what does it mean UWB systems is carrierless?

Hi there
what does it mean UWB systems is carrierless?
UWB does have modulation and modulation actually means carrier...
But i dont get it, what does it mean carrierless?
Thx

< what does it mean carrierless?
I guess easier to understand SSB signal
https://en.wikipedia.org/wiki/Single...and_modulation

no, modulation doesn't mean carrier
modulation is the information that can be superimposed onto a carrier
and as yura717 is hinting at in his link, the carrier can be suppressed as in SSB ( single sideband) DSB suppressed carrier ( Double Sideband)
Double sideband with carrier is basically AM

UWB or spread-spectrum transmission doesn't have a single freq. that can be considered the carrier freq

Apart from the SSB link in yura's post, also google spread spectrum transmission techniques

cheers
Dave