questions about the SDR reloaded project

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questions about the SDR reloaded project

Postby mariocannistra » Wed Jul 27, 2016 12:45 pm

Hi all.
About the new Elektor SDR receiver:

1) did anyone measure the noise figure of the receiver ?
2) did anyone try to interface directly a couple of ADCs with the 2 SDR output channels ?

mario

Some reference links:

Lab link:
https://www.elektormagazine.com/labs/so ... 150515-1#/

News link 1:
https://www.elektormagazine.com/news/ne ... r-receiver

News link 2:
https://www.elektormagazine.com/news/ge ... sdr-shield

Article link:
https://www.elektormagazine.com/magazin ... 1607/29124
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Re: questions about the SDR reloaded project

Postby Antonywatts » Mon Jan 23, 2017 11:02 am

1 Noise figure. The problem is the RX does not have a standard 50R input impedance. Which make it very un-useful for connecting to the usual types of antenna and noise measurement instruments. Would be better if they left out the input FET-follower stage, as the detector has about a 50R input...
2 Audio outputs interface very well to an A/D converter from Startech (https://www.amazon.co.uk/StarTech-com-E ... USBAUDIO2D)
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Re: questions about the SDR reloaded project

Postby sarma » Tue Feb 28, 2017 10:27 am

i Suppose that terminating the circuit with 50 ohms and removal of the FET stage , kills the receiver sensitivity.
the higher impedance model working was explained in the 2007 original article if i remember.

All said,
after a decade the revisit appears not so purposeful, as many newer designs emerged that make even transceivers PC or laptop independent.
If anyway the pc was to be used, the designer could well have managed I, Q signals through USB socket that was there on the rig earlier and now has no purpose. Perhaps an ADC or PCM codec would have supported pre digitization.

I bought the pdf copy assuming a wonderful upgrade, which i should have thought before buying.

All the best for the project builders.

regards
sarma
vu3zmv
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