Direct sampling option greyed-out

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Joined: Tue Nov 05, 2019 8:22 am

Direct sampling option greyed-out

Post by phuong112 » Tue Nov 05, 2019 8:29 am

I got a RTL-SDR USB Tuner Receiver/ R820T unit from Amazon.
I use SDRSharp software.

The problem is that in the software settings I cannot activate the "Direct Sampling (Q branch)", in fact this option is greyed out or disabled. The only option I see is "Quadrature sampling".

My unit is not a dongle, it's a unit with two antennas ports: HF and UV. I well understood, HF frequencies below 30MHz can only be received by using a long wire antenna attached to the HF port.
So far, the only antenna I have is the provided one (test antenna to be connected to the UV port).

Just to try, I connected such test antenna to the HF port without results...
Question: in order to get the "Direct Sampling (Q branch)" option available/selectable is it sufficient to connect a suitable antenna (long wire) or do I have a software problem (since such an option is greyed out)?

I read about the direct sampling mod for dongles, but in my case having an HF antenna port available (I suppose goes to pins 1 or 2) I need no internal soldering: is that correct?

I also read that frequencies between 14.4 and 28.8 MHz can only be received by using a band pass filter: is it true for dongles or also for my unit?

Thanks for your support (I'm not a big expert...)

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Joined: Sun Sep 01, 2019 12:43 am

Re: Direct sampling option greyed-out

Post by K3RLD » Tue Nov 05, 2019 4:48 pm

Are you using an V3 dongle? It sounds like you are not, and I think thats what that option is for, no? Can you provide a link to the SDR you bought on amazon?

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Re: Direct sampling option greyed-out

Post by rtlsdrblog » Fri Nov 08, 2019 4:30 am

You just need to press the stop button in SDR# first, then the direct sampling option will ungrey. Select Q-branch and start SDR# again.

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