Have you checked out the "Poor Man's Spectrum Analyzer" at=20
<www.science-workshop.com/> ?  They may have circuit blocks that are=20
useful for you.

Searching out "poor mans spectrum analyzer" yields lots of hits -=20
some of those may also be useful.

dwayne


At 01:15 PM 5/24/2012, Herbert Graf wrote:
>Hello all,
>
>well, after a long delay, I've been able to dedicate a little time to my
>idle project: a home built spectrum analyzer based on a TV tuner front
>end.
>
>I've found what I believe the perfect tuner for me (mostly because it's
>something I have in my hands):
>
>http://www.datasheetarchive.com/indexdl/Datasheet-028/DSA00488547.pdf
>
>It's a Temic 4036 RF front end module. I found it on a WinTV PC TV tuner
>PCI card.
>
>It's a I2C based tuner, with single 5V power supply (has an onboard
>DC-DC to get the 33V needed by the tuner). I stuck the card in a PC,
>booted Ubuntu, attached a protocol analyzer (thank you beta version of
>the BitScope software, was a major time saver!) on the I2C pins, started
>TVTime and changed channels. The module is being programmed exactly as
>the datasheet says it should be!
>
>So, with that out of the way, what would be my next step?
>
>First off, the module outputs CVBS (at baseband), and something labelled
>IF2 (at 45.75 MHZ). Obviously I need an RSSI circuit. But do I first
>have to "tune" the output somehow?
>
>What I'm envisioning (and note, I no NOTHING about RF stuff, so this is
>very much a learning project for me) is using a second tuner (some sort
>of home built one chip thing with RSSI output perhaps?) that "tunes"
>somewhere in the CVBS output with a bandwidth of say 10kHz? So basically
>sweeping would be two steps, set the TV tuner to a channel, then sweep
>the second tuner across the ~4MHz bandwidth of the CVBS or IF output.
>Then step the TV tuner to the next range, and sweep the CVBS or IF
>output. Combined I could get everything I need.
>
>Does this sound at all reasonable or am I WAY out of wack here?
>
>Should use the CVBS or the IF output?
>
>Anybody have chip recommendations for how I might build the second
>tuner, one hopefully with an RSSI output?
>
>Is there a simpler way to what I'm after? What kind of resolution should
>I aim for?
>
>Thanks for any pointers!
>
>TTYL
>
>--
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--=20
Dwayne Reid   <dwayner@planet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(780) 489-3199 voice          (780) 487-6397 fax
www.trinity-electronics.com
Custom Electronics Design and Manufacturing

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