Re: Airspy architecture


Alberto I2PHD
 

On 2/2/2015 1:37 PM, 'siegfried jackstien' siegfried.jackstien@... [airspy] wrote:

I would guess the if n and if p means if negative and if positive (balanced
output) and NOT be I/Q signals

The r820t tuner does only have low if out and not 0hz if (i/q)
Yes, that was also my first guess, but the high image rejection made me wondering...
And in any case you can have I/Q outputs also if the IF is not at zero.

On 2/2/2015 3:45 PM, Leif Asbrink leif@... [airspy] wrote:

The R820T2 has I and Q internally and combines
them to a real valued signal with excellent image
suppression. 

The output is balanced to fit the balanced input 
of typical AD converters.

I have no idea how they can get such a good image
suppression...
Hi Leif,

� That explains a lot. From the simplified block diagram found on Internet the use
of a quadrature mixer is not apparent, and that made me scraping my head...

Yes, achieving 65 dB of image rejection working in the analog domain is really
a feat... kudos to them... everything must have been balanced with extraordinary
care...

Thanks Sigi and Leif.


--
73 Alberto I2PHD
Credo Ut Intelligam






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