[opendtv] Re: New Microtune tuner
- From: Doug McDonald <mcdonald@xxxxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Fri, 03 Mar 2006 08:20:46 -0600
Richard Hollandsworth wrote:
> FYI: Here is John Norsworthy's Jun2001 article on ,
> "Broadband Tuners for Modern Systems", re. single and
> double conversion tuners:
> http://rfdesign.com/images/archive/0601Norsworthy67.pdf
> and an even older article:
> http://www.elecdesign.com/Globals/PlanetEE/Content/4028.html
> Still not much insight into how well double conversion
> tuner helps when the RF AGC completely desensitizes the
> front end all the time....
>
> They might be suitable for cable when all signals are
> roughly equal...and provides good selectivity...but how
> well will it pull in a much lower level signal in the
> presence of other strong signals????
>
> The key test condition is trying to receive a relatively
> weak signal in the presence of several strong signals.
> Note that -83 dBm A/74 sensitivity number would be
> meaningless, presuming his 34 dB dynamic range adjustment
> range.
>
This is well put. A non-tuned RF stage is simply
unacceptable for OTA use. Period. It would be impossible
to receive a distant signal if any truly local signal
existed, even if they were 200 MHz apart, unless one
utilized an external switchable tuned preamp.
We are in such a position around here, if one uses
a rooftop bi-directional antenna.
Doug McDonald
----------------------------------------------------------------------
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: