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.
1344822 RBN spots between 2025-12-13 00:00 and 23:59 UTC. 222488 spots (16.5%) were from reference skimmers (*). Average spot flow was 934 per minute from 215 active CW skimmers. 391296 spots from 213 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 +1.2 117 1.000001188 3D2AG -0.4 770 0.999999582 3V/KF5EYY -2.1 2027 0.999997923 5Z4GO +0.5 194 1.000000517 AA0O +1.8 1352 1.000001797 AC0C-1 +0.1 3371 1.000000072 BA4OP -0.2 254 0.999999846 BA6KC +0.0 593 1.000000006 BG0AJO/0 -0.3 37 0.999999733 BG2TFW -1.5 210 0.999998509 BG2UKX +0.8 38 1.000000751 BG2UKX0 +1.0 34 1.000001049 BH4HKZ -0.1 401 0.999999858 BH4RRG +0.4 290 1.000000357 BH4XDZ +0.1 251 1.000000057 BI4MPH +0.2 261 1.000000162 CT1EYQ -2.0 4121 0.999997953 DE1LON -0.8 2865 0.999999249 DF1VB* +0.0 2982 1.000000044 DF2CK +1.1 8621 1.000001147 DF7GB -0.0 3154 0.999999952 DG6FL +0.6 414 1.000000602 DK0TE -1.4 5047 0.999998636 DK3WW +0.5 4701 1.000000549 DK9IP* -0.1 2788 0.999999883 DK9IP-1* -0.2 4004 0.999999838 DL0LA* +0.1 3493 1.000000084 DL1EFW +0.1 2530 1.000000062 DL1HWS +0.8 3942 1.000000842 DL1HWS-3 +2.0 61 1.000001956 DL1HWS-4 +0.2 21 1.000000170 DL5RCN +13.3 2834 1.000013294 DL5RMH -0.4 2235 0.999999616 DL8LAS +0.3 1569 1.000000264 DL8TG* -0.0 4845 0.999999997 DL9GTB +0.0 215 1.000000000 DM5GG* -0.2 4060 0.999999753 DM6EE +0.2 5395 1.000000183 DO4DXA +0.1 5997 1.000000087 DR4W -2.7 3826 0.999997282 DR5X +0.6 1028 1.000000566 E28AC +0.5 222 1.000000475 EA/VE3NZ -0.2 2810 0.999999774 EA2CW -0.7 161 0.999999285 EA2RCF-4 -0.9 1847 0.999999065 EA4FIT +1.4 5 1.000001428 EA5WU* +0.1 1048 1.000000058 ES5PC* +0.1 4783 1.000000060 EU8RO +0.6 200 1.000000603 F4GOU* +0.1 3924 1.000000064 F4VVG +0.2 2523 1.000000211 F5VLY -10.1 1101 0.999989913 F6IIT -1.0 5019 0.999998968 F6KGL -0.5 299 0.999999523 G0KTN +0.4 3309 1.000000433 G3AKX -0.2 1070 0.999999819 G3BJ +0.7 63 1.000000679 G4IRN +0.3 6432 1.000000274 G4ZFE +0.1 3764 1.000000091 GI4DOH +0.1 3651 1.000000131 GX0FRE* +0.2 1252 1.000000154 HA1VHF -1.8 4095 0.999998164 HA5PP +3.2 365 1.000003205 HA6PX* +0.0 3889 1.000000014 HA8TKS* +0.1 2769 1.000000061 HA8TKS-2 +0.1 176 1.000000119 HB9AFZ* +0.1 615 1.000000070 HB9BXE +0.1 1494 1.000000097 HB9DCO -0.3 2052 0.999999665 HB9GVO +0.6 97 1.000000571 HG0Y +7.6 131 1.000007613 HG8A -0.3 4206 0.999999722 IK3STG +2.7 1961 1.000002719 IK4VET +0.6 5017 1.000000595 IK7YTT* +0.1 2647 1.000000062 IQ9RG +0.1 6150 1.000000111 IT9GSF* -0.1 5465 0.999999916 IW9GDC -1.4 2278 0.999998571 IZ2CPS -0.1 1140 0.999999903 JG1DLY -0.6 23 0.999999381 JH4UTP -0.6 524 0.999999372 JH7CSU1 +2.4 304 1.000002425 JI1HFJ +2.0 173 1.000002041 JJ2VLY +1.3 10 1.000001267 JK1QLQ +0.4 18 1.000000396 JN1ILK -0.3 1213 0.999999706 K1RA +1.1 4321 1.000001057 K2PO/7 +0.4 732 1.000000386 K3LR +1.4 353 1.000001439 K3PA-1 +0.4 2519 1.000000383 K3PA-2 -0.0 2495 0.999999973 K4PP -0.3 1481 0.999999741 K5EM +3.1 197 1.000003101 K5TR +3.9 783 1.000003922 K6FOD -0.0 1076 0.999999971 K7CO -1.1 605 0.999998868 K7EK +0.9 110 1.000000911 K9IMM +0.6 64 1.000000613 K9LC +1.0 3033 1.000001011 K9QC +2.2 1553 1.000002180 KC4YVA +3.3 552 1.000003305 KD2OGR +0.4 257 1.000000401 KD7EFG +0.4 394 1.000000404 KH6LC -0.1 629 0.999999943 KL2R -0.4 60 0.999999584 KM3T-2 -0.4 417 0.999999642 KM3T-3 +0.3 3274 1.000000251 KM3T-5 -0.3 510 0.999999652 KP3CW -1.3 551 0.999998742 KV4TT +0.4 1770 1.000000351 LA6TPA -2.9 1025 0.999997112 LB9KJ +1.4 1192 1.000001397 LU6KK +0.1 104 1.000000137 LZ4AE -2.5 4682 0.999997528 LZ4UX* +0.0 3541 1.000000017 LZ5DI +0.8 3043 1.000000804 LZ7AA +0.8 3538 1.000000784 M9PSY* -0.0 3211 0.999999995 MM0GPZ -0.6 180 0.999999392 MM0ZBH +0.2 5224 1.000000219 N2CR +0.1 1129 1.000000122 N2YCH +0.4 4089 1.000000388 N6TV +1.1 96 1.000001077 N7TUG +0.2 44 1.000000162 N8DXE +1.5 544 1.000001517 N9CO +0.3 2313 1.000000302 ND7K -0.6 664 0.999999445 NG7M -0.1 1485 0.999999855 NN3RP +0.8 203 1.000000808 NU4F +0.3 2157 1.000000276 NU4F-2 +0.7 2775 1.000000688 OE3KLU +6.1 125 1.000006116 OE9GHV -0.3 50 0.999999716 OH2BBT -13.5 2494 0.999986500 OH4KA +0.6 694 1.000000638 OH6BG -1.4 1752 0.999998565 OK1FCJ +0.4 4692 1.000000406 OK1HRA -3.5 2122 0.999996453 ON6ZQ* -0.4 880 0.999999608 OZ1AAB +0.1 1062 1.000000075 OZ1BZS +0.5 431 1.000000491 OZ4ADX +0.1 275 1.000000117 PA5KT-4* +0.3 3520 1.000000270 PA8MM* +0.0 3012 1.000000041 PD2RPS* -0.0 1821 0.999999982 PE5TT +0.8 2678 1.000000757 PI4CC +0.4 2556 1.000000428 PR1T -0.4 32 0.999999555 PY2KNK +4.4 1157 1.000004421 PY2PE -0.9 326 0.999999092 R4NCU -0.3 82 0.999999739 RK3TD +0.8 538 1.000000786 RN4WA +2.2 445 1.000002197 S50U +0.3 783 1.000000314 S53A +1.1 5993 1.000001100 S53F +1.2 3271 1.000001196 S54L -0.5 3573 0.999999496 S57C +2.8 5560 1.000002769 SE5E* +0.0 4036 1.000000022 SM1HEV -0.1 1062 0.999999938 SM7IUN -0.0 2073 0.999999992 SP5GQ* +0.1 2744 1.000000058 SQ5J +7.1 3261 1.000007098 SV1CDN +0.3 164 1.000000261 SZ1A -1.0 2891 0.999999009 TF3Y +2.7 1893 1.000002744 TI7W +2.6 1567 1.000002619 TM8O +3.1 1488 1.000003148 UA4M +4.0 412 1.000004042 UT5R -0.2 898 0.999999812 UY2RA -0.8 1302 0.999999161 V51YJ +2.6 1501 1.000002578 VE3EID +0.2 3695 1.000000174 VE6JY +1.2 1491 1.000001166 VE6WZ +2.1 772 1.000002124 VE6WZ-3 -1.6 11 0.999998381 VE7CC +1.0 1616 1.000000990 VK2GEL +0.7 29 1.000000655 VK2RH -0.1 38 0.999999906 VK4CT +0.2 376 1.000000180 VK6ANC +0.7 109 1.000000665 VR2FUN-77 +0.3 1424 1.000000273 VU2TUM +1.1 225 1.000001125 W1NT-2* +0.1 1433 1.000000096 W1NT-6* +0.0 4526 1.000000004 W2MV +0.7 552 1.000000692 W2NAF +3.6 5 1.000003564 W2NNN -0.5 3353 0.999999493 W3DAN +1.4 601 1.000001445 W3LPL -0.6 973 0.999999433 W3OA* +0.3 4426 1.000000303 W3RGA* -0.5 3917 0.999999538 W3RGA-1 +0.0 591 1.000000024 W4KAZ -4.0 901 0.999995984 W6YX -0.4 1825 0.999999607 W8WTS -0.4 3147 0.999999559 W8WWV -2.3 2191 0.999997700 WA7LNW -0.4 2335 0.999999622 WC2L -0.4 3190 0.999999603 WC8GOP -3.1 990 0.999996858 WE9V -2.3 2466 0.999997711 WS2C +10.0 2522 1.000009998 WS3W +0.8 98 1.000000800 WT9U +7.2 1351 1.000007215 WV4P +0.9 1167 1.000000865 WX7V/5 +0.6 64 1.000000556 WZ7I +0.5 5079 1.000000476 YO2CK* +0.1 2761 1.000000053 YO2KAR* -0.1 3186 0.999999948 YU1EW +0.9 1299 1.000000862 ZL3X -0.1 134 0.999999893 ZL4YL +3.2 622 1.000003151 ZS1NN -3.8 369 0.999996241 Last updated 2025-12-14 00:16:50 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 1213 1212 1211 1210 1209 1208 1207 1206 1205 1204 --------------------------------------------------------------------- 3B8GL +1.2 +0.8 +0.2 +0.9 +0.2 +0.9 +1.3 +0.6 +0.3 +1.8 3D2AG -0.4 -0.5 -0.5 -0.1 -0.2 -0.5 +0.0 -0.5 -0.6 -0.3 3V/KF5EYY -2.1 -1.5 -1.5 -1.5 -1.4 -1.4 -1.9 -2.0 -1.8 -1.7 5Z4GO +0.5 +1.0 -0.0 +0.0 +1.0 +1.0 +0.3 +0.0 AA0O +1.8 +1.0 +0.9 +1.0 +1.1 +0.7 +1.0 +1.2 +0.9 +1.1 AC0C-1 +0.1 +0.0 +0.1 -0.0 +0.0 +0.1 +0.0 +0.0 -0.1 -0.3 BA4OP -0.2 -0.1 +0.0 -0.1 -0.2 +0.0 BA6KC +0.0 +0.3 +0.0 -0.1 +0.0 +0.1 -0.1 +0.0 +0.0 +0.2 BD7JNA +0.0 +0.0 -0.3 +0.1 BG0AJO/0 -0.3 +0.8 +0.5 +1.0 +0.4 +0.3 +0.0 +0.2 +1.3 -0.1 BG2TFW -1.5 -0.8 -0.8 -0.4 -1.1 -0.7 -0.9 -1.3 -1.0 +0.8 BG2UKX0 +1.0 +0.7 BG2UKX +0.8 +0.0 +0.0 +3.7 BH4HKZ -0.1 +0.2 +0.5 BH4RRG +0.4 +1.4 +0.8 +0.4 +0.4 +0.4 +0.0 -0.2 BH4XDZ +0.1 +0.3 +0.0 +0.0 +0.0 -0.0 -0.0 +0.2 +1.5 BI4MPH +0.2 +0.4 +0.0 +0.1 +0.0 +0.0 +0.1 CT1EYQ -2.0 -1.5 -1.3 -1.2 -1.1 -1.2 -1.4 -1.2 -1.3 -1.7 DE1LON -0.8 -0.4 -0.6 -0.4 -0.4 -0.4 -0.9 -0.9 -0.5 -0.7 DF1VB +0.0 +0.0 +0.1 -0.0 -0.0 -0.0 +0.0 +0.0 +0.0 -0.0 DF2CK-1 +0.3 +1.8 DF2CK +1.1 +1.1 +1.3 +1.4 +1.2 +1.0 +0.8 +0.5 +0.3 +0.6 DF7GB -0.0 +0.0 -0.0 -0.0 -0.0 -0.0 -0.0 -0.0 +0.0 -0.1 DG6FL +0.6 +0.4 +0.2 +0.2 +0.1 -0.1 +0.4 +0.4 +0.1 -0.2 DJ0OP -0.2 DK0TE -1.4 -0.7 -0.9 -1.0 -0.8 -0.8 -1.3 -1.4 -1.3 -1.0 DK3WW +0.5 +0.1 +0.1 +0.2 +0.0 -0.0 +0.1 +0.2 +0.2 +0.3 DK8NE +0.3 DK9IP -0.1 -0.0 -0.0 -0.1 +0.0 +0.0 -0.0 -0.1 -0.0 -0.1 DK9IP-1 -0.2 -0.0 -0.1 -0.1 -0.1 -0.0 -0.1 -0.1 -0.1 -0.1 DL0LA +0.1 +0.1 -0.1 +0.0 -1.0 +0.0 -0.2 +0.1 +0.1 +0.1 DL1EFW +0.1 DL1HWS +0.8 +0.6 +0.4 +0.6 +0.5 +0.4 +0.7 +0.6 +0.5 +0.6 DL1HWS-3 +2.0 +1.6 +1.3 +1.5 +1.5 +1.8 +1.5 +1.5 +1.7 DL1HWS-4 +0.2 +0.8 +0.7 +0.7 +0.3 +0.5 +0.9 +0.4 +0.7 +0.9 DL5RCN +13.3 +13.1 +13.5 +13.4 +13.4 +12.9 +12.1 +12.9 DL5RMH -0.4 -0.3 DL8LAS +0.3 +0.3 +0.3 +0.3 +0.2 +0.2 +0.5 +0.3 +0.2 +0.2 DL8TG -0.0 -0.0 +0.2 -0.2 DL9GTB +0.0 +0.3 -3.7 -3.4 +0.5 +0.5 +0.6 +0.6 DM5GG -0.2 -0.2 +0.6 +0.5 +0.8 +0.6 +0.7 +0.6 +0.6 -0.3 DM6EE +0.2 +0.2 +0.1 +0.2 +0.2 +0.1 +0.1 +0.2 +0.1 +0.2 DO4DXA +0.1 +0.1 +0.0 +0.0 +0.0 +0.1 +0.0 +0.0 -0.0 DR4W -2.7 -3.0 -2.0 -2.6 -2.1 -2.0 -3.3 -3.4 -3.5 -3.6 DR5X +0.6 +0.8 +0.8 +0.7 +0.6 +0.6 +0.6 +0.6 +0.6 +0.6 E28AC +0.5 +0.5 +0.3 +1.0 +0.2 +0.4 +1.1 +0.6 +0.1 +0.4 EA2CW -0.7 -0.6 -1.3 -1.0 -0.7 -1.0 -0.9 -1.4 -1.2 -1.1 EA2RCF-4 -0.9 -0.8 -0.8 -0.8 -0.6 -0.8 -0.9 -1.0 -0.9 -1.1 EA4FIT +1.4 +0.8 EA5WU +0.1 -0.0 -0.1 -0.1 -0.0 -0.1 +0.0 +0.0 -0.1 +0.1 EA8/DF4UE -0.3 -0.2 -0.3 -0.2 EA/VE3NZ -0.2 -0.3 -0.4 -0.6 -0.4 -0.2 -0.7 -0.6 -0.2 -0.6 ES4O -0.9 -0.9 -0.9 -1.0 ES5PC +0.1 +0.0 -0.0 -0.0 -0.0 -0.0 -0.1 -0.0 +0.0 EU8RO +0.6 +0.4 +0.2 F4BPO -0.7 -0.9 F4GOU +0.1 -0.0 +0.1 +0.0 +0.0 -0.1 -0.6 -0.9 -0.7 +0.1 F4VVG +0.2 +0.2 +0.1 +0.1 +0.3 -0.1 +0.1 +0.1 +0.1 +0.1 F5VLY -10.1 -7.9 F6IIT -1.0 -0.9 -0.8 -0.8 -1.0 -0.6 -0.8 -0.7 -1.1 -1.4 F6KGL -0.5 -6.1 -5.5 -5.1 -7.9 -6.3 -5.5 -5.7 +0.2 +0.3 F8DGY -4.4 G0KTN +0.4 +0.4 +0.5 +0.4 +0.3 +0.3 +0.4 +0.4 +0.3 +0.4 G3AKX -0.2 +0.1 -0.0 +0.0 +0.0 +0.1 G3BJ +0.7 +0.1 +0.2 +0.4 +0.3 +0.4 +0.4 +0.2 G4IRN +0.3 +0.2 +0.2 +0.2 +0.2 +0.2 +0.3 +0.2 +0.0 +0.1 G4ZFE +0.1 +0.5 +0.6 +0.5 +0.6 +0.7 +0.6 +0.6 +0.5 +0.5 GI4DOH +0.1 +0.1 +0.0 +0.2 +0.1 +0.1 +0.1 +0.3 +0.0 +0.1 GX0FRE +0.2 +0.2 -0.7 +0.1 +0.0 +0.1 +0.3 +0.2 +0.3 HA1VHF -1.8 -1.1 -1.2 -1.3 -1.1 -1.2 -1.4 -1.6 -1.5 -1.4 HA5PP +3.2 +1.9 +2.9 HA6PX +0.0 -0.0 -0.0 -0.1 +0.0 +0.0 -0.0 +0.0 -0.0 -0.0 HA8TKS +0.1 +0.0 -0.0 +0.1 +0.1 -0.2 +0.1 -0.0 +0.1 +0.1 HA8TKS-2 +0.1 +0.1 +0.1 +0.1 -0.1 -0.3 +0.1 +0.0 +0.1 -0.2 HB9AFZ +0.1 +0.5 +0.5 +0.3 +0.4 +0.3 HB9BXE +0.1 +0.5 +0.0 +0.2 +0.3 +0.3 +0.3 +0.3 +0.3 +0.3 HB9DCO -0.3 -0.2 -0.3 -0.1 -0.2 -0.2 -0.3 -0.3 -0.2 -0.2 HB9GVO +0.6 +0.3 +0.5 HB9TSU +20.7 +10.0 HG0Y +7.6 HG8A -0.3 +0.1 +0.0 -0.1 -0.0 +0.4 -0.1 +0.0 +0.3 +1.2 IK3STG +2.7 +3.3 +3.7 +3.4 +3.0 +3.0 +3.7 +3.4 +3.5 +3.6 IK4VET +0.6 +0.4 +0.4 +0.6 +0.4 +0.4 +0.2 +0.4 +0.2 +0.3 IK7YTT +0.1 +0.0 -0.1 -0.0 -0.0 -0.1 -0.0 -0.0 -0.1 -0.0 IQ9RG +0.1 +0.0 +0.0 +0.0 -0.1 +0.0 +0.0 +0.1 -0.1 -0.2 IT9GSF -0.1 -0.1 -0.1 -0.1 -0.1 +0.0 -0.1 -0.0 -0.1 -0.0 IW9GDC -1.4 -1.2 -1.0 -1.0 -1.1 -1.0 -1.1 -1.4 -1.0 IZ2CPS -0.1 -0.2 -0.7 -0.7 -0.8 -0.5 -0.8 +0.0 -0.6 JG1DLY -0.6 JH4UTP -0.6 -0.9 -2.7 JH7CSU1 +2.4 +2.3 +1.7 +0.1 +2.1 +1.3 +2.1 +1.7 +0.9 +1.1 JI1HFJ +2.0 -0.8 +1.0 +0.3 +2.0 -3.6 -4.8 JJ2VLY +1.3 -8.2 -1.2 +0.4 -0.8 -1.5 -1.4 -0.8 JK1QLQ +0.4 +0.0 -0.7 JN1ILK -0.3 +0.5 +0.4 -0.7 -0.5 +0.0 +0.8 +0.2 +0.9 +1.4 K1RA +1.1 +0.7 +0.4 +0.6 +0.3 +0.2 -0.0 +0.3 +0.1 +0.0 K2PO/7 +0.4 +0.0 +0.4 +0.2 +0.1 +0.5 +0.3 +0.3 +0.3 +0.1 K3LR +1.4 +3.6 +3.4 +3.3 +2.6 +3.3 +3.7 +2.5 +4.9 +2.1 K3PA-1 +0.4 +0.2 +0.2 +0.2 +0.2 -0.0 +0.2 +0.2 +0.1 +0.1 K3PA-2 -0.0 -0.0 -0.1 -0.2 -0.0 -17.7 -16.9 -17.0 -17.2 -17.1 K4PP -0.3 -0.1 -0.3 -0.8 -0.2 -0.7 -0.2 -0.3 +0.0 -0.5 K5EM +3.1 +3.2 +2.3 +2.8 +3.3 +2.6 +2.4 +3.5 +2.4 K5TR +3.9 +4.4 +3.3 +4.2 +3.0 +2.8 +4.9 +3.3 +2.0 +2.3 K6FOD -0.0 -0.2 -0.1 +0.0 -0.0 +0.0 -0.0 +0.1 +0.3 -0.5 K7CO -1.1 -0.4 -0.4 -0.5 -0.4 -0.6 -0.7 -0.6 -1.5 -1.4 K7EK +0.9 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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 KM3T-5 LZ4UX OE9GHV Last updated 2025-12-14 00:17:16 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.