Thank you for the helpful information, Vasile. I appreciate it. I do have a Hewlett Packard Spectrum analyzer, a Tektronics Spectrum analyzer and another in my lab for actually looking for harmonics, transients, etc. But I want to put one in an instrument I am designing and I was hoping to find someone who has already designed and built one as a guide line that I could follow. Thank you. You are the recourse I was hoping for. I was hoping also to find some receiver components and IF components to design into the overall circuit. I have see the front end for receivers in small metal boxes in TVs and Radios. I built some oscillators but the sinewave distorted over a range of 10MHz. I think I need to readjust the LC ratios. That will probably lower the Q but it may not matter if selective sharp resonance is not a factor. I find that theory only works after you adjust it by trial and error and error and error :-) I am very grateful for your help. You have anticipated several of my questions. Thank you. Regards Rich ----- Original Message ----- From: "Vasile Surducan" To: "Microcontroller discussion list - Public." Sent: Monday, June 05, 2006 12:49 AM Subject: Re: EE Spectrum Analyzer circuit > Rich, > There are many like this. Before buying a spectrum analyzer I've > played with many > "homebrewed" solutions. For 0 to 20Mhz I have two clues for the main > oscillator: > 1. for a programable span rate use AD9851, a nice DDS, unfortunately > you'll not be able to get a SNR better than 60dB (SFDR=40dBc) only > with programable filters which are quite difficult to buid and to > switch. > This is not a masked AD (no more modules available left): > http://www.surducan.netfirms.com/modul.html > at the bottom of the page, just for the pictures > > 2. for a fixed span of 28MHz there are some very cheap FM single IC > tuner covering 80-108MHz with fixed sweep time. Mixing the result with > 80MHz you'll be able to get 80+/-(80...108) = 0 ...+/- 28MHz. > Filtering the unwanted image and bingo (not easy!). SNR could be > better if the 80MHz will be clean (at least 100-110 dBc) > > 3. using a fractional PLL looks to be the best choice but at this > small frequency is difficult to found (you have to design your own > PLL) and you need a good VCO in this range. However theoretically you > could go up to 80-90dB SNR (I didn't succeed yet). > > I don't want to make you some false illusions, you can't do it without > already having a spectrum analyzer (or at least an oscilloscope with > FFT analyses) because the border of 60dB SNR is very difficult to pass > (seems to be much difficult than from Mexic to USA...:) > > greetings, > Vasile > > On 6/5/06, Rich Graziano wrote: >> Thank you for the reply Vasile. >> Very useful. >> Rich >> ----- Original Message ----- >> From: "Vasile Surducan" >> To: "Microcontroller discussion list - Public." >> Sent: Sunday, June 04, 2006 3:50 AM >> Subject: Re: EE Spectrum Analyzer circuit >> >> >> > Just to make an ideea about what a spectrum analyzer means >> > (using multiple FI stages and no DDS or IQ arhitecture): >> > >> > http://www.hanssummers.com/electronics/equipment/spectrumanalyser/index.htm >> > >> > greetings, >> > Vasile >> > >> > On 6/4/06, Rich Graziano wrote: >> >> Hi All: Does anyone have a proven circuit for a spectrum analyzer for >> >> a >> >> frequency range 20 Hz to 20 MHz:? Something I could fit on a small PC >> >> Card? >> >> Rich >> >> -- >> >> 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 >> >> -- >> 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 -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist