[opendtv] Re: White paper from CEA
- From: Richard Hollandsworth <holl_ands@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Thu, 3 Nov 2005 23:55:39 -0800 (PST)
But an IF derived AGC only responds to on-channel and adjacent channel signals.
A typical RF Front End might have a 3 dB bandwidth that is not much more than
three channels wide. I've only seen a few claims re RF bandwith, mostly in the
15-30 MHz range, depending on the operating frequency (Q less than 40). Very
few Tuner manufacturers include this (or overload) in their posted spec sheets.
[Probably because they are just too embarassed...]
With only a single stage of L-C tuning and the relatively low Q of typical
varactors, I wouldn't expect very much suppression several channels away.
These are the "other" signals that can drive a LNA into non-linearity,
preventing reception of weak signals.
<holl_ands>
////////////////////////////////////////
Allen Le Roy Limberg <allimberg@xxxxxxxxxxxx> wrote:
An IF derived AGC control voltage is OK if it is a wideband IF amplifier
driving the AGC detector. One that responds to Adjacent Channel
Interference (ACI). A narrowband IF amplifier using a SAW filter will drive
the demodulator.
Al Limberg
---------------------------------
Yahoo! FareChase - Search multiple travel sites in one click.
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:
- Using the UNSUBSCRIBE command in your user configuration settings at
FreeLists.org
- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
unsubscribe in the subject line.
Other related posts:
