file names are fine. Second, the products you saved do not appear to be the zlib-compressed NIDS products. In support of the files not looking like the zlib-compressed images I note that the file sizes are exceedingly large: % ls -alt *.N0RARX -rw-rw-r-- 1 ldm ustaff 24366 Nov 29 11:31 200011291829.N0RARX -rw-rw-r-- 1 ldm ustaff 28621 Nov 29 11:31 200011291730.N0RARX -rw-rw-r-- 1 ldm ustaff 28393 Nov 29 11:31 200011291740.N0RARX -rw-rw-r-- 1 ldm ustaff 27250 Nov 29 11:31 200011291750.N0RARX -rw-rw-r-- 1 ldm ustaff 26702 Nov 29 11:31 200011291800.N0RARX -rw-rw-r-- 1 ldm ustaff 26188 Nov 29 11:31 200011291810.N0RARX -rw-rw-r-- 1 ldm ustaff 25232 Nov 29 11:31 200011291819.N0RARX Note that these files are all larger than about 25 KB. I suspect that these files are probably the encrypted ones from the datastream, not the zlib-compressed ones. Compare these sizes with a slew of zlib-compressed NIDS products: % ls -alt *_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 14359 Dec 7 05:03 200012071201_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 14419 Dec 7 04:53 200012071151_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 14557 Dec 7 04:43 200012071141_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 14903 Dec 7 04:33 200012071132_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 15145 Dec 7 04:25 200012071122_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 14645 Dec 7 04:14 200012071112_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 14598 Dec 7 04:04 200012071102_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 14938 Dec 7 03:54 200012071052_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 15190 Dec 7 03:44 200012071042_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 15245 Dec 7 03:34 200012071033_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 15046 Dec 7 03:24 200012071023_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 14623 Dec 7 03:15 200012071013_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 14605 Dec 7 03:05 200012071003_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 14349 Dec 7 02:55 200012070953_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 14354 Dec 7 02:45 200012070943_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 14502 Dec 7 02:35 200012070934_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 13793 Dec 7 02:25 200012070924_N0RARX.nidz -rw-rw-r-- 1 ldm ustaff 14060 Dec 7 02:16 200012070914_N0RARX.nidz The current file sizes are typically less than 15 KB AND the station in question (ARX, La Crosse, WI) is just now seeing some weather. Back on Nov 29, the radar was continuously operating in clear air mode, so one could expect the file sizes to be smaller since there was less data to compress. To test my server against altered zlib-compressed NIDS files, I did the following: o copy a set of the *.nidz files to a separate directory o appended two-byte sequence to the end of each file (0x010a instead of 0x0000) o ran my ADDE image list and get servers against those files In this test, everything ran fine, so I feel confident that my servers will work on altered zlib-compressed NIDS products. >The pqact entry: > ># save FLOATER >NMC3 ^FLOATER SDUS5. .... ([0-3][0-9])([0-2][0-9])([0-5][0-9]) >/p(......) > FILE data/radar/(\1:yyyy)(\1:mm)\1\2\3.\4 ># Can you check to make sure that the files being redirected here are not the encrypted ones instead of the zlib-compressed ones? It would be _very_ useful to me to clear up the discrepency with the test files you saved soon. I am just about to announce the availability of my distribution to the McIDAS community, and I would rather not have to release patches to fix a potential problem after the official release. Tom -- +-----------------------------------------------------------------------------+ * Tom Yoksas UCAR Unidata Program * * (303) 497-8642 (last resort) P.O. Box 3000 * * address@hidden Boulder, CO 80307 * * Unidata WWW Service http://www.unidata.ucar.edu/* +-----------------------------------------------------------------------------+