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
376410 RBN spots between 2025-02-21 00:00 and 23:59 UTC. 105894 spots (28.1%) were from reference skimmers (*). Average spot flow was 261 per minute from 207 active CW skimmers. 186174 spots from 200 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 ------------------------------------- 2E0INH +0.3 101 1.000000274 3B8GL +0.1 28 1.000000127 3D2AG +0.0 113 1.000000032 3V8SS +5.4 104 1.000005421 5Z4GO +0.3 15 1.000000317 7N4XCV +0.6 38 1.000000564 AA0O +0.3 48 1.000000272 AC0C-1 -0.1 498 0.999999915 BA6KC -0.2 113 0.999999832 BD8CS -0.1 167 0.999999943 BG0AJO +0.1 78 1.000000071 BG2TFW +10.2 181 1.000010181 BH4RRG +0.1 81 1.000000059 BH4XDZ -0.1 88 0.999999932 BI4MPH-1 +0.2 69 1.000000206 BI4UYX -0.0 77 0.999999954 BY4XRA +1.1 82 1.000001077 CT1EYQ -0.8 2236 0.999999211 DC8YZ* -0.0 2519 0.999999981 DD5XX -0.5 1663 0.999999546 DE1LON +2.8 1541 1.000002823 DF2CK* -0.0 3357 0.999999996 DF4UE -1.8 1839 0.999998244 DF7GB* +0.0 1670 1.000000022 DK0TE +0.4 1695 1.000000426 DK3WW* +0.2 1992 1.000000182 DK9IP -0.1 1177 0.999999875 DK9IP-1* -0.2 1578 0.999999846 DL0LA -0.2 765 0.999999772 DL1HWS -0.1 1967 0.999999896 DL1HWS-3 +0.3 1123 1.000000294 DL1HWS-4 -0.2 432 0.999999788 DL8LAS +0.5 1605 1.000000546 DL8TG* -0.2 1756 0.999999845 DL9GTB +1.0 274 1.000001024 DM5GG +1.0 2792 1.000000967 DM6EE +0.2 58 1.000000246 DO4ZT* +0.1 1375 1.000000098 DP5G-15 -3.8 378 0.999996234 DP7D +0.5 506 1.000000523 DR4W -4.3 2010 0.999995680 E28AC +5.4 44 1.000005409 EA1RX -1.1 61 0.999998916 EA1URA +0.6 1232 1.000000604 EA2CW* +0.0 1370 1.000000033 EA2RCF-4 +0.1 959 1.000000123 EA5RQ +0.3 109 1.000000262 EA5RQ/A +0.0 5 1.000000000 EA5WU* -0.0 1438 0.999999952 ES2RR* -0.0 1732 0.999999997 ES5PC* -0.1 2398 0.999999929 F4GOU +5.4 1595 1.000005383 F4VVG* +0.1 864 1.000000118 F8UKP -3.3 74 0.999996684 G0KTN* +0.1 1703 1.000000118 G3XBI +0.1 605 1.000000070 G3YPP +0.1 123 1.000000096 G4AON +1.3 184 1.000001324 G4IRN +0.5 2170 1.000000503 G4ZFE +0.5 1841 1.000000501 GE0FRE +1.1 924 1.000001110 GI4DOH-2 +0.2 1403 1.000000181 GI4DOH-3 +0.6 551 1.000000556 GX0FRE +6.9 929 1.000006946 HA1VHF* -0.1 1742 0.999999889 HA6PX +0.1 283 1.000000128 HA8TKS -0.3 1026 0.999999681 HB9BXE +0.2 1420 1.000000173 HB9DCO -0.5 1130 0.999999505 HG0Y +6.1 608 1.000006096 HG8A* -0.2 1955 0.999999841 IK3STG +3.4 1362 1.000003435 IK4VET +1.2 1454 1.000001192 IK7YTT* -0.1 1744 0.999999918 JH7CSU1 +1.3 130 1.000001260 JI1HFJ -4.7 45 0.999995309 JN1ILK +0.7 271 1.000000731 K1RA -1.8 2044 0.999998228 K2PO/7 +0.2 1162 1.000000246 K3LR +0.2 638 1.000000166 K3PA-1* +0.0 678 1.000000046 K3PA-2 +14.0 282 1.000014011 K4PP* -0.1 1124 0.999999920 K5EM* +0.1 750 1.000000088 K5TR +0.6 1628 1.000000568 K6FOD -0.4 491 0.999999616 K7CO +0.7 773 1.000000709 K7EK +0.1 307 1.000000115 K9IMM* -0.0 1442 0.999999978 K9LC* +0.2 1542 1.000000196 K9QC +0.1 230 1.000000124 KA7OEI +0.3 513 1.000000287 KD2OGR +0.2 739 1.000000220 KH6LC +0.0 172 1.000000023 KM3T-2 -0.3 1490 0.999999669 KM3T-3* +0.2 990 1.000000191 KM3T-5* -0.1 1542 0.999999927 KO7SS -0.8 481 0.999999243 KV4TT -0.2 1310 0.999999819 LA6TPA -6.0 1034 0.999993959 LA7GIA -0.1 147 0.999999945 LB9KJ -9.5 575 0.999990515 LZ3CB* -0.2 669 0.999999843 LZ4AE +1.7 1633 1.000001703 LZ4UX* +0.1 1285 1.000000069 LZ5DI +0.3 669 1.000000335 LZ7AA +0.5 1239 1.000000528 MM0ZBH +0.2 2226 1.000000218 MM3NDH* +0.1 1682 1.000000079 N2CR -0.3 685 0.999999724 N6TV +0.3 673 1.000000319 N7TUG +16.8 12 1.000016833 N8DXE +0.8 544 1.000000759 N9CO* +0.2 1331 1.000000230 ND7K -0.5 803 0.999999491 NG7M* -0.0 768 0.999999972 NN3RP -0.0 371 0.999999966 NT6Q -5.7 758 0.999994318 NU4F -0.1 881 0.999999873 OE6TZE +0.1 1110 1.000000136 OE9GHV* -0.0 2095 0.999999990 OH4KA -3.8 1534 0.999996176 OH6BG -0.6 2038 0.999999413 OH8KA +3.6 370 1.000003594 OK1FCJ +0.2 2271 1.000000186 OK1HRA -4.3 1865 0.999995675 ON6ZQ -0.6 1434 0.999999393 OZ1AAB +0.2 529 1.000000207 OZ1BZS +0.7 303 1.000000676 OZ4ADX +0.3 179 1.000000350 PA2SQ +1.4 8 1.000001394 PE5TT -0.2 1643 0.999999832 PI4CC* +0.0 1877 1.000000013 R1LB -0.1 398 0.999999875 R9IR* +0.1 470 1.000000112 RK3TD +0.5 1132 1.000000455 RK3TD-2 +4.1 1511 1.000004058 RN4WA +1.2 1105 1.000001204 RU9CZD +0.4 840 1.000000428 S50ARX* +0.0 1654 1.000000021 S50U* -0.1 707 0.999999908 S51CAB -0.0 190 0.999999963 S53A -0.4 81 0.999999649 S53F +0.6 95 1.000000554 S53WW -2.9 1759 0.999997071 SE5E -0.2 2236 0.999999766 SM0TCZ +1.7 80 1.000001709 SM1HEV -0.1 816 0.999999862 SM7IUN* -0.0 1844 0.999999956 SQ5J +8.6 1616 1.000008555 SV1CDN +0.0 72 1.000000050 SZ1A* +0.0 1463 1.000000032 TF3Y +2.0 1649 1.000002001 TI7W -0.4 1863 0.999999649 UA0S +0.6 505 1.000000570 UA4CC +12.9 340 1.000012872 UA9LIF +13.6 86 1.000013595 UY2RA +0.3 366 1.000000320 V51YJ +1.6 52 1.000001605 VE3EID* +0.1 2314 1.000000110 VE6AO -2.0 427 0.999998050 VE6JY +0.5 1068 1.000000534 VE6WZ +3.4 1423 1.000003413 VE7CC +0.4 472 1.000000433 VK2GEL +0.8 114 1.000000845 VK2RH +0.0 19 1.000000000 VK3RASA +0.8 25 1.000000761 VK6ANC +0.2 116 1.000000239 VR2FUN-77 -0.6 631 0.999999422 VU2CPL +0.0 5 1.000000000 VU2PTT +0.0 98 1.000000045 W1NT-2* +0.2 1579 1.000000180 W1NT-6 +0.2 2499 1.000000196 W2MV +0.6 171 1.000000584 W2NAF +0.5 1054 1.000000515 W3DAN +0.8 509 1.000000755 W3LPL -0.8 356 0.999999200 W3OA* +0.1 1682 1.000000063 W3RGA -0.2 1526 0.999999814 W4AX +4.4 117 1.000004374 W4KAZ -4.3 1096 0.999995677 W6YX -0.1 1153 0.999999885 W8WTS -0.4 1179 0.999999645 W8WWV -1.5 1474 0.999998526 WA7LNW -0.2 1375 0.999999811 WB6BEE* -0.1 1149 0.999999932 WC2L -0.2 315 0.999999796 WC8GOP +8.0 64 1.000007978 WE9V* -0.7 1373 0.999999313 WS2C +3.6 885 1.000003596 WS3W +4.3 264 1.000004312 WT9U +0.9 282 1.000000919 WZ7I -4.2 2240 0.999995802 YO2CK -0.7 1690 0.999999254 YO2MAX* +0.1 1865 1.000000066 YO4RDW -9.0 164 0.999990960 ZF9CW -6.1 453 0.999993905 ZL3X +0.0 227 1.000000022 ZL4YL +1.5 481 1.000001473 ZS1NN -3.5 56 0.999996468 Last updated 2025-02-22 00:15:36 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 0221 0220 0219 0218 0217 0216 0215 0214 0213 0212 --------------------------------------------------------------------- 2E0INH +0.3 +0.1 +0.1 +0.0 +0.1 +0.0 +0.0 +0.0 -0.1 +0.0 3B8GL +0.1 -0.1 +0.0 +0.0 +0.3 +0.2 +0.2 +0.3 +0.3 +1.2 3D2AG +0.0 +0.2 +0.3 +0.0 +0.1 +0.3 +1.0 +0.6 +0.3 +0.6 3V8SS +5.4 +5.7 +5.5 +5.7 +6.1 +4.2 +1.8 5Z4GO +0.3 +0.3 +0.0 +0.6 +0.9 +0.9 +0.0 +2.4 +0.3 7N4XCV +0.6 +0.0 +0.0 +0.9 +0.7 +0.9 +0.8 +1.0 +0.6 AA0O +0.3 +0.7 -2.4 +0.4 +0.0 AC0C-1 -0.1 +0.2 -0.0 -0.0 -0.2 -0.1 -0.2 -0.1 -0.0 -0.1 BA6KC -0.2 +0.1 +0.0 +0.2 -0.0 -0.0 +0.0 -0.0 +0.4 -0.1 BD7DT +0.0 +0.0 +0.1 +0.2 +0.1 +0.1 +0.2 -9.3 -9.5 BD7JNA -0.8 +0.2 +0.0 -0.1 -0.0 +0.0 +0.1 -0.2 BD8CS -0.1 +0.2 +0.1 -0.0 -0.0 +0.1 +0.0 +0.1 +0.2 -0.0 BG0AJO +0.1 +0.1 +0.2 -0.1 +0.0 +0.2 -0.0 +0.0 +0.0 +0.2 BG2TFW +10.2 +10.8 +11.4 +11.0 +11.0 +10.4 +10.3 +11.4 +11.1 +11.4 BG4GOV +0.4 +0.4 BH4RRG +0.1 +1.0 -0.0 +0.8 -0.1 +0.1 +0.2 +0.0 +1.1 +0.0 BH4RXP -1.2 +0.0 -0.6 -0.4 BH4XDZ -0.1 +0.4 +0.0 -0.3 +0.0 +0.0 -0.1 -0.5 +0.9 +0.1 BI4MPH-1 +0.2 +0.6 +0.0 +0.0 -0.4 +0.0 BI4UYX -0.0 +0.1 +0.1 -0.4 -0.1 -0.1 -0.2 -1.2 +0.8 +0.1 BY4XRA +1.1 +0.8 +0.2 -0.2 +0.8 +0.1 +0.1 +0.0 +0.3 +0.0 CT1EYQ -0.8 -0.7 -0.7 -0.4 -0.8 -0.9 -1.0 -0.6 +0.5 CT7ANO +5.6 +5.7 CX7ACH +18.5 DC8YZ -0.0 +0.0 -0.0 -0.1 +0.0 +0.0 +0.0 +0.1 +0.0 +0.1 DD5XX -0.5 -1.7 -2.7 -2.3 -2.2 -2.7 -2.7 -2.5 -1.7 -1.1 DE1LON +2.8 +2.2 +2.4 +2.2 +2.5 +3.2 +3.1 +2.6 +2.6 +2.4 DF2CK -0.0 -0.1 +0.2 -0.3 -0.2 -0.2 -0.1 -0.2 -0.1 +0.2 DF2CK-1 -1.7 -1.5 -1.4 -1.9 -5.6 -5.8 -0.2 DF2CK-2 -1.2 -0.7 -0.6 DF4UE/1 -11.5 -11.9 DF4UE -1.8 -1.9 -2.1 -1.8 -2.0 -2.3 -9.2 -11.8 DF7GB +0.0 +0.0 +0.0 -0.0 -0.1 -0.0 +0.1 +0.1 +0.0 -0.0 DG6FL +0.3 DK0TE +0.4 +0.0 +0.1 +0.2 -0.1 +0.1 +0.2 +0.0 +0.3 +0.3 DK1MAX +0.1 -0.2 -0.1 DK3UA -2.1 -0.9 -0.7 -0.2 DK3WW +0.2 +0.2 +0.3 +0.2 +0.2 +0.1 +0.4 +0.6 +0.7 +0.6 DK9IP -0.1 -0.2 -0.2 -0.2 -0.1 -0.3 -0.2 -0.1 -0.1 -0.0 DK9IP-1 -0.2 -0.2 -0.3 -0.2 -0.2 -0.3 -0.2 -0.2 -0.1 -0.1 DL0LA -0.2 -0.1 -0.2 -0.1 -0.1 -0.2 -0.2 -0.0 -0.8 +0.0 DL0PF +5.0 +4.3 +4.1 +3.2 +3.3 +4.1 +5.2 +3.4 DL1EFW +0.4 +0.3 +0.1 +0.1 DL1HWS -0.1 -0.1 -0.0 +0.0 -0.2 -0.1 -0.2 -0.2 -0.1 -0.1 DL1HWS-3 +0.3 +0.5 +0.4 +0.4 +0.5 +0.4 +0.3 +0.4 DL1HWS-4 -0.2 -0.2 -0.0 -0.2 +0.0 -0.1 -0.1 -0.1 DL3OBQ -8.9 -8.7 +4.3 -0.6 -4.0 -1.4 -0.1 +3.1 DL5RCN +11.8 +11.5 +6.2 +4.5 +13.1 DL8LAS +0.5 +1.5 +1.7 +1.0 +1.2 -0.2 +0.5 -0.0 DL8TG -0.2 -0.0 -0.1 +0.1 -0.2 -0.2 -0.1 -0.0 -0.1 DL9GTB +1.0 DM5GG +1.0 +0.8 +0.8 +0.5 +0.5 +0.9 +0.9 +0.6 +0.9 +0.8 DM6EE +0.2 +0.1 -0.0 +0.1 +0.0 -0.0 +0.0 -0.0 DO4ZT +0.1 -0.0 -0.1 -0.1 -0.0 -0.1 -0.1 +0.0 +0.0 +0.1 DP5G-15 -3.8 -4.2 -3.9 -3.9 -4.0 -3.2 DP7D +0.5 -0.2 -0.2 -0.1 -0.3 +0.4 DR4W -4.3 -4.5 -3.7 -4.0 -3.8 -4.2 DR5X +0.8 E28AC +5.4 +1.0 +2.0 +3.4 +1.8 +1.4 +1.7 +1.2 +1.1 +1.9 EA1RX -1.1 -2.6 -0.1 +0.1 EA1URA +0.6 +0.7 +0.6 +0.3 +0.4 +0.5 +0.7 +0.4 +0.2 +0.1 EA2CW +0.0 +0.1 -0.0 -0.0 +0.1 -0.0 -0.2 -0.1 -0.2 -0.0 EA2RCF-4 +0.1 +0.2 +0.3 +0.2 +0.3 +0.2 +0.1 -0.1 -0.2 -0.0 EA5RQ +0.3 +0.2 -0.1 +0.0 +0.0 -0.0 -0.0 +0.0 +0.1 -0.2 EA5RQ/A +0.0 +0.3 +0.3 +0.5 EA5WU -0.0 +0.0 -0.0 -0.0 -0.1 +0.0 -0.0 +0.0 +0.0 -0.0 ES2RR -0.0 +0.0 -0.1 -0.0 +0.0 -0.0 +0.0 -0.0 -0.1 +0.0 ES5PC -0.1 +0.0 +0.0 -0.1 +0.1 +0.0 -0.0 +0.1 -0.0 +0.1 EU1ST +3.8 F4GOU +5.4 +4.7 +5.1 +4.7 +4.8 +5.0 +5.1 +5.2 +5.1 +4.8 F4VVG +0.1 +0.1 +0.2 +0.2 +0.1 +0.0 +0.1 +0.0 -0.0 +0.2 F6IIT -1.2 F6KGL +0.2 +0.1 +0.2 F6KOP +0.7 -0.9 F8DGY -6.3 F8UKP -3.3 -4.1 -3.0 -2.7 -2.9 -3.2 -3.0 G0FRE +1.3 +0.8 +1.0 +1.2 +1.3 +1.0 +0.4 G0KTN +0.1 +0.1 +0.1 +0.0 +0.1 +0.0 +0.1 +0.0 -0.1 +0.2 G3XBI +0.1 +0.2 +0.1 +0.3 +0.5 +0.4 +0.5 +0.3 +0.2 +0.3 G3YPP +0.1 +0.1 -0.0 +0.0 +0.1 -0.0 +0.1 +0.1 +0.1 +0.1 G4AON +1.3 +1.3 +1.0 +0.7 +0.9 +0.9 +1.3 +0.9 G4IRN +0.5 +0.5 +0.3 +0.2 +0.2 +0.4 +0.4 +0.2 +0.1 +0.2 G4PNF +0.6 G4ZFE +0.5 +0.4 +0.3 +0.2 +0.4 +0.2 +0.2 +0.4 +0.2 +0.2 GE0FRE +1.1 +0.5 +0.4 +4.2 +4.2 +3.9 +4.0 +4.2 +4.2 +0.5 GI4DOH-2 +0.2 +0.2 -0.0 -0.1 +0.2 +0.2 +0.2 -0.1 -0.0 +0.1 GI4DOH-3 +0.6 +0.0 +0.2 +0.2 +0.3 +0.6 +0.8 -1.2 -1.3 +0.4 GX0FRE +6.9 +6.1 +6.5 -0.1 -0.5 +4.6 +4.9 +5.3 +5.0 +0.7 HA1VHF -0.1 -0.1 -0.4 -0.1 -0.2 +0.0 -0.0 -0.0 -0.1 +0.1 HA5PP +2.7 +3.2 +2.5 +3.4 -2.5 HA6PX +0.1 +0.1 -0.1 +0.0 -0.1 -0.0 -0.0 +0.0 +0.0 -0.1 HA8TKS -0.3 -0.1 -0.3 -0.3 -0.3 -0.3 -0.4 -0.2 -0.2 -0.2 HB9BXE +0.2 +0.1 +0.1 +0.1 +0.1 +0.2 +0.2 +0.2 +0.2 +0.1 HB9DCO -0.5 -0.5 -0.3 -0.4 -0.6 -0.6 -0.5 -0.3 -0.3 -0.2 HB9GVO +2.9 HG0Y +6.1 +6.3 +6.1 +6.7 +6.4 HG8A -0.2 -0.5 -0.4 -0.6 -0.6 -1.4 -1.8 -0.4 -0.1 -0.2 IK2LFF +0.4 +0.4 IK3STG +3.4 +2.7 +3.0 +2.6 +2.2 +2.5 +3.2 +2.6 +2.6 +2.4 IK4VET +1.2 +1.2 +1.0 +0.8 +1.1 +1.3 +1.3 +1.2 +1.1 +1.1 IK7YTT -0.1 -0.5 -0.1 +0.0 -0.1 -0.1 -0.0 -0.3 -0.2 J68HZ +15.9 +15.5 +15.6 +16.0 JG1DLY -0.6 +1.2 JH4UTP +0.3 +0.1 -0.4 JH7CSU1 +1.3 +1.7 +1.2 +1.4 +2.5 +1.9 JI1HFJ -4.7 -1.4 -2.5 -7.2 -2.9 -2.6 -2.1 -2.7 -1.0 -3.0 JK1QLQ +0.9 +0.8 JN1ILK +0.7 +0.5 K1RA -1.8 -1.6 -1.5 -0.8 -0.7 -0.4 -0.7 -0.5 -0.3 -0.6 K2PO/7 +0.2 +0.1 +0.3 +0.3 +0.3 +0.4 +0.3 +0.3 +0.2 +0.2 K3LR +0.2 +0.0 +0.2 -0.4 +0.1 +0.3 +0.6 +0.9 +0.1 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-2.7 Last updated 2025-02-22 00:15:44 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 2025-02-22 00:15:44 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.