HFU HF Underground

Technical Topics => SDR - Software Defined Radio => Topic started by: Andrew Yoder on January 04, 2019, 2258 UTC

Title: Noisy WinRadio power supply
Post by: Andrew Yoder on January 04, 2019, 2258 UTC
My WinRadio is much noisier than my R8 or R-5000. Just wondered what you guys do to reduce the noise floor. I haven't heard many people talk about computer/electrical noise with these, but it's fairly significant (typically around S6 or S7 on 43m)
Title: Re: Noisy WinRadio power supply
Post by: Josh on January 04, 2019, 2314 UTC
Top of the head response is replacing any switching supply with a linear, and ferrites on everything. Or even better, using a battery.
Title: Re: Noisy WinRadio power supply
Post by: redhat on January 05, 2019, 2130 UTC
It must be either your computer or the power supply.  With the antenna line disconnected, bandwidth set to 3KHz, USB selected, mine goes to less than S1, about 0.13uV on the meter.  I'm using a 12V linear brick that came with a cambridge soundwerks USB soundcard.  Not sure what it came with originally.

Title: Re: Noisy WinRadio power supply
Post by: Andrew Yoder on January 09, 2019, 0316 UTC
Thanks for the responses. I was thinking about trying to find a matching connector and going straight to battery. Guess it might be worth my time to load the software on another laptop & compare noise levels
Title: Re: Noisy WinRadio power supply
Post by: kris on January 11, 2019, 2053 UTC
       Yes, the noise problem is complex and is the sum of several sources. I am not an expert, however, I am saying that the noise irritates me especially in the receiver of SDR RTL. Forgive me that I will repeat what I have read and have checked practically so far, maybe it will help someone improve their reception.
- antennas are more or less skimming depending on the type (for example Beverege vs vertical) and execution (type and matching of the power line). Use maching baloons and ferrite rings on connecting cables. Use band antennas and for broadband antennas matching the antenna box. The unmatched antenna may have more than 1 kohm of resistance in the band, so it will be hissing and not providing station signals. Even a simple LC filter will improve it.
- good grounding. Ground for the antenna system should be separated from the power supply system.
- classic linear power supplies are less noise than impulse ones used to power computers. Where possible, use shielding and grounding, unnoice filters, ferrite rings, inductors and blocking capacitors.
- making a computer (including a sound card) can affect the level of noise. My previous HP laptop with its power supply had high noise at -125dB. I gathered parts to build a linear power supply, thankfully my son got a Dell laptop and this one has noise at -141dB. Switching to work from the internal battery practically does not reduce the level of noise.
- the computer has a lot of oscillators producing garbage, but I did not meet those who buried in his motherboard. I did not have the chance to compare a Mac computer to a Windows PC. At the same time, I have the impression that the software that supports the computer / receiver can have different noise levels. My Icom is less harshly controlled by TalkPCR than controlled by PCRAnyWhere program.
The signal processed by the sound card has more noise than the receiver's audio amplifier or active loudspeaker. It is possible that the external USB sound card will have less noise than integrated in the computer.
- use HF band filters before entering the receiver. Using an ATT greatly improves the ratio of noise to signal. Check if it is better to set the HF gain manually or by AGC. Use possibly narrow IF filters. On the audio side in a difficult situation, readability can be improved by the Equalizer.
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