Re: $129 spectrum analyzer Re: [Open-graphics] PCIe know-how?
James Richard Tyrer wrote: There is no filter response shape to worry about. This has always been a serious issue with an analog spectrum analyzer. In theory, it should be a Gaussian distribution. This is not realizable because it would have to extent to infinity. But even taking a polynomial distribution, it is still impossible to exactly realize a band pass filter with that response function. And, the filter also needs to have linear phase response. So, this -- the scan filter response shape -- is an important feature and something that is better in more expensive units. I suspect that the band pass response shape in these devices is not anything near a Gaussian response or linear phase. -- JRT ___ Open-graphics mailing list Open-graphics@duskglow.com http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
Re: $129 spectrum analyzer Re: [Open-graphics] PCIe know-how?
Dieter wrote: You can get a 2.4 GHz spectrum analyzer for $129. http://www.dunehaven.com/lcsa.html That's expensive :-). This one is just $99: http://www.smallnetbuilder.com/content/view/24766/96/ (nice detailed article). ciao, Carlo ___ Open-graphics mailing list Open-graphics@duskglow.com http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
Re: $129 spectrum analyzer Re: [Open-graphics] PCIe know-how?
Carlo Salinari wrote: Dieter wrote: You can get a 2.4 GHz spectrum analyzer for $129. http://www.dunehaven.com/lcsa.html That's expensive :-). This one is just $99: http://www.smallnetbuilder.com/content/view/24766/96/ (nice detailed article). Nice piece of hardware. But, like the other device, this is a signal strength meter/WiFi network detector -- not a spectrum analyzer suitable to do Fourier analysis of an AC signal. -- JRT ___ Open-graphics mailing list Open-graphics@duskglow.com http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
Re: $129 spectrum analyzer Re: [Open-graphics] PCIe know-how?
Dieter wrote: So the question is whether you can make a good PC card digital oscilloscope for $100.00. You need an oscillator, frequency divider, PLL, sample hold, and DAC as well as the PCIe interface. I seriously doubt that this is possible for $100.00 but it does depend on the maximum input frequency you wish to use, sample rate, and the accuracy (and number of bits) needed. Actually, you can spend over $100. on a good DAC You can get a 2.4 GHz spectrum analyzer for $129. http://www.dunehaven.com/lcsa.html If a 2.4 GHz spectrum analyzer can be sold for $129, why not a lower frequency unit? This device isn't really a digital spectrum analyzer. It is a sweeping RF signal strength meter. Such a device is quite useful but it isn't going to work for lower frequencies. Okay, I'll bite. What's the difference between a spectrum analyzer and a sweeping meter? Don't most (perhaps all) analog spectrum analyzers work by sweeping a filter through the desired frequency range? There isn't a great deal of difference between how this thing works and an *analog* spectrum analyzer. This thing doesn't sweep, it collects data on individual frequencies. However, there is a great deal of difference between this thing and a *digital* spectrum analyzer which computes the Fourier series for a wave form in software. There is no filter response shape to worry about. -- JRT ___ Open-graphics mailing list Open-graphics@duskglow.com http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
$129 spectrum analyzer Re: [Open-graphics] PCIe know-how?
So the question is whether you can make a good PC card digital oscilloscope for $100.00. You need an oscillator, frequency divider, PLL, sample hold, and DAC as well as the PCIe interface. I seriously doubt that this is possible for $100.00 but it does depend on the maximum input frequency you wish to use, sample rate, and the accuracy (and number of bits) needed. Actually, you can spend over $100. on a good DAC You can get a 2.4 GHz spectrum analyzer for $129. http://www.dunehaven.com/lcsa.html If a 2.4 GHz spectrum analyzer can be sold for $129, why not a lower frequency unit? ___ Open-graphics mailing list Open-graphics@duskglow.com http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
Re: $129 spectrum analyzer Re: [Open-graphics] PCIe know-how?
On 3/5/07, Dieter [EMAIL PROTECTED] wrote: You can get a 2.4 GHz spectrum analyzer for $129. http://www.dunehaven.com/lcsa.html If a 2.4 GHz spectrum analyzer can be sold for $129, why not a lower frequency unit? My instinct is to wonder what it's missing. I've found some great deals before, just to find that I had gotten a shoddy product that didn't work well and fell apart. -- Timothy Normand Miller http://www.cse.ohio-state.edu/~millerti Favorite book: The Design of Everyday Things, Donald A. Norman, ISBN 0-465-06710-7 ___ Open-graphics mailing list Open-graphics@duskglow.com http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
Re: $129 spectrum analyzer Re: [Open-graphics] PCIe know-how?
Dieter wrote: So the question is whether you can make a good PC card digital oscilloscope for $100.00. You need an oscillator, frequency divider, PLL, sample hold, and DAC as well as the PCIe interface. I seriously doubt that this is possible for $100.00 but it does depend on the maximum input frequency you wish to use, sample rate, and the accuracy (and number of bits) needed. Actually, you can spend over $100. on a good DAC You can get a 2.4 GHz spectrum analyzer for $129. http://www.dunehaven.com/lcsa.html If a 2.4 GHz spectrum analyzer can be sold for $129, why not a lower frequency unit? This device isn't really a digital spectrum analyzer. It is a sweeping RF signal strength meter. Such a device is quite useful but it isn't going to work for lower frequencies. -- JRT ___ Open-graphics mailing list Open-graphics@duskglow.com http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
Re: $129 spectrum analyzer Re: [Open-graphics] PCIe know-how?
Dieter wrote: So the question is whether you can make a good PC card digital oscilloscope for $100.00. You need an oscillator, frequency divider, PLL, sample hold, and DAC as well as the PCIe interface. I seriously doubt that this is possible for $100.00 but it does depend on the maximum input frequency you wish to use, sample rate, and the accuracy (and number of bits) needed. Actually, you can spend over $100. on a good DAC You can get a 2.4 GHz spectrum analyzer for $129. http://www.dunehaven.com/lcsa.html If a 2.4 GHz spectrum analyzer can be sold for $129, why not a lower frequency unit? The reason it only does 2.4GHz is because it just uses one special-purpose mass-produced IC that can only do 2.4GHz (due to it having internal coupling capacitors and a frequency synthesizer with limited range). Real spectrum analysers only come from analog and RF designers. That 2.4GHz thing is nothing much more than cutting and pasting circuits off the data sheet. To cover arbitrary frequency ranges with decent performance, you'll need to design wideband fast-sweeping frequency synthesizers and multiple intermediate frequency amplifier and filter stages. -- Russell Shaw, B.Eng, M.Eng(Research) ___ Open-graphics mailing list Open-graphics@duskglow.com http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
Re: $129 spectrum analyzer Re: [Open-graphics] PCIe know-how?
So the question is whether you can make a good PC card digital oscilloscope for $100.00. You need an oscillator, frequency divider, PLL, sample hold, and DAC as well as the PCIe interface. I seriously doubt that this is possible for $100.00 but it does depend on the maximum input frequency you wish to use, sample rate, and the accuracy (and number of bits) needed. Actually, you can spend over $100. on a good DAC You can get a 2.4 GHz spectrum analyzer for $129. http://www.dunehaven.com/lcsa.html If a 2.4 GHz spectrum analyzer can be sold for $129, why not a lower frequency unit? This device isn't really a digital spectrum analyzer. It is a sweeping RF signal strength meter. Such a device is quite useful but it isn't going to work for lower frequencies. Okay, I'll bite. What's the difference between a spectrum analyzer and a sweeping meter? Don't most (perhaps all) analog spectrum analyzers work by sweeping a filter through the desired frequency range? BTW, I'm not suggesting that the $129 unit can do the things that a $ HP or Tek SA can do. ___ Open-graphics mailing list Open-graphics@duskglow.com http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
