Author Topic: Does the HF upconverter work well with RTL Dongle?  (Read 3022 times)

Anton Janovsky (ZR6AIC)

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Does the HF upconverter work well with RTL Dongle?
« on: January 14, 2014, 12:12:50 PM »
Does the HF upconverter work well with RTL Dongle?


Anton Janovsky (ZR6AIC)

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Re: Does the HF upconverter work well with RTL Dongle?
« Reply #1 on: January 14, 2014, 12:42:50 PM »
no. ???

SDR software can only differentiate between different signals by having a large dynamic range in the digitised sampled signal.
What dose this mean ?

Whel if you have a 8bit analogue to digital converter you only have 256 differential points to measure a analogue signal.

if I had had a 12bit analogue to digital converter I would have 4096 differential points to measure a analogue signal.

So if the SDR software have to identify one signal from another and both signals is very close in frequency and amplitude it would be much more difficult to differentiate the two signals from itch other if it was a 8bit (A/d) converter compared to a 12bit (A/D) converter.

The problem with the RTL dongle is that it only has a 8bit A/D converter and therefore suffer from adjacent channel disturbance. :(

So the only way to get a proper HF up converter would be to have a good front end filter to help with the adjacent channel disturbance but that still will be difficult to do as you will have to make the filter tunable to the frequency you are listening on. :(

Almost all the up converters available don't have the tunable nosh filter. :(

My suggestion would be to rather build or get a pre-build Softrock HF receiver and connect it to your computer sound card witch is normally 16bit A/D. and will not suffer from the adjacent channel disturbance problem.

If you can get a 12bit or better A/D dongle it would work fine with up-converter. :)

Some people have modified the rtl dongle to do direct conversion by bypassing the Tuner in the RTL dongle. ( The best option here is to create a small toroid ring changing the impedance for your 50ohm antenna and adding a preamp and filter would possibly work better for a fixed frequency). read more about here http://superkuh.com/rtlsdr.html
« Last Edit: June 27, 2014, 07:55:03 AM by Anton Janovsky (ZR6AIC) »

ThomasDite

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Does the HF upconverter work well with RTL Do
« Reply #2 on: May 02, 2016, 12:26:38 AM »
Thanks - I'm on the DIY site already.

I already do Entec PRO - but people are saying their Lynx dongle does not work - so there is some difference.

Joe