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 ten minutes 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, 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.

243951 RBN spots between 2021-08-05 00:00 and 23:59 UTC.
44504 spots (18.2%) were from reference skimmers (*).
Average spot flow was 169 per minute from 164 active CW skimmers.

103850 spots from 155 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       +0.0     16   1.000000000
  3V8SS       +1.1   1648   1.000001104
  5W1SA       +0.2     39   1.000000183
  9A1CIG      +9.1    321   1.000009107
  AC0C-1*     +0.2    664   1.000000195
  BA7KW       +5.3     50   1.000005324
  BA7PC      +23.0     73   1.000023001
  BD8SZ       +0.1    223   1.000000128
  BG6SNJ      +0.5     59   1.000000483
  BG8DIV      -6.0     36   0.999993960
  BG8PA       -0.0     68   1.000000000
  BH4RRG1     -1.0     35   0.999998982
  BH4RRG4     -0.2     35   0.999999796
  BH4XDZ      -0.0      7   0.999999999
  BI4RFP      +5.9     18   1.000005941
  CX6VM       -0.4     17   0.999999581
  DD5XX       +0.4   1294   1.000000395
  DE1LON      +0.2   1542   1.000000196
  DF4XX       +1.1    586   1.000001106
  DF7GB*      +0.0   1443   1.000000045
  DJ2BC*      +0.1   1602   1.000000075
  DK0TE       +2.9   1318   1.000002930
  DK3UA       -0.6    136   0.999999427
  DK9IP       +0.2   1371   1.000000200
  DL0LA       +1.4   1402   1.000001378
  DL3DTH      +0.2   2023   1.000000197
  DL8LAS      +1.5   1226   1.000001519
  DL8TG       -0.8    578   0.999999171
  DM6EE       -0.9   1554   0.999999060
  DO4DXA*     -0.2    809   0.999999839
  DR4W        +0.6   1616   1.000000553
  E28AC       +3.3    239   1.000003318
  EA1RX       +0.5     42   1.000000509
  EA1URA      +4.7   1313   1.000004662
  ET3AA       +0.2     36   1.000000197
  F4VSQ       +4.9    313   1.000004916
  F5AHD       +0.3    221   1.000000269
  F8DGY       +1.6   1314   1.000001617
  G3XBI       +0.0      8   1.000000000
  G4AON       +0.7     99   1.000000672
  G4ZFE       -0.3   1710   0.999999741
  GI4DOH      +0.6    607   1.000000589
  GM6DX       +0.5    313   1.000000547
  HA1AG       +0.8    545   1.000000840
  HA1VHF      +0.1   2168   1.000000113
  HA6PX       -0.8    790   0.999999182
  HA7GN       +0.3    628   1.000000307
  HB9BXE      +1.9   1524   1.000001931
  HB9DCO*     -0.1   2472   0.999999923
  HB9JCB      +1.8   1618   1.000001774
  HG8A        -0.0   1449   0.999999980
  IK3STG      +1.6    507   1.000001566
  IK4VET      +3.1     41   1.000003131
  IK4VET-1    +3.0   2084   1.000003019
  JA4ZRK      -0.8     83   0.999999227
  JH7CSU1     +5.4     84   1.000005404
  JI1HFJ      -2.8     35   0.999997192
  JJ2VLY      +1.8    244   1.000001783
  JQ1BVI      +0.0    186   1.000000000
  K1TTT       -0.3   1238   0.999999702
  K3PA-1      -0.1    778   0.999999881
  K4PP        +0.6    339   1.000000587
  K4XD       +23.5    299   1.000023514
  K5TR        +0.4    708   1.000000397
  K7EG        +1.8    170   1.000001780
  K7MJG       +0.7    122   1.000000699
  K9IMM       +0.2   1021   1.000000185
  K9LC*       +0.0    903   1.000000033
  K9TM-4      +0.6    610   1.000000593
  KC0VKN      -0.8    291   0.999999154
  KC4YVA      +5.4    456   1.000005369
  KD2OGR      -0.8    245   0.999999239
  KD7YZ       +1.0    978   1.000000979
  KH6LC       +0.0     18   1.000000000
  KM3T*       +0.2    422   1.000000213
  KM3T-2*     -0.2   1256   0.999999795
  KO7SS       +0.2    980   1.000000229
  KO7SS-7     +1.2    425   1.000001181
  KQ8M        +8.0    331   1.000007950
  KU7T        +1.1    477   1.000001070
  LA6TPA      +2.5    745   1.000002518
  LZ3CB*      +0.1    755   1.000000106
  LZ4AE       +1.7    812   1.000001662
  LZ4UX*      -0.3    425   0.999999675
  LZ7AA       +0.4    840   1.000000352
  MM0ZBH*     -0.1   1013   0.999999874
  N4RLI       -2.2     77   0.999997783
  N4TVC       +0.9    483   1.000000903
  N4ZR        +0.3    540   1.000000349
  N6TV        +0.5    221   1.000000547
  N7TUG       +2.4    188   1.000002420
  N9MKC       +0.0    486   1.000000038
  NA0B        +1.2    210   1.000001218
  NC7J        +1.3    474   1.000001256
  OE6ADD      +1.3   1636   1.000001347
  OE9GHV*     -0.0   1924   0.999999974
  OH6BG*      +0.5   1017   1.000000481
  OL7M        +1.4   1158   1.000001355
  ON3URE      +0.5   1461   1.000000462
  ON6ZQ       +1.1   1176   1.000001052
  PA0MBO      -0.0    260   0.999999965
  PJ2A        -1.5    239   0.999998457
  R6YY        +0.7    138   1.000000660
  RK3TD       -0.7   1303   0.999999317
  RN4WA*      -0.0   1389   0.999999964
  RU9CZD      +3.6    357   1.000003565
  S50ARX      +0.6    500   1.000000645
  SE5E*       -0.1   2080   0.999999861
  SJ2W        +0.1   2145   1.000000150
  SM0TCZ      +1.9     75   1.000001898
  SM6FMB      +0.1   1335   1.000000093
  SM7IUN*     +0.1   2055   1.000000102
  SP8R        +0.0     92   1.000000001
  SV1CDN     +11.8    241   1.000011820
  SV8RV       +0.4    352   1.000000410
  SZ1A        +4.1    139   1.000004102
  TF3Y        -0.5    543   0.999999452
  TF4X        -1.4   2541   0.999998646
  UA0S        -2.0     55   0.999997961
  UY2RA       +0.3    152   1.000000310
  V51YJ       +1.3     48   1.000001285
  VE2WU       -0.5    742   0.999999510
  VE6AO       -0.5     55   0.999999482
  VE6JY       +0.3    449   1.000000253
  VE6WZ       +2.6    462   1.000002554
  VE7AB       +1.1     26   1.000001095
  VE7CC       +1.0    326   1.000001026
  VK2GEL      +2.8      5   1.000002849
  VK3RASA     +0.3     29   1.000000341
  VK4CT       -2.2    194   0.999997808
  VK6ANC      -1.7     39   0.999998283
  VU2PTT      -0.1    102   0.999999914
  VY0ERC      -0.8     17   0.999999161
  W1NT-2      -0.6   1238   0.999999366
  W1NT-6      +0.0   1600   1.000000017
  W2AXR       +1.3    805   1.000001294
  W2LB        +3.8    154   1.000003785
  W2MV        +0.1    122   1.000000058
  W3LPL       +1.3   1732   1.000001314
  W3OA        +0.6    298   1.000000557
  W3UA        +3.9   1501   1.000003876
  W4AX        +4.7    261   1.000004651
  W4KAZ       -0.4    718   0.999999568
  W6YX        +0.1    196   1.000000073
  W7HR        +1.1    196   1.000001088
  W8WTS       -0.4    524   0.999999597
  W8WWV       +0.5    925   1.000000457
  WA7LNW      -0.6    573   0.999999403
  WB6BEE      -0.2    274   0.999999750
  WC2L        +0.3    698   1.000000273
  WE9V        +1.3   1150   1.000001339
  WF7T        +0.2     40   1.000000178
  WS3W*       +0.0    631   1.000000001
  WZ7I        -0.1   1436   0.999999944
  ZL4YL       +2.7     85   1.000002680

Last updated 2021-08-06 00:10:22 UTC

Historical skimmer frequency accuracy

Below you will find historical accuracy data for the past five 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      21-08-05  21-08-04  21-08-03  21-08-02  21-08-01
-------------------------------------------------------------
3B8CW          +0.0      -0.3      +0.0      +0.0      -0.1
3V8SS          +1.1      +1.0      +0.7      +1.0      +1.4
5W1SA          +0.2      +0.3      +0.0      +0.2      +0.6
9A1CIG         +9.1      +6.6      +7.2      +8.3      +9.7
AC0C-1         +0.2      -0.1      +0.1      -0.0      +0.1
BA7KW          +5.3      +4.4      +3.8      +5.5      +3.9
BA7PC         +23.0     +22.2     +22.5     +23.0     +22.3
BD8SZ          +0.1      +0.2      +0.1      +0.4      +0.4
BG0ARE                                                +22.0
BG4WOM                             +9.4     +10.3      +9.8
BG6SNJ         +0.5      +0.1      +0.7      +1.0      +0.4
BG6SZD                                                 +6.5
BG7DOD                                                 +2.6
BG8DIV         -6.0      -6.7      -3.9      -5.3      -3.6
BG8PA          -0.0      -0.0      -0.1      +0.0      -0.0
BH4RRG1        -1.0      -0.3      -0.4      +0.0      -6.6
BH4RRG4        -0.2      +1.2      +0.2      +0.0      +7.7
BH4XDZ         -0.0      +0.7      +0.0                +2.8
BI4RFP         +5.9      +5.3      +4.3      +4.8      +2.1
CX6VM          -0.4      +0.0      +0.0      +0.0      -1.6
DD5XX          +0.4      +0.4      +0.3      +0.3      +0.4
DE1LON         +0.2      +0.0      +0.0      +0.1      +0.2
DF4XX          +1.1      +1.1      +1.0      +0.9      +1.2
DF7GB          +0.0      +0.0      +0.0      -0.1      +0.0
DJ2BC          +0.1      +0.1      +0.2      +0.1      +0.1
DK0TE          +2.9      +2.5      +2.4      +2.6      +2.9
DK3UA          -0.6      -0.4      -1.1      -0.5      -0.9
DK8NE                                        +0.0      -0.5
DK9IP          +0.2      +0.2      +0.1      +0.2      +0.2
DL0LA          +1.4      +1.3      +1.1      +0.8          
DL3DTH         +0.2      +0.1      +0.3      +0.2      +0.2
DL8LAS         +1.5      +1.3      +1.3      +1.0      +1.4
DL8TG          -0.8      -1.1      -1.1      -0.8      -1.2
DL9GTB                   -0.1      -0.6                    
DM6EE          -0.9      -0.6      -1.2      -0.8      -1.7
DO4DXA         -0.2      -0.2      -0.1      -0.1      +0.1
DR4W           +0.6      +0.3      -6.1     -11.5     -11.1
E28AC          +3.3                                        
EA1RX          +0.5      +0.3                              
EA1URA         +4.7      +4.1      +4.0      +3.9      +2.2
ET3AA          +0.2      +0.0      -0.6      +0.0      -0.1
F4VSQ          +4.9      +5.4                +5.8      +7.3
F5AHD          +0.3      +0.3      -0.1                +0.4
F8DGY          +1.6      +1.2      +1.1      +1.3      +1.6
G0KTN                                        +0.4      +0.7
G3XBI          +0.0                +0.0      +0.2          
G4AON          +0.7      +1.3      +0.8      +1.9          
G4ZFE          -0.3      -0.3      -0.1      +0.1      +0.2
GI4DOH         +0.6      +0.4      +0.4      +0.4      +0.5
GM6DX          +0.5      +0.8      +0.8      +0.5      +0.6
HA1AG          +0.8      +1.0      +1.1      +1.1          
HA1VHF         +0.1      +0.1      +0.1      +0.1      +0.4
HA5PP                                                  +1.5
HA6PX          -0.8      -0.5      -0.5      -0.7      +0.2
HA7GN          +0.3      +0.7      +0.7      +0.8      +1.0
HA8TKS                             +0.1      +0.0          
HB9BXE         +1.9      +1.3      +1.1      +1.3      +1.6
HB9DCO         -0.1      -0.1      -0.1      -0.1      +0.0
HB9JCB         +1.8      +1.6      +1.4      +1.4      +1.6
HG8A           -0.0      -0.1      -0.1      +0.1      +0.5
HS8KVH                                       -0.6          
IK3STG         +1.6      +1.2      +1.6      +1.5      +1.5
IK4VET-1       +3.0      +3.0      +2.7      +3.0      +3.2
IK4VET         +3.1                                        
JA4ZRK         -0.8      +0.1      -0.0      +0.0      -0.1
JH7CSU1        +5.4      +3.4      +2.9      +2.9      +3.6
JI1HFJ         -2.8      -6.4      -6.2                -5.4
JJ2VLY         +1.8      +1.5      +1.8      +1.4      +1.7
JQ1BVI         +0.0      +0.4      -0.0      +0.2      +0.2
K1TTT          -0.3      -0.4      -0.3      -0.2      -0.4
K3PA                                                   -0.0
K3PA-1         -0.1      +0.1      +0.0      -0.2      +0.1
K4PP           +0.6      +0.3      +0.3      +0.2      +0.4
K4XD          +23.5     +23.3     +24.1     +25.3     +25.0
K5TR           +0.4      +0.1      +0.2      +0.4      +0.2
K7EG           +1.8      +0.9      +0.7      +1.1      +1.5
K7MJG          +0.7      +0.0      +0.4      -0.1      +0.4
K9IMM          +0.2      +0.4      +0.2      +0.2      +0.4
K9LC           +0.0      +0.1      -0.1      +0.1      +0.2
K9TM-4         +0.6      +0.7      +0.5      +0.3      +0.3
KC0VKN         -0.8      -0.7      -0.5      -0.8      -1.3
KC4YVA         +5.4      +5.0      +4.1      +3.8      +4.4
KD2OGR         -0.8      -0.3      -0.3      -0.3      -0.1
KD7YZ          +1.0      +1.0      +0.6      +0.6      +0.6
KH6LC          +0.0      +0.0      +0.6      +0.0      +0.0
KM3T           +0.2      +0.0      +0.4      -0.0      +0.0
KM3T-2         -0.2      -0.2      -0.2      -0.1      -0.2
KO7SS          +0.2      +1.0      +0.3      -0.0      -0.2
KO7SS-7        +1.2      +0.3      +0.6                    
KQ8M           +8.0      +5.9      +5.4      +6.0      +4.9
KU7T           +1.1      +0.6      +0.4      +0.7      +0.7
KV4TT                              +0.4      +0.4      -0.4
LA6TPA         +2.5      +1.1      +0.7      +1.2      +0.8
LU1MAW                  +14.3     +13.2                    
LZ3CB          +0.1      -0.0      +0.3      -0.1      -0.0
LZ4AE          +1.7      +1.7      +1.1      +1.2      +1.5
LZ4UX          -0.3      -0.2      -0.1      -0.3      -0.2
LZ7AA          +0.4      +0.3      +0.1      +0.1      +0.4
MM0ZBH         -0.1      +0.1      -0.0      -0.3      -0.1
N4RLI          -2.2      -3.0                -0.7          
N4TVC          +0.9      +0.6      +0.5      +0.5      +0.5
N4ZR           +0.3      -0.2      -0.2      -0.0      +0.2
N6TV           +0.5      +0.5      +0.6      +0.5      +0.6
N7TUG          +2.4      +0.8      +0.7      +1.4      +2.1
N9MKC          +0.0      -0.1      -0.0      -0.1      -0.0
NA0B           +1.2      -0.2      -0.7      -0.8      +0.1
NC7J           +1.3      +0.9      +0.5      +0.6      +0.6
OE6ADD         +1.3      +1.4      +1.1      +1.3      +1.4
OE9GHV         -0.0      -0.1      -0.0      +0.0      -0.0
OG73X                                                  +0.5
OH6BG          +0.5      -0.0                          +1.7
OL7M           +1.4      +1.6      +1.2      +1.2      +1.5
ON3URE         +0.5      +0.3      +0.8      +0.3      +1.0
ON6ZQ          +1.1      +0.8      +0.9      +0.9      +1.0
PA0MBO         -0.0                                        
PA2SQ                    +1.9      +4.7      +0.2      +5.5
PE1RDP                  +11.4                              
PJ2A           -1.5                                        
R6YY           +0.7      +2.7                +1.1      +0.6
RK3TD          -0.7      -0.7      -0.6      -0.8      -0.9
RN4WA          -0.0      +0.2      +0.3      -0.1      +0.1
RU9CZD         +3.6      +3.3      +1.9      +3.0      +3.0
S50ARX         +0.6      +1.0      +1.0      +0.4      +1.1
SE5E           -0.1      -0.1      +0.1      -0.0      -0.2
SJ2W           +0.1      +0.1      +0.2      +0.2      +0.2
SM0TCZ         +1.9      +1.4      +0.4      +1.5      +2.0
SM6FMB         +0.1      +0.1      +0.3      +0.1      +0.2
SM7IUN         +0.1      -0.1      -0.0      -0.2      +0.0
SP8R           +0.0      +0.4      +0.6      +0.7      +1.1
SV1CDN        +11.8     +12.3     +10.7     +11.7     +11.6
SV8RV          +0.4      -0.4      -0.1      -0.2      +0.1
SZ1A           +4.1      +3.2      +2.8      +4.2      +2.6
TF3Y           -0.5      -0.5      -0.7      -0.4      -0.5
TF4X           -1.4      -1.4      -1.5      -1.4      -1.6
UA0S           -2.0      -1.8      -2.6      -3.3      -2.7
UY2RA          +0.3      +0.0      +0.7      +0.1      +0.5
V51YJ          +1.3      +1.7      +0.7      +1.0      +0.9
VE2WU          -0.5      +0.4      +0.7      +0.2      -0.0
VE6AO          -0.5      -0.7      -0.4      -0.2      -0.4
VE6JY          +0.3      +0.4      +0.3      +0.5      +0.4
VE6WZ          +2.6      +1.8      +1.4      +1.9      +2.1
VE7AB          +1.1      +0.0                +1.5      +0.6
VE7CC          +1.0      +0.2      +0.3      +0.3      +0.3
VK2GEL         +2.8      +0.0                              
VK3RASA        +0.3      -1.0      -0.9      -1.0      -0.4
VK4CT          -2.2      -3.8      -1.8      -0.7      -0.8
VK6ANC         -1.7      -2.1      -1.6      -0.9      -0.9
VU2PTT         -0.1      +0.4      +0.1      -0.1      -0.2
VY0ERC         -0.8      +0.0                +0.0      +0.0
W1NT-2         -0.6      -0.7      -0.7      -0.6      -0.7
W1NT-6         +0.0      -0.1      -0.1      +0.1      -0.0
W2AXR          +1.3                +0.6      +1.0      +0.8
W2LB           +3.8      +1.4      +1.8      +5.5          
W2MV           +0.1      +0.5      +0.4      +0.2      +0.6
W3LPL          +1.3      +1.4      +1.3      +1.4          
W3OA           +0.6      +0.2      +0.0      +0.2      +0.1
W3UA           +3.9      +3.9      +3.5      +3.8      +3.9
W4AX           +4.7      +4.9      +3.4      +3.7      +4.0
W4KAZ          -0.4      -0.1      -0.1      +0.2      +0.2
W6YX           +0.1      +0.4      +0.6      +0.6      +0.5
W7HR           +1.1      +0.6      +0.0      +0.2      +0.8
W8WTS          -0.4      -0.9      -0.7      -0.6      -0.3
W8WWV          +0.5      +0.3      +0.4      +0.4      +0.4
WA7LNW         -0.6      -0.9      -0.7      -0.9      -0.7
WA9VEE                   +0.0      +0.0                +0.0
WB6BEE         -0.2      -0.1      -0.0      -0.1      -0.1
WC2L           +0.3      +0.3      +0.4      +0.4      +0.4
WE9V           +1.3      +1.0      +0.9      +0.7      +1.3
WF7T           +0.2      +0.7      +0.7      +0.9      +0.0
WS3W           +0.0      +0.5      -1.6      -2.1      -1.1
WZ7I           -0.1      +0.1      +0.0      +0.0      +0.1
ZL2BR                                                  -7.1
ZL4YL          +2.7      +2.3      +1.4      +0.6      +1.2

Last updated 2021-08-06 00:10:26 UTC

Activity statistics

Summary of unique calls spotted and active skimmers per band and continent.

RBN activity between 2021-08-05 00:00 and 23:59 UTC.
243951 spots with 6909 unique callsigns from 170 active skimmers.

        Unique callsigns spotted per continent and band
---------------------------------------------------------------
    160m  80m  60m  40m  30m  20m  17m  15m  12m  10m   6m
AF     0    9    1   40    5   46    3    4    0    1    2   90
AS     6   36    0  325   58  254   67   63   13   10   32  672
EU    42  402   67 1226  536 1877  317  192   35  248   81 3547
NA    21  242   22 1192  288  966  127   87   21  164  126 2388
OC     6   12    1   56    9   34    3    4    0    1    2  102
SA     1   11    0   42    2   51   13   18    1    3    0  110
      76  712   91 2881  898 3228  530  368   70  427  243

        Active skimmers per continent and band
---------------------------------------------------------------
    160m  80m  60m  40m  30m  20m  17m  15m  12m  10m   6m
AF     1    2    0    4    3    4    4    4    2    1    0    4
AS     3    9    0   20   15   20   17   20   10    6    7   21
EU    38   56   12   61   55   63   42   54   25   48   15   69
NA    38   45   14   53   42   55   39   43   24   37   15   64
OC     5    6    0    8    6    7    3    4    0    0    0    9
SA     1    1    0    2    2    3    2    2    1    0    0    3
      86  119   26  148  123  152  107  127   62   92   37

Last updated 2021-08-06 00:10:47 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.

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.

AC0C-1 DF7GB K3PA-1 KM3T LZ3CB OE9GHV WB6BEE 

Last updated 2021-08-06 00:10:47 UTC