Post by thread:[EE] TV Tuner Based Spectrum Analyzer

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

Have you checked out the "Poor Man's Spectrum Analyzer" at <http://www.science-workshop.com/> ? They 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: {Quote hidden}>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 >

I have seen that before. That site seems to just offer for purchase the details, 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: {Quote hidden}> Have you checked out the "Poor Man's Spectrum Analyzer" at > <http://www.science-workshop.com/> ? They 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 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): >> >> 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 >> >> -

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 <spam_OUThkgrafTakeThisOuTgmail.com> wrote: {Quote hidden}> I have seen that before. That site seems to just offer for purchase the details, 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 >> <http://www.science-workshop.com/> ? They 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 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): >>> >>> 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 >>> >>> --

>From what I recall of a kit using a tuner unit out of a vcr, the was a VCO that did the tuning, and a RSSI voltage out. A sawtooth was fed to the VCO input, and X input of a scope. The RSSI was fed to the Y input of the scope. This was a kit available from Dick Smith Electronics New Zealand in the late 90's Herbert Graf <EraseMEhkgrafspam_OUTTakeThisOuTgmail.com> wrote: Wow, that would be awesome! Might someone here have a copy of one of these projects they could scan and send to me? Thanks! TTYL On Sun, 2012-05-27 at 19:54 +1000, cdb wrote: {Quote hidden}> Of not much help (because I can't find mycopy), Electronics Australia > (defunct) did a Spectrum Analyser project based on a TV tuner, I can't > recall how the sweep component worked. I vaguely recall an early Elektor > magazine (70's or 80's) also did one. > > Colin > -- > cdb, colinspam_OUTbtech-online.co.uk on 27/05/2012 > > Web presence: http://www.btech-online.co.uk > > Hosted by: http://www.justhost.com.au > > > This email is to be considered private if addressed to a named individual > or Personnel Department, and public if addressed to a blog, forum or news > article. > > > >