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
473970 RBN spots between 2025-04-18 00:00 and 23:59 UTC. 101005 spots (21.3%) were from reference skimmers (*). Average spot flow was 329 per minute from 212 active CW skimmers. 216543 spots from 208 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 ------------------------------------- 3D2AG +1.0 119 1.000001038 5Z4GO +0.5 15 1.000000475 AA0O +0.0 16 1.000000000 AA4VV -0.0 736 0.999999986 AC0C-1 -0.1 196 0.999999891 BA6KC* -0.0 356 0.999999953 BD7JNA +0.1 144 1.000000099 BD8CS* -0.0 443 0.999999994 BG0AJO +0.5 311 1.000000497 BG0AJO/0 +0.0 10 1.000000000 BG2TFW +9.5 273 1.000009509 BG4GOV +0.5 62 1.000000460 BH4RRG +0.1 132 1.000000108 BH4XDZ +0.1 199 1.000000137 BI4MPH-1 +0.1 278 1.000000077 BI4UYX +0.2 121 1.000000157 BY4XRA +0.1 216 1.000000099 CT1EYQ -0.5 545 0.999999497 CX6VM +1.4 196 1.000001362 DD5XX +0.3 1966 1.000000311 DE1LON +1.7 1909 1.000001724 DF2CK +1.3 4140 1.000001255 DF2CK-1 +4.4 457 1.000004387 DF5EG +1.1 104 1.000001095 DF7GB* +0.0 2839 1.000000023 DK0TE +0.9 2464 1.000000868 DK1MAX -0.4 20 0.999999643 DK9IP* -0.1 1919 0.999999906 DK9IP-1* -0.0 2370 0.999999976 DL0LA -0.2 1085 0.999999806 DL0PF +8.8 2259 1.000008787 DL1AMQ +0.8 18 1.000000791 DL1AXX +0.0 14 1.000000000 DL1HWS +0.2 2923 1.000000221 DL1HWS-3 +0.5 1088 1.000000473 DL1HWS-4* -0.1 328 0.999999931 DL4CF -0.2 69 0.999999794 DL5RCN +12.8 1531 1.000012834 DL8LAS +0.4 1944 1.000000446 DL8TG* -0.0 2355 0.999999958 DL9GTB +0.6 1965 1.000000573 DM5GG +0.4 3321 1.000000396 DO4DXA* -0.0 2713 0.999999991 DO4ZT* -0.0 2094 0.999999982 DP7D +0.4 363 1.000000373 DR4W -2.0 2998 0.999998046 EA2CW* -0.0 1287 0.999999962 EA2RCF-4 +0.5 1395 1.000000519 EA5RQ +0.0 120 1.000000020 EA5WU* +0.0 2509 1.000000044 ES2RR* -0.0 1940 0.999999983 ES5PC* +0.0 2953 1.000000008 F4GOU +4.3 2358 1.000004266 F4VVG +0.1 1232 1.000000081 F6IIT -0.8 2235 0.999999229 G0KTN* +0.1 2395 1.000000075 G3XBI* +0.4 921 1.000000375 G3YPP -2.0 173 0.999997979 G4AON +0.9 413 1.000000882 G4IRN +0.4 1854 1.000000442 G4ZFE +0.3 2476 1.000000272 GI4DOH-2 +0.3 2410 1.000000255 GI4DOH-3 +0.7 831 1.000000684 GX0FRE +0.1 1484 1.000000075 HA1VHF +2.1 2684 1.000002082 HA6PX* +0.0 2363 1.000000004 HA8TKS +0.4 1214 1.000000373 HB9BXE +0.2 2544 1.000000239 HB9DCO -0.2 1918 0.999999811 HB9GVO +0.7 139 1.000000717 HG8A +0.6 2591 1.000000641 IK3STG +2.0 2319 1.000002010 IK4VET +2.8 2940 1.000002819 IK7YTT* -0.1 1681 0.999999902 JG1DLY -0.8 19 0.999999249 JH4UTP +1.9 206 1.000001869 JH7CSU1 +1.5 471 1.000001539 JI1HFJ -5.3 158 0.999994696 JJ2VLY +15.0 299 1.000015021 JK1QLQ +0.3 110 1.000000324 JN1ILK +2.4 836 1.000002382 K1RA +0.1 911 1.000000105 K2PO/7 +0.3 518 1.000000348 K3PA-1* -0.1 747 0.999999928 K3PA-2 -0.2 37 0.999999807 K4PP +0.2 565 1.000000188 K5EM +0.4 330 1.000000367 K5TR +0.4 1062 1.000000439 K6FOD -0.3 196 0.999999738 K7CO +0.5 383 1.000000462 K7EK +4.6 66 1.000004638 K9IMM +0.1 578 1.000000109 K9LC +0.2 655 1.000000185 K9QC +0.1 117 1.000000061 KC4YVA -3.2 201 0.999996816 KD2OGR* +0.2 437 1.000000156 KD7EFG +0.1 256 1.000000128 KH6LC +0.0 114 1.000000014 KM3T-2* +0.0 836 1.000000045 KM3T-3* +0.1 546 1.000000052 KM3T-5* -0.1 795 0.999999902 KO7SS +0.4 239 1.000000387 KP2RUM* +0.0 923 1.000000018 KP3CW +0.1 487 1.000000059 KV4TT* +0.0 884 1.000000035 LA6TPA -2.1 473 0.999997900 LB9KJ +0.5 941 1.000000505 LU8XW -0.4 33 0.999999568 LZ3CB* -0.1 1682 0.999999948 LZ4AE +0.4 2297 1.000000434 LZ4UX* -0.1 1794 0.999999882 LZ5DI +0.9 2661 1.000000908 LZ7AA +0.6 2005 1.000000622 M0ORD -1.0 2417 0.999999009 MM0GPZ -9.6 1995 0.999990366 MM0ZBH -0.5 3206 0.999999548 N2CR -0.1 422 0.999999869 N6TV +0.3 324 1.000000250 N7OR -0.2 149 0.999999801 N9CO -0.0 359 0.999999960 ND7K -0.5 465 0.999999483 NG7M -0.1 413 0.999999876 NN3RP -0.1 231 0.999999938 NT6Q -3.1 435 0.999996909 NU4F* -0.0 912 0.999999977 OE6ADD +0.1 2726 1.000000099 OE6TZE +0.0 17 1.000000000 OE9GHV -0.1 2194 0.999999949 OG66X* +0.0 1164 1.000000037 OH4KA +0.8 767 1.000000827 OH6BG -0.5 1151 0.999999521 OH8KA +4.0 1510 1.000003962 OK1FCJ +0.4 2533 1.000000404 OK1HRA -3.8 2684 0.999996180 OK4QRO +1.7 2243 1.000001653 ON6ZQ* -0.2 2117 0.999999756 OZ1AAB +0.1 904 1.000000124 OZ1BZS +0.5 557 1.000000483 OZ4ADX +1.1 714 1.000001108 PA0MBO +0.4 944 1.000000375 PA8MM +0.2 2079 1.000000162 PE5TT* +0.2 2275 1.000000152 PI4CC* +0.2 2097 1.000000158 PY2KJ +0.9 62 1.000000882 PY2PE +7.4 10 1.000007407 R1LB +6.8 916 1.000006831 R4NCU -0.9 317 0.999999145 R6YY* -0.1 844 0.999999946 R9IR +0.4 1087 1.000000363 RK3TD-2* +0.1 1552 1.000000082 RN4WA +1.2 1451 1.000001176 RU9CZD -0.3 1486 0.999999739 S50U +0.4 1484 1.000000366 S51CAB +0.3 278 1.000000295 S53A +0.8 3040 1.000000779 S53WW -0.4 2576 0.999999614 SE5E +0.3 2490 1.000000342 SM0TCZ -0.5 61 0.999999493 SM1HEV +0.5 1185 1.000000496 SM7IUN* +0.0 1302 1.000000041 SQ5J +9.9 2318 1.000009913 SZ1A -1.7 2249 0.999998320 TF3Y +1.6 911 1.000001643 TI7W +0.2 1058 1.000000174 UA0S +3.0 1203 1.000003009 UD4FD +2.3 314 1.000002338 UT4QM +5.1 43 1.000005137 UT5R +3.6 454 1.000003550 UT5R-1 +2.6 970 1.000002631 UY2RA -0.7 1701 0.999999257 V51YJ +0.9 65 1.000000892 VE3EID* -0.0 1151 0.999999969 VE6JY +1.5 612 1.000001488 VE6WZ +3.3 512 1.000003260 VE7CC +0.7 195 1.000000718 VK2GEL +0.7 205 1.000000670 VK2RH -0.7 76 0.999999296 VK3RASA +1.7 27 1.000001718 VK6ANC -0.1 158 0.999999865 VR2FUN-77 +0.9 1242 1.000000888 VU2CPL +2.1 204 1.000002052 VU2PTT +0.0 250 1.000000038 VU2TUM +0.6 215 1.000000639 W1NT-2* +0.1 896 1.000000068 W1NT-6* +0.0 1220 1.000000029 W2MV +0.4 116 1.000000369 W3OA +0.1 859 1.000000112 W3RGA -0.3 810 0.999999714 W3UA -0.1 35 0.999999898 W4AX +3.6 87 1.000003637 W4KAZ -0.7 743 0.999999327 W6YX -0.0 566 0.999999987 W8WTS -0.2 430 0.999999840 W8WWV -0.9 585 0.999999117 WA7LNW +0.1 489 1.000000123 WB6BEE -0.2 658 0.999999805 WC2L +0.1 739 1.000000106 WC8GOP +8.7 32 1.000008668 WE9V +0.5 641 1.000000513 WS2C +5.1 590 1.000005082 WS3W +0.3 221 1.000000314 WT9U +0.3 106 1.000000254 WV4P +0.5 294 1.000000524 WZ7I +0.2 1419 1.000000201 YO2CK +1.6 632 1.000001577 YO2MAX +0.1 2519 1.000000139 ZL3X -0.0 611 0.999999981 ZS1NN -3.9 90 0.999996109 Last updated 2025-04-19 00:15:44 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 0418 0417 0416 0415 0414 0413 0412 0411 0410 0409 --------------------------------------------------------------------- 3B8GL +0.2 +0.3 +0.3 +0.1 +0.4 +0.7 +0.4 +0.2 +0.1 3D2AG +1.0 +0.5 +1.1 +0.6 +0.3 +1.0 +1.1 +0.9 +0.8 +0.6 3V9A -2.4 -1.5 -1.4 -1.5 -1.4 -1.4 5Z4GO +0.5 +0.0 +0.7 +0.4 -0.8 +1.1 +0.6 7N4XCV -0.3 +0.5 +0.4 +1.6 +0.0 AA0O +0.0 +0.6 +0.4 +0.4 +0.6 -8.8 -1.2 +0.6 +0.4 +0.9 AA4VV -0.0 -0.0 -0.1 +0.0 -0.0 +0.1 -0.0 -0.0 +0.2 -0.1 AC0C-1 -0.1 -0.0 +0.0 +0.1 +0.1 +0.0 +0.0 +0.0 +0.0 -0.3 BA6KC -0.0 +0.2 +0.0 +0.2 -0.1 -0.0 +0.0 -0.1 -0.1 +0.0 BD7JNA +0.1 -0.6 +0.0 +0.1 +5.6 BD8CS -0.0 +0.0 -0.1 +0.0 -0.1 +0.0 -0.0 -0.0 -0.1 BG0AJO/0 +0.0 +0.1 +0.0 +0.0 -0.2 +0.0 BG0AJO +0.5 +0.3 +0.3 +0.2 -0.4 +0.4 +0.4 +0.1 +0.2 +0.8 BG2TFW +9.5 +8.5 +8.9 +7.6 +7.8 +8.4 +9.0 +9.0 +9.3 BG4GOV +0.5 +0.6 -0.4 BH4RRG +0.1 +0.0 +0.0 +0.4 -0.9 +0.2 +0.2 +0.3 +0.4 +0.0 BH4XDZ +0.1 +0.0 -0.2 +0.0 -0.3 -0.0 -0.0 +0.1 -0.3 +0.0 BI4MPH-1 +0.1 +0.0 +0.0 +0.0 +0.3 +0.2 +0.1 +0.1 +0.0 +0.0 BI4UYX +0.2 +0.0 +0.0 -0.2 +0.5 +0.0 +0.0 BY4XRA +0.1 +0.0 CT1EYQ -0.5 -0.3 +0.0 -0.4 +0.0 -0.1 +0.1 -0.0 -0.1 CX6VM +1.4 +1.3 +1.0 +0.9 +1.0 +1.7 +1.8 +1.9 +1.1 +0.7 DD5XX +0.3 +0.4 +0.8 +0.8 +0.9 +1.1 +1.2 +0.7 +0.6 +0.6 DE1LON +1.7 +1.4 +1.4 +1.6 +2.0 +2.0 +2.1 +1.7 +1.7 +1.7 DF2CK +1.3 +0.6 +1.0 +1.5 +1.1 +1.2 +1.1 +0.5 +0.6 +0.7 DF2CK-1 +4.4 +4.1 +3.6 DF5EG +1.1 -0.0 DF7GB +0.0 +0.1 -0.0 +0.0 +0.0 +0.0 +0.0 -0.0 +0.1 -0.1 DG6FL +0.0 DK0TE +0.9 +0.7 +0.5 +0.7 +0.9 +1.6 +1.6 +1.1 +1.0 +0.6 DK1MAX -0.4 +0.2 -0.4 -0.3 -0.2 -0.2 DK3UA +0.1 +0.0 -0.7 DK3WW -0.1 +0.0 DK8NE -0.1 DK9IP -0.1 -0.1 -0.1 -0.1 -0.1 -0.1 -0.0 -0.2 -0.1 -0.2 DK9IP-1 -0.0 -0.0 -0.1 -0.0 -0.1 -0.1 -0.1 -0.1 -0.1 -0.1 DL0LA -0.2 -0.0 -0.2 -0.3 -0.2 -0.2 -0.3 -0.1 -0.2 -0.3 DL0PF +8.8 +9.2 +10.0 +10.0 +8.7 +8.3 +7.8 +8.5 +7.3 +7.6 DL1AMQ +0.8 DL1AXX +0.0 +0.0 DL1HWS +0.2 +0.2 +0.1 +0.2 +0.2 +0.1 +0.0 +0.1 DL1HWS-3 +0.5 +0.7 +0.3 +0.3 +0.4 +0.7 +0.6 +0.6 +0.4 +0.5 DL1HWS-4 -0.1 -1.4 +0.0 +0.1 +0.1 +0.1 +0.1 +0.1 +0.1 DL4CF -0.2 -0.0 -0.2 +0.0 +0.3 +0.0 +0.1 DL5RCN +12.8 +13.3 +13.0 +12.6 +12.9 +12.7 DL8LAS +0.4 +0.9 +0.6 +0.7 +0.8 +0.7 +0.6 DL8TG -0.0 -0.0 -0.1 +0.0 +0.1 -0.0 +0.1 +0.0 -0.0 +0.2 DL9GTB +0.6 +0.2 +0.2 +0.4 +0.6 +0.6 +0.6 +0.4 +0.4 +0.4 DM5GG +0.4 +0.4 +1.3 +1.4 +0.4 +1.0 +0.5 +1.3 +1.4 +1.2 DO4DXA -0.0 -0.0 -0.0 -0.1 +0.0 -0.1 +0.0 +0.0 -0.0 -0.0 DO4ZT -0.0 -0.0 +0.1 +0.1 +0.0 +0.0 -0.0 -0.2 -0.0 -0.1 DP7D +0.4 +0.3 +0.5 +0.5 +0.8 +0.7 +1.1 +0.0 +0.2 -0.2 DR4W -2.0 -0.8 -0.5 -0.7 -1.4 -3.1 -1.8 -2.2 -2.1 -1.5 EA1RX -4.3 EA2CW -0.0 -0.2 -0.2 -0.0 +0.0 +0.1 +0.1 +0.1 +0.1 +0.0 EA2RCF-4 +0.5 +0.5 +0.4 +0.4 +0.5 +0.8 +0.6 +0.6 +0.7 +0.5 EA5RQ +0.0 -0.0 -0.4 -0.1 -0.2 -0.1 -0.1 -0.3 -0.0 +0.3 EA5RQ/A -0.2 +0.0 +0.2 +0.1 +0.0 -0.2 -0.2 -0.6 EA5WU +0.0 -0.1 -0.0 +0.0 -0.1 -0.0 ES2RR -0.0 -0.0 +0.0 -0.0 -0.0 -0.0 -0.0 -0.0 -0.1 +0.0 ES5PC +0.0 -0.1 -0.0 -0.0 -0.0 +0.0 +0.0 +0.0 -0.1 -0.1 F4GOU +4.3 +4.0 +3.4 +3.9 +4.8 +5.2 +5.2 +4.6 +4.9 +4.7 F4VVG +0.1 -0.0 +0.1 -0.1 -0.0 +0.0 +0.0 +0.0 +0.1 +0.1 F6IIT -0.8 -0.7 -0.8 -0.5 -0.6 +0.0 -0.5 F6KGL +0.2 G0KTN +0.1 +0.1 +0.2 +0.1 +0.1 +0.2 +0.3 +0.3 +0.2 +0.1 G0TMX +0.3 -0.0 G3XBI +0.4 +0.1 +0.2 +0.3 -0.1 +0.5 +0.4 +0.0 G3YPP -2.0 -7.1 -7.9 -7.0 -6.7 -6.1 -6.8 -7.3 -7.2 -7.1 G4AON +0.9 +0.7 +0.8 +0.4 +0.5 +0.5 G4IRN +0.4 +0.4 +0.4 +0.5 +0.6 +0.7 +0.7 +0.5 +0.5 +0.4 G4ZFE +0.3 +0.2 +0.4 +0.3 +0.4 +0.6 +0.6 +0.5 +0.2 +0.2 GI4DOH-2 +0.3 +0.1 +0.2 -0.0 -0.2 +0.3 +0.3 GI4DOH-3 +0.7 +0.5 +0.2 +0.4 +0.7 GX0FRE +0.1 -0.0 +0.1 +0.0 +0.3 +0.0 HA1VHF +2.1 +2.1 +1.9 +1.7 +1.6 +2.1 +1.9 +1.1 +0.9 +0.9 HA6PX +0.0 +0.1 +0.0 +0.0 +0.0 +0.0 -0.0 +0.0 -0.0 +0.0 HA8TKS +0.4 +0.2 +0.2 +0.2 +0.3 +0.3 +0.4 +0.3 +0.4 +0.2 HB9BXE +0.2 +0.2 +0.2 +0.2 +0.2 +0.4 +0.4 +0.4 +0.3 +0.3 HB9DCO -0.2 -0.1 -0.1 -0.0 -0.1 -0.1 -0.2 -0.2 -0.1 -0.3 HB9GVO +0.7 +0.8 +0.7 +1.3 +1.7 +1.9 -0.1 +1.3 +0.9 +1.1 HG8A +0.6 +0.5 +0.4 +0.1 +0.2 +0.1 +0.1 +0.0 +0.1 -0.1 IK3STG +2.0 +1.9 +1.9 +1.9 +1.9 +2.5 +2.7 +2.0 +2.5 +2.3 IK4VET +2.8 +2.8 +2.7 +2.6 +2.7 +3.8 +3.4 +3.1 +2.4 IK7YTT -0.1 +0.0 +0.1 -0.0 -0.0 -0.0 -0.1 -0.1 -0.1 IU0MVD -11.5 -13.3 JG1DLY -0.8 -0.7 -0.3 -0.9 -0.1 JH4UTP +1.9 JH7CSU1 +1.5 +0.8 +1.5 +0.8 +1.1 +1.7 +1.7 +0.7 +1.5 +1.3 JI1HFJ -5.3 -4.2 -6.7 -2.1 -1.8 -4.2 -4.6 -5.9 -2.7 JJ2VLY +15.0 +14.4 +13.0 +13.5 +14.4 +14.1 +14.2 +14.3 +14.0 +14.4 JK1QLQ +0.3 +0.0 +0.3 +0.0 JN1ILK +2.4 +1.9 +1.0 +1.5 +4.2 +4.6 +4.6 +3.8 +5.3 +4.1 K1RA +0.1 +0.1 -0.0 +0.1 +0.5 +0.0 +0.1 +0.3 +0.4 +0.1 K2PO/7 +0.3 +0.5 +0.5 +0.3 +0.5 +0.4 +0.2 +0.4 +0.5 +0.4 K3PA -0.0 +0.1 K3PA-1 -0.1 -0.1 -0.2 -0.2 +0.0 -0.1 -0.1 +0.1 -0.0 -0.1 K3PA-2 -0.2 -0.1 -3.8 -2.6 +0.2 +0.1 +0.2 +0.6 +0.2 +0.4 K4PP +0.2 +0.2 +0.0 +0.3 +0.2 -0.0 -0.2 -0.1 +0.1 -0.3 K5EM +0.4 +0.5 +0.4 +0.3 +0.1 +0.6 +0.3 +0.6 +0.7 +0.6 K5KHK +0.6 +0.4 +0.6 +0.4 +0.0 +0.0 +1.4 +0.2 K5TR +0.4 +0.6 +0.5 +0.4 +0.4 +0.3 +0.4 +0.4 +0.5 +0.5 K6FOD -0.3 -0.2 -0.2 -0.1 -0.2 +0.0 -0.0 -0.1 +0.1 -0.4 K7CO +0.5 +1.7 +2.9 +2.3 +1.5 +1.7 +3.7 +5.2 +2.7 K7EK +4.6 +5.6 -1.0 -9.6 -2.8 +2.2 -4.7 -11.2 -10.2 K9IMM +0.1 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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 2025-04-19 00:15:54 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.