RBN Analytics

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

280460 RBN spots between 2025-05-06 00:00 and 23:59 UTC.
67873 spots (24.2%) were from reference skimmers (*).
Average spot flow was 195 per minute from 202 active CW skimmers.

126495 spots from 197 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 
  -------------------------------------
  3D2AG       +0.5     30   1.000000475
  3V9A        -0.9    726   0.999999124
  5Z4GO       +0.8      5   1.000000803
  7N4XCV      +0.7     10   1.000000713
  AC0C-1      +0.1     99   1.000000144
  BA6KC       +0.1    107   1.000000085
  BG0AJO      -0.1    102   0.999999907
  BG0AJO/0    +0.0     25   1.000000000
  BG2TFW      +8.4     95   1.000008381
  BG4GOV      +0.0      9   1.000000000
  BH4RRG      +0.0     18   1.000000000
  BH4RRG-     +0.0     20   1.000000000
  BH4XDZ      -1.3     28   0.999998726
  BI4MPH-1    +0.0     12   1.000000000
  BY4XRA      -0.1     43   0.999999917
  CT1EYQ      -0.1    802   0.999999916
  CX6VM       +2.7    118   1.000002661
  DD5XX       +0.7   1786   1.000000657
  DE1LON      +2.0   1004   1.000002039
  DF2CK       +1.5   2792   1.000001523
  DF7GB*      +0.1   1464   1.000000069
  DK0TE       +0.8   1287   1.000000774
  DK3UA*      +0.4    498   1.000000390
  DK3WW       +0.2   1539   1.000000219
  DK9IP       +0.0    793   1.000000006
  DK9IP-1*    +0.0   1346   1.000000026
  DL0LA*      -0.0    694   0.999999978
  DL0PF       +8.4   2289   1.000008424
  DL1HWS      +0.3   1617   1.000000299
  DL1HWS-3    +0.6   1168   1.000000565
  DL1HWS-4    +0.2    214   1.000000172
  DL5RCN     +12.6    179   1.000012608
  DL8LAS      +0.3    805   1.000000269
  DL9GTB      -0.1    990   0.999999870
  DM5GG*      -0.2   2347   0.999999766
  DM6EE*      +0.0   1543   1.000000024
  DO4DXA*     +0.1   1988   1.000000077
  DO4ZT*      +0.1   1108   1.000000102
  DR4W        -4.9   1033   0.999995084
  E28AC       +0.1     32   1.000000136
  EA2CW       +0.2    822   1.000000220
  EA2RCF-4    +0.4    590   1.000000415
  EA5RQ       -0.3     15   0.999999683
  EA5RQ/A     +0.0      8   1.000000000
  EA5WU*      +0.0   1237   1.000000008
  ES2RR*      -0.1   1295   0.999999886
  ES5PC*      +0.0   1911   1.000000021
  F4BPO       -1.1    561   0.999998884
  F4GOU       +5.1   1074   1.000005058
  F4VVG*      -0.4    598   0.999999617
  F6IIT       -1.0   1225   0.999998969
  G0KTN       +0.3   1334   1.000000254
  G3XBI       +0.2    232   1.000000154
  G3YPP       +0.7    119   1.000000737
  G4IRN       +0.6   1465   1.000000603
  G4ZFE       +0.2   1172   1.000000224
  GI4DOH-2*   +0.1   1184   1.000000129
  GX0FRE      -0.0    248   0.999999997
  HA1VHF      +0.2   1661   1.000000244
  HA6PX*      +0.1   1617   1.000000067
  HA8TKS      +0.3   1061   1.000000329
  HB9BXE      +0.2   1309   1.000000186
  HB9DCO      -0.2   1036   0.999999793
  HB9GVO      +0.7     40   1.000000714
  HG8A        +0.6   1680   1.000000589
  IK4VET      +4.1   1939   1.000004137
  IK7YTT      +0.0   1368   1.000000048
  IT9GSF      +0.7    232   1.000000737
  JI1HFJ      +4.3     17   1.000004334
  JJ2VLY     +14.8     66   1.000014773
  JN1ILK      -0.0    232   0.999999957
  K1RA        +0.0    217   1.000000040
  K2PO/7      +0.6    365   1.000000579
  K3PA-1      +0.1    356   1.000000064
  K3PA-2      +0.0     33   1.000000000
  K4PP*       +0.1    455   1.000000086
  K5EM        +0.8    267   1.000000791
  K5TR        +0.8    337   1.000000823
  K6FOD       +0.3    201   1.000000263
  K7CO        -0.1    363   0.999999876
  K7EK        +0.5    144   1.000000456
  K9IMM       +0.2    506   1.000000168
  K9LC        +0.4    578   1.000000404
  K9QC        +0.3     49   1.000000258
  KC4YVA      -3.2    231   0.999996808
  KD2OGR      +0.3    318   1.000000348
  KD7EFG      +0.4    163   1.000000398
  KH6LC       +0.2     31   1.000000230
  KM3T-2      +0.4    626   1.000000440
  KM3T-3*     +0.1    883   1.000000095
  KM3T-5*     -0.1    510   0.999999877
  KO7SS       +0.3    198   1.000000330
  KP2RUM      +0.2    805   1.000000213
  KP3CW       +0.2    349   1.000000225
  KV4TT*      -0.0    600   0.999999961
  LA6TPA      -2.6    446   0.999997378
  LB9KJ       +1.1    360   1.000001056
  LU6KK       +0.0     12   1.000000000
  LZ3CB       -0.0    811   0.999999968
  LZ4AE       +1.1   1462   1.000001107
  LZ4UX*      -0.1    949   0.999999919
  LZ5DI       +1.5   1611   1.000001457
  LZ7AA       +1.3   1158   1.000001278
  MM0GPZ      -0.2   1255   0.999999798
  MM0ZBH      -0.6   1597   0.999999449
  N2CR        -0.0    374   0.999999980
  N6TV        +0.8    219   1.000000758
  N7OR        -0.1    104   0.999999863
  N8DXE       +2.8     15   1.000002845
  N9CO        +0.2    283   1.000000186
  ND7K        -0.2    362   0.999999826
  NG7M        +0.4    286   1.000000368
  NN3RP       +0.5    189   1.000000548
  NT6Q        -4.1    390   0.999995890
  NU4F*       +0.0    475   1.000000029
  OE3KLU-3   +12.8     30   1.000012826
  OE6TZE      -0.4     19   0.999999625
  OE9GHV*     -0.1    478   0.999999940
  OG66X       +0.1    241   1.000000118
  OH4KA       +0.4    312   1.000000421
  OH6BG*      +0.0   1821   1.000000019
  OH8KA       -4.6   1488   0.999995352
  OK1FCJ      +0.5   1625   1.000000533
  OK1HRA      -4.4   1552   0.999995568
  OK4QRO      +1.9   1462   1.000001893
  ON6ZQ*      +0.1   1113   1.000000078
  OZ1BZS      +0.5    192   1.000000536
  OZ4ADX*     +0.1    473   1.000000141
  PA8MM*      +0.2    501   1.000000186
  PE5TT       +0.4   1148   1.000000417
  PI4CC       +0.2   1653   1.000000234
  PY2KJ       +1.1     23   1.000001137
  PY2PE       +5.6     10   1.000005592
  R1LB        -0.1    528   0.999999932
  R4NCU       -0.4    142   0.999999649
  R9IR        +0.5   1020   1.000000535
  RK3TD       +0.2    767   1.000000232
  RK3TD-2*    -0.0    897   0.999999965
  RN4WA       +1.0   1007   1.000001033
  RU9CZD      -0.0    936   0.999999967
  S50U        +0.4    104   1.000000422
  S53A        +0.5   1025   1.000000516
  S53F        +1.1    655   1.000001096
  S53WW       +0.1   1518   1.000000143
  SE5E        +0.4   1893   1.000000447
  SM0TCZ      -0.8     21   0.999999207
  SM1HEV      +0.1    384   1.000000076
  SM7IUN*     +0.1   1042   1.000000118
  SQ5J        +9.0    446   1.000008977
  SV1CDN      +1.0      7   1.000001020
  SZ1A        -2.1   1311   0.999997937
  TF3Y        +1.4    264   1.000001445
  TI7W        +0.5    694   1.000000547
  UT5R        +4.6    898   1.000004626
  UT5R-1      +2.2   1085   1.000002199
  UY2RA       -2.6    719   0.999997447
  V51YJ       +1.5     12   1.000001494
  VE3EID      +0.7    803   1.000000657
  VE6JY       +3.5    280   1.000003460
  VE6WZ       +4.8    386   1.000004763
  VE7CC       +1.0     87   1.000001009
  VK2GEL      +0.2     53   1.000000224
  VK2RH       +0.0      5   1.000000000
  VK3RASA     +0.5     43   1.000000498
  VK6ANC      +0.1     39   1.000000122
  VR2FUN-77   +0.8    733   1.000000795
  VU2PTT      +0.8     72   1.000000759
  VU2TUM      +0.3    166   1.000000253
  W1NT-2      -0.0    310   0.999999977
  W1NT-6*     -0.1    743   0.999999933
  W2MV        +0.8     72   1.000000791
  W2NAF       +1.1    495   1.000001057
  W3DAN       +1.6     18   1.000001584
  W3OA        +0.1    643   1.000000146
  W3RGA*      -0.1    335   0.999999851
  W3UA        +0.1     52   1.000000069
  W4AX        +4.9     85   1.000004905
  W4KAZ       -0.2    568   0.999999781
  W6YX        +0.5    378   1.000000515
  W8WTS*      -0.0    321   0.999999978
  W8WWV       -0.8    562   0.999999243
  WA7LNW      +0.3    505   1.000000309
  WB6BEE      +0.0    489   1.000000006
  WC2L        +0.4    581   1.000000374
  WC8GOP     +11.0     36   1.000011009
  WE9V        +3.3    636   1.000003313
  WS2C        +6.3    390   1.000006267
  WS3W        +0.6     97   1.000000587
  WT9U        +0.6     80   1.000000603
  WV4P*       -0.0    285   0.999999975
  WX7V/5      +1.1     19   1.000001120
  WZ7I        +0.6   1047   1.000000628
  YO2CK*      -0.2   2244   0.999999834
  YO2MAX*     +0.0   1906   1.000000024
  ZL3X        -0.2    116   0.999999815
  ZL4YL       +1.4    213   1.000001398
  ZS1NN       -4.7     16   0.999995292

Last updated 2025-05-07 00:15:26 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    0506  0505  0504  0503  0502  0501  0430  0429  0428  0427
---------------------------------------------------------------------
2E0INH                                   -0.1                        
3D2AG      +0.5  +0.5  +0.1  +0.4  +0.1  +0.6  +0.7  +0.5  +1.0  +1.3
3V9A       -0.9  -1.0  -1.5  -1.4  -1.3  -1.3                        
5Z4GO      +0.8  +1.1  +0.2  +0.5  +0.0        +0.0  -0.3  +0.3  +1.0
7N4XCV     +0.7  +0.3  +0.5  +0.4  +0.0  +0.4  +1.0  +0.1  +0.1  +0.5
AA0O                         +1.0        +0.0  +0.7  +0.3  +0.5  +1.0
AA4VV                                                            -9.9
AC0C-1     +0.1  +0.0  -0.3  +0.0  -0.2        +0.0  -0.1  +0.0  +0.0
BA6KC      +0.1  +0.5  +0.1  -0.0  -0.1  -0.0  -0.0  +0.0  +0.0  +0.0
BD7JNA           +0.0  -1.2                                          
BD8CS                              +0.1  -0.0  +0.1  +0.0  +0.1  +0.1
BG0AJO/0   +0.0  -1.2  +0.1  +0.0  -0.1  +0.0  +0.0  +0.0  +0.0  +0.0
BG0AJO     -0.1  -0.2  +0.4  +0.7  +0.3  +0.4  +0.2  +0.6  +0.7  +0.4
BG2TFW     +8.4  +9.1  +9.2  +9.9  +8.8  +9.3  +9.2  +9.5  +8.9  +8.9
BG4GOV     +0.0        +0.1  +0.3  +0.0                              
BH4RRG     +0.0  +0.0  +0.2  +0.1  +0.4  +0.0  +0.2  +0.1  -0.1  +0.2
BH4RRG-    +0.0  +3.2                                                
BH4XDZ     -1.3  +0.0  +0.2  +0.1  +0.0  -0.1  +0.7  +0.0  +0.2  +0.0
BI4MPH-1   +0.0  +0.0  +0.0  -0.0  +0.0  +0.0  +0.0  +0.0  +0.0  -0.1
BY4XRA     -0.1  +0.0  +0.1  +0.2  +0.0  +0.1  +0.2  +0.0  +0.1  +0.1
CT1EYQ     -0.1  -0.1  -0.3  -0.1  -0.0  -0.2  -0.2  -0.0  -0.3  -0.1
CX6VM      +2.7  +1.7  +2.1  +2.3  +1.0  +0.8  +0.9  +0.9  +1.1  +1.4
DD0VS                                                           +16.1
DD5XX      +0.7  +0.6  +1.1  +1.6  +1.4  +1.1  +1.1  +1.0  +1.1  +1.0
DE1LON     +2.0  +2.0  +2.0  +2.7  +2.8  +2.6  +2.4  +1.8  +2.2  +2.3
DF2CK      +1.5  +1.1  +1.4  +1.9  +1.5  +1.4  +1.3  +1.2  +1.1  +1.1
DF5EG                                                            -0.3
DF7GB      +0.1  -0.1  -0.0  +0.0  -0.0  -0.0  +0.0  +0.0  +0.1  +0.0
DK0TE      +0.8  +0.5  +2.0  +2.5  +1.8  +1.7  +1.7  +1.0  +1.0  +1.2
DK1MAX                 +0.0                                          
DK3UA      +0.4  -0.4  +1.2  +0.2  +0.1  +0.4                        
DK3WW      +0.2  +0.2  -0.0  -0.1  +0.1  -0.1  -0.0  +0.2  +0.4  +0.3
DK8NE                  +0.0                                +0.0      
DK9IP      +0.0  -0.1  -0.2  -0.0  -0.0        -0.0  -0.1  -0.1  -0.2
DK9IP-1    +0.0  -0.1  -0.1  -0.1  +0.0        +0.0  -0.1  -0.1  -0.1
DL0LA      -0.0  -0.0  -0.1  -0.1  -0.1  -0.2  -0.1  -0.0  -0.1  -0.1
DL0PF      +8.4  +9.4  +8.2  +8.3  +8.8  +9.2  +7.5  +8.5  +9.1  +8.3
DL1AMQ                                               -1.2            
DL1EFW                       +0.1                    -0.4            
DL1HWS     +0.3  +0.2  +0.4  +0.4  +0.3  +0.3  +0.3  +0.2  +0.4  +0.5
DL1HWS-3   +0.6  +0.4  +0.6  +0.6  +0.5  +0.5  +0.6  +0.5  +0.7  +0.3
DL1HWS-4   +0.2  +0.2  +0.3  +0.4  +0.3  +0.3  +0.2  +0.0  +0.9  +0.7
DL3OBQ           -7.4  -7.1                                      -9.9
DL4CF                              +0.0  +0.2        +0.0            
DL5RCN    +12.6  -0.3                   +13.2 +12.6 +12.7 +12.6 +12.4
DL5RMH                 +0.1  +0.1                                    
DL8LAS     +0.3  +0.5  +0.5  +0.8  +0.9                              
DL8TG                        +0.0  +0.1  +0.0  -0.1  -0.0  +0.2  +0.1
DL9GTB     -0.1  -0.3  +0.4  +0.8  +0.7  +0.9  +0.3  +0.3  +0.5  +0.6
DM5GG      -0.2  +0.1  +0.4  +0.5  +0.4  +0.3  +0.2  +0.1  +0.3  +0.4
DM6EE      +0.0  +0.1  +0.1  -1.4              +0.1  +0.1            
DO4DXA     +0.1  -0.0  -0.1  -0.0  +0.0  -0.0  -0.0  -0.1  +0.0  +0.0
DO4ZT      +0.1  -0.0  -0.0  +0.0  -0.0  +0.0  +0.0  -0.0  +0.1  -0.0
DR4W       -4.9  -4.9  -2.8  -2.6  -2.5  -2.7  -2.7  -3.2  -3.5  -4.8
E28AC      +0.1  +0.0  -1.1  -0.9  -0.5  -0.2  -1.3  +3.4  +4.3  +4.4
EA1DIW                 +4.7                                          
EA1RX                  +0.5  -1.4                                +0.2
EA2CW      +0.2  +0.3  +0.5  +0.6  +0.5  +0.3  +0.3  +0.1  +0.1  -0.1
EA2RCF-4   +0.4  +0.7  +0.8  +0.8  +0.5  +0.6  +0.7  +0.5  +0.8  +0.7
EA5RQ      -0.3  -0.0  +0.0  -0.1  +0.0  -0.0  -0.1  -0.1  -0.0  +0.0
EA5RQ/A    +0.0  +0.1  +0.0  +0.3                    +0.3            
EA5WU      +0.0  +0.1  +0.0  -0.0  +0.1  +0.0  +0.0  -0.0  +0.2  +0.0
ES2RR      -0.1  -0.0  -0.0  -0.0  -0.0  -0.1  -0.1  -0.0  +0.0  +0.0
ES5PC      +0.0  +0.1  -0.0  +0.0  -0.0  +0.0  +0.0  -0.0  +0.0  +0.0
F4BPO      -1.1  -0.8  -0.9  -0.6  -0.3  -0.3  -0.6  +0.0  -0.9  -1.1
F4GOU      +5.1  +5.2  +6.0  +6.4  +6.0  +5.9  +5.6  +5.1  +4.9  +4.7
F4VVG      -0.4  -0.3  +0.1                    +0.1  -0.0  +0.2  +0.2
F5AHD                                                            +0.8
F5VLY                              +0.4  +0.1  +0.0  -0.1  +1.4  +0.5
F6IIT      -1.0  -1.1  -0.7  -0.2  -0.3  -0.3  -0.1  -0.4  -0.4  -0.7
G0KTN      +0.3  +0.3  +0.3  +0.5  +0.5  +0.5  +0.4  +0.4  +0.6  +0.5
G0TMX                  +0.1                                          
G3XBI      +0.2  +0.4  +0.4  +0.2  +0.1  +0.2  +0.1  -0.3  +0.2  +0.5
G3YPP      +0.7  -1.0  +0.2  +0.0  -0.0  +1.1  +0.5  +0.1  +0.0  -0.0
G4IRN      +0.6  +0.6  +0.6  +0.8  +0.6  +0.5  +0.6  +0.5  +0.7  +0.7
G4ZFE      +0.2  +0.3  +0.5  +0.9  +0.8  +0.7  +0.7  +0.5  +0.7  +0.4
GI4DOH-2   +0.1  +0.0  +0.0  +0.0  +0.1  +0.3  +0.3  +0.2  +0.2  +0.2
GI4DOH-3                                                   +0.5  +0.4
GX0FRE     -0.0  -0.4  +0.4  +0.5  +0.1        +0.4  +0.6  +0.4  +0.4
HA1VHF     +0.2  +0.5  +0.8  +1.0  +0.7  +0.5  +0.5  +0.2  +0.4  +0.2
HA6PX      +0.1  -0.0  -0.0  -0.0  +0.0  +0.0  -0.0  +0.0  +0.1  -0.0
HA8TKS     +0.3  +0.4  +0.3  +0.4  +0.3  +0.3  +0.4  +0.3  +0.4  +0.4
HB9BXE     +0.2  -0.0  +0.1  +0.2  +0.1  -0.0  +0.0  +0.0  +0.2  +0.2
HB9DCO     -0.2  -0.3  -0.4  -0.3  -0.2  -0.3  -0.1  -0.1  -0.1  -0.3
HB9GVO     +0.7  +1.1  +0.5  +0.6  +0.0  +1.2  +0.7  +0.0  +0.8  +1.1
HG0Y                   +8.1  +8.0  +7.8  +7.7  +7.8  +7.5  +7.6  +7.4
HG8A       +0.6  +0.8  +1.0  +1.0  +0.6  +0.7  +0.6  +0.4  +0.6  +0.7
IK3STG           +1.2  +1.8  +2.0  +1.6  +1.9  +2.2  +1.9  +2.2  +2.3
IK4VET     +4.1  +3.8  +4.2  +4.4  +3.9  +3.7  +3.9  +3.8  +3.8  +3.9
IK7YTT     +0.0  +0.1  +0.0  +0.0  +0.0  -0.0  -0.0  -0.0  +0.0  -0.0
IT9GSF     +0.7  +0.0  +0.8        +0.2        +0.2  +0.1  +0.3  +0.5
JG1DLY           -1.3  -0.3  -0.4                          -0.9  -0.8
JH4UTP                                                           +0.5
JH7CSU1          +4.8  +2.1  +1.4  +0.7  +0.8        +2.6  +1.4  +1.6
JI1HFJ     +4.3  +4.0  -3.5  -3.7  -3.7  -0.2  -3.8  -1.9  -2.5  -2.3
JJ2VLY    +14.8       +14.8 +14.9 +14.6 +14.8 +14.8 +14.6 +14.7 +14.7
JK1QLQ           +0.0  +0.0  +0.0        +0.0  +0.0  +0.0  +0.0  +0.1
JN1ILK     -0.0  +0.1  +0.3  +0.2  -0.2  +0.3  -0.1  -0.4  +1.2  +1.4
K1RA       +0.0              +0.7  +0.5  +0.5  +0.7  +0.1  +0.3  -0.2
K2PO/7     +0.6  +0.4  +0.5  +0.8  +0.2  +0.3  +0.6  +0.4  +0.4  +0.5
K3PA-1     +0.1  -0.1  -0.0  -0.2  +0.0  -0.1  -0.0  -0.1  -0.0  -0.0
K3PA-2     +0.0  -0.5  -0.3  -0.2        -0.4  +0.0  +0.0  -0.2  -0.2
K4PP       +0.1  -0.2  -0.2  +0.2  +0.3  +0.2  +0.3  +0.2  +0.5  +0.2
K5EM       +0.8  +0.5  +0.6        +0.8  +0.5  +0.8  +0.6  +0.5  +0.7
K5TR       +0.8  +0.7  +0.7  +0.7  +0.3  +0.5  +0.8  +1.3  +0.6  +0.3
K6FOD      +0.3  +0.0  +0.1  -0.0  -0.1  +0.1  -0.1  -0.0  -0.0  -0.0
K7CO       -0.1  +0.3  +0.9  +0.8  +0.3  +0.6  +0.2  -0.1  -0.1  +0.5
K7EK       +0.5  +1.3  +1.0  +0.5  -2.3  -3.4  -1.9  -3.8  -1.7  -2.2
K9IMM      +0.2  +0.4  +0.4  +0.5  +0.1  +0.3  +0.4  +0.3  +0.4  +0.3
K9LC       +0.4  +0.4  +0.6  +0.5  +0.2  +0.5  +0.6  +0.5  +0.6  +0.5
K9QC       +0.3  +0.4  +0.3  +0.7  +0.0  +1.1  +0.6  +0.5  +0.9  +0.6
KC4YVA     -3.2  -3.0  -2.4  -0.9  -2.1  -4.2  -1.2  -1.6  -2.3  -0.3
KD2OGR     +0.3  +0.4  +0.5  +0.5  +0.2  +0.4  +0.6  +0.4  +0.3  +0.5
KD7EFG     +0.4  +0.2  +0.4  +0.3  +0.2  +0.2  +0.5  +0.2  +0.5  +0.4
KH6LC      +0.2  +0.2  +0.1  +0.2  +0.0  -0.2  +0.2  +0.1  +0.0  +0.1
KM3T-2     +0.4  +0.6  +0.7  +0.5  +0.4  +0.4  +0.7  +0.3  +0.5  +0.6
KM3T-3     +0.1  -0.1  +0.1  +0.1  +0.0  +0.0  -0.0  -0.0  +0.1  +0.0
KM3T-5     -0.1  -0.0  -0.0  -0.1  -0.2  -0.1  +0.1  +0.0  -0.0  -0.0
KO7SS      +0.3  +0.5  +0.5  +0.4  +0.7  +0.5  +0.3  +0.2  +0.3  +0.4
KP2RUM     +0.2  +0.1  +0.3  +0.3  +0.1  +0.1  +0.3  +0.4  +0.7  +0.3
KP3CW      +0.2  -0.2  -0.2  -0.3  -0.0  -0.2  -0.2  -0.1  -0.1  -0.0
KV4TT      -0.0  -0.2  +0.0  -0.1  -0.1  -0.1  -0.1  -0.1  +0.3  +0.4
LA6TPA     -2.6  -2.6  -2.9  -2.3  -2.0  -1.9  -2.4  -1.6  -1.7  -2.3
LA7GIA                 +0.1  +0.0  +0.0  -0.0  -0.1  -0.2  -0.0  -0.2
LB9KJ      +1.1 +13.4  -1.8  -9.9 -13.1  -9.6  +0.3  +0.1  +0.2  +0.2
LU6KK      +0.0  +0.0  -0.1  +0.2  +0.0  -0.1  +0.5  +0.3  +0.0  +0.2
LU8XW            -0.4  -0.2  +1.0  +0.4  +0.0  +0.1  +0.4  +0.3  +0.1
LY2XW                  +0.7  +0.5  +0.5                              
LY3G                               +0.7                              
LZ3CB      -0.0              +0.0  -0.0  +0.0  +0.0  +0.0  +0.1  -0.1
LZ4AE      +1.1  +1.3  +1.5  +1.4  +0.9  +0.9  +0.8  -0.0  +0.2  +0.5
LZ4UX      -0.1  -0.0  -0.1  -0.0  -0.1  -0.0  +0.1  +0.0  +0.0  +0.0
LZ5DI      +1.5  +1.4  +1.3  +1.4  +0.9  +1.0  +0.9  +0.7  +0.7  +1.1
LZ7AA      +1.3  +1.2  +1.4  +1.5  +1.0  +1.1  +0.9  +0.6  +0.8  +1.1
MM0GPZ     -0.2  -0.1  -0.3  -0.2  -0.0 +13.8  +0.3  -0.0  +0.1  -0.5
MM0ZBH     -0.6  +0.1  -0.7  +0.2  +0.3  +0.5  +0.8  +0.5  +0.3  +0.1
N2CR       -0.0  -0.1  +0.5  +0.3  -0.2  -0.1  +0.2  +0.1  +0.2  -0.4
N6TV       +0.8  +1.0  +0.6  +0.5  +0.3  +0.4  +0.6  +0.7  +0.7  +0.9
N7OR       -0.1  -0.1  +0.0  +0.1        -0.1  +0.0  -0.0  -0.0  +0.0
N8DXE      +2.8  +1.4  +0.0                          +0.0            
N9CO       +0.2  -0.0  -0.0  -0.1  +0.0  -0.0  -0.2  +0.1  +0.2  -0.0
ND7K       -0.2  -0.5  -0.2  -0.2  -0.8  -0.3  -0.4  -0.3  -0.6      
NG7M       +0.4  -0.2  -0.0  -0.1  -0.1  +0.2  +0.0  -0.1  +0.1  +0.1
NN3RP      +0.5  +0.5  +0.6  +0.6  +0.8  +0.6  +0.4  +0.5  +0.4  +0.7
NT6Q       -4.1  -3.6  -3.8  -2.7  -3.9  -3.1  -3.0  -2.9  -2.8  -2.4
NU4F       +0.0  -0.0  +0.1  -0.0  +0.1  +0.1  +0.2  +0.1  +0.0  +0.0
OE3KLU                 +2.0              +0.0        +2.1            
OE3KLU-3  +12.8                                                      
OE6ADD                 +0.0  +0.0  -0.2  -0.1  -0.1  +0.0  -0.1  -0.4
OE6TZE     -0.4  -0.6  -0.1  -0.1  +0.0                              
OE9GHV     -0.1  +0.1  -0.0  +0.2  -0.0  -0.0  +0.0  +0.0  +0.0  +0.0
OG66X      +0.1  +0.2  -1.6        -0.4  +0.2  +0.0  +0.1  -0.1  -0.3
OH4KA      +0.4  -0.0  +0.3  +0.6  +0.4  +0.4  +0.4  +0.4  +0.8  +0.1
OH6BG      +0.0  -0.1  -0.1  -0.0  -0.0  -0.2  -0.5  -0.6  -0.6  -0.7
OH8KA      -4.6  -8.0  -4.7  -4.7  +4.3  +2.6  +3.7  +4.1  +4.2  +3.3
OK1FCJ     +0.5  +0.4  +0.6  +0.7  +0.5  +0.5  +0.5  +0.4  +0.6  +0.5
OK1HRA     -4.4  -4.3  -3.7  -4.5  -3.8  -3.9  -4.5  -4.2  -4.1  -4.7
OK4QRO     +1.9  +1.9  +2.2  +2.5  +1.8  +1.9  +1.1                  
ON6ZQ      +0.1  +0.0  +0.1  +0.2  +0.3  +0.1  +0.1  +0.1  -0.2  -0.3
OZ1BZS     +0.5  +0.1  +0.5  +0.6  +0.0  +0.5        +1.2  +0.9  +0.6
OZ4ADX     +0.1  +0.0  +0.0  +0.0  -0.2  +0.0  -0.1  -0.1  +0.0  +0.1
PA0MBO                             +0.9  +0.6  +0.6  +0.4  +1.0  +0.7
PA8MM      +0.2  +0.2  +0.2  +0.4  +0.2                          +0.2
PE5TT      +0.4  +0.6  +0.7  +1.2  +0.9  +0.6  +0.7  +0.7  +1.0  +0.5
PI4CC      +0.2  -0.3  -0.4  -0.4  -0.3  -0.3  -0.2  +0.1  -0.5  -0.5
PY2KJ      +1.1  +1.1  +0.8  +1.2  +0.9  +0.3  +0.7  +1.1  +0.9  +1.0
PY2PE      +5.6  +1.6  +7.5  +6.4  +3.5  +0.0                    +2.7
R1LB       -0.1  +0.1  -0.1  -0.0  -0.1  -0.2  +0.0  -0.0  +0.0  -0.0
R2AJA                                    +0.3  +0.4  +0.0        +0.5
R4NCU      -0.4  -0.7  -0.6  -0.5  -0.2  -0.5  -0.6  -0.5  -0.4  -0.5
R6YY             -0.3  -0.0  +0.0  +0.0  -0.1  -0.0  +0.0  -0.2  -0.1
R9IR       +0.5  +0.4  +0.5  +0.6  +0.3  +0.5  +0.5  +0.3  +0.5  +0.4
RK3TD      +0.2  +0.2  +0.2  +0.3  +0.1  +0.3              +0.4  +0.4
RK3TD-2    -0.0  -0.0  -0.0  -0.1  -0.1                          -0.1
RN4WA      +1.0  +0.7  +1.3  +1.5  +1.1  +1.0  +1.1  +0.9  +1.4  +1.5
RU9CZD     -0.0  +0.1  +0.3  +0.3  +0.1  +0.0  -0.0  -0.1  -0.2  +0.0
S50U       +0.4  +0.0  +0.2  +0.3  +0.2  +0.2  +0.2  +0.2  +0.7  +0.4
S53A       +0.5  +0.8  +0.7  +1.1  +1.3        +1.0  +0.9  +0.8  +0.8
S53F       +1.1  +1.2  +1.3        +0.9  +0.9  +0.8  +0.9  +0.6      
S53WW      +0.1  +0.3  +0.6        +0.1  +0.3                    +0.1
SE5E       +0.4  +0.3  +0.5  +0.5  +0.4  +0.5  +0.5  +0.4  +0.4      
SM0TCZ     -0.8  -0.0  +0.7  +0.3  -1.0  +0.8  +0.7  +0.2  +0.1  -0.2
SM1HEV     +0.1  +0.0  -0.2  +0.3  +0.2  +0.1  +0.2  +0.3  +0.6  +0.2
SM7IUN     +0.1  +0.1  -0.1  -0.1  -0.0  +0.1  +0.1  -0.1  -0.1  -0.1
SQ5J       +9.0 +11.1  +9.4  +9.6  +9.8  +9.7  +9.5  +9.4  +9.7  +9.4
SV1CDN     +1.0        -0.2  -0.2  +0.0  +0.0  -0.0  +0.1  +0.2  -0.1
SZ1A       -2.1  +0.3  +0.3  +0.4  -1.1  -0.8  +0.1  -0.2  +0.0  -1.2
TF3Y       +1.4  +1.5  +1.7  +1.9  +1.7  +1.8  +1.5  +1.7  +1.5  +1.7
TI7W       +0.5  +0.7  +0.8  +0.8  +0.3  +0.4  +0.5  +0.4  +0.5  +0.6
UA0S                                                       +3.2  +4.9
UT5R-1     +2.2  +2.2  +1.5  +2.4  +1.9  +2.5  +2.4  +3.0  +3.2  +2.9
UT5R       +4.6  +4.2  +4.1  +4.7  +4.0  +4.4  +4.9  +4.8  +4.7  +4.4
UY2RA      -2.6  -2.0  -2.5  -2.6  -1.7  -2.0  -1.7  -2.0  -2.0  -2.1
V51YJ      +1.5  +0.0  +1.3  +1.5  +3.2  +1.3  +1.4  +1.3  +1.3  +2.3
VE3EID     +0.7  +0.6  +0.2  -0.3  -0.5  -0.2  +0.2  +0.6  +0.1  -0.3
VE6AO                  -0.4  -0.6  -0.8  -0.8  -0.9  -0.7  -0.8  -1.0
VE6JY      +3.5  +2.9  +3.8  +4.5  +2.2  +1.1  +1.4  +1.3  +1.8  +2.7
VE6WZ      +4.8  +4.0  +4.0  +5.1  +3.6  +3.2  +2.9  +3.6  +3.9  +3.9
VE7CC      +1.0  +0.7  +0.9  +1.3  +0.3  +1.2  +1.0  +0.7  +0.9  +1.1
VK2EBN                                                           +0.1
VK2GEL     +0.2  +0.3  +0.6  +0.3  +0.2  +0.2  +0.3  +0.6  +0.6  +0.7
VK2RH      +0.0        +0.0  -2.0  +1.8  +0.0  +0.0  +0.0  -0.3  -0.3
VK3RASA    +0.5  +0.2  +0.1  -2.0  -1.7  -1.1  -1.9  -1.5            
VK6ANC     +0.1  -1.7  +0.3  -0.0  +0.2  +0.2  +0.0  +0.2  -0.2  -0.1
VR2FUN-77  +0.8  +0.8                                +0.8  +0.8  +0.9
VU2CPL                             +0.0  -0.1  +0.1  +0.0  +0.0  +0.2
VU2PTT     +0.8  +1.5  +2.3  +2.0  +0.0  -0.1  -0.1  +0.3  -0.0  +0.1
VU2TUM     +0.3  -0.3  +0.2  +0.1  +0.0  +0.2  +0.7  +0.2  +0.3  +0.0
W1NT-2     -0.0  -0.2  +0.1  +0.1  -0.1  -0.1  +0.1  -0.0  +0.1  +0.0
W1NT-6     -0.1  -0.1  +0.0  -0.0  -0.0  +0.0  +0.2  +0.0  -0.0  +0.0
W2MV       +0.8  +0.5  +0.3  +0.6  +0.0  +0.3  +0.9  +0.8  +0.3  +0.6
W2NAF      +1.1  +1.2  +1.4  +1.6  +1.0  +1.2                    +2.4
W3DAN      +1.6  +1.6  +1.9                                +0.0      
W3OA       +0.1  +0.2  +0.4  +0.3  +0.2  +0.2  +0.3  +0.2  +0.2  +0.2
W3RGA      -0.1  +0.1  +0.4  +0.5  +0.0  +0.1  +0.2  -0.0  +0.1  -0.1
W3UA       +0.1  -0.4  -9.0  -7.7  -0.8  -0.1  -0.0  -0.0  +0.0  +0.0
W4AX       +4.9  +6.1  +4.4  +5.4  +4.5  +4.9  +5.0  +5.1  +4.5  +5.3
W4KAZ      -0.2  -0.4  -0.3  -0.1  -0.1  -0.0  -0.1  -0.5  -0.6  -0.5
W6YX       +0.5  +0.6  +0.0  +0.2  -0.0  +0.3  +0.2  +0.2  -0.0  -0.1
W7VJ                                                       -0.4  -1.1
W8WTS      -0.0  +0.2  -0.1  +0.0  -0.2  -0.2  -0.1  -0.3  -0.2  -0.1
W8WWV      -0.8  -1.2  -1.2  -1.3  -0.8  -1.1  -1.7  -0.8  -1.1  -1.6
WA7LNW     +0.3  +0.5  +1.1  +1.3  +0.6  +0.5  +0.8  +0.5  +0.5  +0.8
WB6BEE     +0.0  +0.1  +0.1  -0.0  -0.3  -0.0  -0.0  -0.0  -0.0  +0.1
WC2L       +0.4  +0.4  +0.5  +0.6  +0.4  +0.3  +0.3  +0.3  +0.4  +0.3
WC8GOP    +11.0 +10.2  +8.1 +10.3  +9.2  +9.2 +11.4 +11.5 +11.7 +11.0
WE9V       +3.3  +2.9  +2.7  +1.3  +0.2  +0.6  +0.3  +0.5  +0.2  +0.0
WS2C       +6.3  +6.3  +7.6  +7.6  +6.8  +6.1  +6.3  +5.9  +5.6  +6.4
WS3W       +0.6  +0.8  +0.5  +0.7  -1.2  -0.2  +0.1  -0.2  -0.1  +1.4
WT9U       +0.6  +1.5  +1.7  +2.1  +0.2  +0.8  +1.4  +0.3  +0.2  +0.4
WV4P       -0.0  +0.0  +0.1  +0.1  +0.1  +0.1  +0.2  +0.1  +0.2  -2.4
WX7V/5     +1.1  +2.4  +1.1  +0.4  +0.0  +0.8  +0.5  +0.5  +0.8  +0.2
WZ7I       +0.6  +0.4        +0.6  +0.1  +0.3  +0.5  +0.4  +0.4  +0.5
YO2CK      -0.2  -0.1  -0.2  +0.4  +8.1  +8.3  +8.2  +8.3  +8.3  +8.1
YO2MAX     +0.0  +0.1  +0.2  +0.2  +0.0  +0.1  +0.0  +0.0  +0.1  +0.1
ZL3X       -0.2  -0.8  -0.5  -8.6  -0.7  -0.7  -0.8  -0.1  +0.0  -0.6
ZL4YL      +1.4  +0.8  +1.1  +1.3  +1.0  +1.0  +1.3  +1.3  +1.5  +1.6
ZS1NN      -4.7  -4.8  -4.1  -4.5  -4.4  -3.8  -4.2  -4.2  -3.4  -4.1

Last updated 2025-05-07 00:15:32 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 2025-05-07 00:15:32 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.