Skimmer frequency accuracy
To be a good RBN citizen a skimmer should have a frequency accuracy of 2ppm or better.
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 different bands, the deviation number may thus not represent the actual deviation for a particular band.
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 criterion 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
493327 RBN spots between 2024-03-18 00:00 and 23:59 UTC. 136534 spots (27.7%) were from reference skimmers (*). Average spot flow was 343 per minute from 198 active CW skimmers. 264783 spots from 195 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* -0.1 1853 0.999999907 3B8CW +0.2 453 1.000000230 3D2AG +0.1 32 1.000000112 9M2CNC +0.7 115 1.000000690 AA0O* +0.2 721 1.000000176 AA4VV* +0.0 1152 1.000000038 AC0C-1 -0.4 1525 0.999999644 BA6KC -0.1 83 0.999999886 BD4TUC -8.9 111 0.999991122 BD7JNA +0.0 190 1.000000019 BD8CS* +0.1 455 1.000000074 BD8CS-1 +0.0 73 1.000000000 BG4GOV +0.0 6 1.000000000 BH4RRG -0.2 140 0.999999842 BH4RXP -0.1 243 0.999999868 BH4XDZ +0.2 110 1.000000220 BI4MPH +0.1 66 1.000000108 BI4MPH1 +0.3 132 1.000000297 BI4RFP +0.1 125 1.000000066 CX6VM -1.5 173 0.999998478 DC8YZ* +0.1 3778 1.000000107 DD5XX -0.4 1788 0.999999631 DE1LON* -0.1 2605 0.999999911 DF2CK -1.0 5012 0.999998953 DF7GB* -0.1 2536 0.999999920 DJ2BC +0.0 13 1.000000000 DJ9IE* -0.0 3639 0.999999972 DK0TE +0.4 2522 1.000000445 DK3UA -9.0 1480 0.999990952 DK9IP* +0.0 1773 1.000000018 DK9IP-1* +0.1 2240 1.000000059 DL0LA +0.3 1473 1.000000291 DL0PF* -0.1 3005 0.999999876 DL1HWS +0.2 2986 1.000000174 DL8LAS +0.2 5418 1.000000159 DL8TG* -0.0 2912 0.999999987 DL9GTB +0.3 3418 1.000000319 DM5GG -0.5 3811 0.999999512 DR4W -2.9 2932 0.999997088 E28AC +5.2 73 1.000005211 EA1RX -1.5 119 0.999998493 EA1URA -1.1 1992 0.999998924 EA2CW +0.9 1991 1.000000896 EA2RCF-4 +0.4 1519 1.000000375 ES2RR* +0.0 3251 1.000000033 F4VVG +0.2 1615 1.000000152 F6IIT -0.7 2720 0.999999325 G0KTN +0.2 2085 1.000000245 G3XBI +0.5 305 1.000000455 G3YPP +0.1 79 1.000000090 G4AON +0.8 75 1.000000781 G4IRN +0.2 2687 1.000000246 G4YBU +5.8 1098 1.000005834 G4ZFE +0.5 3305 1.000000542 GI4DOH +0.4 644 1.000000421 HA1VHF +2.4 1444 1.000002366 HA2NA +0.8 1817 1.000000784 HA2NA-5 +0.2 2199 1.000000191 HA6PX* -0.0 2624 0.999999967 HB9BXE +0.2 1850 1.000000172 HB9DCO -0.5 1831 0.999999528 HG0Y +5.5 166 1.000005501 HG8A* -0.0 2448 0.999999959 IK3STG +2.6 2815 1.000002645 IK4VET +2.0 2799 1.000002016 J68HZ +11.4 19 1.000011365 JH7CSU1 +2.6 211 1.000002583 JI1HFJ -2.6 134 0.999997412 JN1ILK +1.4 598 1.000001350 K1RA* -0.0 2198 0.999999978 K3PA-1* +0.0 1504 1.000000024 K3PA-2 -0.9 142 0.999999083 K4PP -0.4 1526 0.999999626 K5EM -0.1 267 0.999999886 K5TR +0.5 172 1.000000533 K6FOD -0.1 627 0.999999851 K7EK -0.1 403 0.999999930 K7MJG -0.2 223 0.999999808 K7RUT +16.5 137 1.000016513 K9IMM* -0.1 2042 0.999999942 K9LC* +0.1 2140 1.000000080 KA7OEI +0.4 849 1.000000441 KC4YVA +5.3 672 1.000005317 KD2OGR +0.4 959 1.000000389 KH6LC +0.1 228 1.000000146 KM3T* -0.0 2200 0.999999984 KM3T-2 +0.3 2530 1.000000290 KM3T-3 +0.3 2919 1.000000250 KO7SS -1.2 1683 0.999998818 KP3CW +0.4 1770 1.000000394 KV4TT -0.2 2253 0.999999775 LA6TPA -5.3 1345 0.999994740 LB9KJ -13.0 669 0.999986970 LU8XW -1.0 20 0.999999048 LZ3CB* -0.0 1724 0.999999957 LZ4AE +2.4 169 1.000002437 LZ4UX* +0.1 1724 1.000000079 LZ5DI +0.5 2278 1.000000493 LZ7AA +0.6 1429 1.000000594 MM0ZBH +1.4 3766 1.000001368 MM3NDH* +0.0 3163 1.000000006 MW0MUT* +0.2 2471 1.000000167 N0OI +0.7 523 1.000000680 N2QT +0.4 1287 1.000000372 N4ZR* -0.1 843 0.999999948 N6TV +0.4 880 1.000000395 N9CO* -0.1 1604 0.999999924 ND7K -2.3 1636 0.999997655 NG7M -0.7 1094 0.999999288 NN3RP -0.2 353 0.999999798 NT6Q +3.2 630 1.000003220 NU6XB +0.7 135 1.000000721 OE6ADD* -0.1 2960 0.999999898 OE6TZE* +0.1 2159 1.000000083 OE9GHV* -0.1 2976 0.999999913 OG66X -0.1 205 0.999999942 OH6BG +4.2 2820 1.000004246 OH8KA +3.7 69 1.000003651 OK1FCJ* -0.1 3076 0.999999920 OK1HRA -3.8 2617 0.999996245 OK4QRO +1.4 2713 1.000001376 ON4EM +0.0 17 1.000000000 ON6ZQ -0.3 2070 0.999999734 OZ1AAB +0.1 206 1.000000069 OZ1BZS -0.2 658 0.999999850 OZ4ADX* +0.0 642 1.000000015 PA0MBO* +0.0 293 1.000000039 PA8MM -4.0 1869 0.999996002 PE5TT* +0.1 2143 1.000000140 PJ2A -0.2 314 0.999999814 R1LB -0.2 40 0.999999822 R6YY* +0.2 457 1.000000150 R9IR +0.3 836 1.000000340 RK3TD* +0.1 2495 1.000000128 RK3TD-2 +0.2 2624 1.000000211 RN4WA +1.0 1754 1.000000975 RU9CZD +11.1 1361 1.000011060 RW9AV -0.6 105 0.999999404 S50U* +0.1 1354 1.000000050 S53A +1.4 3612 1.000001354 S53WW -0.5 2862 0.999999467 SE5E +0.0 91 1.000000000 SM0TCZ -1.4 237 0.999998643 SM7IUN* -0.0 2921 0.999999957 SQ5J +3.4 1965 1.000003436 SQ5OUO +4.9 2786 1.000004896 SV1CDN -1.1 162 0.999998943 SZ1A +1.0 1488 1.000001024 TF4M -1.7 3121 0.999998253 TI7W -0.4 958 0.999999629 UA0S +0.4 866 1.000000381 UY2RA +1.9 1412 1.000001859 V51YJ +1.4 41 1.000001421 VE6AO -1.4 503 0.999998565 VE6JY +2.6 556 1.000002647 VE6WZ -8.4 796 0.999991598 VE7CC +0.6 93 1.000000605 VK2GEL +4.7 71 1.000004694 VK2RH +0.0 24 1.000000000 VK3RASA +1.8 169 1.000001821 VK6ANC -1.1 245 0.999998887 VR2FUN-74 +6.3 500 1.000006340 VR2FUN-77 -1.1 1031 0.999998880 VU2CPL +2.4 120 1.000002425 VY0ERC +2.0 27 1.000001971 W1NT-2 +0.3 2220 1.000000296 W1NT-6 +0.2 3109 1.000000204 W2LB +0.9 225 1.000000885 W2MV +0.3 113 1.000000347 W2NAF +1.5 1621 1.000001470 W3LPL -3.7 2828 0.999996276 W3OA +0.2 450 1.000000162 W3RGA -0.4 2361 0.999999603 W3UA* -0.0 1934 0.999999958 W4AX +5.0 234 1.000004951 W4KAZ -1.5 588 0.999998504 W6BB +0.7 281 1.000000654 W6YX -0.2 1277 0.999999848 W8WWV -2.0 1949 0.999997968 WA7LNW -0.9 2029 0.999999076 WB6BEE* -0.0 1247 0.999999967 WC2L -1.2 1915 0.999998831 WC8GOP +5.0 46 1.000005034 WE9V +0.1 2107 1.000000133 WF7U -0.3 626 0.999999683 WS3W +2.1 554 1.000002084 WV4P +1.0 790 1.000000963 WZ7I* -0.1 2782 0.999999922 YO2MAX +4.7 2268 1.000004668 YO4RDW +0.7 264 1.000000679 YU7GM +0.5 45 1.000000476 ZF1A +1.2 1561 1.000001243 ZF9CW* +0.2 2621 1.000000178 ZL3X -0.4 352 0.999999554 ZL4YL +2.0 91 1.000002008 Last updated 2024-03-19 00:15:44 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 0318 0317 0316 0315 0314 0313 0312 0311 0310 0309 --------------------------------------------------------------------- 2E0INH -0.1 -0.2 -0.2 -0.2 -0.2 -0.3 -0.7 -0.6 +0.1 +0.4 3B8CW +0.2 +0.4 +0.2 +0.1 -0.0 -0.1 -0.1 -0.0 +0.1 +0.3 3D2AG +0.1 -0.0 +0.0 +0.4 -0.1 +0.6 +0.4 +0.3 +0.4 +0.1 7N4XCV +0.5 +0.7 +0.9 +0.5 +0.7 +0.8 +0.5 -0.6 9M2CNC +0.7 +1.1 +0.6 +0.6 +0.7 +0.3 +1.0 +0.6 +0.7 +1.1 AA0O +0.2 -0.1 +0.2 +0.1 +0.0 -0.0 +0.0 +0.1 +0.1 +0.1 AA4VV +0.0 -0.0 +0.0 +0.0 -0.0 +0.0 -0.1 +0.1 +0.0 -0.0 AC0C-1 -0.4 +0.0 +0.3 +0.4 +0.3 +0.1 +0.2 +0.2 +0.2 BA6KC -0.1 -0.0 -0.2 -0.1 +0.2 +0.0 -0.1 +0.0 -0.1 +0.1 BD4TUC -8.9 -7.8 -5.8 -7.6 -9.1 -8.0 -8.3 -7.5 -8.6 BD7JNA +0.0 -0.3 +0.6 +1.8 +1.7 +1.1 +1.4 +1.0 +1.1 +3.2 BD8CS +0.1 +0.0 -0.0 +0.1 -0.1 -0.1 +0.0 -0.1 +0.0 -0.0 BD8CS-1 +0.0 -0.1 -0.1 +0.0 BG4GOV +0.0 +0.3 +0.2 +0.0 -0.7 -0.1 -0.1 -0.0 +0.0 +0.2 BH4RRG -0.2 -0.1 -0.2 -0.0 -0.1 -0.0 -0.3 -0.6 -0.0 +0.1 BH4RXP -0.1 +0.0 -0.0 +0.0 -0.1 +0.1 -0.0 -0.2 -0.1 +0.1 BH4XDZ +0.2 +0.3 +0.3 +0.5 +0.3 +0.0 +0.4 +0.4 +0.2 +0.2 BI4MPH +0.1 +0.0 +0.3 +0.2 BI4MPH1 +0.3 -0.0 -0.0 +0.1 +0.2 +0.1 +0.1 +0.5 +0.6 +0.5 BI4RFP +0.1 +0.1 +0.2 +0.2 +0.2 -0.1 +0.1 +0.7 +0.1 +0.1 CX6VM -1.5 -2.6 -2.4 -2.6 -1.1 -0.9 -1.2 -1.6 -1.5 -1.2 DC8YZ +0.1 +0.1 +0.1 +0.0 +0.1 +0.1 -0.0 +0.1 +0.1 +0.1 DD5XX -0.4 -0.9 -0.3 -0.2 -1.1 -1.0 -1.3 -1.0 -0.6 -0.8 DE1LON -0.1 -0.4 -0.2 -0.1 -0.1 -0.3 -0.2 +0.2 -0.1 -0.1 DF1DR -0.3 -0.3 -0.5 -0.3 -0.1 -0.2 DF2CK -1.0 -1.2 -0.2 +0.5 -0.3 +0.1 -0.4 +0.1 -0.5 -0.5 DF7GB -0.1 -0.0 -0.1 +0.0 -0.0 -0.0 +0.0 -0.0 -0.0 -0.0 DJ1RK -3.1 -3.4 -3.8 -4.0 DJ2BC +0.0 -0.8 +0.1 -0.7 -0.8 -0.8 -0.8 -1.1 -0.8 -0.9 DJ9IE -0.0 +0.0 -0.0 +0.0 -0.0 DK0TE +0.4 +0.7 +0.8 +0.7 +0.3 +0.1 +0.5 +0.5 +0.5 +0.6 DK3UA -9.0 -5.0 -6.0 -8.0 -8.5 -6.2 -8.3 -9.2 -8.9 -9.0 DK9IP +0.0 -0.1 -0.1 -0.1 -0.2 -0.1 -0.0 -0.0 -0.1 -0.0 DK9IP-1 +0.1 +0.1 +0.1 +0.1 +0.0 +0.0 +0.1 +0.2 +0.1 +0.1 DL0LA +0.3 +0.2 +0.2 +0.1 +0.1 +0.1 +0.2 +0.3 +0.3 +0.2 DL0PF -0.1 -0.4 -0.4 -0.5 -0.4 -0.4 -0.4 -0.6 -0.4 -0.5 DL1AMH +0.0 DL1EFW +15.1 +15.2 +10.3 +14.6 +15.1 DL1HWS +0.2 +0.3 +0.3 +0.2 +0.1 +0.1 +0.1 +0.3 +0.1 +0.2 DL8LAS +0.2 +0.1 +0.2 +0.3 +0.2 +0.2 -0.0 +0.1 +0.1 +0.0 DL8LAS-1 +0.2 +0.1 +0.1 DL8TG -0.0 +0.0 -0.0 -0.0 +0.0 -0.0 -0.0 -0.1 -0.1 DL9GTB +0.3 -0.1 +0.2 +0.5 +0.8 +1.2 +0.5 +0.3 +0.4 +0.1 DM5GG -0.5 -0.8 -0.3 +0.3 +0.2 +0.1 +0.2 +0.2 -0.4 -0.9 DM6EE +0.1 +0.1 +0.1 -0.0 +0.0 +0.1 +0.0 DR4W -2.9 -3.9 -3.3 -2.9 -2.8 -3.5 -3.0 -2.6 -3.0 -3.3 E28AC +5.2 +4.2 +4.4 +4.5 +4.5 +5.4 +4.8 +4.3 +4.1 +3.9 EA1RX -1.5 -3.5 -2.5 -3.2 -2.0 +0.3 -3.2 -3.1 -3.3 EA1URA -1.1 -0.6 -0.8 -0.4 -0.4 -0.2 +0.0 +0.6 +0.8 +0.6 EA2CW +0.9 +0.8 +0.8 +0.6 +0.4 +0.5 +0.4 +0.3 +0.3 +0.3 EA2RCF-4 +0.4 +0.4 +0.3 +0.3 +0.1 +0.1 -0.0 -0.0 -0.0 -0.1 EI6LF -17.4 ES2RR +0.0 -0.0 -0.0 -0.0 -0.1 -0.0 -0.1 -0.1 -0.0 -0.0 ET3AA -0.8 -1.1 F4VVG +0.2 +0.2 +0.2 +0.1 +0.1 +0.2 +0.2 +0.1 +0.0 -0.0 F5AHD +0.5 +0.6 F6IIT -0.7 -0.5 -0.8 -0.8 -1.1 -0.9 F8DGY -0.1 -0.2 -0.3 -0.2 -3.7 -0.2 G0KTN +0.2 +0.4 +0.3 +0.4 +0.4 +0.4 +0.3 +0.3 +0.3 +0.3 G3BJ +0.3 G3XBI +0.5 +0.3 +0.3 +0.5 +0.1 +0.2 +0.3 +0.4 +0.2 G3YPP +0.1 +0.1 +0.1 +0.0 +0.1 +0.3 +0.2 +0.0 +0.1 +0.1 G4AON +0.8 +0.7 +1.4 +1.0 +1.0 +1.8 +1.3 G4IRN +0.2 +0.4 -3.9 +0.9 +0.7 +1.0 +0.6 +0.6 +0.6 +0.6 G4MKR +0.2 +0.0 +0.0 G4YBU +5.8 +0.3 -0.4 -0.3 +0.1 +0.3 +0.1 +0.2 +0.3 +0.2 G4ZFE +0.5 +0.6 +0.5 +0.5 +0.4 +0.7 +0.3 +0.3 +0.3 +0.4 GI4DOH +0.4 +0.5 +0.5 +0.3 +0.4 +0.2 +0.3 +0.3 +0.3 +0.3 HA1VHF +2.4 +2.2 +3.2 +2.5 +1.7 +1.9 +1.7 +1.7 +1.9 +1.8 HA2NA +0.8 +1.5 +1.6 +1.3 +1.0 +1.0 +1.0 +1.0 +1.0 +0.7 HA2NA-5 +0.2 +0.4 +0.4 +0.3 +0.2 +0.2 +0.3 +0.2 +0.3 +0.2 HA5PP +4.5 HA6PX -0.0 -0.0 -0.1 -0.0 -0.0 -0.1 -0.0 -0.0 -0.1 -0.1 HA8TKS +0.3 +0.2 +0.2 +0.2 +0.2 +0.1 +0.2 +0.2 +0.3 HB9BXE +0.2 +0.2 +0.2 +0.2 +0.2 +0.1 +0.0 +0.0 +0.1 +0.1 HB9DCO -0.5 -0.3 -0.6 -0.5 -0.1 +0.1 +0.0 +0.0 +0.1 -0.0 HG0Y +5.5 +5.8 +5.8 +5.4 +5.5 +6.2 +5.6 +5.3 +5.5 +5.5 HG8A -0.0 -0.1 -0.3 -0.0 -0.1 -0.1 +0.2 -0.4 -0.4 IK3STG +2.6 +3.2 +3.3 +2.9 +2.6 +3.1 +2.9 +2.8 +2.9 +2.8 IK4VET +2.0 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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.
AA4VV DF7GB ES2RR KM3T LZ3CB LZ4UX MM3NDH OE9GHV WB6BEE Last updated 2024-03-19 00:15:55 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.