But sometimes they can be very helpful indication off where the propagation is coming from. For Scandinavia listen on 27.445 for a type of tone and a clicking noise on 27425. 27.515 there is a similar tone A very good indication of propagation for North America is on 27.185 AM, yes the CB channel 19. If you listen on here and point your beam to the USA there is a very loud, what I can only describe as a rumbling noise the louder this noise the better the propagation, don't get the noise confused with other propagation though. The best times of year to contact various parts of the world.
Same system applies to other areas of the world.
Winter time is the always the best. In summer the sporadic E takes over. South America - all year round with the winter months being the best. South Africa - late August to mid march again winter being the best. Australia - late September to March.