RBN Analytics

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 here is based on archived RBN data from the previous day, 00:00 to 23:59 UTC. When making adjustments, this means that changes in calibration will not have full impact on the listed data until the second day after the change.

The deviation estimates listed below are based on spots on all active bands (40m and above) 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.

The software used to calculate the tables below can be found here. It runs as a cron job in an Ubuntu container on my server and uploads to this WordPress site shortly after midnight UTC every night.

The calculation of deviation estimates 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 reference drastically increases the geographical coverage of the algorithm, in turn increasing the number of qualifying spots, thus leading to 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 is 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.

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.

311796 RBN spots between 2021-12-01 00:00 and 23:59 UTC.
77125 spots (24.7%) were from reference skimmers (*).
Average spot flow was 217 per minute from 173 active CW skimmers.

131332 spots from 168 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 
  -------------------------------------
  3B8CW       -0.1     32   0.999999851
  3D2AG       +0.0    109   1.000000022
  3V8SS       -1.2   1465   0.999998795
  5W1SA       +1.0    281   1.000001031
  9A1CIG      +4.3    327   1.000004317
  9M2CNC      +1.5     56   1.000001505
  AA4VV*      -0.1   1844   0.999999925
  AC0C-1      -0.0   1645   0.999999952
  BA7QT       +0.0      9   1.000000000
  BG4GOV      -0.4     19   0.999999623
  BG4WOM      -7.5    121   0.999992540
  BG8DIV      -4.3     41   0.999995653
  BH4RRG     +21.7     11   1.000021687
  CX6VM       +0.6     59   1.000000600
  DD5XX*      +0.2    882   1.000000163
  DE1LON      -0.2   1227   0.999999755
  DF2CK*      -0.0    608   0.999999965
  DF4XX       -0.6    890   0.999999358
  DF7GB*      +0.1   1131   1.000000064
  DJ2BC       -0.3   1063   0.999999658
  DK0TE       +1.0    957   1.000001050
  DK3UA*      +0.1    474   1.000000122
  DK9IP*      -0.2    916   0.999999804
  DL0LA       +0.9   1064   1.000000884
  DL0PF*      -0.2    748   0.999999845
  DL1AXX*     +0.2   1207   1.000000242
  DL1HWS      +2.0   1147   1.000001959
  DL3DTH*     +0.2   1429   1.000000199
  DL6KBG      +0.0      5   1.000000000
  DL8TG       -1.1   1446   0.999998912
  DL9GTB      -0.8   1440   0.999999212
  DM6EE       -0.4   1257   0.999999582
  DM7EE       +0.4    638   1.000000407
  DO4DXA*     -0.1    676   0.999999875
  DR4W        -1.5    349   0.999998488
  E28AC       +2.0    230   1.000002033
  E76C       +20.2    572   1.000020244
  EA1URA      +0.5    915   1.000000478
  EA5WU       -0.8   1307   0.999999181
  ES5PC*      -0.1   1508   0.999999938
  ET3AA       +0.0     13   1.000000000
  EY8ZE       -0.4    637   0.999999556
  F4EGZ       +0.8    993   1.000000777
  F6IIT       -3.5   1411   0.999996490
  G0KTN       +0.4   1152   1.000000431
  G4AON       +0.5    149   1.000000510
  G4HSO       -0.5   1164   0.999999482
  G4ZFE*      -0.0    942   0.999999965
  GI4DOH      -0.4    526   0.999999623
  GM6DX       +0.6    192   1.000000557
  HA1AG       +0.4    459   1.000000443
  HA1VHF      -1.3   1412   0.999998689
  HA7GN       -0.8    420   0.999999151
  HA8TKS*     +0.1    559   1.000000146
  HB9BXE*     -0.0   1326   0.999999994
  HB9DCO*     -0.0   1044   0.999999980
  HB9JCB      +1.4   1088   1.000001359
  HG8A        +0.1   1360   1.000000095
  HS8KVH      +2.5     64   1.000002460
  IK3STG     +14.3     81   1.000014282
  IK4VET      -1.4   1842   0.999998639
  JA4ZRK      +0.0      6   1.000000000
  JH7CSU1     +3.0     67   1.000002990
  JI1HFJ      -4.3     10   0.999995728
  JJ2VLY      -0.5     27   0.999999471
  JQ1BVI      -0.6     31   0.999999387
  K1TTT       -0.7   1345   0.999999297
  K2PO/7      +0.6    392   1.000000580
  K3LR        -1.0     41   0.999998962
  K3PA-1*     +0.0   1274   1.000000038
  K4PP        -0.5    763   0.999999470
  K5TR        +0.5    237   1.000000541
  K7EG        +1.3    502   1.000001291
  K7MJG       -8.9    322   0.999991148
  K9IMM*      -0.0   1500   0.999999960
  K9LC        -0.3   1599   0.999999742
  K9TM-4      +1.1   1233   1.000001137
  KC0VKN      -0.8    553   0.999999179
  KC4YVA      +5.1    614   1.000005092
  KD2OGR*     -0.0    595   0.999999971
  KD7YZ*      -0.1   1682   0.999999928
  KH6LC       +0.2     98   1.000000218
  KI4PAD     -10.6    689   0.999989444
  KM3T*       -0.0   2219   0.999999979
  KM3T-1      +0.2    492   1.000000173
  KM3T-2      -1.8   2281   0.999998178
  KO7SS       -0.8   1674   0.999999152
  KO7SS-7*    -0.0   1032   0.999999966
  KP2RUM*     +0.0   1515   1.000000039
  LA6TPA      -1.6    345   0.999998422
  LZ3CB       -0.0    543   0.999999959
  LZ4UX*      +0.1    628   1.000000061
  LZ7AA       +0.2    856   1.000000241
  M7RMZ       +0.0     11   1.000000000
  MM0ZBH      -1.6   1627   0.999998382
  MW0MUT      +0.8   1476   1.000000756
  N2QT        +1.7   1966   1.000001671
  N4RLI       -1.9    902   0.999998134
  N4ZR*       +0.3    327   1.000000320
  N6TV        +0.1    683   1.000000052
  N6WIN-7*    +0.0   1366   1.000000002
  N7TUG       +4.1    162   1.000004065
  N9MKC*      +0.1   1382   1.000000072
  NA0B*       -0.0    376   0.999999962
  NC7J*       -0.1    845   0.999999949
  NN3RP       +0.5    648   1.000000548
  OE9GHV*     +0.0   1733   1.000000039
  OG66X       -4.0     19   0.999995994
  OH4KA       -3.7    766   0.999996278
  OH6BG*      +0.1   1793   1.000000091
  OH8KA       +3.2    958   1.000003232
  OK1FCJ*     +0.0   1201   1.000000046
  OK1FPS      -0.4    246   0.999999585
  OL7M        -0.6    400   0.999999415
  ON6ZQ       -0.5   1095   0.999999482
  PA0MBO*     +0.3    479   1.000000263
  PA1T       +11.6     53   1.000011554
  PJ2A        -1.4     89   0.999998576
  R9IR        -0.5    122   0.999999455
  RK3TD*      +0.2    701   1.000000194
  RN4WA       -0.4    607   0.999999611
  RW9AV       -0.3    184   0.999999707
  S50ARX      +0.8    372   1.000000773
  S50U        +1.2    297   1.000001215
  SE5E        -2.0   1698   0.999998018
  SJ2W*       -0.1    678   0.999999949
  SM0TCZ      +1.0    232   1.000000982
  SM6FMB*     -0.0    774   0.999999964
  SM7IUN      -0.2   1412   0.999999795
  SP8R        -6.6    395   0.999993412
  SV8RV       +0.4    728   1.000000363
  TF3Y        +0.5    680   1.000000473
  TF4X        -1.6    581   0.999998382
  UA0S        -3.7    107   0.999996268
  UA4M        +4.1    972   1.000004128
  UP2L        -3.4    361   0.999996555
  UT4U        -4.4    355   0.999995621
  V51YJ       +1.2    154   1.000001175
  VE2WU*      +0.1    422   1.000000068
  VE6AO       -1.3    354   0.999998715
  VE6WZ       +2.6    853   1.000002588
  VE7CC       +0.4    435   1.000000364
  VK2GEL      +4.1     34   1.000004147
  VK3RASA     +2.1    106   1.000002117
  VK4CT       -0.3    393   0.999999716
  VK6ANC      -0.3    178   0.999999677
  VU2PTT      -0.0     48   0.999999984
  W1NT-2      -1.2   1785   0.999998772
  W1NT-6      -0.7   2328   0.999999279
  W2MV        +1.0    178   1.000000958
  W2NAF       +0.9   1769   1.000000883
  W3LPL       +1.0   2182   1.000001046
  W3OA*       +0.1   1474   1.000000075
  W3RGA       -0.8    542   0.999999212
  W3UA*       -0.2   1156   0.999999844
  W4AX        +4.5    504   1.000004465
  W4KAZ       -1.6    222   0.999998380
  W6YX        +1.3   1313   1.000001306
  W7HR        +1.0    352   1.000000996
  W8WTS       -1.8   1041   0.999998163
  W8WWV       +0.4   1528   1.000000436
  WA7LNW      +0.7   1225   1.000000733
  WC2L*       -0.1   1393   0.999999914
  WE9V        +0.3   1598   1.000000293
  WS3W        +1.1   1501   1.000001093
  WZ7I*       -0.0   1992   0.999999993
  ZL2BR       -7.5     19   0.999992492
  ZL4YL       +1.5    281   1.000001533

Last updated 2021-12-02 00:15:28 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    1201  1130  1129  1128  1127  1126  1125  1124  1123  1122
---------------------------------------------------------------------
3B8CW      -0.1  -0.1  +0.1  +0.4  +0.3  +0.2  +0.1  -0.5  +0.4  +0.3
3D2AG      +0.0  +0.0  +0.0  +0.0  +0.1  +2.0  -0.1  +0.1  -0.3  +0.8
3V8SS      -1.2  -1.8  -1.7  -1.3  -1.7  -3.5  -0.9  -0.8  -0.6  -0.5
5W1SA      +1.0  +0.7  +0.5  +0.7  +1.0  +0.7  +0.8  +0.8  +0.6  +0.1
7N4XCV                                   +1.9  +3.6  +2.0  +0.0      
9A1CIG     +4.3  +4.3  +4.0  +3.8  +3.5  +3.1  +3.1  +4.5  +4.0  +4.1
9G2DX                        +1.5        +1.0                        
9M2CNC     +1.5  +1.8  +0.7  +2.1  +1.7  +0.2  +0.2  +0.7  +0.6  +1.3
9W2RUT                       +0.0  +0.0  -0.4                    +0.3
AA4VV      -0.1  +0.0  -0.0              -0.3  -0.1  +0.1  +0.0  -0.1
AC0C-1     -0.0  +0.0  -0.1  -0.1  -0.1  -0.1  -0.2  -0.0  +0.2  -0.3
BA1DU                  +0.0  +0.4  +0.1                              
BA7QT      +0.0  -0.6                          +0.0  +0.2  +0.0      
BD5XM                        +3.7  +2.6  +3.3  +2.8  +2.2  +1.8  +4.2
BD7DT                 +19.9 +18.9 +18.5 +17.8 +20.0 +17.6 +20.5 +19.4
BD7JNA                       -0.7  +0.4  -0.4  -3.0  +3.6        -1.4
BD7LAE                       +0.2  +0.2 -13.1 -14.4                  
BD7LLL                -16.2 -12.8 -13.8 -17.9 -20.8                  
BD8CS                        +0.4  +0.3  +0.2  +0.0  -0.0  +0.2  -0.1
BG0ARE                      +20.9 +20.3 +20.7 +21.1 +14.3            
BG4GOV     -0.4  -1.0  -6.1  +0.8  +0.9  -0.2  -0.4  -3.1  -0.6  +0.0
BG4WOM     -7.5  -6.4  -4.6  -4.7  -5.5  -7.6  -7.2  -7.2  -6.8  -7.5
BG6SNJ           +0.0  -0.3  -0.1  +0.4  +0.0  -0.0  -0.0  -0.5  +0.4
BG6TDY           -2.4  -0.1  -0.1  +0.3  +0.1  +0.4  +0.7  +1.3  +1.2
BG8DIV     -4.3  -5.0  -4.7  -4.7  -4.8  -3.6  -5.3  -4.3  -4.5  -4.1
BG8PA                  +0.0  +0.1  -0.0  +0.0                        
BH3BBJ                       +4.3        -1.8                        
BH4DEG                             +6.5                              
BH4RRG0         -14.2 -14.3 -13.2       -12.7  -3.4  -3.0  -1.5  -1.3
BH4RRG1         +10.3  +9.0 +11.0 +13.4 +25.6  +7.6  +6.1 +12.7      
BH4RRG    +21.7                                                      
BH4XDZ                       +1.3  +1.1  -1.5              +0.8  +0.0
BY1CY                                                      +0.0      
CT7ANO           -0.8  -0.7  -0.7  -0.7  -0.5                        
CX6VM      +0.6  +0.4  +1.0  +1.4  +1.2  +1.0  +1.6  +0.7  +0.7  +0.8
CX7ACH                       +2.9  +2.1                              
DD0VS                        +6.0  +2.4                              
DD5XX      +0.2  +0.2  +0.1  +0.2  +0.1  +0.1  -0.0  +0.1  +0.1  +0.0
DE1LON     -0.2  -0.4  +0.1  -0.0  +0.0  -0.3  -0.3  -0.5  -0.1  -0.1
DF0RW                  -1.4              -6.1  -1.9  -2.6  -2.3  -2.4
DF2CK      -0.0  -0.8        -0.0  -0.2  -0.3  -0.0  -0.4  -0.1  -0.3
DF4XX      -0.6  -0.8  -0.9  -0.8  -0.4  -0.3  -0.5  -0.3  -0.4  -1.2
DF7GB      +0.1  +0.1  -0.1  +0.0  +0.0  +0.0  +0.0  +0.0  -0.0  -0.1
DH3AKA                             +1.9  +0.3        +0.7  +1.5  +1.6
DJ2BC      -0.3  -0.5  -0.4  -0.3  -0.4  -0.5  -0.5  -0.6  -0.6  -0.6
DJ9FBA                                         +8.0  +6.2  +7.2      
DK0TE      +1.0  +1.0  +1.1  +2.0  +2.1  +1.2  +1.5  +1.5  +1.4  +1.4
DK1MAX                       +6.1  +5.4                              
DK3UA      +0.1  +0.1  -0.1  -0.2  -0.2  -0.2  -0.0  -0.3  -0.3  -0.4
DK9IP      -0.2  -0.0  -0.1  -0.2  -0.2  -0.2  -0.0  -0.1  -0.1  -0.2
DL0LA      +0.9  +0.9  +0.7  +1.5  +1.6  +0.9  +1.0  +0.9  +1.0  +1.0
DL0PF      -0.2  -0.2  +0.0  +0.2  -0.4  -0.2  -0.5  -0.4  -0.3  -0.2
DL1AMQ                       +0.9  +1.1              -1.6            
DL1AXX     +0.2  +0.1  -0.1  -0.1  +0.0  -0.0  -0.2  -0.3            
DL1HWS     +2.0  +1.8  +0.7  +2.5  +1.2  -1.3  -1.2  -1.1  -0.9  -1.0
DL3DTH     +0.2  +0.3  +0.1  +0.2  +0.2  +0.1  +0.1  +0.1  +0.1  +0.1
DL6KBG     +0.0              +0.3  +0.4  +0.1                        
DL6ZB                        -0.2  -0.3                              
DL8LAS           +7.1  +7.3        +1.4  +0.6  +0.9  +1.0  +0.9  +0.9
DL8TG      -1.1  -0.9  -1.1  -1.3  -1.3  -0.9  -0.7  -1.0  -1.0  -1.0
DL9GTB     -0.8  -1.1  -0.3  -0.2  +0.3  -0.5  -0.3  -0.1  +0.0  +0.1
DM6EE      -0.4  -0.1  -0.6  -1.1  -0.0  -0.2  +0.1  -0.7  -0.6  -0.9
DM7EE      +0.4  +0.5  +0.5  +0.8  +1.0  +0.3  +0.6  +0.5  +0.7  +0.5
DO4DXA     -0.1  -0.2  +0.0  -0.6  -0.7  -0.3  -0.1  -0.1  -0.0  -0.1
DR4W       -1.5  -2.0  -1.5  -1.7  -2.1  -1.5  -1.6  -1.4  -1.5  -1.2
DU3TW                        +7.7                                    
E28AC      +2.0  +2.0  +2.3  +3.1  +3.0  +2.4        +2.4  +3.6  +2.6
E76C      +20.2 +19.2 +20.7 +21.4 +21.5 +21.3 +20.7 +20.2 +22.4      
EA1URA     +0.5  +0.5  +0.3  +0.3  +2.1 +13.3  -0.0  +0.1  +9.5 +14.3
EA5WU      -0.8  -0.8  -1.1  -1.2  -0.9  -0.5  -0.7        -0.5  -0.5
ES5PC      -0.1  +0.0  -0.1  +0.0  +0.0  -0.1  +0.1  +0.0  -0.0  +0.0
ET3AA      +0.0  +0.3  +0.0  +0.6  +0.5  +0.9  +1.0        +0.3  +0.8
EY8ZE      -0.4  -0.2  -0.4  -0.2        -0.6  -0.9  -1.0  -1.2  -1.2
F4EGZ      +0.8  +1.1  +0.6  +0.7  +0.8  +0.4  +0.0        +0.6  +0.8
F4VSQ            +5.0  +5.0        +3.1  +4.7        +4.6  +4.5  +5.0
F5AHD                        -3.6 -10.9                              
F6IIT      -3.5  -6.0  -5.7  -4.1  -4.8  -5.0  -5.1  -3.8  -3.7  -4.7
G0KTN      +0.4  +0.3  +0.1  +0.4  +0.5  +0.2                        
G3BJ                                           +1.0                  
G3WW                                           +0.0  +0.0        +0.0
G3XBI            +0.5  +0.2              +0.3  +0.2  +0.1  +0.3  +0.2
G4AON      +0.5  +1.0                    +0.7  +1.0        +1.0  +1.1
G4HSO      -0.5  -0.6  -1.3  -1.6  -1.6  -0.6  -0.6  -0.5  -0.4  -0.9
G4ZFE      -0.0  -0.1  -0.4  -0.5  -0.5  -0.2  -0.1  -0.3  -0.1  -0.3
GI4DOH     -0.4  -0.4  +0.1  -0.2  -0.4  +0.0  +0.9  +0.5  +0.6  +0.4
GM6DX      +0.6  +0.8  +0.3  +0.8  +0.8  +0.4  +0.9  +0.8  +0.3  +0.3
HA1AG      +0.4  +0.5  +1.2              +1.5  +1.3  +0.8  +1.0  +0.1
HA1VHF     -1.3  -1.2  -1.0  -1.4  -1.4  -1.0  -0.9  -0.7  -0.6  -0.7
HA5PP                        +2.3  +2.0  +0.0  +0.6                  
HA6PX                  -4.9  -4.9  -5.2  -5.5  -4.6  -3.5  -2.3  -1.7
HA7GN      -0.8  -0.9  +0.1              +0.1  -0.5  -0.4  -0.4  -0.3
HA8TKS     +0.1  -0.1  +0.1  +0.2  +0.1  -0.0  -0.1  +0.0  +0.1  +0.1
HB9BXE     -0.0  +0.2  +0.0  -0.2  -0.2  -0.2  +0.0  -0.1  +0.1  +0.1
HB9DCO     -0.0  -0.0  -0.0  -0.1  -0.1  +0.1  -0.0  +0.0  -0.0  +0.0
HB9JCB     +1.4  +1.6  +1.5  +2.4  +2.3  +1.4  +1.5  +1.5  +1.6  +1.5
HB9RB                                    -5.9                        
HG8A       +0.1  -0.4  -0.3  -1.7  -1.6  -0.5  -0.3  -0.8  -0.3  -0.0
HL1VAU                       +3.0                                    
HS8KVH     +2.5  +1.4  +2.3  +3.5        +4.6  +3.0  +2.6  +2.5  +3.0
HS/F8UKP                     -1.1  -1.5  -0.8  -0.4  -2.9  -1.3  -0.7
II9P                                                             +0.8
IK1PMR                 +5.1                                          
IK2LFF                       +4.2  +2.9  +2.6                        
IK3STG    +14.3 +14.5 +15.0 +15.5 +15.4 +14.8 +14.2 +14.2 +14.8 +14.3
IK4VET     -1.4  -1.6  -1.9  -1.7  -1.4  -1.4  -1.4  -1.3  -1.0  -1.4
JA4ZRK     +0.0  -1.4  +0.0  +0.1  +0.1  -1.2  +0.0  +1.1  +0.0  +0.0
JG1DLY                       -0.9  -0.5              +1.1            
JH4UTP                       -0.9  -1.0  -1.5              -0.3      
JH7CSU1    +3.0  +3.2  +3.3  +4.4  +4.1  +3.7  +3.6  +4.1  +3.0  +3.7
JI1HFJ     -4.3        -3.9  -5.1  -6.1  -7.0  -4.9  -4.6  -4.1  -4.9
JJ2VLY     -0.5  -2.3  -3.0  +0.4        +1.1  -1.7  -2.3  -0.6  -0.6
JQ1BVI     -0.6  +0.4  -1.0  -0.9  -0.9  -0.4  -0.4  -0.5  +0.0  -0.2
K1TTT      -0.7  -0.9  -0.6  -0.6  -0.4  -0.3  -0.4  -0.6  -0.6  -0.4
K2PO/7     +0.6  +0.8  +1.0  +0.8  +0.8  +0.3  +0.1  +0.3  +0.2  +0.3
K3LR       -1.0  +0.1  +0.2  -1.2  -1.1  +0.3  +0.4  -0.2  +0.5  +0.3
K3PA-1     +0.0  -0.0  -0.1  +0.1  +0.0  -0.0  -0.0  +0.1  -0.0  +0.0
K4PP       -0.5  -0.4  -0.4  -0.5  -0.5  -0.2  -0.4  -0.5  -0.5  -0.4
K5TR       +0.5  +0.4  +0.5  +0.7  +1.5  +0.5  +0.7  +0.7  +0.5  +0.3
K7EG       +1.3  +0.6  +0.8  +1.1  +1.1  +0.6  +0.7  +0.8  +0.6  +0.3
K7MJG      -8.9 -10.9 -10.0  -9.8  -9.5 -10.2  -9.4  -8.8  -0.3  -0.3
K9IMM      -0.0  -0.0  +0.0  +0.0  +0.0  +0.0  +0.1  +0.1  +0.1  -0.0
K9LC       -0.3  -0.2  -0.2  -0.5  -0.5  -0.3  -0.4  -0.4  -0.3  -0.3
K9TM-4     +1.1  +0.7  +0.7  +1.3  +1.3  +0.8  +0.8  +1.0  +0.8  +0.7
KB9AMG                       +2.3  +3.6                              
KC0VKN     -0.8  -1.3  -0.8  -1.5  -1.6  -1.8  -0.6  -0.9  -0.8  -1.2
KC2IEB                       -9.1                                    
KC4YVA     +5.1  +4.1  +3.8  +5.3  +5.3  +4.3  +4.7  +5.0  +4.9  +3.9
KD2OGR     -0.0  -0.2  +0.0  +0.1  +0.0  -0.1  -0.1  -0.0  +0.0  +0.1
KD7YZ      -0.1  +0.1  -0.0  +0.5  +0.9  +0.7  +0.6  +0.3  +0.2  +0.3
KH6LC      +0.2  +0.0  +0.0  +0.2  +0.1  -0.2  +0.8  +0.2  +0.4  -1.0
KI4PAD    -10.6 -11.7 -12.6 -10.4 -10.9                              
KM3T       -0.0  -0.2  -0.0  -0.0  +0.0  +0.0  -0.0  -0.1  +0.1  -0.1
KM3T-1     +0.2  +0.5  +0.1  +0.0  +0.0  -0.3              -0.4      
KM3T-2     -1.8  -1.9  -1.8  -2.4  -2.0  -1.8  -1.0  -1.1  -1.4  -1.5
KM4SII                       +1.8  +0.8  +0.0                        
KO7SS      -0.8  -0.8  -0.8  -0.1        -1.0  -0.5  -0.5  -0.2  -0.4
KO7SS-7    -0.0  +0.1  -0.1  -0.2  -0.2  -0.1  +0.1  +0.1  +0.2  +0.0
KP2RUM     +0.0  +0.1  +0.1              +0.1  -0.0  -0.0  -0.1  -0.1
KU7T                   -0.2  -0.3  -0.3  -0.3                        
LA6TPA     -1.6  -2.3  -1.8  -2.7  -1.8  -1.0  +0.0  +0.7  +0.4  +0.4
LY3G                                     -0.1  +0.8                  
LZ2ZG                  +4.5  +4.7  +5.4  +1.6  +4.3  +3.0  +4.3  +3.6
LZ3CB      -0.0  +0.0  -0.1  +0.0  +0.1  +0.0  -0.0  +0.1  -0.2  +0.0
LZ4AE                  +0.0  +0.2  +0.4  +0.3  +0.4  +0.6  +1.2  +1.3
LZ4UX      +0.1  +0.2  +0.2  +0.1  +0.1  +0.1  +0.1  +0.1  +0.2  -0.0
LZ5DB                        -1.3                          -0.1  +0.1
LZ7AA      +0.2  +0.3  +0.3  +0.7  +0.5  +0.1  +0.4  +0.2  +0.4  +0.4
M0WJG                              -4.4              -6.1            
M7RMZ      +0.0  +0.0  +0.0                                          
MM0ZBH     -1.6  -1.4  -2.3  -2.0  -2.5  -1.6  -1.6  -1.2  -1.1  -1.6
MW0MUT     +0.8  +0.5  +0.2  +1.4  +1.5  +1.1  +0.7  +0.5  +0.5  +0.5
N2QT       +1.7  +1.3  +1.4  +2.0  +2.2  +1.6  +1.6  +1.8  +1.8  +1.5
N4RLI      -1.9  -1.4  -1.7  -2.1  -2.0  -4.7  -1.6  -1.7  -1.6  -1.3
N4ZR       +0.3  +0.3  -0.1  -0.2  -0.2                    +0.0  +0.1
N6TV       +0.1  +0.1  -0.1  -0.1  -0.2  -0.3  +0.0  +0.4  +0.2  +0.0
N6WIN-7    +0.0  -0.1  -0.7  -0.8  -1.1  -0.6  -0.3  -0.0  +0.1  +0.4
N7TUG      +4.1  +2.1  +2.9  +3.9  +3.4  +2.8  +3.0  +2.5  +3.0  +1.1
N9MKC      +0.1  +0.2  -0.0  +0.1  +0.2  +0.1  +0.1  +0.1  -0.1  -0.0
NA0B       -0.0  +0.2  -0.1  -0.1  -0.0  -0.0              +0.0  -0.1
NC7J       -0.1  +0.1  +0.1  +0.3  +0.3  +0.3  +0.1  +0.1  +0.1  +0.1
NN3RP      +0.5  +0.6  +0.2  +0.6  +0.8  +0.3  +0.2  +0.5  +0.3  +0.5
NU6XB                                                      -1.6  -2.2
NX5M                   +0.0  +1.2  +1.3  +0.2                        
OE6ADD                 +0.7  +1.0  +1.0  +0.4                        
OE9GHV     +0.0  -0.0  -0.0  +0.0  +0.0  +0.1  -0.0  -0.0  -0.1  -0.1
OG66X      -4.0                          -0.6  -0.6  -0.7  -0.7  -0.8
OG73X                        +0.7  +1.0  -0.8  +0.5  -2.8            
OH2BBT                 +1.0  +1.9  +1.8  +1.0                        
OH4KA      -3.7  -3.0  -4.2  -3.6  -3.4  -2.3  -1.4  -1.8  -2.0  -2.7
OH6BG      +0.1  -0.1  -1.4  -0.6  -0.7  +0.2  -1.8        +1.4  +0.9
OH8KA      +3.2  +1.7  +3.8  +6.7  +7.3  +6.8  +7.3  +6.9  +7.4      
OK1FCJ     +0.0  +0.1  -0.1  -0.2  -0.1  -0.1  -0.1  -0.0  -0.0  +0.1
OK1FPS     -0.4  -0.9  -0.6  -0.7  -0.7  -1.9  -1.0  -1.6  -0.3  -0.9
OL7M       -0.6  -0.5  +0.7  +1.0  +1.8  +0.3  -0.2  -0.3  +0.0  +0.2
ON6ZQ      -0.5  -0.4  -0.5  -0.5  -0.3  -0.6  -0.7  -0.6  -0.5  -0.5
PA0MBO     +0.3  +0.2  +0.1  -0.1  -0.1  -0.1  +0.3  +0.0  +0.0  +0.1
PA1T      +11.6              +8.5        +9.7                        
PA3GRM                       +0.2  +0.3                              
PA5KT                  +2.8  +1.0  +0.7  +0.2  +1.2                  
PA8MM                                   -13.2 -12.7 -10.8 -10.9  -8.2
PC5Q                         +1.8  +2.6  +2.4                        
PE1RDP                       +5.4  +8.3                              
PE5TT                              +1.1        +1.7  +0.8            
PJ2A       -1.4  -1.6  -1.2  -1.4  -1.5  -1.2  -1.0  -1.4  -1.1  -1.0
PR1T             -0.3  -0.9  -3.3  -3.2  -1.5  -4.9  -1.6  -1.4      
R3VL                        +12.9 +12.5                              
R6YY                                           +1.3  +1.1            
R9IR       -0.5  -0.8  -0.3  -0.4  -0.9  -0.4  -0.1  -0.3  -0.2  -0.3
RA0FF                                                      -2.1      
RK3TD      +0.2  -0.0  +0.1  +0.3  +0.3  +0.1  +0.1  +0.1  +0.1  +0.2
RN4WA      -0.4  -0.2  -0.3  -0.2  -0.3  -0.2  -0.6  -0.4  -0.3  -0.2
RV7C                   +5.1                                          
RW9AV      -0.3  -0.5  -0.6  -0.7  -0.6  -0.4  -0.5  -0.3  -0.7  -0.2
RX3AFE                       +0.1  +0.0                              
S50ARX     +0.8  +0.7  +0.7  +1.9  +1.9  +1.2  +0.8  +0.7  +1.1  +1.4
S50U       +1.2  +1.3  +1.8  +2.3  +2.2  +1.2  +1.3  +1.5  +1.1  +1.2
S51TC            +0.0                                                
SE5E       -2.0  -1.6  -1.4  -1.5  -1.4  -0.6  -0.4  -0.7  -0.8  -0.7
SJ2W       -0.1  -0.0  -0.1  -0.0  +0.1  +0.1  +0.2  +0.0  +0.1  +0.3
SKIMMER                                                    +1.0      
SM0TCZ     +1.0  +1.1                                                
SM6FMB     -0.0  +0.1  -0.2  +0.0  +0.0  +0.0  +0.0  -0.0  +0.0  -0.1
SM7IUN     -0.2  -0.2  -0.3  -0.4  -0.5  -0.3  +0.1  +0.1  +0.2  -0.1
SP8R       -6.6                          -6.7  -6.7  -6.7  -6.6  -7.0
SV1CDN           +0.0  +0.2  +0.4  +0.2  +0.2  +0.2  +0.2  +0.1  +0.1
SV8RV      +0.4  +0.4  +0.2  +0.6  +0.6  +0.3  -0.2  -2.9  -3.5  -3.4
SZ1A                   +0.0  +3.8              +3.6  +3.6  +2.5  +1.9
TF3Y       +0.5  +0.6  +0.6  +0.9  +1.0  +0.5  +0.8  +0.6  +0.6  +0.7
TF4X       -1.6  -1.8  -2.1  -2.0  -2.3  -2.6  -2.9  -2.7  -2.7  -3.5
TK0C                         +9.9 +10.0  +6.4  +7.0                  
UA0S       -3.7  -4.4  -4.1  -3.9  -3.5  -1.7  -3.0  -4.2  -3.2  -3.9
UA4M       +4.1  +3.6  +3.4  +4.2  +4.1  +4.1  +4.0  +4.2  +3.9  +4.2
UA6SWL                 -2.0  -3.0  -3.8  -2.3                        
UP2L       -3.4  -3.0  -3.3              -4.2  -3.7  -3.3  -3.6  -3.8
UT4U       -4.4  -5.8                                      +0.7      
V51YJ      +1.2  +1.0  +0.9  +1.5  +1.6  +1.1  +1.3  +1.1  +0.7  +1.4
VE2WU      +0.1  -0.7  +0.0  +0.1  +0.0  +1.1  +2.0  +0.5  +0.0  -0.2
VE6AO      -1.3  -1.4  -1.6  -1.6  -1.3  -1.2  -0.9  -1.4  -1.5  -1.6
VE6JY                  +1.4  +2.8  +4.3  +3.6  +2.6  +0.4  +1.3  +3.3
VE6WZ      +2.6  +2.4  +2.1  +3.1  +3.1  +2.4  +2.3  +2.3  +2.6  +1.8
VE7CC      +0.4  -0.1  +0.1  +0.3  +0.2  +0.0  +0.0  +0.2  +0.0  +0.1
VK2EBN                       +0.3  -0.0                              
VK2GEL     +4.1  +3.9  +2.5  +2.1  +2.0  +1.8  +4.1  +2.0  +3.3  +1.1
VK2LX                              -0.9                              
VK3RASA    +2.1  +2.4  +0.8  +0.7  +0.5  -0.0  +0.4  +1.7  +1.9  +0.3
VK4CT      -0.3  -0.6  -0.4  -0.7  -0.7  -0.6  -0.7  -0.7  -0.6  -0.8
VK6ANC     -0.3  -0.6  -0.5  -1.0  -1.0  -0.7  -0.5  -0.6  -1.0  -0.5
VU2PTT     -0.0  +0.1  -0.0  -0.0  -0.0  +0.4  +0.3  -0.1  +0.4  +0.6
VY0ERC           -1.8        -3.9  -4.1  -4.8  +4.3  -3.1            
W1NT-2     -1.2  -1.1  -1.1              -1.1  -0.9  -1.2  -1.0  -1.1
W1NT-6     -0.7  -0.7  -0.7  -0.9  -0.9  -0.6  -0.6  -0.7  -0.5  -0.6
W2AXR                                                      -0.8  -1.1
W2LB                         -1.1  -1.9  +0.2  +0.0  -1.5  -0.6  +0.0
W2MV       +1.0  +1.3  +0.7  +0.4  +0.3  +0.2  +0.4  +0.6  +0.3  +0.6
W2NAF      +0.9  +0.7  +0.7  +1.3  +1.2  +0.8  +0.9  +0.8  +0.8  +1.0
W3LPL      +1.0  +0.6  +0.9  +2.0  +2.0  +1.0  +0.9  +1.1  +1.1  +1.2
W3OA       +0.1  +0.0  +0.0  +0.1  -0.0  +0.1  -0.0  -0.0  -0.2  +0.0
W3RGA      -0.8  +0.0  -0.0  -0.2  +0.2  -0.2  -0.4  -0.2  -0.4  -0.2
W3UA       -0.2  +0.3  +0.1  -0.0  -0.0  +0.0  -0.0  -0.4  -0.0  -0.1
W4AX       +4.5  +3.2  +3.2  +4.7  +4.9  +3.5  +4.1  +4.6  +4.3  +3.4
W4KAZ      -1.6  -3.3  -3.3  -3.2  -3.6  -3.0        -2.2  -3.5  -1.8
W6BB                                                       -2.2  -2.7
W6YX       +1.3  +0.6  +0.6  +1.3  +0.9  +0.0  +0.0  -0.0  +0.1  +0.1
W7HR       +1.0  +0.2  +0.3  +0.7  +0.7  +0.5  +0.2  +0.9  +0.3  +0.2
W8WTS      -1.8  -1.3  -1.6  -2.0  -1.9  -1.5  -1.3  -1.2  -1.0  -0.9
W8WWV      +0.4  +0.1  +0.3  +0.4  +0.4  +0.3  +0.3  +0.3  +0.3  +0.3
WA2ZYU                             +1.7  -0.4                        
WA7LNW     +0.7  +0.5  +0.5  +1.0  +1.0  +0.6  +0.8  +0.7  +0.4  +0.4
WA9VEE                                   +0.0                        
WB6BEE                             +0.1  +0.1  -0.2  -0.1  -0.0  -0.1
WC2L       -0.1  -0.2  -0.1  +0.1  -0.1  +0.1  +0.1  +0.0  -0.0  -0.1
WE9V       +0.3  +0.5  +2.2  +3.4  +3.2  +4.1  +4.4  +4.2  +0.3  +0.6
WS3W       +1.1  -0.0  +0.2  +1.7  +1.6  -0.3  +0.5  +1.4  +1.3  +1.0
WZ7I       -0.0  -0.1  -0.0  -0.0  -0.0  +0.0  -0.1  +0.0  -0.0  +0.1
ZL2BR      -7.5  -5.7  -7.1  -5.8  -6.3  -7.9  -9.8  -7.4  -8.8 -10.1
ZL3X                        +14.8 +15.3             +15.6 +15.8      
ZL4YL      +1.5  +1.3  +1.0                                          

Last updated 2021-12-02 00:15:34 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.

AA4VV AC0C-1 DF7GB K3PA-1 KM3T KM3T-1 OE9GHV 

Last updated 2021-12-02 00:15:34 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.