Skimmer frequency accuracy
To be a good RBN citizen a skimmer should have a frequency accuracy of 2ppm or better.
VERY IMPORTANT: To use the data below to improve the accuracy of your skimmer, multiply the current value of FreqCalibration in your skimmer software’s settings file with the suggested adjustment factor listed below.
The location of the settings files are:
CW Skimmer Server: %appdata%\Afreet\Products\SkimSrv\SkimSrv.ini
CW Skimmer: %appdata%\Afreet\Products\CwSkimmer\CwSkimmer.ini
The data listed below is based on yesterday’s RBN data, 00:00 to 23:59 UTC. This means that when making adjustments, changes in calibration will typically not have full impact on the listed data until the second day after the change.
The deviation estimates are based on spots on all active bands (40m and higher) from the respective skimmer. If different hardware is used for the different bands, the deviation number may thus not represent the actual deviation for a particular band. It is a good practice to run a separate instance of RBN Aggregator with a unique SSID for each hardware, (SM7IUN-1, SM7IUN-2, etc.)
A link to the software used to produce the tables can be found at the bottom of this page. It runs as a cron job in an Ubuntu container on my Synology server and uploads to this WordPress website shortly after midnight UTC daily.
The deviation estimation is done in two steps. The first step uses a small number of highly accurate skimmers (called “anchors” in the code, typically GPSDO-controlled skimmers) as reference. The whole estimation process is then repeated one more time but using both the anchors as well as all skimmers determined to be the “good” as reference. The “good” skimmers are those with less than 0.15ppm average deviation from the anchors, producing more than 100 qualifying spots (the qualification criteria of spots are outlined below.)
Repeating the analysis with this this extended set of skimmers as frequency references drastically increases the geographical coverage of the analysis thereby increasing the number of qualifying spots which means a much more reliable deviation estimates for all skimmers. The skimmers used as reference skimmers in the second stage (i.e. both anchors and “good”) are marked with an asterisk in the table below.
When looking at the numbers, keep in mind that the deviations estimated by the algorithm are 100 to 1000 times smaller than the 100Hz resolution of RBN frequency data. The input data is thus extremely “noisy” which inevitably leads to statistical variations. This is also the reason for not including spots under a certain frequency. Doing so would skew the statistics and cause underestimation of the frequency error.
Due to propagation characteristics, operator behavior (e.g. small QSY), and just statistical variations due to the 100Hz rounding, some skimmers selected as reference skimmers in the first stage may have more than 0.2ppm deviation in the second stage. This is not an error.
If you do not see your skimmer in the list below in spite of it successfully feeding spots to RBN the most likely reason is that it is off in frequency. The analytics discards all spots from skimmers having more than 0.5kHz frequency error.
if you want to implement an automated calibration of your skimmer you can access the skew data in machine-readable CSV format here https://sm7iun.se/rbnskew.csv
310274 RBN spots between 2025-04-15 00:00 and 23:59 UTC. 90346 spots (29.1%) were from reference skimmers (*). Average spot flow was 215 per minute from 206 active CW skimmers. 149382 spots from 199 skimmers qualified for analysis by meeting the following criteria: * Mode of spot is CW. * Also spotted by a reference skimmer within 1000 spots. * Also spotted by a reference skimmer within 10s. * SNR is 3dB or higher. * Frequency is 7000kHz or higher. * Frequency deviation from reference skimmer is 0.5kHz or less. * At least 5 spots from same skimmer in data set. Skimmer [ppm] Spots Adjustment ------------------------------------- 3B8GL +0.3 82 1.000000310 3D2AG +0.6 85 1.000000615 5Z4GO +0.0 5 1.000000000 AA0O +0.4 26 1.000000366 AA4VV +0.0 32 1.000000000 AC0C-1 +0.1 191 1.000000099 BA6KC +0.2 68 1.000000175 BD8CS +0.0 29 1.000000000 BG0AJO +0.2 88 1.000000248 BG0AJO/0 +0.1 27 1.000000149 BG2TFW +7.6 73 1.000007617 BH4RRG +0.4 26 1.000000367 BH4XDZ +0.0 29 1.000000000 BI4MPH-1 +0.0 9 1.000000000 BI4UYX -0.2 26 0.999999817 CT1EYQ -0.4 20 0.999999622 CX6VM +0.9 143 1.000000900 DD5XX +0.8 1303 1.000000820 DE1LON +1.6 1094 1.000001551 DF2CK +1.5 3114 1.000001512 DF7GB* +0.0 1763 1.000000017 DK0TE +0.7 1439 1.000000737 DK1MAX -0.4 16 0.999999554 DK9IP* -0.1 1072 0.999999948 DK9IP-1* -0.0 1412 0.999999969 DL0LA -0.3 566 0.999999748 DL0PF +10.0 2232 1.000009960 DL1HWS-3 +0.3 720 1.000000293 DL1HWS-4 +0.0 209 1.000000047 DL4CF +0.0 7 1.000000000 DL5RCN +13.0 1617 1.000012999 DL8LAS +0.7 938 1.000000653 DL8TG* +0.0 1906 1.000000035 DL9GTB +0.4 1633 1.000000449 DM5GG +1.4 2160 1.000001434 DO4DXA* -0.1 1405 0.999999926 DO4ZT* +0.1 1327 1.000000056 DP7D +0.5 368 1.000000484 DR4W -0.7 1013 0.999999300 EA2CW* -0.0 1340 0.999999976 EA2RCF-4 +0.4 854 1.000000387 EA5RQ -0.1 65 0.999999927 EA5RQ/A +0.0 13 1.000000000 EA5WU* +0.0 1226 1.000000022 ES2RR* -0.0 1854 0.999999954 ES5PC* -0.0 2011 0.999999960 F4GOU +3.9 1589 1.000003874 F4VVG* -0.1 885 0.999999880 F6IIT -0.5 1595 0.999999519 G0KTN* +0.1 1650 1.000000121 G3XBI +0.3 489 1.000000320 G3YPP -7.0 95 0.999993045 G4AON +0.4 96 1.000000372 G4IRN +0.5 1599 1.000000471 G4ZFE +0.3 1708 1.000000319 GI4DOH-2* -0.0 1707 0.999999991 GI4DOH-3 +0.4 689 1.000000404 GX0FRE +0.0 321 1.000000044 HA1VHF +1.7 1928 1.000001692 HA6PX* +0.0 1703 1.000000018 HA8TKS +0.2 833 1.000000241 HB9BXE +0.2 1560 1.000000194 HB9DCO* -0.0 1178 0.999999980 HB9GVO +1.3 95 1.000001349 HG8A* +0.1 1828 1.000000139 IK3STG +1.9 1136 1.000001869 IK4VET +2.6 1945 1.000002566 IK7YTT* +0.1 468 1.000000076 JH7CSU1 +0.8 50 1.000000832 JI1HFJ -2.1 15 0.999997857 JJ2VLY +13.5 77 1.000013517 JN1ILK +1.5 223 1.000001454 K1RA +0.1 1051 1.000000150 K2PO/7 +0.3 595 1.000000293 K3PA-1 -0.2 797 0.999999826 K3PA-2 -2.6 38 0.999997359 K4PP +0.3 739 1.000000298 K5EM +0.3 348 1.000000284 K5KHK +0.4 20 1.000000356 K5TR +0.4 1144 1.000000379 K6FOD -0.1 272 0.999999880 K7CO +2.3 442 1.000002299 K7EK -9.6 108 0.999990414 K9IMM* +0.2 912 1.000000214 K9LC +0.2 968 1.000000248 K9QC +0.6 11 1.000000649 KC4YVA -0.7 159 0.999999290 KD2OGR +0.2 662 1.000000194 KD7EFG -0.0 370 0.999999963 KH6LC +0.0 96 1.000000000 KM3T-2* +0.0 1024 1.000000024 KM3T-3* -0.0 973 0.999999969 KM3T-5* -0.0 938 0.999999993 KO7SS +0.3 363 1.000000274 KP2RUM +0.7 1095 1.000000746 KP3CW +0.0 452 1.000000016 KV4TT* +0.0 1217 1.000000008 LA6TPA -1.5 412 0.999998483 LA7GIA +0.1 54 1.000000102 LB9KJ +0.3 597 1.000000312 LU8XW +0.0 7 1.000000000 LY3G +0.5 57 1.000000503 LZ3CB* +0.1 1191 1.000000066 LZ4AE -0.2 1700 0.999999790 LZ4UX* +0.0 1015 1.000000036 LZ5DI +0.9 1737 1.000000862 LZ7AA +0.3 1179 1.000000326 MM0GPZ -0.3 1728 0.999999735 MM0ZBH* -0.1 2419 0.999999938 N2CR* -0.2 652 0.999999811 N6TV +0.4 445 1.000000441 N8DXE +1.9 15 1.000001894 N9CO -0.2 337 0.999999831 ND7K* -0.3 532 0.999999738 NG7M* +0.0 437 1.000000003 NN3RP +0.3 148 1.000000342 NT6Q -3.9 717 0.999996128 NU4F* +0.0 1140 1.000000019 OE3KLU-3 -2.4 74 0.999997595 OE6TZE +0.2 42 1.000000169 OE9GHV* +0.0 1548 1.000000040 OG66X -0.1 193 0.999999926 OH4KA +0.6 392 1.000000610 OH8KA +4.1 771 1.000004140 OK1FCJ +0.4 1613 1.000000431 OK1HRA -3.9 1744 0.999996096 OK4QRO +1.4 1228 1.000001400 ON6ZQ* -0.1 1356 0.999999924 OZ1AAB* +0.2 439 1.000000165 OZ1BZS +0.3 249 1.000000343 OZ4ADX +0.1 375 1.000000076 PA8MM +0.3 1373 1.000000250 PE5TT +0.7 1278 1.000000746 PI4CC +0.5 2035 1.000000526 PY2KJ +1.1 10 1.000001070 R1LB +3.7 503 1.000003706 R4NCU -0.4 295 0.999999565 R9IR +0.2 436 1.000000196 RK3TD +0.5 27 1.000000527 RK3TD-2* -0.1 753 0.999999949 RN4WA +0.8 909 1.000000825 RU9CZD* -0.0 752 0.999999972 S50U +0.3 856 1.000000275 S53A +0.5 2323 1.000000516 S53F +0.2 86 1.000000166 S53WW -0.5 1680 0.999999511 SE5E +0.4 2139 1.000000356 SM0TCZ -0.6 17 0.999999370 SM1HEV +0.8 1409 1.000000783 SM7IUN* +0.0 1339 1.000000000 SQ5J +10.1 955 1.000010091 SV1CDN -0.2 54 0.999999824 SZ1A +0.2 1546 1.000000213 TF3Y +1.4 537 1.000001389 TI7W +0.2 1172 1.000000236 UA0S +3.4 403 1.000003446 UA4CC +13.1 752 1.000013103 UD4FD +1.1 39 1.000001097 UT5R +3.7 807 1.000003669 UT5R-1 +2.2 142 1.000002200 UY2RA* -0.5 746 0.999999454 V51YJ +1.5 17 1.000001521 VE3EID* -0.0 1415 0.999999989 VE6JY +1.5 859 1.000001515 VE6WZ +2.6 735 1.000002593 VE7CC +0.5 315 1.000000488 VK2GEL +0.5 108 1.000000480 VK2RH +0.0 9 1.000000000 VK6ANC +0.2 58 1.000000157 VR2FUN-77 +0.5 599 1.000000526 VU2CPL +2.3 13 1.000002348 VU2PTT -0.1 41 0.999999865 VU2TUM +0.1 89 1.000000135 W1NT-2* +0.1 919 1.000000074 W1NT-6* -0.0 907 0.999999980 W2MV +0.1 156 1.000000091 W3DAN +1.5 19 1.000001497 W3OA* +0.0 1092 1.000000007 W3OA-1 +1.3 535 1.000001292 W3RGA -0.3 1143 0.999999743 W3UA -0.2 107 0.999999796 W4KAZ -0.5 762 0.999999528 W6YX +0.2 643 1.000000223 W8WTS -0.4 676 0.999999605 W8WWV -1.3 999 0.999998716 WA7LNW +0.7 966 1.000000713 WB6BEE* +0.0 829 1.000000001 WC2L* +0.1 787 1.000000062 WC8GOP +7.9 50 1.000007893 WE9V +0.0 993 1.000000013 WS2C +3.9 647 1.000003925 WS3W -0.7 262 0.999999326 WT9U +0.3 143 1.000000310 WV4P +1.2 478 1.000001238 WZ7I* +0.1 1538 1.000000101 YO2CK +0.6 397 1.000000617 YO2MAX +0.1 2067 1.000000089 ZL3X -0.3 149 0.999999742 ZS1NN -4.6 38 0.999995382 Last updated 2025-04-16 00:15:30 UTC
Historical skimmer frequency accuracy
Below you will find historical accuracy data for the past ten days. Do not be concerned over minor daily variations. Since RBN spots only have 100Hz frequency accuracy, the input data is very noisy. Even for a perfectly accurate skimmer, the typical RMS rounding error across all shortwave bands is around 3ppm. This means that for a skimmer with 1000 spots per day the statistical variation is up to 0.2ppm. For skimmers with less than 100 spots per day the statistical variation can be above 2ppm. The content of the table below is based on the historical content of the above table.
Skimmer 0415 0414 0413 0412 0411 0410 0409 0408 0407 0406 --------------------------------------------------------------------- 3B8GL +0.3 +0.1 +0.4 +0.7 +0.4 +0.2 +0.1 +0.2 +0.3 +0.3 3D2AG +0.6 +0.3 +1.0 +1.1 +0.9 +0.8 +0.6 +0.6 +1.0 +0.8 3V9A -1.5 -1.4 -1.5 -1.4 -1.4 -1.6 -1.5 -1.5 5Z4GO +0.0 +0.7 +0.4 -0.8 +1.1 +0.6 +0.5 +1.3 7N4XCV -0.3 +0.5 +0.4 +1.6 +0.0 AA0O +0.4 +0.6 -8.8 -1.2 +0.6 +0.4 +0.9 +0.4 +0.2 +0.9 AA4VV +0.0 -0.0 +0.1 -0.0 -0.0 +0.2 -0.1 +0.1 AC0C-1 +0.1 +0.1 +0.0 +0.0 +0.0 +0.0 -0.3 +0.0 +0.1 +0.1 BA6KC +0.2 -0.1 -0.0 +0.0 -0.1 -0.1 +0.0 BD7JNA +0.0 +0.1 +5.6 BD8CS +0.0 -0.1 +0.0 -0.0 -0.0 -0.1 -0.1 +0.0 -0.1 BG0AJO/0 +0.1 +0.0 +0.0 -0.2 +0.0 +0.3 +0.2 -0.0 BG0AJO +0.2 -0.4 +0.4 +0.4 +0.1 +0.2 +0.8 +0.1 +0.2 +0.3 BG2TFW +7.6 +7.8 +8.4 +9.0 +9.0 +9.3 +7.7 +8.1 +8.2 BG4GOV +0.6 -0.4 BH4RRG +0.4 -0.9 +0.2 +0.2 +0.3 +0.4 +0.0 +0.2 +0.0 +0.2 BH4XDZ +0.0 -0.3 -0.0 -0.0 +0.1 -0.3 +0.0 +0.0 +0.0 +0.2 BI4MPH-1 +0.0 +0.3 +0.2 +0.1 +0.1 +0.0 +0.0 -0.0 +0.5 +0.1 BI4UYX -0.2 +0.5 +0.0 +0.0 +0.0 CT1EYQ -0.4 +0.0 -0.1 +0.1 -0.0 -0.1 -0.1 -0.3 -0.4 CX6VM +0.9 +1.0 +1.7 +1.8 +1.9 +1.1 +0.7 +1.4 +0.8 +0.7 DC8YZ -0.1 +0.1 DD5XX +0.8 +0.9 +1.1 +1.2 +0.7 +0.6 +0.6 +0.5 +0.3 +0.4 DE1LON +1.6 +2.0 +2.0 +2.1 +1.7 +1.7 +1.7 +1.7 +1.6 +2.1 DF2CK +1.5 +1.1 +1.2 +1.1 +0.5 +0.6 +0.7 +0.7 +0.5 +0.7 DF5EG +0.2 DF7GB +0.0 +0.0 +0.0 +0.0 -0.0 +0.1 -0.1 +0.0 -0.0 +0.0 DG6FL +0.0 +0.0 +0.5 +0.2 DK0TE +0.7 +0.9 +1.6 +1.6 +1.1 +1.0 +0.6 +0.3 +0.8 +1.3 DK1MAX -0.4 -0.3 -0.2 -0.2 -0.7 DK3UA +0.1 +0.0 -0.7 -0.2 -0.7 +0.3 DK3WW -0.1 +0.0 +0.0 +0.2 +0.1 DK9IP -0.1 -0.1 -0.1 -0.0 -0.2 -0.1 -0.2 -0.1 +0.1 -0.1 DK9IP-1 -0.0 -0.1 -0.1 -0.1 -0.1 -0.1 -0.1 -0.0 -0.1 -0.2 DL0LA -0.3 -0.2 -0.2 -0.3 -0.1 -0.2 -0.3 -0.1 -0.1 -0.2 DL0PF +10.0 +8.7 +8.3 +7.8 +8.5 +7.3 +7.6 +7.8 +8.5 +7.6 DL1HWS +0.2 +0.2 +0.1 +0.0 +0.1 +0.0 +0.1 +0.1 DL1HWS-3 +0.3 +0.4 +0.7 +0.6 +0.6 +0.4 +0.5 +0.4 +0.5 +0.6 DL1HWS-4 +0.0 +0.1 +0.1 +0.1 +0.1 +0.1 +0.1 +0.0 +0.1 +0.0 DL4CF +0.0 +0.3 +0.0 +0.1 DL5RCN +13.0 +12.6 +12.9 +12.7 +12.7 +12.8 +12.8 DL8LAS +0.7 +0.8 +0.7 +0.6 DL8TG +0.0 +0.1 -0.0 +0.1 +0.0 -0.0 +0.2 DL9GTB +0.4 +0.6 +0.6 +0.6 +0.4 +0.4 +0.4 +0.3 +0.5 +0.8 DM5GG +1.4 +0.4 +1.0 +0.5 +1.3 +1.4 +1.2 +0.7 +0.2 +0.3 DO4DXA -0.1 +0.0 -0.1 +0.0 +0.0 -0.0 -0.0 -0.0 +0.1 -0.0 DO4ZT +0.1 +0.0 +0.0 -0.0 -0.2 -0.0 -0.1 -0.0 -0.1 -0.0 DP7D +0.5 +0.8 +0.7 +1.1 +0.0 +0.2 -0.2 +1.0 +0.2 +0.2 DR4W -0.7 -1.4 -3.1 -1.8 -2.2 -2.1 -1.5 -3.1 -2.5 -3.6 EA1RX -4.3 -0.4 EA2CW -0.0 +0.0 +0.1 +0.1 +0.1 +0.1 +0.0 +0.1 +0.1 +0.4 EA2RCF-4 +0.4 +0.5 +0.8 +0.6 +0.6 +0.7 +0.5 +0.6 +0.5 +0.8 EA5RQ -0.1 -0.2 -0.1 -0.1 -0.3 -0.0 +0.3 +0.1 +0.1 -0.1 EA5RQ/A +0.0 +0.2 +0.1 +0.0 -0.2 -0.2 -0.6 +0.0 +0.1 EA5WU +0.0 -0.1 -0.0 +0.0 +0.0 +0.1 ES2RR -0.0 -0.0 -0.0 -0.0 -0.0 -0.1 +0.0 +0.1 +0.0 +0.0 ES5PC -0.0 -0.0 +0.0 +0.0 +0.0 -0.1 -0.1 +0.0 +0.1 +0.0 F4BPO -1.4 -1.3 F4GOU +3.9 +4.8 +5.2 +5.2 +4.6 +4.9 +4.7 +4.8 +4.4 +5.2 F4VVG -0.1 -0.0 +0.0 +0.0 +0.0 +0.1 +0.1 +0.0 +0.0 +0.0 F6IIT -0.5 -0.6 +0.0 -0.5 -0.4 -0.4 -0.5 F6KGL +0.2 +0.3 +0.3 +0.2 G0KTN +0.1 +0.1 +0.2 +0.3 +0.3 +0.2 +0.1 +0.3 +0.3 +0.2 G0TMX +0.3 -0.0 G3XBI +0.3 -0.1 +0.5 +0.4 +0.0 +0.0 +0.5 +0.4 G3YPP -7.0 -6.7 -6.1 -6.8 -7.3 -7.2 -7.1 -7.1 -7.1 -6.8 G4AON +0.4 +0.5 +0.5 +0.7 +0.6 G4IRN +0.5 +0.6 +0.7 +0.7 +0.5 +0.5 +0.4 +0.5 +0.6 +0.6 G4ZFE +0.3 +0.4 +0.6 +0.6 +0.5 +0.2 +0.2 +0.3 +0.3 +0.4 GI4DOH-2 -0.0 -0.2 +0.3 +0.3 +0.3 +0.1 +0.2 GI4DOH-3 +0.4 +0.7 GX0FRE +0.0 +0.3 +0.0 +0.1 HA1VHF +1.7 +1.6 +2.1 +1.9 +1.1 +0.9 +0.9 +0.9 +1.4 +2.0 HA6PX +0.0 +0.0 +0.0 -0.0 +0.0 -0.0 +0.0 -0.0 -0.1 +0.0 HA8TKS +0.2 +0.3 +0.3 +0.4 +0.3 +0.4 +0.2 +0.3 +0.3 +0.4 HB9BXE +0.2 +0.2 +0.4 +0.4 +0.4 +0.3 +0.3 +0.3 +0.3 +0.3 HB9DCO -0.0 -0.1 -0.1 -0.2 -0.2 -0.1 -0.3 -0.0 -0.2 -0.1 HB9GVO +1.3 +1.7 +1.9 -0.1 +1.3 +0.9 +1.1 +0.7 +1.8 +0.8 HG8A +0.1 +0.2 +0.1 +0.1 +0.0 +0.1 -0.1 -0.1 -0.0 +0.3 IK3STG +1.9 +1.9 +2.5 +2.7 +2.0 +2.5 +2.3 IK4VET +2.6 +2.7 +3.8 +3.4 +3.1 +2.4 +1.9 +2.1 +2.5 IK7YTT +0.1 -0.0 -0.0 -0.0 -0.1 -0.1 -0.1 -0.1 -0.1 -0.1 IU0MVD -11.5 -13.3 JG1DLY -0.7 -0.3 -0.9 -0.1 -0.9 JH7CSU1 +0.8 +1.1 +1.7 +1.7 +0.7 +1.5 +1.3 +1.6 +1.0 +2.2 JI1HFJ -2.1 -1.8 -4.2 -4.6 -5.9 -2.7 +0.6 -5.1 -1.9 JJ2VLY +13.5 +14.4 +14.1 +14.2 +14.3 +14.0 +14.4 +13.9 +13.2 +14.6 JK1QLQ +0.0 +0.3 +0.0 +0.0 +0.5 JN1ILK +1.5 +4.2 +4.6 +4.6 +3.8 +5.3 +4.1 +8.0 +3.9 +4.6 K1RA +0.1 +0.5 +0.0 +0.1 +0.3 +0.4 +0.1 +0.0 +0.0 +0.1 K2PO/7 +0.3 +0.5 +0.4 +0.2 +0.4 +0.5 +0.4 +0.3 +0.4 +0.4 K3PA -0.0 +0.1 K3PA-1 -0.2 +0.0 -0.1 -0.1 +0.1 -0.0 -0.1 +0.1 +0.3 -0.0 K3PA-2 -2.6 +0.2 +0.1 +0.2 +0.6 +0.2 +0.4 +0.1 +0.3 +0.5 K4PP +0.3 +0.2 -0.0 -0.2 -0.1 +0.1 -0.3 -0.1 +0.1 +0.5 K5EM +0.3 +0.1 +0.6 +0.3 +0.6 +0.7 +0.6 +0.4 +0.6 +0.5 K5KHK +0.4 +0.6 +0.4 +0.0 +0.0 +1.4 +0.2 +0.3 +1.2 +0.2 K5TR +0.4 +0.4 +0.3 +0.4 +0.4 +0.5 +0.5 +0.4 +0.5 +0.3 K6FOD -0.1 -0.2 +0.0 -0.0 -0.1 +0.1 -0.4 -0.1 -0.3 -0.1 K7CO +2.3 +1.5 +1.7 +3.7 +5.2 +2.7 +3.0 +2.8 +1.1 K7EK -9.6 -2.8 +2.2 -4.7 -11.2 -10.2 -9.2 -8.2 -7.3 K9IMM +0.2 +0.2 +0.3 +0.1 +0.0 +0.3 +0.2 +0.2 +0.3 +0.3 K9LC +0.2 +0.5 +0.3 +0.3 +0.4 +0.6 +0.5 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Anchor skimmers
The below skimmers use external frequency references and are confirmed to have continuous, high accuracy. Their accuracy is also confirmed against each other on a daily basis.
AA4VV DF7GB ES2RR KM3T-5 LZ3CB LZ4UX OE9GHV WB6BEE Last updated 2025-04-16 00:15:37 UTC
It is the owners of these skimmers who make this web page possible. Thank you.
To get good geographic coverage and a good size dataset, a two-step method is used for the analysis shown above. Since the second step also relies on spots from skimmers with slightly lower accuracy the displayed error for the anchor skimmers may not always be 0.0, even though they are perfectly accurate.
Software
The software powering this page can be found on github.