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.
310084 RBN spots between 2026-05-12 00:00 and 23:59 UTC. 116749 spots (37.7%) were from reference skimmers (*). Average spot flow was 215 per minute from 201 active CW skimmers. 180684 spots from 198 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 -0.2 113 0.999999825 5Z4GO +0.3 21 1.000000339 9M2CNC +0.1 136 1.000000146 AA4PA +0.3 544 1.000000284 AC0C-1* -0.1 1341 0.999999924 AK6RI-1* +0.0 272 1.000000042 BA6KC -0.2 241 0.999999809 BD4UNT +0.1 87 1.000000137 BD7JNA +0.0 61 1.000000000 BD8CS* +0.0 612 1.000000035 BG0AJO/0 +0.6 132 1.000000630 BG2TFW +0.3 29 1.000000328 BH4RRG +0.5 24 1.000000496 BH4XDZ +0.0 44 1.000000000 BI4MPH +0.3 107 1.000000318 BI7JMD +0.0 18 1.000000000 CT1EYQ -0.5 1150 0.999999545 DC8YZ* +0.0 1384 1.000000024 DE1LON -0.4 529 0.999999616 DF7GB* -0.0 1943 0.999999998 DK0TE -0.1 1821 0.999999889 DK3WW* -0.0 1828 0.999999969 DL0LA* +0.0 861 1.000000008 DL1HWS +0.7 1552 1.000000749 DL1HWS-4 +0.7 192 1.000000674 DL5RCN +14.1 783 1.000014088 DL8LAS +1.2 3307 1.000001216 DL8LAS-1 +0.0 1919 1.000000043 DL8LAS-3 +1.3 1646 1.000001255 DM5GG +1.0 2068 1.000000991 DM6EE +0.2 1726 1.000000156 DO4DXA* +0.0 2379 1.000000013 DP5G +0.0 248 1.000000011 DR4W -2.9 1142 0.999997131 E28AC +4.5 8 1.000004549 EA1DAV* +0.1 1138 1.000000064 EA2CW -0.3 86 0.999999719 EA2RCF-4* +0.1 648 1.000000123 EA5WU* -0.1 476 0.999999934 EI4HQ* -0.1 2159 0.999999949 ES2RR* -0.0 2542 0.999999965 ES5PC* +0.0 2552 1.000000001 EY8ZE -0.2 617 0.999999832 F1EYG -1.9 3760 0.999998148 F4BPO +0.2 557 1.000000231 F4GOU* +0.1 510 1.000000056 F6IIT -1.1 40 0.999998932 F6KGL* +0.1 1938 1.000000137 F8DGY -6.3 1352 0.999993700 G0KTN +0.2 1876 1.000000218 G4IRN +0.3 2857 1.000000263 G4ZFE* +0.1 2262 1.000000091 GI4DOH* +0.1 1357 1.000000073 GX0FRE* +0.0 1180 1.000000011 HA1VHF +0.4 1978 1.000000407 HA8TKS* +0.1 1017 1.000000130 HA8TKS-2 +0.0 9 1.000000000 HB9BXE +0.3 837 1.000000298 HB9DCO* -0.1 1547 0.999999894 HB9GVO* +0.1 353 1.000000121 HB9YC-SDR +0.4 354 1.000000362 HG0Y +7.9 110 1.000007906 HG8A +1.7 1931 1.000001684 HS0ZGZ +0.6 153 1.000000557 IK3STG +2.9 934 1.000002854 IK4VET +3.1 2022 1.000003140 IK7YTT* +0.0 1779 1.000000025 IQ9RG* +0.1 1181 1.000000074 IT9GSF* -0.0 3143 0.999999985 IZ2CPS* +0.0 254 1.000000028 JA1CCA -1.4 90 0.999998623 JH7CSU1 +1.3 124 1.000001332 JI1HFJ -1.9 49 0.999998109 JJ2VLY +0.3 166 1.000000262 JK1QLQ +0.0 6 1.000000000 JN1ILK +2.1 516 1.000002094 JQ1BVI +0.0 17 1.000000000 K1RA +0.3 1234 1.000000303 K1RA-4 -0.3 1060 0.999999706 K3GMQ +0.2 196 1.000000181 K3PA-1 +0.4 1051 1.000000394 K4PP +0.3 622 1.000000308 K5EM +3.8 412 1.000003805 K5TR +6.8 1185 1.000006797 K6FOD +0.1 225 1.000000119 K7CO +1.8 557 1.000001778 K7EK -0.2 233 0.999999801 K9IMM* -0.0 971 0.999999996 K9LC +0.5 781 1.000000535 KC4YVA +0.7 560 1.000000742 KD2OGR +0.3 414 1.000000327 KD7EFG +0.3 372 1.000000337 KH6LC +0.1 88 1.000000055 KM3T-2* +0.1 403 1.000000141 KM3T-3 +0.2 1457 1.000000232 KM3T-5* +0.0 1281 1.000000036 KO4BHX +0.2 1311 1.000000196 KW7MM +0.4 1278 1.000000394 KW7MM-2 +0.5 1162 1.000000517 KW7MM-3 -3.6 45 0.999996406 LB9KJ +1.4 992 1.000001381 LU6KK +0.5 15 1.000000476 LU8XW +0.0 6 1.000000000 LZ3CB* -0.0 1163 0.999999985 LZ4AE +0.5 2884 1.000000477 LZ4UX* +0.0 1360 1.000000002 LZ7AA +0.5 1248 1.000000494 MM0ZBH* +0.1 2777 1.000000072 MM9PSY* -0.0 2209 0.999999978 N2CR +0.8 336 1.000000801 N2YCH +1.6 1050 1.000001612 N5RZ +1.9 1310 1.000001942 N6TV +0.6 463 1.000000574 N7TUG +0.6 25 1.000000570 N8DXE +1.0 264 1.000001023 N9CO* +0.0 786 1.000000027 ND7K* -0.2 879 0.999999785 NG7M -0.0 316 1.000000000 NU4F* +0.1 661 1.000000076 OE9GHV* -0.0 2213 0.999999991 OH4KA +1.4 418 1.000001439 OH6BG -0.3 2440 0.999999712 OH8KA -2.6 381 0.999997372 OK1FCJ* +0.0 2438 1.000000048 OK1HRA -3.6 1802 0.999996364 ON6ZQ -0.3 1642 0.999999731 OZ1AAB* -0.1 677 0.999999895 OZ1BZS +0.3 433 1.000000309 PA5KT-4 -0.3 1964 0.999999710 PE5TT* +0.1 1505 1.000000086 PI4CC* -0.0 2456 0.999999984 PT2FHC -0.1 120 0.999999881 PY2KNK +2.4 365 1.000002365 PY2PE +0.3 143 1.000000268 RK3TD +0.2 1260 1.000000241 RK3TD-2 +0.6 1407 1.000000561 RN4WA +1.0 172 1.000001018 RU9CZD* +0.0 2018 1.000000007 S50U* -0.1 1175 0.999999926 S53A +0.7 1738 1.000000653 S53WW* -0.1 1943 0.999999893 S54L +0.2 2098 1.000000155 S58W* -0.0 1109 0.999999994 SE5E* +0.0 2752 1.000000049 SM0TCZ -0.1 90 0.999999920 SM1HEV* -0.1 1568 0.999999891 SM7IUN* +0.0 1074 1.000000007 SP5GQ* -0.1 1492 0.999999873 SQ5J +8.5 1755 1.000008525 SV1CDN +0.9 38 1.000000877 SZ1A +0.2 639 1.000000224 TF3Y +1.5 1533 1.000001450 TI7W +1.2 1169 1.000001151 UA4M +6.1 18 1.000006074 UT5R +0.1 271 1.000000079 UY2RA -1.2 335 0.999998785 V51YJ +1.3 54 1.000001335 VE4DRK +0.6 188 1.000000631 VE6AO -0.7 205 0.999999348 VE6JY +3.8 862 1.000003843 VE6WZ -1.3 712 0.999998729 VE6WZ-3 -1.3 722 0.999998705 VE7CC +1.0 163 1.000000990 VK2GEL +0.0 24 1.000000000 VK2RH +0.0 26 1.000000000 VK3RASA +0.1 41 1.000000067 VK6ANC +0.1 52 1.000000092 VR2FUN-77 +1.3 606 1.000001332 VU2CPL -4.5 21 0.999995455 VU2OY +0.1 108 1.000000066 VU2TUM +0.4 244 1.000000373 W1NT-2 +0.2 1223 1.000000212 W1NT-6 +0.2 1591 1.000000219 W2MV +0.1 58 1.000000123 W2NNN +2.4 60 1.000002398 W3DAN +0.0 6 1.000000000 W3LPL -0.5 470 0.999999505 W3RGA -0.2 1157 0.999999832 W3UA* -0.0 746 0.999999965 W4KAZ -0.7 598 0.999999298 W6YX +0.5 821 1.000000461 W8WTS -0.2 416 0.999999812 WA7LNW -2.2 796 0.999997773 WB6BEE* +0.1 1076 1.000000080 WC2L +0.4 692 1.000000356 WE9V +0.1 1007 1.000000120 WF8Z -0.3 55 0.999999743 WS2C +7.8 437 1.000007812 WS3W +0.1 280 1.000000051 WT9U -0.0 490 1.000000000 WX7V/5 +0.4 300 1.000000380 WZ7I +0.4 963 1.000000381 YO2CK* -0.0 1503 0.999999968 YO2KAR* -0.2 1352 0.999999815 ZF1A* -0.0 1799 0.999999992 ZF9CW +0.3 1488 1.000000324 ZL2KS -0.2 162 0.999999763 ZS1NN -4.6 64 0.999995371 Last updated 2026-05-13 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 0512 0511 0510 0509 0508 0507 0506 0505 0504 0503 --------------------------------------------------------------------- 3D2AG -0.2 +0.0 +0.1 -0.0 +0.1 +0.1 +0.1 +0.1 -0.1 +0.1 5Z4GO +0.3 +0.0 +0.8 +0.6 +0.3 +0.4 +0.0 +0.0 +0.6 9M2CNC +0.1 +0.2 +0.3 +0.6 +0.4 +0.2 +0.4 +0.3 -0.0 +0.4 AA4PA +0.3 +0.4 +0.5 +0.6 +0.3 +0.4 +0.5 +0.3 +0.5 +0.8 AC0C-1 -0.1 -0.0 -0.1 -0.0 -0.0 -0.1 +0.1 -0.2 -0.1 +0.0 AK6RI-1 +0.0 +0.1 -0.1 +0.0 BA6KC -0.2 -0.0 -0.0 -0.0 +0.0 -0.0 -0.0 -0.0 +0.0 -0.0 BD4UNT +0.1 -0.1 +0.2 +0.2 +0.2 +0.1 +0.1 +0.1 +0.1 +0.1 BD7JNA +0.0 -0.1 -0.0 +0.0 +0.0 +0.0 +0.1 +0.2 -0.0 +0.0 BD8CS +0.0 -0.0 -0.0 +0.0 +0.1 -0.0 -0.0 -0.0 -0.1 +0.0 BG0AJO/0 +0.6 +0.7 +0.6 +0.8 +0.3 +0.3 +0.6 +0.4 +0.3 +0.4 BG2TFW +0.3 +0.5 +1.2 +1.1 +1.3 +0.3 +0.2 +0.7 +0.4 +0.4 BG4GOV +0.1 -0.1 -0.0 BH4HKZ -0.0 BH4RRG +0.5 +0.2 +0.3 +0.7 +0.4 +0.2 +0.1 +0.0 +0.1 +0.2 BH4XDZ +0.0 +0.2 -0.0 +0.2 +0.1 +0.0 -0.1 -0.1 -0.1 -0.0 BI4MPH +0.3 +0.2 +0.1 +0.1 +0.2 +0.0 +0.1 +0.1 +0.0 +0.1 BI7JMD +0.0 +0.2 +0.1 +0.2 +0.2 -0.0 -0.0 -0.0 -0.0 -0.1 CT1EYQ -0.5 -0.6 -1.0 -0.6 -0.3 -0.6 -0.5 -0.7 -0.5 -0.6 DC8YZ +0.0 +0.1 +0.2 +0.3 +0.2 +0.2 +0.2 +0.2 +0.0 +0.2 DD5XX -1.5 -0.2 +0.0 +0.1 +0.3 DE1LON -0.4 -0.4 -0.4 -0.4 -0.3 -0.3 -0.3 -0.4 -0.4 -0.4 DF2JP +1.2 DF4UE +0.2 DF7GB -0.0 -0.0 +0.0 +0.1 +0.0 -0.0 -0.1 -0.0 +0.0 -0.0 DK0TE -0.1 -0.6 +0.7 +0.8 +0.3 +0.1 +0.1 +0.1 -0.1 +0.8 DK3WW -0.0 -0.0 -0.1 -0.2 -0.0 +0.0 +0.2 +0.1 +0.2 +0.2 DK8NE +0.0 +0.2 DK9IP -0.3 +0.1 +0.0 DK9IP-1 +0.0 -0.1 -0.0 DL0LA +0.0 +0.0 +0.0 +0.0 -0.0 -0.0 +0.1 -0.1 -0.0 DL1EFW -0.6 DL1HWS +0.7 +0.8 +1.1 +1.1 +0.6 +0.8 +0.8 +0.8 +0.6 +1.1 DL1HWS-3 +1.4 +1.6 +1.8 +1.2 +1.6 +1.5 +1.8 DL1HWS-4 +0.7 +1.1 +1.0 +0.9 +0.6 +1.0 +1.0 +0.7 DL5RCN +14.1 +14.3 +14.3 +13.0 +13.8 DL5RMH +4.4 DL8LAS-1 +0.0 +0.0 +0.1 +0.0 +0.1 -0.0 -0.0 +0.1 +0.2 +0.3 DL8LAS +1.2 +0.9 +0.8 +0.9 +0.6 +0.7 +0.8 +0.8 +1.0 +1.3 DL8LAS-3 +1.3 +1.9 +2.3 +2.4 +1.7 +2.1 +2.2 +2.6 +3.0 +3.5 DM5GG +1.0 +1.2 +1.3 +1.4 +0.9 +1.0 +0.9 +0.9 +1.0 +1.3 DM6EE +0.2 +0.2 +0.1 +0.2 +0.2 +0.2 +0.2 +0.2 +0.1 -0.0 DO4DXA +0.0 -0.0 +0.1 +0.1 +0.0 +0.0 -0.0 -0.0 +0.1 +0.0 DP5G +0.0 -0.1 -0.0 +0.0 +0.0 +0.1 +0.0 -0.0 -0.1 +0.0 DR4W -2.9 -1.3 -1.9 -1.6 -2.9 -2.6 -2.1 -1.3 -1.0 -1.4 E28AC +4.5 +0.2 +1.0 +0.5 +0.8 +0.9 +0.5 +0.5 +0.5 EA1DAV +0.1 +0.0 +0.0 +0.0 +0.0 +0.1 +0.0 -0.0 +0.0 +0.0 EA2CW -0.3 -0.2 -0.3 -0.5 -0.2 -0.1 -0.4 -0.1 -0.1 -0.2 EA2RCF-4 +0.1 +0.1 +0.3 +0.4 +0.3 +0.3 +0.3 +0.3 +0.3 +0.6 EA5WU -0.1 -0.1 +0.0 -0.0 +0.0 +0.2 +0.1 -0.0 +0.0 EI4HQ -0.1 -0.0 -0.1 -0.0 ES2RR -0.0 -0.1 +0.0 -0.0 -0.0 +0.0 -0.0 -0.0 -0.0 -0.0 ES5PC +0.0 -0.1 +0.0 +0.0 +0.1 +0.1 -0.0 -0.1 -0.0 -0.0 EY8ZE -0.2 -0.2 -0.1 -0.1 -0.1 -0.2 -0.2 -0.4 -0.6 F1EYG -1.9 -1.6 -2.0 -2.0 -1.4 -1.9 -2.0 -1.5 -1.6 -1.9 F4BPO +0.2 +0.6 +0.5 +1.6 +0.0 +0.7 F4GOU +0.1 -0.0 +0.1 +0.0 -0.1 +0.0 +0.0 -0.0 -0.2 -0.1 F6IIT -1.1 +0.0 -0.6 -0.2 +0.0 +0.0 +0.0 -1.5 -0.4 F6KGL +0.1 +0.2 +0.2 +0.4 +0.3 +0.4 +0.1 +0.1 +0.1 +0.2 F8DGY -6.3 -5.3 -9.8 G0KTN +0.2 +0.2 +0.4 +0.6 +0.3 +0.3 +0.3 +0.2 +0.3 +0.4 G0TMX -0.1 +0.3 +0.2 G1VWC +3.4 G3BJ +0.4 +0.1 +0.3 G3YPP -0.0 +0.3 -0.2 -0.5 -0.0 +0.3 -0.0 +0.3 +0.0 G4IRN +0.3 +0.3 +0.5 +0.5 +0.4 +0.4 +0.4 +0.3 +0.4 +0.5 G4KCM -0.2 -0.0 G4ZFE +0.1 +0.1 +0.3 +0.5 +0.2 +0.2 +0.2 +0.1 +0.1 +0.3 GI4DOH +0.1 +0.1 +0.0 +0.2 +0.3 +0.0 +0.0 +0.0 +0.1 +0.3 GX0FRE +0.0 +0.0 +0.1 +0.2 +0.0 +0.1 +0.1 +0.0 +0.1 +0.3 HA1VHF +0.4 +0.5 +0.7 +0.8 +0.4 +0.6 +0.6 +0.6 +0.5 +0.5 HA5E +0.0 +0.1 +0.2 HA5PP +0.2 +0.1 HA8TKS +0.1 -0.0 +0.1 +0.2 +0.2 +0.1 +0.1 +0.0 -0.0 +0.1 HA8TKS-2 +0.0 -0.1 +0.0 -0.1 +0.0 -0.1 -0.1 +0.4 -0.0 -0.1 HB9BXE +0.3 +0.3 +0.4 +0.6 +0.2 +0.3 +0.3 +0.2 +0.3 +0.5 HB9DCO -0.1 -0.3 -0.3 -0.3 -0.1 -0.2 -0.1 -0.1 -0.4 -0.3 HB9GVO +0.1 +0.2 +0.5 +0.9 +0.5 +0.6 +0.2 +0.6 +0.3 +0.6 HB9YC/RX1 -0.1 +0.4 HB9YC-SDR +0.4 +0.4 +0.6 +0.3 +0.4 +0.0 +0.3 +0.4 HB9YC/SDR +0.8 HG0Y +7.9 +7.9 +7.9 +8.1 +7.7 +7.7 +7.8 +7.4 +7.7 +7.8 HG8A +1.7 +2.4 +2.5 +2.5 +1.7 +2.2 +1.9 +1.2 +1.6 +1.2 HS0ZGZ +0.6 +0.8 +1.1 +0.9 +0.4 +0.2 +0.6 +0.3 +0.4 +0.7 IK3STG +2.9 +3.0 +3.3 +3.6 +2.4 +3.1 +3.2 +3.4 +2.6 +3.7 IK4VET +3.1 +3.2 +3.7 +4.0 +3.0 +2.8 +2.2 +2.4 +3.3 +3.4 IK7YTT +0.0 +0.0 -0.0 +0.0 -0.1 -0.0 +0.0 +0.1 +0.0 -0.0 IQ9RG +0.1 +0.1 +0.2 +0.2 +0.2 +0.0 +0.1 +0.1 +0.1 +0.1 IT9GSF -0.0 +0.0 -0.0 -0.0 +0.0 -0.0 -0.0 -0.0 -0.1 -0.1 IZ2CPS +0.0 +0.2 -0.0 -0.0 +0.1 -0.2 -0.4 -0.4 IZ8EYP +0.1 JA1CCA -1.4 -1.6 -1.4 -1.4 -1.1 -1.3 -0.8 -0.7 -0.8 -0.9 JH7CSU1 +1.3 +1.9 +2.2 +2.0 +1.8 +1.3 +1.4 +1.2 +1.2 +2.4 JI1HFJ -1.9 -1.8 -0.9 -1.8 -2.5 -1.7 -4.3 -5.5 -5.7 -0.3 JJ2VLY +0.3 +0.6 +1.4 +0.9 +1.7 +0.3 -0.4 +1.1 +1.3 JK1QLQ +0.0 +0.3 +0.4 +1.4 +0.0 -0.1 +0.5 -0.1 +0.2 JM8SMO -5.8 JN1ILK +2.1 +3.1 +1.6 +1.1 +1.6 +0.5 -0.1 -0.2 -0.0 +0.3 JQ1BVI +0.0 +0.8 +0.0 +0.5 -1.4 +0.0 +0.0 +0.0 -0.1 +0.3 K1RA +0.3 +0.2 +0.8 +1.1 +0.4 +0.5 +0.9 +0.5 +0.2 +0.3 K1RA-4 -0.3 -0.6 -0.0 +0.1 -0.1 -0.4 +0.3 +0.3 -0.0 -0.4 K3GMQ +0.2 +0.2 +0.1 +0.1 +0.0 +0.1 -0.1 +0.3 +0.4 K3PA-1 +0.4 +0.4 +0.5 +0.5 +0.5 +0.4 +0.4 +0.2 +0.4 +0.6 K3PA-2 +0.0 +0.0 +0.3 K4PP +0.3 +0.5 +0.5 +0.7 +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.
DF7GB ES2RR KM3T-5 LZ3CB LZ4UX OE9GHV WB6BEE Last updated 2026-05-13 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.