Synchronous Reception - Revision history

Strange Attractor at 16:11, 26 January 2010

2010-01-26T16:11:54Z

← Older revision		Revision as of 16:11, 26 January 2010
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	*[http://www.radio-electronics.com/info/receivers/synchdet/sync_det.php Synchronous Demodulation/Detection ]		*[http://www.radio-electronics.com/info/receivers/synchdet/sync_det.php Synchronous Demodulation/Detection ]
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		+	[[Category:Radio engineering]]

DimBulb: Add a link to sync detector tech note, update description

2007-11-16T18:13:04Z

Add a link to sync detector tech note, update description

← Older revision		Revision as of 18:13, 16 November 2007
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-	'''Synchronous Reception''' is a term that refers to circuitry in a shortwave radio that attempts to eliminate ~~[[Adjacent Channel Interference]], as well as [[Multipath Distortion]], and [[Fading]],~~ in an [[AM]] signal. ~~It works by eliminating~~ the ~~carrier and one sideband from~~ the ~~received signal. The radio then substitutes its own, internally-generated carrier~~ signal. ~~The user~~ of the ~~radio uses a switch to select which sideband~~ is ~~kept,~~ to be ~~combined with~~ the ~~synthesized~~ carrier to ~~produce the audio~~.	+	'''Synchronous Reception''' is a term that refers to circuitry in a shortwave radio that attempts to eliminate distortion in an [[AM]] signal primarily caused by selective fading. Rather than using a diode to convert the signal to audio (envelope detection) the signal is run through a mixer that converts it down to audio frequencies. This type of detector is more complicated than an envelope detector because the oscillator that is fed to the mixer must be locked to the frequency of the original carrier (which may have faded to nothing).

-	Adjacent channel interference can be minimized by choosing the sideband that is farthest from the adjacent signal. If the interfering signal is higher in frequency, then the lower sideband may be more intelligible. Likewise, an interfering station on a lower frequency may be minimized by choosing the upper sideband. Notably, [[Upper Sideband]] is the Manliest of Modes.	+	== See also ==

-	[~~[Multipath Distortion]], caused by signal reception from the transmitter via several different paths, is minimized by the fact that the carrier is synthesized locally~~. ~~Thus, the distortion caused by several carriers being received is reduced; the~~ receivers ~~circuitry is not "confused" as the various paths rise and fall in intensity, since it is using its own, local carrier~~.	+	*[http://www.radio-electronics.com/info/receivers/synchdet/sync_det.php Synchronous Demodulation/Detection ]
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-	~~By the same method, the effects of [[Fading~~]~~] can be minimized. Since the local carrier can be controlled in amplitude, it is not linked to fading of the carrier received from the transmitter.~~	+

Al Fansome: New page: '''Synchronous Reception''' is a term that refers to circuitry in a shortwave radio that attempts to eliminate Adjacent Channel Interference, as well as Multipath Distortion, and [...

2007-11-09T04:37:15Z

New page: '''Synchronous Reception''' is a term that refers to circuitry in a shortwave radio that attempts to eliminate Adjacent Channel Interference, as well as Multipath Distortion, and [...

New page

'''Synchronous Reception''' is a term that refers to circuitry in a shortwave radio that attempts to eliminate [[Adjacent Channel Interference]], as well as [[Multipath Distortion]], and [[Fading]], in an [[AM]] signal. It works by eliminating the carrier and one sideband from the received signal. The radio then substitutes its own, internally-generated carrier signal. The user of the radio uses a switch to select which sideband is kept, to be combined with the synthesized carrier to produce the audio.

Adjacent channel interference can be minimized by choosing the sideband that is farthest from the adjacent signal. If the interfering signal is higher in frequency, then the lower sideband may be more intelligible. Likewise, an interfering station on a lower frequency may be minimized by choosing the upper sideband. Notably, [[Upper Sideband]] is the Manliest of Modes.

[[Multipath Distortion]], caused by signal reception from the transmitter via several different paths, is minimized by the fact that the carrier is synthesized locally. Thus, the distortion caused by several carriers being received is reduced; the receivers circuitry is not "confused" as the various paths rise and fall in intensity, since it is using its own, local carrier.

By the same method, the effects of [[Fading]] can be minimized. Since the local carrier can be controlled in amplitude, it is not linked to fading of the carrier received from the transmitter.