For what it's worth, I think that you are basically on the right track, Herbert. Good Tektronix or HP spectrum analyzers have resolution bandwidths down to at least 1kHz and many go down to 100Hz or even 10Hz (or even lower but that is almost always done in post-processing by digitizing and then doing an FFT on each block of samples). You will see the terms "resolution bandwidth (RBW)" and "video bandwidth (VBW)". Then there is also averaging or peak detection on top of this. The distinction is as follows: RBW is the bandwidth of the RF chain before the detector (power measurement device). VBW is the bandwidth of the signal chain after the detector. Averaging or peak detection then refer to how the digital storage portion of the device records samples - it takes several samples per time step and saves only one sample and it can save either the average of the samples or the highest one. The RBW determines the RF noise floor and also how close two signals can be and still be resolved by the analyzer into two separate peaks. The VBW determines how finely the analyzer can discriminate between two different power levels. This is because a narrower VBW removes noise in the detector output. I believe that the averaging/peak detection is somewhat redundant with the VBW - in other words, they roughly have the same kind of effect on the signal as decreasing or increasing the VBW, except that the analyzer often allows you to average signals below some power level and peak-detect those above that same threshold, whereas VBW is fixed for an entire scan. On Thu, May 24, 2012 at 11:38 PM, Herbert Graf wrote: > I have seen that before. That site seems to just offer for purchase the d= etails, or parts. > > I will have a look to see what kind of hits "poor mans spectrum analyzer"= gets me. Thanks for the pointer. > > TTYL > > > On 2012-05-24, at 5:48 PM, Dwayne Reid wrote: > >> Have you checked out the "Poor Man's Spectrum Analyzer" at >> ? =A0They may have circuit blocks that are >> useful for you. >> >> Searching out "poor mans spectrum analyzer" yields lots of hits - >> 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 m= y >>> 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 tune= r >>> 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, starte= d >>> 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 labelle= d >>> 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 basicall= y >>> 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 shoul= d >>> I aim for? >>> >>> Thanks for any pointers! >>> >>> TTYL >>> >>> -- >>> http://www.piclist.com PIC/SX FAQ & list archive >>> View/change your membership options at >>> http://mailman.mit.edu/mailman/listinfo/piclist >> >> >> -- >> Dwayne Reid =A0 >> Trinity Electronics Systems Ltd =A0 =A0Edmonton, AB, CANADA >> (780) 489-3199 voice =A0 =A0 =A0 =A0 =A0(780) 487-6397 fax >> www.trinity-electronics.com >> Custom Electronics Design and Manufacturing >> >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .