[PPRAANet] Fwd: Fwd: double sideband supressed carrier

[John Bloodgood]

Attachments are generally not allowed on the reflectors.

Traditional AM is double sideband, full carrier where basically half the power is eaten up by the carrier which contains no information.  Not only is most of the power wasted, but since the information on each sideband is the same, it wastes bandwidth.

DSB-SC (double sideband - suppressed carrier) is essentially AM, but the carrier is removed so all the power goes into the modulated signals carrying the information.  Much better from a power standpoint, but still wastes bandwidth.

ISB (independent sideband) is kind of like DSB-SC in that it has no carrier, except the upper and lower sidebands have different information on them, such as voice on the lower sideband and data on the upper sideband.  Note that some systems have multiple upper sidebands and lower sidebands  such as USB2, USB1, LSB1, and LSB2, all containing different information.  Used to use ISB a lot for long haul comm in the military when in the field/deployed including 2 sideband and 4 sideband systems.

SSB (single sideband) uses only one of the two sidebands (LSB or USB) and has no carrier.

AME (AM equivalent AKA SSB-RC) is essentially SSB, but with a reduced carrier so that it can be demodulated by a normal AM radio, but it takes half the bandwidth and puts more power in the information than AM does.








John Bloodgood, KD0SFY


________________________________
From: ppraanet-bounces at mailman.qth.net <ppraanet-bounces at mailman.qth.net> on behalf of Glenn <n3ulw at comcast.net>
Sent: Wednesday, January 2, 2019 3:41 PM
To: ***Reflector PPRAA***
Subject: [PPRAANet] Fwd: Fwd: double sideband supressed carrier


I had to strip off the attachments as it made the message to big!

This topic came up on the Thursday night PPRAA net. Dick, KD8EQ took it
upon himself to find the answer. Thanks Dick!!

Glenn

n3ulw

P.S. next time in your car the radio's, in newer cars, that shows the
station and what song is playing and with sound is using DSB-SC


RDS is one place where DSB-SC is used.

73 Dick KD8EQ

Links

https://en.wikipedia.org/wiki/Double-sideband_suppressed-carrier_transmission

https://en.wikipedia.org/wiki/Radio_Data_System

Subject:         Fwd: double sideband supressed carrier
Date:    Wed, 2 Jan 2019 15:04:45 -0700
From:    Glenn <n3ulw at comcast.net>
To:      ***Reflector PPRAA*** <ppraanet at mailman.qth.net>

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