On 09/07/2021 16:54, Al Pawlowski wrote:
Given FT8’s growth, a built-in way to ask for a jump to an clear frequency, or
channel, certainly seems like a good idea. However, a larger channel is what
really seems to be needed. This could be accomplished (other mode user squawks
not considered) by just setting the WSJTx, and radio, rx bandwidths higher.
With my setup, I can work up to a 4500Hz FT8 channel. If more users were to use
larger BW, it might be a significant congestion relief.
Though my rig can go to 9999Hz rx BW and WSJTx v2.4.0 set to 6000Hz, 4500kHz is
all I can get - above that, decodes stop and the waterfall fills with noise. I
wonder if the limit is due to my CPU speed (usage increases with BW and channel
activity) or a WSJTx thing. Reports from others doing larger BW would be
interesting.
Al Pawlowski, K6AVP
Los Osos, CA USA
Hi Al,
the Rx bandwidth of the WSJT-X application is limited to around 5000 Hz,
this is fundamental as the first processing step is to down-sample the
audio source to 12,000 Hz which in turn is LP filtered to 5000 Hz to
eliminate artefact aliases due to the wrap around nature of DFT.
73
Bill
G4WJS.
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