[R-390] OT: IMD distortion measurements

[Jon Schlegel]

Paolo,

This sounds more like a test for Cross Modulation than 
Intermodulation.  In words - How much of the modulation on the 
interfering signal shows up on the unmodulated desired signal.  Does 
this make sense regarding the test requirements you are reading?

Regards,
Jon WA3MVM




At 08:41 PM 1/1/2009 +0100, Paolo Mantovani wrote:
>Hello everybody and happy new year!
>
>I would like to better understand IMD distortion measurements. The 
>manuals of a couple of receivers I own (Siemens E311 and R&S EK-07) 
>say the "resistance to intermodulation" must be:
>
>"Intermodulation <= 10%, with an unmodulated useful input of 50uV 
>and an interfering input of 15mV, modulated m = 50% and 20kHz away" (E311)
>
>and very similarly for the EK-07 but 50mV instead of 15 for the 
>interfering input, this possibly meaning a stronger resistance.
>
>That means to me that I should tune the useful signal and measure a 
>level of modulation lower than 10%, that is generated by IMD 
>distortion with the interfering input which is modulated 50%. What I 
>can't understand is if and how this compares with the two-tone IMD 
>level measurement method, when one injects two unmodulated signals 
>of equal power and measures the level of IMD products.
>
>I did not found any source of information on the above measurement 
>method, any help would be appreciated.
>
>Thank you
>Paolo
>
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