locked Why frequencies steps are not locked on 50Hz? #frequency


Pedro Silva <cs7bac@...>
 

Hi!
I believe someone already had this idea before, but anyway...
I think it would be much more organized and band efficient if the frequency choice for Tx and Rx was only possible in 50Hz steps, as this is the chunk for one FT8 tone.
As per my observation the spectrum is always messy due to a lot of people transmitting in completely off-position frequencies, and when many people do the same we reduce the effective quantity of available slots, as many people overlap one another.
Thanks!
73
CS7BAC
Pedro Silva


Alan G4ZFQ
 

I think it would be much more organized and band efficient if the frequency choice for Tx and Rx was only possible in 50Hz steps, as this is the chunk for one FT8 tone.
Pedro,

This would be very inefficient:-)
The decoders work very well on signals which are very close together.

73 Alan G4ZFQ


Ellis Birt (G7SAI)
 

To elaborate, if you consider the ft8 band to be 2kHz wide, that is 40 50Hz bands. The decoder can discriminate between signals much closer, I.e. overlapping. A 10Hz step can accommodate 200 signals.

Now factor in people transmitting 'over' others signals because they cannot hear them. If there are only 40 slots, this is more likely. It is highly unlikely two signals will exactly overlay each other, allowing the decoder to decode both.

The elephant in the room is the strong local station of the one over-modulating which can overwhelm your receive path.


Pedro Silva <cs7bac@...>
 

Yes, i got it and i had no clue that the decoder can handle much smaller
chunks like this.
in this case, no doubt we are in the perfect path.
Thanks guys!
73

On Wed, May 4, 2022 at 8:29 AM Ellis Birt (G7SAI) via groups.io <ellis.birt=
googlemail.com@groups.io> wrote:

To elaborate, if you consider the ft8 band to be 2kHz wide, that is 40
50Hz bands. The decoder can discriminate between signals much closer, I.e.
overlapping. A 10Hz step can accommodate 200 signals.

Now factor in people transmitting 'over' others signals because they
cannot hear them. If there are only 40 slots, this is more likely. It is
highly unlikely two signals will exactly overlay each other, allowing the
decoder to decode both.

The elephant in the room is the strong local station of the one
over-modulating which can overwhelm your receive path.