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.
317168 RBN spots between 2025-10-01 00:00 and 23:59 UTC. 85041 spots (26.8%) were from reference skimmers (*). Average spot flow was 220 per minute from 198 active CW skimmers. 147670 spots from 196 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 +0.0 9 1.000000000 3D2AG +0.3 99 1.000000323 5Z4GO +0.0 9 1.000000000 AA0O +1.5 45 1.000001547 AC0C-1 -0.1 280 0.999999915 BA4OP -0.0 73 0.999999952 BA6KC -0.2 52 0.999999840 BD4UNT +0.1 53 1.000000067 BD7JNA -0.1 59 0.999999871 BG0AJO +0.1 89 1.000000147 BG0AJO/0 +0.3 13 1.000000309 BG2TFW +0.1 98 1.000000146 BG4GOV +0.0 10 1.000000000 BH4HKZ +4.2 15 1.000004186 BH4RRG +0.4 23 1.000000414 BH4XDZ +0.2 31 1.000000179 BI4MPH +0.0 12 1.000000000 CT1EYQ -0.1 1195 0.999999880 DE1LON +0.5 1512 1.000000469 DF1VB* -0.1 1524 0.999999855 DF2CK -0.2 2872 0.999999835 DF7GB +0.0 1890 1.000000001 DK0TE -0.2 1568 0.999999774 DK3WW* -0.1 2163 0.999999915 DK9IP* -0.0 1024 0.999999963 DK9IP-1* -0.1 1291 0.999999918 DL1HWS +0.4 1872 1.000000442 DL1HWS-3 +0.0 29 1.000000000 DL8LAS* +0.2 2058 1.000000165 DL8TG* -0.1 1867 0.999999863 DM5GG* +0.1 2030 1.000000109 DO4DXA* -0.1 2067 0.999999942 DR4W -3.1 1746 0.999996903 DR5X +1.9 1253 1.000001931 EA/VE3NZ +0.2 46 1.000000155 EA2CW -0.4 1489 0.999999557 EA2RCF-4 -0.6 990 0.999999357 EA5WU* +0.0 777 1.000000006 ES2RR* -0.0 1583 0.999999979 ES5PC* +0.0 2195 1.000000004 F1UVN +16.6 1848 1.000016597 F4GOU +4.5 1754 1.000004525 F4VVG* +0.0 872 1.000000025 F8DGY -3.1 945 0.999996945 G0KTN +0.3 1355 1.000000306 G3YPP +0.5 157 1.000000468 G4AON +1.0 90 1.000000972 G4HSO +0.6 1675 1.000000628 G4IRN +0.2 1466 1.000000154 G4ZFE +0.5 1723 1.000000536 GI4DOH +0.2 1425 1.000000209 GX0FRE +0.4 740 1.000000430 HA1VHF +0.2 1833 1.000000175 HA5JI-8 -2.3 1599 0.999997742 HA5PP -0.5 608 0.999999503 HA6PX* -0.1 1978 0.999999927 HA8TKS* +0.1 1199 1.000000122 HA8TKS-2 +0.0 123 1.000000000 HB9BXE* +0.1 1605 1.000000134 HB9DCO -0.3 1335 0.999999740 HB9GVO +0.7 119 1.000000718 HG0Y +7.4 314 1.000007355 HG8A +0.6 1845 1.000000608 IK3STG +1.7 1667 1.000001696 IK4VET +1.6 2089 1.000001576 IK7YTT* +0.1 2602 1.000000059 IT9GSF* -0.0 1513 0.999999974 IW9GDC -0.5 662 0.999999484 JH7CSU1 +1.8 21 1.000001756 JI1HFJ -0.4 17 0.999999581 JJ2VLY +1.7 21 1.000001736 JN1ILK -0.4 125 0.999999563 K1RA +1.0 818 1.000000978 K3PA-1 +0.2 896 1.000000228 K3PA-2 -17.4 10 0.999982640 K4PP +0.4 686 1.000000405 K5EM +3.5 280 1.000003544 K5TR +1.9 930 1.000001865 K7CO -0.0 550 0.999999986 K7EK +1.0 173 1.000001050 K9IMM +0.1 708 1.000000123 K9LC +1.0 832 1.000000964 KD2OGR +0.3 423 1.000000331 KD7EFG +0.3 258 1.000000289 KH6LC -0.1 45 0.999999894 KM3T-2* +0.2 560 1.000000187 KM3T-3 +0.1 112 1.000000127 KM3T-5 -0.1 590 0.999999911 KO7SS +0.5 195 1.000000501 KP2RUM +0.0 5 1.000000000 KP3CW +0.0 52 1.000000000 KV4TT* +0.2 776 1.000000249 KW7MM +0.0 761 1.000000009 KW7MM/7 +0.5 688 1.000000503 LA6TPA -0.7 278 0.999999320 LB9KJ -0.3 584 0.999999651 LU8XW +1.1 14 1.000001105 LZ3CB* +0.0 1362 1.000000023 LZ4UX* +0.0 1348 1.000000033 MM0GPZ* -0.0 1805 0.999999993 MM0ZBH* +0.1 1978 1.000000086 MM3NDH +0.2 1566 1.000000175 N2CR +0.4 392 1.000000424 N2YCH* +0.1 949 1.000000091 N6TV +1.0 383 1.000000953 N7TUG +0.1 49 1.000000145 N8DXE +1.6 315 1.000001580 N9CO +0.4 752 1.000000374 ND7K -0.3 715 0.999999667 NG7M -0.1 499 0.999999903 NN3RP +0.5 173 1.000000468 NT6Q +3.1 400 1.000003097 NU4F* +0.1 491 1.000000064 OE3KLU -5.7 5 0.999994330 OE6ADD* -0.1 2013 0.999999913 OE9GHV* -0.0 620 0.999999996 OG66X +0.2 443 1.000000193 OH4KA +1.1 194 1.000001126 OH6BG -0.4 1425 0.999999630 OH8KA +4.6 219 1.000004598 OK1FCJ +0.2 2230 1.000000177 OK1HRA -4.3 1680 0.999995716 OK2ZAW* -0.0 1086 0.999999984 ON6ZQ* +0.2 1209 1.000000188 OZ1AAB +0.4 304 1.000000370 OZ1BZS +0.4 331 1.000000366 OZ4ADX -0.1 181 0.999999921 PA5KT-4* +0.0 1939 1.000000021 PA8MM -5.3 1144 0.999994743 PE5TT +0.6 1367 1.000000555 PI4CC -0.0 231 1.000000000 PY2KNK +4.0 54 1.000003962 PY2PE -0.9 51 0.999999091 R4NCU -0.7 120 0.999999287 RK3TD +0.3 190 1.000000325 RK3TD-2 +0.5 1006 1.000000460 RN4WA +1.5 909 1.000001535 RU9CZD -0.2 508 0.999999836 S50U -0.2 1315 0.999999806 S53A +0.7 218 1.000000696 S53F -2.0 227 0.999998011 S53WW -0.3 1939 0.999999678 S54L* -0.0 1013 0.999999956 SE5E* -0.0 2110 0.999999969 SM1HEV -0.6 508 0.999999435 SM7IUN* -0.1 490 0.999999913 SQ5J +7.4 1116 1.000007388 SV1CDN +0.2 321 1.000000244 SZ1A +0.4 1734 1.000000352 TF3Y +1.7 276 1.000001743 TI7W +1.3 735 1.000001285 UA4CC +14.2 784 1.000014183 UT5R +5.3 103 1.000005303 UT5R-1 +3.1 217 1.000003132 UY2RA -2.0 394 0.999998048 V51YJ +1.3 129 1.000001293 VE3EID -0.1 213 0.999999944 VE6AO -1.1 177 0.999998939 VE6JY +1.0 457 1.000000998 VE6WZ +0.6 120 1.000000626 VE6WZ-3 -1.2 12 0.999998813 VE7CC -5.5 9 0.999994455 VK2RH +0.0 8 1.000000000 VK3RASA -0.2 63 0.999999774 VK6ANC -0.1 64 0.999999889 VU2CPL +0.1 90 1.000000079 VU2OY +9.9 178 1.000009892 VU2TUM +1.4 146 1.000001393 W1NT-2* -0.2 978 0.999999777 W1NT-6* -0.1 1075 0.999999869 W2MV +1.2 58 1.000001226 W2NAF +1.6 975 1.000001612 W2NNN +12.9 691 1.000012895 W3DAN +1.4 341 1.000001418 W3OA +0.3 773 1.000000267 W3RGA* -0.2 998 0.999999774 W4KAZ -0.3 578 0.999999698 W8WTS +0.3 557 1.000000272 W8WWV -1.8 803 0.999998236 WA7LNW +3.1 682 1.000003092 WB6BEE -0.1 236 0.999999950 WC2L +0.4 727 1.000000422 WC8GOP +13.4 32 1.000013391 WE9V +0.1 885 1.000000077 WS2C +10.3 454 1.000010255 WS3W +0.8 466 1.000000763 WT9U +6.4 169 1.000006443 WV4P +0.6 677 1.000000557 WX7V/5 +0.0 21 1.000000000 WZ7I -2.4 1098 0.999997609 YO2CK +0.3 1676 1.000000339 YO2KAR -0.4 1279 0.999999605 YO5LD +0.3 96 1.000000296 ZF1A +9.2 918 1.000009209 ZL2KS -2.5 14 0.999997457 ZS1NN -4.6 46 0.999995410 Last updated 2025-10-02 00:10:33 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 1001 0930 0929 0928 0927 0926 0925 0924 0923 0922 --------------------------------------------------------------------- 3B8GL +0.0 +0.5 +0.8 +1.6 +1.0 +0.0 +0.0 +1.5 3D2AG +0.3 +0.1 +0.3 +0.0 +0.3 +0.3 +0.7 +0.4 +0.3 +0.2 3V9A -1.4 3V/KF5EYY -1.5 5Z4GO +0.0 +1.1 +1.4 +0.8 +0.5 +1.1 +0.5 +0.2 +0.7 +0.6 7N4XCV +0.9 +0.2 +2.4 +0.6 +0.2 +1.2 +1.3 AA0O +1.5 +0.8 +0.6 +0.7 +1.1 +0.6 +0.8 +0.9 +0.7 +0.7 AC0C-1 -0.1 -0.1 +0.1 -0.1 -0.0 +0.0 -0.0 -0.1 -0.1 +0.0 BA4OP -0.0 +0.0 +0.0 -0.1 +0.0 +0.1 -0.1 -0.1 -0.2 +0.1 BA6KC -0.2 -0.4 +0.1 +0.0 -0.1 +0.2 -0.1 -0.0 +0.1 -0.1 BD4UNT +0.1 +0.5 +0.6 +0.2 +0.1 +0.2 -0.0 -0.4 +0.1 +0.2 BD7JNA -0.1 -0.6 +0.0 +0.0 +0.0 +0.0 BG0AJO/0 +0.3 +0.0 +0.4 +0.3 +0.3 +0.0 +0.4 +0.6 +0.3 +0.3 BG0AJO +0.1 +0.1 -0.0 +0.1 +0.1 -0.1 -0.1 -0.0 -0.0 +0.0 BG2TFW +0.1 +0.0 +0.6 +0.3 +0.3 +0.3 +0.3 +0.2 +0.2 +0.5 BG4GOV +0.0 +0.0 +0.0 +0.3 +0.2 +0.1 -0.2 +0.1 +0.0 +0.9 BH4HKZ +4.2 +4.8 BH4RRG +0.4 +0.0 +0.9 +0.1 +0.7 +0.2 +0.1 +0.1 -0.1 +0.2 BH4XDZ +0.2 +0.0 +0.2 +0.1 +0.1 +0.5 +0.0 +0.1 +0.0 -0.0 BI4MPH +0.0 +0.0 +0.8 +0.3 +0.4 +0.8 +0.0 +0.8 +0.0 +0.3 BI4UYX +0.0 CN3A +10.5 +10.1 CT1EYQ -0.1 -0.2 -0.3 -0.7 -0.6 -0.4 -0.4 -0.4 -0.5 -0.6 DE1LON +0.5 +0.4 +0.8 +0.7 +0.7 +0.4 +0.4 +0.5 +0.6 +0.8 DE2SAX -1.0 -0.7 -0.5 DF1VB -0.1 -0.1 -0.1 DF2CK -0.2 -0.2 -0.1 +0.3 +0.0 -0.2 -0.4 -0.2 +0.2 +0.1 DF2JP +0.0 +19.4 DF7GB +0.0 +0.0 -0.0 +0.0 +0.0 +0.0 +0.0 -0.1 -0.0 DK0TE -0.2 -0.5 -0.5 -0.3 -0.2 -0.1 -0.1 -0.1 -0.1 -0.3 DK3WW -0.1 -0.2 -0.0 +0.1 -0.1 -0.0 +0.1 DK9IP -0.0 -0.1 +0.0 -0.0 +0.0 -0.1 +0.1 +0.0 +0.0 +0.1 DK9IP-1 -0.1 -0.1 +0.0 -0.1 -0.0 -0.1 +0.0 -0.1 +0.0 +0.1 DL0LA -0.2 -0.1 -0.2 -0.1 -0.1 -0.0 DL1AMQ +0.1 -0.8 DL1EFW -0.8 DL1HWS +0.4 +0.4 +0.6 +0.7 +0.7 +0.5 +0.6 +0.6 +0.5 +0.6 DL1HWS-3 +0.0 +0.7 +0.9 +0.0 DL5RCN +12.8 +12.6 +12.8 +12.5 +13.2 +13.2 DL8LAS +0.2 +0.2 +0.3 +0.3 +0.4 +0.2 +0.3 +0.3 +0.2 +0.3 DL8TG -0.1 -0.2 -0.0 -0.2 -0.1 -0.4 DM5GG +0.1 +0.4 +0.3 +0.7 +0.2 -0.3 +0.4 -0.1 +0.0 +0.6 DM6EE +0.1 -0.0 -0.1 +0.0 -0.0 +0.0 -0.0 DO4DXA -0.1 -0.1 +0.1 -0.0 -0.0 -0.0 -0.0 -0.1 DR4W -3.1 -2.3 -1.6 -2.6 -2.4 -2.8 -2.7 -2.4 -2.6 -2.0 DR5X +1.9 +2.0 +2.1 +2.2 +2.2 +2.0 +2.3 +2.6 +1.9 +2.1 EA1URA +1.0 EA2CW -0.4 -0.5 -0.3 -0.6 -0.7 -0.7 -0.6 -0.5 -0.4 -0.3 EA2RCF-4 -0.6 -0.7 -0.6 -0.7 -0.9 -0.7 -0.7 -0.5 -0.3 -0.2 EA5WU +0.0 -0.0 +0.0 +0.0 -0.1 +0.0 -0.0 -0.1 +0.0 EA8/DF4UE -0.1 -0.0 -0.0 -0.1 -0.1 -0.0 EA/VE3NZ +0.2 -0.2 -0.3 ES2RR -0.0 -0.0 +0.0 -0.1 -0.0 -0.1 -0.1 +0.0 -0.0 -0.0 ES5PC +0.0 -0.1 -0.0 -0.0 -0.0 -0.0 -0.1 +0.0 ET3AA -12.7 -11.2 EU1ST -0.1 -0.2 F1UVN +16.6 +16.2 +16.6 +15.4 +16.0 +15.1 +15.2 +15.6 +15.5 +15.4 F4GOU/1 +7.5 +5.5 F4GOU +4.5 +4.6 +4.9 +5.4 +5.1 +4.5 +5.1 +5.1 +4.9 +5.8 F4VVG +0.0 +0.1 +0.2 +0.2 +0.3 F6KGL +0.3 +0.1 +0.3 +0.2 +0.1 +0.3 F8DGY -3.1 -3.3 -3.2 -2.9 G0KTN +0.3 +0.3 +0.4 +0.3 +0.3 +0.2 +0.2 +0.3 +0.2 +0.3 G1VWC +6.4 G3BJ +0.0 G3YPP +0.5 +0.1 +0.6 +0.3 +0.5 +0.2 +0.2 +0.6 +0.2 +0.0 G4AON +1.0 +0.7 +0.9 +1.0 +1.1 +1.2 +1.2 G4HSO +0.6 +0.7 +0.7 +0.7 G4IRN +0.2 +0.1 +0.2 +0.2 +0.3 +0.2 +0.2 +0.2 +0.2 +0.2 G4ZFE +0.5 +0.5 +0.7 +0.6 +0.8 +0.5 +0.6 +0.6 +0.3 +0.5 GI4DOH +0.2 -0.0 -0.0 -0.1 +0.1 +0.0 +0.1 +0.1 -0.1 -0.6 GX0FRE +0.4 +0.3 +0.3 +0.2 +0.3 +0.4 +0.0 HA1VHF +0.2 +0.1 +0.3 +0.4 +0.4 +0.2 +0.4 +0.4 +0.5 +0.8 HA5JI-8 -2.3 -1.3 -0.6 +0.1 +0.2 -1.1 -2.7 -1.7 -0.9 -0.8 HA5PP -0.5 -0.9 -0.2 -0.4 -0.3 +0.2 +0.7 +0.2 HA5PP-2 +0.1 -0.2 HA6PX -0.1 -0.1 +0.0 -0.0 -0.1 HA8TKS +0.1 +0.1 +0.2 +0.2 +0.1 +0.2 +0.3 +0.3 +0.1 +0.3 HA8TKS-2 +0.0 +0.1 +0.1 +0.0 +0.0 -0.0 +0.0 -0.0 -0.0 +0.1 HB9BXE +0.1 +0.1 +0.0 +0.1 +0.2 +0.0 +0.0 +0.1 +0.1 +0.3 HB9DCO -0.3 -0.3 -0.2 -0.4 -0.4 -0.3 -0.3 -0.4 -0.3 -0.1 HB9GVO +0.7 +0.6 +0.3 +1.2 +1.0 +0.6 +1.1 +0.8 +0.7 +0.5 HG0Y +7.4 +7.5 +7.5 +7.4 +7.5 +7.8 +7.7 +8.0 HG8A +0.6 +0.7 +0.9 +1.4 +1.7 +1.2 +1.6 +2.1 +2.5 +2.8 IK3STG +1.7 +1.5 +1.4 +1.9 +1.9 +1.5 +1.5 +1.6 +1.1 +1.3 IK4VET +1.6 +2.2 +2.3 +2.1 +2.3 +1.9 +2.3 +3.1 +3.2 +3.2 IK7YTT +0.1 -0.0 +0.0 +0.0 +0.0 +0.0 +0.0 +0.0 +0.0 +0.0 IT9GSF -0.0 -0.1 -0.0 -0.1 +0.1 +0.1 +0.1 -0.0 +0.0 IU0MVD -6.1 IW9GDC -0.5 -0.4 -0.3 -0.6 -0.5 -0.3 -0.3 -0.4 -0.3 -0.2 JG1DLY +0.0 -0.3 JH7CSU1 +1.8 +1.8 +2.1 +2.3 +1.6 +2.8 +1.6 +2.2 +1.6 +1.9 JI1HFJ -0.4 +1.5 +1.1 +0.2 -0.5 +0.5 -0.4 +0.4 +0.2 -0.8 JJ2VLY +1.7 +1.4 +1.7 +2.5 +2.5 +2.1 +2.0 +2.3 +0.8 +2.3 JK1QLQ +0.0 +0.0 JN1ILK -0.4 +0.1 +0.3 +0.0 -0.1 +0.0 -0.4 -0.7 -0.6 -0.8 K1RA +1.0 +0.8 +0.9 +0.8 +1.6 +1.0 +1.3 +1.3 +0.9 +0.7 K2PO/7 +0.6 +0.1 +0.5 +0.6 +0.5 +0.2 K3PA-1 +0.2 +0.3 +0.1 +0.0 +0.1 +0.1 +0.1 -0.0 +0.0 +0.1 K3PA-2 -17.4 -17.4 -16.8 -16.9 -17.1 -17.1 -17.0 -17.0 -17.0 -17.1 K4PP +0.4 +0.2 +0.2 +0.4 +0.8 +0.3 +0.3 +0.3 +0.2 +0.3 K5EM +3.5 +2.7 +2.3 +2.3 +3.1 +2.8 +3.3 +2.6 +2.4 +2.0 K5TR +1.9 +1.5 +1.5 +2.0 +2.2 +1.6 +1.9 +1.8 +2.0 +1.8 K7CO -0.0 +0.2 +0.5 +0.2 +0.7 +0.5 +0.1 +0.0 +0.3 K7EK +1.0 +1.1 -0.0 +1.4 -0.3 +0.7 -0.6 -0.2 -0.7 +0.4 K7RUT -1.3 -1.6 -2.1 -3.0 -1.9 -2.1 -1.1 -1.4 K9IMM +0.1 +0.1 -0.0 -0.1 +0.0 -0.1 -0.0 -0.0 -0.0 +0.0 K9LC +1.0 +0.5 +0.8 +0.5 +1.1 +0.6 +0.9 +1.0 +0.9 +0.8 KC4YVA +1.6 +3.1 +4.3 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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.
DF7GB ES2RR KM3T-5 LZ3CB LZ4UX OE9GHV WB6BEE Last updated 2025-10-02 00:10:41 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.