On Mon Sep 01, 2008 at 10:41:29PM +0100, Andy Farnell wrote:
Single sideband modulation.
It comes from radio culture really. In the modulation schemes for analogue broadcast you havethe same spectral model with radio waves as we use for sound synthesis. But using up more bandwidth by having two sidebands is less desirable if you want to squeeze more channels into the same spectrum, so SSB was devised to minimise interference between stations.
the carrier is a really loud sine, relative to the other material . reduced carrier was projected to occur (in the 70s/80s or so), with enough power for a phase reference under typical conditions.. i think -15db or so
so broadcasting the carrier and the duplicate sidebands saves a lot of energy ( in addition to spectrum )
its how Lou from Barcelona running 1.7kW sounds as good as Radio Exterior Espana running 250 kW or something insane
The tradeoff is that fewer sidebands mean less information is carried by the signal.
nope the sidebands are typically identical but frequency mirrored
the main tradeoff is finding the beat frequency, without a carrier. to get the right pitch base for the spectral information. not only do you lose the phase reference, you lose the frequency reference!
Anyone know any novel or unusual patches for SSB. Presumably, for a single frequency you need only a fixed delay.
im thinking about getting a QS1R and using PD for demodulation
should i?