Passive ionospheric sounding and ranging -The G3PLX Project

Excepted frequencies

It's worth knowing what frequencies are likely to be blanked, because you can occassionally choose one by mistake and wonder why there's no chirps on it. The Official list of channels to be blanked looks like this.

Most sounders seem to stick to this. There are some exceptions, and some strange extra blanked bands. For example Falklands is blanked over the entire CB band but not the 28MHz amateur band.

Frequency list

2091.0	Distress and Safety (Japan only)
2174.5	Distress and Safety, Narrow Band Direct Printing (NBDP) telegraphy - (GMDSS)
2182.0	(carrier) Distress and Safety (GMDSS)
2187.5	Distress and Safety, Digital SELCAll (DSC) (GMDSS)
2500.0	Standard frequency and time
3023.0	(carrier) Search and Rescue (GMDSS)
4000.0	Standard frequency and time (FN 516) (Region 3)
4125.0	(carrier) Distress, Safety, Search and Rescue (GMDSS)
4177.5	Distress and Safety (NBDP) (GMDSS)
4207.5	Distress and Safety (DSC) (GMDSS)
4209.5	Meteorological, navigational warnings, urgent Info (GMDSS)
4210.0	Maritime safety information (NBDP) (GMDSS)
5000.0	Standard frequency and time
5680.0	(carrier) Search and Rescue (GMDSS)
6215.0	(carrier) Distress and Safety (GMDSS)
6268.0	Distress and Safety (NBDP) (GMDSS)
6312.0	Distress and Safety (DSC) (GMDSS)
6314.0	Maritime safety information (NBDP) (GMDSS)
8000.0	Standard frequency and time (FN 529) (Region 3)
10000.0	Standard frequency and time
12290.0	(carrier) Distress and Safety (GMDSS)
12520.0	Distress and Safety (NBDP) (GMDSS)
12577.0	Distress and Safety (DSC) (GMDSS)
12579.0	Maritime safety information (NBDP) (GMDSS)
13360-13410	Fixed service/radio astronomy (Regions 1,2, and 3)
15000.0	Standard frequency and time
16000.0	Standard frequency and time (FN 536) (Region 3)
16420.0	(carrier) Distress and Safety (GMDSS)
16695.0	Distress and Safety (NBDP) (GMDSS)
16804.5	Distress and Safety (DSC) (GMDSS)
16806.5	Maritime safety information (NBDP) (GMDSS)
19680.5	Maritime safety information (NBDP) (GMDSS)
20000.0	Standard frequency and time
21850-21870	Region 1 (R) channels in Bulgaria, Hungary, Mongolia, Poland, Czechoslovakia, and Russia
22376.0	Maritime safety information (NBDP) (GMDSS)
25000.0	Standard frequency and time
25550-25670	Radio astronomy (Regions 1, 2, and 3) FN 545
26100.5	Maritime safety information (NBDP) (GMDSS)
27524.0	Meteorological aid (Japan only)

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Copyright John Coppens, 2003 -

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