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 below is based on archived RBN data from the previous day, 00:00 to 23:59 UTC. This means that when making adjustments, 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.

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 every night.

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 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.

264972 RBN spots between 2022-05-17 00:00 and 23:59 UTC.
66963 spots (25.3%) were from reference skimmers (*).
Average spot flow was 184 per minute from 185 active CW skimmers.

128886 spots from 181 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       +0.6     84   1.000000594
  3D2AG       +0.5     44   1.000000486
  3V8SS       -2.3   1204   0.999997701
  5W1SA       +0.5     55   1.000000454
  9A1CIG      +8.3    475   1.000008295
  9M2CNC      +0.2    192   1.000000165
  AA4VV*      +0.1   1067   1.000000053
  AC0C-1      -0.3    309   0.999999714
  BA6KC       +0.9     22   1.000000865
  BD4QJP      +1.5     66   1.000001477
  BG4GOV      -1.0     29   0.999998989
  BG8DIV      -4.9     72   0.999995114
  BG8PA       -0.1     74   0.999999904
  BH4DEG      +4.3     13   1.000004293
  BH4RRG0     +0.0      6   1.000000000
  CX6VM       +0.6     80   1.000000615
  DD5XX       +0.4    869   1.000000442
  DE1LON      +0.8   1773   1.000000803
  DF2CK       +0.9   2253   1.000000897
  DF4XX       +0.1    941   1.000000070
  DF7GB*      +0.0   1573   1.000000042
  DG6FL       -1.6     18   0.999998416
  DJ2BC       -0.6    742   0.999999382
  DK0TE       +3.0   1382   1.000003006
  DK9IP*      +0.0   1253   1.000000008
  DL0LA       +0.2   1141   1.000000193
  DL0PF       +4.9    831   1.000004877
  DL1AXX      +0.2     69   1.000000206
  DL1HWS      +0.2   2000   1.000000242
  DL8LAS      +1.2   2021   1.000001222
  DL9GTB      -0.4   1777   0.999999555
  DM5GG*      +0.1   2297   1.000000112
  DM6EE       -1.1   1853   0.999998893
  EA1URA      +0.5   1342   1.000000477
  EA2NN       -0.2    152   0.999999812
  EA5WU       +0.3   1414   1.000000303
  EA8BFK      +0.4   1832   1.000000436
  ES2RR       +0.2   2053   1.000000193
  ES5PC*      -0.1    755   0.999999896
  EY8ZE       +0.5    618   1.000000495
  F4VSQ       +5.7    214   1.000005716
  F6IIT       -0.2   1664   0.999999787
  F8DGY       +1.1    372   1.000001110
  G0KTN*      +0.0   1485   1.000000035
  G1VWC       +0.2     68   1.000000209
  G3XBI       +0.2    181   1.000000183
  G4AON       +1.2    177   1.000001208
  G4KZD       +0.8    588   1.000000823
  G4MKR       +1.3     16   1.000001338
  G4ZFE*      -0.0   1693   0.999999993
  GI4DOH      +0.4    640   1.000000391
  GM6DX       +0.7    227   1.000000701
  HA1VHF*     +0.0   1472   1.000000009
  HA5PP       -0.6      6   0.999999405
  HA6PX       +0.1    690   1.000000140
  HA8TKS*     +0.1   1082   1.000000120
  HB9BXE      +1.0   1201   1.000001036
  HB9DCO*     -0.1   1801   0.999999884
  HG8A        +4.4   1854   1.000004405
  HS/F8UKP    -0.5     72   0.999999528
  HS8KVH      +5.5    207   1.000005498
  IK3STG      +7.1    311   1.000007088
  IK4VET      +0.4   2363   1.000000371
  IZ2CPS      +0.4   1058   1.000000356
  JA4ZRK      +0.0     13   1.000000000
  JH7CSU1     +4.5     97   1.000004543
  JI1HFJ      -3.0     50   0.999996987
  JJ2VLY      +0.1    181   1.000000059
  JN1ILK      -0.2    347   0.999999758
  JQ1BVI      +0.1    133   1.000000107
  K2PO/7      +0.6    117   1.000000588
  K3PA-1      +0.4    858   1.000000422
  K4PP*       +0.0    367   1.000000020
  K5TR        +1.5    712   1.000001497
  K6FOD       +1.0     50   1.000000995
  K7EG        +0.6    241   1.000000565
  K7EK       -10.3    228   0.999989739
  K7MJG      -14.6    137   0.999985435
  K9IMM       -0.2    401   0.999999827
  K9LC*       -0.0    788   0.999999968
  K9TM-4      +1.2   1010   1.000001177
  KC0VKN      -1.0    186   0.999999042
  KC4YVA      +4.7    366   1.000004700
  KD2OGR*     -0.1    636   0.999999853
  KG7V        -0.5    185   0.999999536
  KH6LC       +0.1     99   1.000000144
  KM3T*       +0.1   1573   1.000000057
  KM3T-1      +0.3    278   1.000000307
  KM3T-2      +1.2    654   1.000001198
  KO7SS       +0.8    992   1.000000764
  KO7SS-7     +0.2    565   1.000000200
  KP2RUM*     -0.1   1180   0.999999949
  LA6TPA      +0.4    686   1.000000386
  LZ3CB*      -0.0    845   0.999999976
  LZ4AE       +2.3    863   1.000002315
  LZ4UX*      -0.0    782   0.999999992
  LZ5DB       +0.5    403   1.000000504
  LZ7AA       +0.5   1049   1.000000493
  MM0ZBH*     -0.1   1884   0.999999853
  N4ZR        +0.2   1350   1.000000227
  N6TV        +0.5    341   1.000000534
  N7TUG       +5.5     93   1.000005539
  NA0B        +0.1    219   1.000000065
  NC7J        +0.8    489   1.000000765
  NN3RP       +0.6    451   1.000000638
  NR4U        +0.0      5   1.000000000
  NT6Q        +0.9    149   1.000000930
  NU6XB       -0.5    133   0.999999518
  OE8TED      +1.1    975   1.000001083
  OE9GHV*     -0.0   2235   0.999999954
  OG66X       -0.8    243   0.999999241
  OH4KA       -0.5    924   0.999999542
  OH6BG       +2.5   2476   1.000002482
  OH8KA       -3.7   1559   0.999996269
  OK1FCJ      +0.2   1953   1.000000198
  OK1HRA      -6.2    532   0.999993769
  OK2ZAW      +1.5    774   1.000001510
  ON6ZQ       -0.3    335   0.999999745
  PA0MBO      -0.3    375   0.999999746
  PA8MM       -5.9    149   0.999994068
  PS8CW       +0.1    105   1.000000090
  R9IR        -0.1    110   0.999999921
  RK3TD*      -0.1   1300   0.999999931
  RN4WA       -0.4   1387   0.999999647
  RU9CZD      +0.5   1390   1.000000492
  S53WW       -1.8   1959   0.999998237
  SE5E*       +0.1   2193   1.000000086
  SM0TCZ      +0.7     20   1.000000713
  SM6FMB      +0.2   1195   1.000000217
  SM7IUN*     -0.1   1467   0.999999938
  SP8R        -6.7    571   0.999993301
  SV1CDN      +0.5     37   1.000000514
  SV8RV       +0.3    694   1.000000342
  SZ1A        +1.4    806   1.000001407
  TF3Y        +1.0   1434   1.000000952
  TF4X        -1.5   1702   0.999998544
  UA0S*       -0.0    496   0.999999976
  UA3REO      +0.3    268   1.000000287
  UA4M        +4.6     69   1.000004620
  UP2L        -5.2    396   0.999994841
  V51YJ       +1.4     62   1.000001381
  VE2WU       +0.2    493   1.000000173
  VE6AO       -0.4    124   0.999999633
  VE6JY       +0.9    987   1.000000937
  VE6WZ       +2.6    527   1.000002552
  VE7CC       -0.2    378   0.999999800
  VK2GEL      +2.7     67   1.000002720
  VK3RASA     -0.0    176   0.999999975
  VK4CT       -0.3    415   0.999999662
  VK6ANC      -1.5     67   0.999998529
  VU2PTT      +6.6    128   1.000006572
  W1NT-2      -1.3   1505   0.999998745
  W1NT-6*     -0.1   1926   0.999999894
  W2LB        +0.8    167   1.000000764
  W2MV        +0.4    160   1.000000401
  W2NAF       +1.2   1392   1.000001239
  W3LPL       +1.1   1253   1.000001134
  W3OA*       +0.0    402   1.000000036
  W3RGA*      +0.2    837   1.000000204
  W3RGA-2*    +0.1    569   1.000000135
  W3UA*       -0.1    275   0.999999930
  W4AX        +3.5    230   1.000003468
  W4KAZ       -0.5   1208   0.999999493
  W6BB        -0.7    176   0.999999326
  W6YX        +0.7    609   1.000000650
  W7HR        +0.5    260   1.000000542
  W8WTS       -0.7    716   0.999999275
  W8WWV       +0.8   1024   1.000000820
  W9XG        +1.8    569   1.000001805
  WA2ZYU      +3.6     12   1.000003569
  WA7AI       +0.3    322   1.000000289
  WA7LNW      +0.6    531   1.000000610
  WB6BEE*     +0.1    715   1.000000061
  WC2L        +0.0     86   1.000000000
  WE9V*       -0.2   1038   0.999999767
  WF7U        +1.1    352   1.000001061
  WS3W        +1.1   1075   1.000001119
  WZ7I*       +0.0    829   1.000000040
  ZL2HAM      -0.7    414   0.999999348
  ZL2KS       -4.8    150   0.999995179
  ZL4YL       +1.7    145   1.000001653

Last updated 2022-05-18 00:15:23 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    0517  0516  0515  0514  0513  0512  0511  0510  0509  0508
---------------------------------------------------------------------
3B8CW      +0.6  +0.0  +0.2  +0.4  +0.5  +0.3  -0.0  +0.3  +0.0  +0.4
3D2AG      +0.5  +0.0  +1.8  +0.5  +0.6  +0.0  +0.4        -0.2  -0.1
3V8SS      -2.3  -2.4  -2.6  -2.3  -2.1  -2.6  -2.5  -2.4  -2.5  -2.5
5W1SA      +0.5  +0.7              +0.3        +0.8  +0.8  +0.7  +0.7
9A1CIG     +8.3  +8.8  +9.8  +6.7  +6.0  +7.4  +7.7 +11.6  +9.4  +5.7
9M2CNC     +0.2  -0.2  +0.9  +0.6  +1.0              +0.6  +0.2  +0.3
AA4VV      +0.1  -0.1  -0.1  -0.2  -0.0  -0.0  -0.0  +0.0  -0.0  -0.0
AC0C-1     -0.3  +0.1  -0.3  +0.1  -0.1  -0.1  +0.0  +0.0  -0.1  -0.0
AC0C-2                       +0.2  +0.0  +0.1  +0.0        +0.1  -0.1
BA6KC      +0.9  +1.1  +0.7  +1.0  +0.7  +0.4  +0.7              +0.0
BD4QJP     +1.5  +2.0  +2.1  +0.9  +1.9  +1.3  +2.1                  
BD7JNA                       +0.7        +0.0                        
BG4GOV     -1.0  +0.2  -0.0  -0.3  +0.0  -0.8  -0.3  -0.9  -1.4  -0.1
BG8DIV     -4.9  -5.1  -4.1  -4.6  -4.3  -3.8  -4.8  -4.4  -4.3  -3.5
BG8FZU                 +4.5  +3.1  +3.5  +4.7  +5.2  +5.0  +4.2      
BG8PA      -0.1  -0.1  +2.1 +11.3 +11.0 +11.5 +11.4 +11.0            
BH3BBJ                 +2.9  -3.1  -1.2  -0.5  -3.9                  
BH4DEG2                +2.1  +2.1  +1.9  +1.2                    +1.1
BH4DEG     +4.3  +4.0  +4.8  +3.3  +4.0  +4.1  +3.1  +3.8  +3.5  +4.5
BH4RRG0    +0.0  +0.0  +0.1  +0.8  +0.4  +0.6        -0.4        -0.3
BH4XDZ                 +1.6  +1.4  +0.6  +0.3  +0.8  +0.6  +1.0  +1.7
CT7ANO                                                           +0.1
CX6VM      +0.6  +0.5  +0.1  +0.8  +0.8  +1.1  +0.9  +1.2  +1.2  +1.3
DD5XX      +0.4  +0.3  +0.4  +0.5  +0.4  +0.4  +0.4  +0.3  +0.3  +0.3
DE1LON     +0.8  +0.5  +0.6  +0.7  +0.4  +0.5  +0.8  +0.5  +0.3  +0.4
DF2CK      +0.9  +0.7  +0.8  +1.0  +0.9  +0.8  +0.5  +0.5  +0.4  -0.7
DF2CK/1                -0.0  -0.1  +0.2                              
DF4XX      +0.1  +0.2  +0.2  +0.3  +0.0  +0.2  +0.2  +0.1  +0.2  +0.0
DF7GB      +0.0  +0.0  -0.0  -0.0  -0.0  -0.1  -0.0  -0.0  -0.0  -0.1
DG6FL      -1.6  -1.1  -0.6  -0.6  -2.1  -3.4  -0.4  +0.0  -0.9  -0.8
DJ2BC      -0.6  -0.7  -0.7  -0.6  -0.5  -0.7              -0.4  -0.1
DK0TE      +3.0  +2.8  +3.3  +2.9  +2.5  +2.8  +3.0  +2.2  +2.6  +3.0
DK3UA                                                -0.3  -0.4  -0.6
DK9IP      +0.0  -0.1  -0.1  +0.0  +0.0  -0.0  +0.1  -0.1  -0.1  -0.1
DL0LA      +0.2  +0.2  +0.3  +0.3  +0.2  +0.2  +0.2        -0.0  +0.2
DL0PF      +4.9  +4.2  +4.6  +4.6  +4.5  +4.6  +4.5  +4.2  +3.7  +4.0
DL1AXX     +0.2        +0.5  +0.4  +0.1  +0.2  +0.0  +0.3  +0.1  +0.1
DL1HWS     +0.2  +0.2  +0.2  +0.1  +0.2  +0.2  +0.2  +0.1  +0.1  +0.1
DL5RMH                                                     +0.0      
DL8LAS     +1.2  +1.1  +1.4  +1.3  +0.9  +1.1  +1.4  +1.2  +1.2  +1.3
DL8TG                              -1.1  -1.0  -1.0  -0.9  -1.0  -1.1
DL9GTB     -0.4  -0.5  -0.3  -0.8  -0.4  +0.2  +0.2  +0.1  +0.0  -0.3
DM5GG      +0.1  +0.0  +0.1  +0.1  -0.0  +0.1  +0.1  +0.0  -0.0  +0.1
DM6EE      -1.1  -1.5  -1.7  -0.2  -0.6  -1.1  -1.0  -1.1  -1.7  -1.4
DO4DXA                             -0.1  -0.1  -0.1        +0.1  +0.0
DU3TW                       -11.6  +0.6  -1.4  -0.8  -1.1  -1.9  +0.0
EA1URA     +0.5  +0.3  +0.3  +0.3  +0.1  +0.1  +0.2  +0.3  +0.4  +0.2
EA2NN      -0.2  -0.1  +0.2  +0.1  +0.2                              
EA5WU      +0.3  +0.1  +0.1  +0.3  +0.0  +0.2  -0.0  +0.0  +0.1  +0.1
EA8BFK     +0.4  +0.4  +0.5  +0.4  +0.4  +0.4  +0.5  +0.3  +0.3  +0.4
ES2RR      +0.2  +0.2  -0.0  +0.4  +0.4  +0.1  +1.0  +0.2  +0.4  +0.4
ES5PC      -0.1  -0.1  -0.1  -0.1  -0.1  -0.0  +0.1  -0.1  -0.1  -0.0
ET3AA                              +0.8  +0.4  +0.9  +0.9  +0.7      
EY8ZE      +0.5  +0.4  +0.7  +0.6  +0.5  +0.5  +0.6  +0.5  +0.4  +0.5
F4VSQ      +5.7  +5.4  +4.3  +4.2  +5.0        +4.5  +4.8  +4.5      
F6IIT      -0.2  -0.3  -0.4  -0.5  -0.5  -0.5  -0.4  -0.4  -0.7  -0.7
F8DGY      +1.1                                            +0.3  +0.6
G0KTN      +0.0  -0.1  +0.1  +0.3  +0.1  +0.1  +0.0  +0.2  +0.1  +0.1
G0TMX                                                            -0.0
G0TTV                                                +0.9            
G1VWC      +0.2  +0.2  -0.1  -0.3                    +0.0  -0.1  -0.1
G3XBI      +0.2  +0.0              +0.0  +0.2  +0.0  +0.1            
G4AON      +1.2  +0.8              +1.2  +0.8  +1.4  +1.6  +1.2      
G4IRN                                                +0.0            
G4KZD      +0.8  +0.5  +0.4  +0.8  +0.6  -0.1  +0.2  +0.4  -0.0  +0.1
G4MKR      +1.3              +0.4                                    
G4ZFE      -0.0  -0.0  -0.1  +0.0  +0.0  -0.0  -0.0  +0.1  +0.0  -0.0
GI4DOH     +0.4  +0.0  +0.6  +0.6  +0.2  +0.5  +0.5  +0.5  +0.3  +0.4
GM6DX      +0.7  +0.5  +0.6              +0.2  +0.7  +0.5  +0.6  +0.6
HA1VHF     +0.0  +0.0  -0.0  -0.1  +0.0  +0.0  -0.0  -0.2  -0.2  -0.4
HA5PP      -0.6        +2.3  -1.7              +3.6                  
HA5PP-2                                  +0.5                        
HA6PX      +0.1  +0.1  +0.2  +0.2  +0.4  +0.4  +0.2  -0.4  -0.5  -0.7
HA7GN                  -0.5  -0.5  +2.8  +1.3  +1.2 -10.6 -13.4 -13.1
HA8TKS     +0.1  +0.1  +0.1  +0.0  +0.2  +0.2  +0.1  +0.1  +0.1  +0.2
HB9BXE     +1.0  +1.1  +1.2  +1.5  +2.5 +10.7  +9.4  +9.4  +9.0      
HB9CAT                                         +4.8  +4.2  +4.3  +4.2
HB9DCO     -0.1  -0.2  +0.0  -0.2  -0.2  -0.2  -0.1  -0.1  -0.1  -0.1
HG8A       +4.4  +4.4  +4.3  +4.3  +4.5  +4.7  +4.2  +3.9  +3.7  +3.7
HS8KVH     +5.5  +5.5  +4.7  +4.9        +1.5  +2.1  +2.0  +0.6  +0.2
HS/F8UKP   -0.5  -0.1  -0.6  -0.4  -0.2  -0.6  -0.3  -0.4  -0.4  -0.4
IK3STG     +7.1  +7.2  +6.6  +7.0  +7.5  +6.9  +7.0  +6.6  +6.8  +6.5
IK4VET     +0.4  +0.4  +0.6  +0.4  +0.4  +0.4  +0.4  +0.8            
IQ8SN                  +1.1  +1.0                                    
IZ2CPS     +0.4  +0.2  +0.3  +0.3  +0.5  +0.4  +0.3  +0.2  +0.1  +0.1
JA4ZRK     +0.0  -0.3  +0.2  -0.2  +0.0  +0.5  +0.0  +2.8  +0.7  -0.2
JH7CSU1    +4.5  +5.5  +4.7  +4.4  +4.5  +5.3  +5.1  +4.2  +5.2  +5.0
JI1HFJ     -3.0  +2.9  -2.4  -5.5  -5.7        -4.1  -4.0  -5.3  -2.8
JJ2VLY     +0.1  -0.1  +1.4  +0.9  +0.2  -0.2  +0.5  +0.2  +0.1  +0.3
JN1ILK     -0.2  -0.0  +0.7  +1.1  +1.0  +0.7  +0.9  +0.7  +0.8  +1.2
JQ1BVI     +0.1  -0.0  +0.1  -0.2  -0.3  -0.5  +0.2  -0.1  +0.6  +0.5
K2PO/7     +0.6  +0.5  +0.5  +0.6  +0.6  +0.3  +0.8  +0.3  +0.3  +1.0
K3PA                                                       -0.0      
K3PA-1     +0.4  -0.1  +0.1  +0.3  +0.0  +0.0  +0.0  -0.0  -0.0  -0.0
K4PP       +0.0  +0.2  +0.4  +0.2  +0.3  +0.2  +0.2  +0.1  +0.1  -0.1
K5TR       +1.5  +1.4  +1.4  +1.4  +0.7  +0.2  +0.2  +0.4  +1.1  +1.5
K6FOD      +1.0  +0.4  +0.3  +0.0  +0.3  -0.2  +0.1  +0.4  +0.0  +0.2
K7EG       +0.6  +0.7  +0.6  +0.7  +0.6  +0.8  +1.1  +0.7  +0.8  +0.9
K7EK      -10.3  -9.9 -10.4  -8.4  -9.3 -10.7  -9.7  -9.8  -9.3  -9.2
K7MJG     -14.6 -15.0 -14.6 -15.1  +5.9 -18.1 -17.2 -19.8 -18.0 -17.5
K9IMM      -0.2  +0.1  +0.0  -0.0  +0.0  +0.0  +0.1  +0.1  +0.1  +0.1
K9LC       -0.0  +0.0  -0.0  -0.1  -0.0  +0.0  +0.0  +0.1  -0.1  -0.3
K9TM-4     +1.2  +0.9  +1.0  +1.1  +1.0  +0.7  +1.1  +0.9  +0.9  +1.1
KC0VKN     -1.0  -0.7  -1.0  -1.5  -1.2  -1.0  -1.1  -1.0  -0.7  -1.1
KC4YVA     +4.7  +5.4  +4.2  +5.1  +5.2  +5.7  +5.2  +5.1  +4.8  +5.7
KD2OGR     -0.1  -0.2  -0.1  +0.0  -0.2  -0.2  -0.0  -0.0  -0.0  +0.0
KG7V       -0.5  -1.0  -0.9  -0.9  -1.0  -1.4  -1.1  -0.8  -1.2  -1.3
KH6LC      +0.1  +0.3  -0.1  +0.1  +0.1  -0.1  -0.0  +0.2  +0.0  +0.1
KM3T       +0.1  -0.1  -0.1  -0.1  -0.0  +0.1  -0.0  +0.0  -0.0  -0.1
KM3T-1     +0.3  +0.0  -0.5  +0.0  +0.0  -0.0  -0.0  +0.2  -0.3  -0.2
KM3T-2     +1.2  +1.0  +0.8  +1.3  +0.6  +0.6  +0.4  +0.4  +0.2  +0.1
KO7SS      +0.8  +0.5  +0.5  +0.1  -0.1  -0.2  -0.3  -0.2  -0.2  +0.2
KO7SS-7    +0.2  +0.2  +0.2  +0.2  +0.1  +0.1  +0.1  +0.3  +0.2  +0.6
KP2RUM     -0.1  -0.1  -0.0  +0.1  -0.1  +0.0  +0.1  +0.1  -0.0  -0.0
LA6TPA     +0.4  +0.1  +0.0  +0.2  +0.4  +0.7  +1.4  +3.1  +1.6  +1.1
LZ3CB      -0.0  -0.1  -0.1  +0.0  -0.1  +0.0  +0.1  -0.1  -0.1  -0.0
LZ4AE      +2.3  +2.6  +3.0  +2.5  +1.8              +1.9  +1.9  +2.2
LZ4UX      -0.0  -0.1  -0.2  -0.1  -0.1  +0.0  +0.0  +0.0  -0.1  -0.0
LZ5DB      +0.5  +0.4  +0.0                                          
LZ7AA      +0.5  +0.4  +0.5  +0.5  +0.6  +0.5  +0.6  +0.5  +0.3  +0.5
M7RMZ                  +0.4  +0.4  +0.0                              
MM0ZBH     -0.1  -0.5  +1.8  +2.2  +1.1  +0.9  +1.9  +1.1  +1.1  -2.2
N4ZR       +0.2  +0.3  +0.3  +0.3  +0.2  +0.3  +0.2  +0.3  +0.1  +0.0
N6TV       +0.5  +0.5  +0.6  +0.7  +0.4  +0.5  +0.5  +0.3  +0.3  +0.6
N6WIN-7                                        +0.5  +0.5  +0.4  +0.6
N7TUG      +5.5  +5.7  +5.4  +6.1  +5.6  +4.5  +5.5  +5.5  +6.5  +4.8
NA0B       +0.1  +0.0  +0.1  -0.4  +0.0  +0.1  +0.2  +0.1  -0.0  -0.0
NC7J       +0.8  +0.4  +0.5  +0.5  +0.4  +0.6  +0.8  +0.2  +0.3  +0.3
NH6HI                        +5.9                                    
NN3RP      +0.6  +0.5  +1.3  +0.6  +0.5  +0.6  +0.6  +0.5  +0.3  +0.6
NR4U       +0.0                                                      
NT6Q       +0.9  +0.7  +1.0  +0.8  +0.6  +0.4  +0.5  +0.5  +0.7  +0.9
NU6XB      -0.5  -1.5  -1.1  -1.3  -0.9                              
OE8TED     +1.1  +1.0  +1.0  +1.3  +1.4  +1.9  +1.5  +0.6  +0.3  +0.1
OE9GHV     -0.0  -0.1  +0.0  -0.0  -0.1  -0.1  -0.0  -0.0  -0.0  -0.0
OG66X      -0.8  -0.9  -0.8  -0.6  -0.6  -0.9  -0.8  -0.8  -0.8  -1.0
OH4KA      -0.5  -0.4  -0.5  +0.3  +0.0  -0.2  -0.1  -0.1  -0.6  -0.6
OH6BG      +2.5  +2.5  +3.0  +1.9  +2.5  +2.6  +2.9  +2.6  +2.7  +2.7
OH8KA      -3.7  -3.6              +0.0  +7.7  +8.8  +8.7  +5.4  +4.4
OK1FCJ     +0.2  +0.1  +0.1  +0.1  +0.2  +0.1  +0.2  -0.1  -0.0  -0.2
OK1HRA     -6.2  -5.7  -5.8  -5.6  -5.2  -5.6        -5.8  -5.7      
OK2ZAW     +1.5  +1.5  +2.0  +1.5  +1.3  +1.3  +1.4  +1.2  +1.3  +1.4
ON6ZQ      -0.3  +0.1  -0.1  -0.2  -0.2  -0.2  -0.1  -0.2  -0.2  -0.2
PA0MBO     -0.3  -0.1  +0.5  +0.6  +0.3  +0.4  +0.7  -0.2  +0.3  +0.0
PA2SQ                        +0.0                                    
PA8MM      -5.9                                                      
PE5TT                                                            +0.8
PS8CW      +0.1  +0.0        +0.3  +0.2                              
PY7ZC            -3.8  -4.0  -3.8  -3.8  -3.5  -3.6  -4.5  -5.1  -3.7
R2AT                   -8.7  -7.4                                    
R3VL                   +6.6  +2.3                                    
R9IR       -0.1  +0.0  +0.0  -0.1  -0.1  -0.6        -0.0  -0.2  +0.1
RK3TD      -0.1  -0.1  +0.1  -0.1  -0.1        +0.0  -0.1  -0.1  -0.0
RL3A                         +4.9  +5.0  +5.1  +5.4  +4.7  +5.0  +5.3
RN4WA      -0.4  -0.4  -0.5  -0.6  -0.3  -0.2  -0.0  -0.2  -0.0  -0.0
RU9CZD     +0.5  +1.4  +1.3  +0.1              +0.8  +1.3  +0.6  +1.7
RV7C                         +0.1                                    
RW9AV            -0.1  -0.1  +0.3  -0.1  -0.1  -0.1  -0.2  -0.2  +0.0
S53WW      -1.8  -0.6  +1.4  +1.4  +1.0  +1.1  +1.2  +0.7  +0.8  +1.3
SE5E       +0.1  +0.1  +0.0                    +0.1  +0.1  +0.1  +0.1
SM0TCZ     +0.7  +3.6  +1.3  +2.0  +1.6  +2.8  +3.3        +2.8  +3.0
SM6FMB     +0.2  +0.2  +0.2  +0.3  +0.3  +0.2  +0.2  +0.2  +0.3  +0.2
SM7IUN     -0.1  -0.1  -0.0  +0.1  +0.0  +0.1  -0.0  -0.0  +0.0  +0.1
SP5OSF                 +0.0  +0.0  +0.5                    +0.8  +0.4
SP8R       -6.7  -6.3  -6.8  -7.1  -7.5              +0.3  +0.4  +0.5
SQ5M/P           +7.6  -5.2              +3.6  +8.2  +8.9  +8.5  +8.4
SV1CDN     +0.5  +0.5  -0.8        +0.0  +0.1  +0.2  +0.3  +0.5  +0.0
SV8RV      +0.3  +0.1  +0.1  +0.2  +0.2  +0.1  +0.3  +0.3  +0.2  +0.3
SZ1A       +1.4  +1.3  +1.1  +1.1  +0.5  +0.5  +0.6  +0.6  -0.0  +0.5
TF3Y       +1.0  +0.9  +0.7                    +1.4  +0.8  +0.6  +0.9
TF4X       -1.5  -1.2  -1.4  -1.5  -1.3  -1.2  -1.2  -1.1  -1.6  -1.3
UA0S       -0.0  -2.8  -4.9  -4.7  -2.8  -0.8  -0.9  -5.4  -4.5  -0.9
UA3REO     +0.3  +0.5  +0.6  +0.5  +0.3  -0.0  +1.2  +0.6  +0.1  +0.2
UA4M       +4.6  +5.1  +4.1  +3.1  +2.8  +3.1                    +4.2
UA9LIF                      +13.3 +13.3                              
UP2L       -5.2  -4.8        -4.2  -4.7  -5.2  -5.4  -5.5  -5.2  -5.2
V51YJ      +1.4  +2.7  +1.4  +1.6  +1.3  +0.7  +1.0  +0.9  +0.9  +1.8
VE2WU      +0.2  +0.1  +0.1  -0.2  +0.4  +1.6  -0.1  -0.0  -0.0  -0.0
VE6AO      -0.4  -0.4  -0.4  -0.7  -1.1                          -0.9
VE6JY      +0.9  +0.8  +0.7  +0.8  +1.3  +1.0  +0.3  +1.0  +1.2  +1.0
VE6WZ      +2.6  +2.7  +2.4  +2.6  +2.8  +2.6  +3.0  +3.0  +2.8  +3.1
VE7CC      -0.2  +0.0  -0.0  -0.1  -0.1  -0.3  -0.1  +0.0  -0.0  -0.1
VK2EBN                       +0.0  +0.0  +0.0                        
VK2GEL     +2.7  +2.5  +3.1  +3.1  +1.9  +0.9  +1.9  +2.0  +1.2  +2.9
VK3RASA    -0.0  +0.1  +1.5  +0.3                    +0.6  +0.3  -0.1
VK4CT      -0.3  -0.3  -0.1  -0.7  -1.0  -0.7  -0.8  -1.0  -1.6  -1.0
VK6ANC     -1.5  -2.0  -2.0  -1.9  -1.8  -2.2  -0.7  -1.0  -1.4  -1.3
VU2PTT     +6.6  +7.6  +8.0  +7.0  +7.2  +7.2  +7.2  +7.0  +7.1  +7.2
W1NT-2     -1.3  -1.3  -1.3  -1.7  -1.6  -2.0  -2.0  -1.7  -1.8  -1.9
W1NT-6     -0.1  -0.0  +0.0  -0.2  -0.4  -0.5  -0.6  -0.4  -0.5  -0.5
W2LB       +0.8  +6.5  +6.5  +6.4  +4.1  +1.0  +3.5        +0.2  +1.4
W2MV       +0.4  +0.3  +0.4  +0.3  +0.3  +0.5  +0.4  +0.3  +0.4  +0.5
W2NAF      +1.2  +1.1  +1.1  +1.1  +0.9  +0.9  +1.0  +1.1  +1.0  +1.3
W3LPL      +1.1              +1.5  +1.0  +0.8  +1.1  +0.7  +0.7  +1.1
W3OA       +0.0  -0.0                    +0.1  +0.2  +0.3  +0.1  +0.1
W3RGA      +0.2  +0.2  +0.1  +0.2  +0.1  +0.4  +0.3  +0.1  +0.0  +0.1
W3RGA-2    +0.1  +0.2  +0.1  +0.2  +0.1  +0.3  +0.3  +0.2  -0.0      
W3UA       -0.1  +0.0              -0.1  -0.3  -0.0  +0.2  -0.2  +0.0
W4AX       +3.5  +4.8  +4.1  +5.3  +5.1  +5.4  +4.7  +4.1  +3.7  +5.2
W4KAZ      -0.5  -0.5                                                
W6BB       -0.7  -1.1  -0.9  -1.2  -1.1                              
W6YX       +0.7  +1.0  +0.9  +0.9  +0.7  +0.6  +0.4  +0.4  +0.3  +0.8
W7HR       +0.5  +0.6  +0.4  +0.5  +0.6  +0.4  +0.8  +0.8  +0.9  +0.9
W8WTS      -0.7  -0.5  -0.8  -1.0  -0.9  -1.2  -1.5  -1.4  -1.3  -1.6
W8WWV      +0.8  +0.4  +0.6  +0.7  +0.4  +0.4  +0.7  +0.6  +0.6  +0.6
W9XG       +1.8  +1.7  +1.5  +1.7  +1.0  +1.4  +1.3  +1.5  +1.3  +1.4
WA2ZYU     +3.6  +3.2  +3.1  +3.0  +2.3        +1.5  +2.5  +3.6      
WA7AI      +0.3  +0.8  +0.4  +0.5  -0.2  +0.0  +0.2  +0.2  +0.4  +1.0
WA7LNW     +0.6  +0.6  +0.1  +0.4  +0.6  +0.5  +0.7  +0.4  +0.2  +0.9
WB6BEE     +0.1  +0.0  -0.0  -0.1  +0.1  -0.0  +0.1  +0.0  -0.1  -0.0
WC2L       +0.0  +0.0  +0.3  +0.8  +0.6  +0.1  +0.2  -0.3  +0.6  +0.1
WE9V       -0.2  -0.4  +0.0  +0.1  -0.2  -0.1  -0.3  -0.3  -0.5  -0.7
WF7U       +1.1  +1.1  +1.1  +1.0  +1.2  +1.0  +1.5  +1.1  +1.2  +1.1
WS3W       +1.1  +1.6  +0.5  +2.0  +1.3  +0.3  +1.4  +1.1  +1.3  +2.0
WZ7I       +0.0  -0.1  -0.0  -0.1  -0.1  +0.1  -0.1  +0.1  -0.0  -0.1
XQ6MO                       -28.5                                    
YU7GM                  +0.2  +0.7  +1.0  +0.5  +0.6  +0.3  +0.5  +0.3
ZL2HAM     -0.7  -0.7  -0.7  -0.9  -0.6  -0.7  -0.5  -0.6  +3.2 +13.2
ZL2KS      -4.8  -5.2  -4.8  -4.5  -4.7  -5.6  -5.0  -5.3  -4.2  -3.6
ZL4YL      +1.7  +1.1  +1.6  +1.6  +1.4  +1.5  +1.7  +1.1  +1.0  +1.7

Last updated 2022-05-18 00:15:28 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 DF7GB KM3T LZ3CB OE9GHV WB6BEE 

Last updated 2022-05-18 00:15:28 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.