$129 spectrum analyzer Re: [Open-graphics] PCIe know-how?

[James Richard Tyrer]

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