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
An skimmer calibration automation based on Windows PowerShell can be found here. It scrapes the calibration adjustment from this page and can be configured to update two CW Skimmer Server instances, two RTTY Skimmer Servers, and one CWSL_DIGI instance.
404761 RBN spots between 2026-04-17 00:00 and 23:59 UTC. 122487 spots (30.3%) were from reference skimmers (*). Average spot flow was 281 per minute from 207 active CW skimmers. 209134 spots from 204 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 +0.0 60 1.000000000 9M2CNC +0.3 284 1.000000268 AA4PA +0.5 518 1.000000457 AC0C-1* -0.1 1158 0.999999927 AK6RI-1 -0.0 276 1.000000000 BA4OP* -0.2 516 0.999999811 BA6KC +0.1 565 1.000000095 BD4UNT +0.0 339 1.000000012 BD7JNA +0.0 243 1.000000023 BD8CS +0.0 805 1.000000044 BG0AJO/0 +0.6 707 1.000000608 BG2TFW +0.5 283 1.000000545 BG4GOV +0.0 230 1.000000000 BH4RRG +0.2 75 1.000000190 BH4XDZ -0.1 221 0.999999936 BI4MPH -0.1 242 0.999999941 BI7JMD -0.2 205 0.999999849 CT1EYQ -0.3 1259 0.999999732 DC8YZ* +0.0 1467 1.000000001 DD5XX* +0.1 1744 1.000000069 DE1LON -0.3 2058 0.999999692 DF7GB* -0.1 2328 0.999999935 DK0TE* +0.0 2091 1.000000044 DK3WW* +0.1 2570 1.000000097 DK9IP* -0.0 1437 0.999999967 DK9IP-1* -0.0 1916 0.999999979 DL0LA -0.2 80 0.999999822 DL1HWS +0.6 2153 1.000000635 DL1HWS-3 +1.2 960 1.000001207 DL1HWS-4 +0.6 218 1.000000561 DL3OBQ -7.5 247 0.999992461 DL5RCN +12.7 56 1.000012690 DL8LAS +0.4 4014 1.000000377 DL8LAS-1* -0.0 2624 0.999999984 DL8LAS-3 +1.2 1378 1.000001203 DL8TG* +0.0 2541 1.000000038 DM5GG +0.9 2293 1.000000904 DM6EE +0.2 1431 1.000000203 DO4DXA* +0.0 2283 1.000000013 DR4W -1.2 2419 0.999998799 EA1DAV* +0.0 1074 1.000000008 EA2CW -0.3 139 0.999999692 EA2RCF-4* +0.1 1181 1.000000078 EA5WU* +0.1 2024 1.000000054 ES2RR* -0.1 1715 0.999999909 ES5PC* -0.1 2568 0.999999933 EY8ZE* -0.2 602 0.999999771 F1EYG -1.6 4389 0.999998370 F4GOU* -0.1 1784 0.999999949 F6IIT -0.3 2750 0.999999656 G0KTN +0.2 2107 1.000000243 G4IRN +0.2 2968 1.000000223 G4KCM* -0.1 1050 0.999999937 G4ZFE* +0.2 2124 1.000000155 HA1VHF +0.2 2479 1.000000177 HA8TKS* -0.0 1066 0.999999991 HA8TKS-2 -0.3 56 0.999999704 HB9AFZ +0.3 530 1.000000345 HB9BXE +0.3 1967 1.000000340 HB9DCO -0.3 1651 0.999999713 HB9GVO +0.6 462 1.000000555 HG0Y +7.4 298 1.000007369 HG8A +1.1 2079 1.000001104 HS0ZGZ +0.5 296 1.000000540 IK3STG +2.8 718 1.000002846 IK4VET +2.7 2188 1.000002739 IK7YTT* -0.0 1673 0.999999955 IQ9RG* -0.0 1521 0.999999964 IT9GSF* -0.1 3386 0.999999870 JA1CCA +7.2 46 1.000007153 JG1DLY -1.1 114 0.999998874 JH7CSU1 +1.7 540 1.000001720 JI1HFJ -2.8 106 0.999997245 JJ2VLY +0.6 238 1.000000638 JM8SMO -3.1 7 0.999996943 JN1ILK -0.4 1069 0.999999639 K1RA +1.1 1836 1.000001110 K1RA-4* +0.1 1122 1.000000082 K3GMQ* +0.1 745 1.000000067 K3PA-1 +0.4 978 1.000000432 K3PA-2 +0.0 7 1.000000000 K4PP +0.3 714 1.000000338 K5EM +3.4 250 1.000003378 K5TR +5.5 1201 1.000005495 K6FOD -0.0 251 1.000000000 K7CO -0.5 632 0.999999478 K7EK +1.4 269 1.000001350 K7RUT -0.8 101 0.999999240 K9IMM* -0.0 553 0.999999956 K9QC +0.4 81 1.000000439 KC4YVA +0.5 332 1.000000544 KD2OGR +0.2 537 1.000000247 KD7EFG +0.4 343 1.000000383 KH6LC +0.0 85 1.000000000 KL2R -0.3 17 0.999999675 KM3T-2 +0.2 543 1.000000210 KM3T-3 +0.1 1888 1.000000118 KM3T-5* -0.0 664 0.999999993 KO4BHX +0.2 1410 1.000000176 KP3CW -0.6 233 0.999999440 KW7MM +0.6 1269 1.000000567 KW7MM-3 -1.0 112 0.999998969 LA7GIA -0.1 320 0.999999874 LB9KJ +3.1 1971 1.000003077 LU6KK +0.0 12 1.000000000 LU8XW +0.2 29 1.000000246 LY3G +0.5 92 1.000000525 LZ3CB +0.2 228 1.000000156 LZ4AE* +0.0 1341 1.000000041 LZ4UX* +0.0 1736 1.000000003 LZ5DI +2.8 3748 1.000002849 LZ7AA +0.3 1633 1.000000343 M1GEO +3.2 982 1.000003244 MM0ZBH* +0.1 2925 1.000000072 MM9PSY* +0.1 2260 1.000000062 N2CR +0.6 521 1.000000636 N2YCH +3.7 1353 1.000003699 N6TV +0.3 419 1.000000333 N7TUG +0.3 74 1.000000331 N8DXE +0.7 425 1.000000704 N9CO -0.2 847 0.999999752 ND7K -0.7 327 0.999999311 NG7M* +0.1 478 1.000000108 NU4F +0.0 473 1.000000022 OE6ADD* +0.1 2681 1.000000111 OE9GHV* -0.1 2586 0.999999940 OH4KA +1.8 814 1.000001830 OH8KA +8.9 579 1.000008867 OK1FCJ +0.2 2015 1.000000194 OK1HRA -3.2 1635 0.999996813 ON6ZQ* -0.1 1194 0.999999874 OZ1AAB* -0.0 410 0.999999979 PE5TT +0.6 1622 1.000000641 PI4CC* +0.0 2722 1.000000012 PY2KNK +5.6 164 1.000005599 PY2PE -0.3 106 0.999999686 R4NCU -0.5 213 0.999999464 RK3TD +0.2 1273 1.000000192 RK3TD-2 +0.8 1126 1.000000844 RN4WA +0.9 272 1.000000893 RU9CZD +0.1 2518 1.000000112 S50U +0.2 1074 1.000000202 S53A +0.7 3380 1.000000695 S53F-1 +14.5 23 1.000014481 S53WW -0.2 2296 0.999999776 S54L +1.0 2320 1.000000965 S58W* -0.1 1455 0.999999918 SE5E* -0.0 2992 0.999999987 SM0TCZ -1.0 30 0.999999048 SM1HEV +0.4 1723 1.000000405 SM7IUN* +0.1 2127 1.000000050 SP5GQ* +0.0 1773 1.000000022 SQ5J +8.3 794 1.000008312 SV1CDN +0.0 20 1.000000000 TF3Y +1.3 1840 1.000001348 TI7W +1.5 1069 1.000001479 UT5R -0.3 364 0.999999735 UY2RA -1.2 231 0.999998842 V51YJ +1.1 86 1.000001077 VE4DRK +9.1 427 1.000009101 VE6JY +1.2 250 1.000001233 VE6WZ +0.2 510 1.000000228 VE6WZ-3 -0.7 148 0.999999289 VE7CC +0.7 210 1.000000686 VK2GEL -0.1 104 0.999999863 VK2RH -0.1 68 0.999999895 VK3RASA -0.2 150 0.999999763 VK6ANC -0.1 152 0.999999906 VR2FUN-77 +1.1 1113 1.000001071 VU2CPL -0.5 62 0.999999458 VU2OY +0.3 253 1.000000253 VU2TUM* -0.0 573 0.999999966 W1NT-2 +0.2 1444 1.000000186 W1NT-6 +0.2 1866 1.000000193 W2MV +0.0 17 1.000000000 W2NNN +1.4 761 1.000001355 W3DAN +0.7 427 1.000000735 W3LPL -0.4 845 0.999999606 W3OA +0.3 779 1.000000267 W3RGA +0.2 760 1.000000237 W3UA +0.1 451 1.000000073 W4KAZ* -0.1 756 0.999999906 W5ZN +1.7 1059 1.000001660 W6YX -0.1 781 0.999999888 W8WTS -0.2 578 0.999999768 WA7LNW +0.3 695 1.000000322 WB6BEE* +0.0 1479 1.000000040 WC2L +0.5 958 1.000000484 WC8GOP -2.0 6 0.999998020 WE9V +0.1 1128 1.000000140 WS2C +8.0 356 1.000007986 WS3W* -0.0 540 0.999999974 WT8P -0.1 51 0.999999860 WT9U -0.2 197 0.999999839 WX7V/5 +0.1 204 1.000000140 WZ7I +0.4 1619 1.000000367 YO2CK* -0.1 1799 0.999999925 YO2KAR +0.3 1774 1.000000264 ZF1A* -0.0 1994 0.999999970 ZF9CW -0.2 1792 0.999999765 ZL2KS -0.1 67 0.999999917 ZL3X +0.3 411 1.000000295 ZL4YL +0.4 240 1.000000444 ZS1NN -4.8 121 0.999995191 Last updated 2026-04-18 00:15:38 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 0417 0416 0415 0414 0413 0412 0411 0410 0409 0408 --------------------------------------------------------------------- 3D2AG +0.0 -0.2 -0.0 +0.3 +0.1 +0.1 -0.0 +0.0 +0.3 +0.1 5Z4GO +0.0 +0.5 +0.6 +0.2 +1.6 9M2CNC +0.3 +0.2 +0.5 +0.3 +0.4 +0.3 +0.3 +0.2 +0.3 +0.3 AA4PA +0.5 +0.3 +0.3 +0.0 -0.1 +0.0 AC0C-1 -0.1 -0.2 +0.0 -0.0 -0.0 -0.1 -0.0 -0.1 -0.1 -0.0 AK6RI-1 -0.0 +0.4 -0.1 -0.2 +0.1 -0.0 -0.1 -0.5 -0.0 +0.1 BA4OP -0.2 -0.2 +0.0 +0.2 +0.1 -0.1 -0.1 -0.1 -0.1 -0.3 BA6KC +0.1 -0.1 -0.0 +0.1 +0.1 -0.0 +0.0 -0.1 -0.2 +0.1 BD4UNT +0.0 +0.0 +0.2 +0.1 -0.1 +0.2 +0.1 -0.2 +0.1 +0.3 BD7JNA +0.0 -0.0 +0.2 -0.1 +0.2 +0.1 +0.1 +0.0 +0.0 -0.5 BD8CS +0.0 -0.0 +0.1 +0.1 +0.0 -0.1 -0.0 +0.0 -0.0 +0.0 BG0AJO/0 +0.6 +0.6 +0.4 +0.4 +0.3 +0.6 +0.5 +0.7 +0.5 +0.6 BG2TFW +0.5 +0.6 +0.7 +0.0 +0.6 +0.5 +0.3 +0.3 +0.2 +0.0 BG4GOV +0.0 +0.0 BH4HKZ -0.2 -0.0 BH4RRG +0.2 +0.0 +0.2 +0.2 +0.0 +0.3 +0.2 +0.0 +0.1 +0.0 BH4XDZ -0.1 +0.0 -0.2 +0.0 +0.1 -0.0 +0.0 +0.2 +0.0 -0.3 BI4MPH -0.1 -0.1 +0.5 +0.1 +0.1 +0.1 +0.1 +0.1 +0.3 +0.1 BI7JMD -0.2 -0.1 +0.1 +0.0 +0.1 -0.0 +0.1 -0.1 +0.0 CT1EYQ -0.3 -0.9 -0.8 -0.8 -0.8 -0.9 -0.8 -0.6 -1.1 -1.0 DC8YZ +0.0 +0.1 +0.1 +0.0 +0.2 +0.1 +0.2 -0.0 -0.0 +0.1 DD5XX +0.1 -0.4 -0.6 -0.8 -0.6 -0.7 +0.1 -0.3 +0.0 DE1LON -0.3 -0.4 -0.4 -0.3 -0.3 -0.4 -0.3 -0.3 -0.4 -0.2 DF2JP -5.9 DF7GB -0.1 +0.0 +0.0 +0.0 -0.0 -0.0 +0.0 -0.0 +0.0 +0.1 DK0KK +0.1 +0.0 -0.0 +0.0 -0.0 DK0TE +0.0 -0.1 -0.5 -0.9 -1.8 +0.2 +0.2 +0.1 +0.2 +0.3 DK3WW +0.1 -0.0 +0.1 +0.2 +0.1 -0.4 -0.3 -0.0 -0.2 -0.1 DK8NE +0.0 DK9IP -0.0 +0.2 +0.0 +12.6 +12.9 -10.1 -11.8 -11.4 -11.6 -11.4 DK9IP-1 -0.0 +0.0 +0.1 +0.1 +0.2 -0.0 +0.1 +0.1 -0.0 -0.0 DL0LA -0.2 +0.2 -0.0 -0.1 +0.0 +0.2 +0.2 +0.8 -0.4 +0.1 DL1HWS +0.6 +0.6 +0.7 +0.7 +0.8 +0.9 +0.8 +0.5 +0.6 +0.7 DL1HWS-3 +1.2 +1.1 +1.0 +1.7 +1.9 +2.1 +1.6 +1.4 +1.3 +1.6 DL1HWS-4 +0.6 +0.4 +0.7 +1.3 +1.0 +0.7 +0.4 +0.8 +1.1 +1.1 DL3OBQ -7.5 -7.4 -7.8 -7.5 -7.5 -8.3 -7.6 -7.4 DL5RCN +12.7 +13.7 +13.6 +14.1 +13.8 +13.9 +13.5 DL5RMH +0.6 +0.5 DL8LAS +0.4 +0.4 +0.3 +0.2 +0.4 +0.5 +0.3 +0.3 +0.3 +0.6 DL8LAS-1 -0.0 -0.0 -0.0 -0.2 -0.2 -0.1 -0.2 -0.1 -0.2 -0.2 DL8LAS-3 +1.2 +1.0 +0.9 +1.0 +1.0 +1.5 +1.2 +1.1 +1.2 +1.3 DL8TG +0.0 +0.0 +0.1 +0.0 +0.0 -0.0 +0.0 +0.0 +0.0 +0.1 DL9GTB -23.6 -24.2 DM5GG +0.9 +0.4 +0.9 +0.9 +1.1 +1.1 +1.0 +0.8 +0.9 +0.8 DM6EE +0.2 +0.0 +0.0 +0.3 +0.1 +0.2 +0.1 +0.1 +0.2 DO4DXA +0.0 +0.0 +0.0 +0.1 +0.0 +0.0 +0.4 +0.0 +0.0 +0.1 DP5G +0.1 -0.1 -0.0 DR4W -1.2 -1.5 -1.9 -1.8 -1.9 -3.4 -2.1 -2.9 -2.4 -2.7 E28AC +1.5 +1.1 +1.2 +1.5 +1.0 +0.7 +1.2 +1.8 +0.8 EA1DAV +0.0 +0.0 -0.0 +0.5 +0.5 +0.3 +0.2 +0.1 +0.1 +0.1 EA2CW -0.3 -0.7 -0.1 -0.8 -1.0 -0.6 -0.8 -0.4 -1.0 -0.1 EA2RCF-4 +0.1 +0.0 -0.1 -0.2 -0.0 +0.1 +0.2 +0.1 +0.1 +0.1 EA5WU +0.1 -0.0 -0.0 -0.0 +0.0 +0.0 -0.0 +0.0 +0.0 -0.2 ES2RR -0.1 -0.1 +0.0 -0.1 +0.0 -0.1 +0.0 -0.1 +0.1 -0.0 ES5PC -0.1 -0.0 -0.1 -0.0 -0.0 -0.0 -0.0 +0.0 -0.0 +0.0 EY8ZE -0.2 -0.1 -0.1 -0.1 -0.2 -0.3 -0.2 -0.1 -0.2 -0.3 F1EYG -1.6 -1.5 -1.4 -1.5 -1.4 -2.0 -2.1 -1.4 -1.6 -1.6 F4BPO +0.2 +1.8 +0.8 F4GOU -0.1 -0.0 +0.0 -0.0 -0.0 -0.2 -0.2 +0.2 +0.1 +0.3 F5VLY -2.3 -1.3 F6IIT -0.3 -1.0 -0.5 -0.7 -0.4 -0.2 -0.6 F6KGL +0.4 +0.3 +0.1 +0.2 F8DGY -4.9 -5.9 G0KTN +0.2 +0.2 +0.3 +0.2 +0.3 +0.2 +0.3 +0.1 +0.3 +0.4 G0TMX +0.3 +0.3 G1VWC -0.4 G4IRN +0.2 +0.3 +0.5 +0.3 +0.4 +0.3 +0.2 +0.2 +0.3 +0.3 G4KCM -0.1 -0.2 G4ZFE +0.2 +0.1 +0.3 +0.2 +0.2 +0.0 +0.1 +0.2 +0.2 +0.3 GI4DOH -0.2 -0.1 +0.0 -0.1 +0.2 +0.1 GX0FRE +0.1 +0.0 +0.0 +0.4 +0.2 +0.2 +0.3 +0.3 +0.4 HA1VHF +0.2 +0.0 -0.0 -0.1 -0.1 -0.3 -0.2 +0.1 +0.2 +0.3 HA5PP +0.5 HA8TKS -0.0 +0.0 +0.0 +0.1 -0.0 +0.0 +0.0 +0.1 -0.0 +0.1 HA8TKS-2 -0.3 +0.0 +0.1 +0.1 +0.2 +0.0 +0.1 +0.0 +0.1 +0.1 HB9AFZ +0.3 +0.1 HB9BXE +0.3 +0.3 +0.4 +0.3 +0.4 +0.5 +0.5 +0.3 +0.3 +0.5 HB9DCO -0.3 -0.6 -0.5 -0.4 -0.5 -0.4 -0.3 -0.3 -0.3 -0.3 HB9GVO +0.6 +0.5 +0.5 +0.3 +0.5 +0.6 +0.5 +0.5 +0.3 +0.6 HG0Y +7.4 +7.4 +7.5 +7.5 +7.5 +7.1 +7.1 +7.4 HG8A +1.1 +0.9 +0.9 +0.8 +0.9 +0.9 +0.9 +0.7 +0.7 +1.0 HS0ZGZ +0.5 +0.3 +1.0 +0.3 +0.3 +0.7 +0.6 +0.4 +0.3 +0.7 IK3STG +2.8 +2.8 +3.6 +3.6 +3.5 +3.8 +3.3 +3.5 +3.6 +3.7 IK4VET +2.7 +1.7 +1.1 +1.0 +1.5 +2.0 +2.6 +2.5 +2.7 +3.5 IK7YTT -0.0 -0.1 +0.0 -0.0 -0.0 -0.0 +0.0 -0.0 +0.0 +0.0 IQ9RG -0.0 +0.1 +0.1 +0.1 +0.1 +0.1 +0.1 IT9GSF -0.1 -0.0 -0.1 +0.0 -0.0 -0.0 +0.1 IZ8EYP -0.2 JA1CCA +7.2 +5.0 +5.1 +6.3 +6.7 +6.4 +5.9 +5.3 JG1DLY -1.1 JH7CSU1 +1.7 +1.2 +1.5 +1.3 +0.7 +2.5 +1.8 +1.1 +1.6 +1.6 JI1HFJ -2.8 -0.4 -3.0 -4.6 -1.3 -1.3 -2.4 -2.0 -1.2 -1.8 JJ2VLY +0.6 +0.7 +0.9 +0.4 -0.2 +2.0 +1.1 +0.5 -0.3 +0.6 JK1QLQ +0.0 +0.0 +0.0 +0.1 +0.0 +0.0 +2.4 JK2RCP1 +0.3 +0.0 JM8SMO -3.1 JN1ILK -0.4 +0.8 +0.9 +0.0 +0.4 +0.2 -0.1 -0.1 -0.6 -0.6 K1RA +1.1 +1.9 +1.5 +0.9 +0.8 +0.5 +0.6 +0.4 -0.0 -0.3 K1RA-4 +0.1 +0.3 +0.1 +0.0 +0.0 -0.1 -0.2 -0.2 -0.2 -0.1 K2PO/7 +2.0 K3GMQ +0.1 +0.3 +0.2 +0.1 +0.2 +0.0 +0.0 -0.0 +0.2 +0.1 K3PA-1 +0.4 +0.5 +0.5 +0.3 +0.4 +0.2 +0.4 +0.3 +0.4 +0.4 K3PA-2 +0.0 +0.0 +0.0 -0.2 +0.0 +0.5 +0.0 K4PP +0.3 +0.8 +0.4 +0.4 +0.3 +0.2 +0.3 +0.4 +0.3 -0.0 K5EM +3.4 +2.7 +3.1 +2.7 +3.4 +3.5 K5TR +5.5 +5.6 +6.2 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updated 2026-04-18 00:15:47 UTC
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.
DF7GB ES2RR KM3T-5 LZ3CB LZ4UX OE9GHV WB6BEE Last updated 2026-04-18 00:15:47 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.