Tag Archives: Noise Reduction

Checking out the Xiegu GNR1 Digital Audio Noise Filter

By Jock Elliott, KB2GOM

Call me a retro-crank, an old-schooler, but part of the joy of listening to shortwave is that the signals sound like they have come from far away. There is nothing like hearing the music, the news, the commentary “filtered through the shortwaves” . . . as Edward R. Murrow once put it.

At the same time, I am a content DXer (thanks David Goren for that phrase; it fits perfectly what I do).  Merely hearing some scratchy, barely audible signal won’t scratch the itch; I want to hear what is being broadcast clearly enough to make sense of it.

And when something particularly catches my ear, there are times when I would like to minimize the noise.

That’s where the Xiegu GNR1 Digital Audio Noise Filter comes in. According to the Radioddity website (they loaned me the unit for testing) — https://www.radioddity.com“The Xiegu GNR1 digital audio noise filter is an audio processing device integrating digital noise reduction and digital filtering. It can be widely used in the external audio processing sector of all types of wireless receiving equipment such as radio transceiver, receiver, radio, to effectively reduce the background noise, improve the signal-to-noise ratio, and improve the signal identifiable degree.”

What I found is a mixed bag. I had some difficulty getting the unit to work at first when I plugged my headphones into the headphones jack on the front panel. Once I plugged the phones into the SP #2 jack on the rear panel, I found the GNR1 will, indeed, reduce the noise on a relatively “fat” shortwave broadcast signal, rolling off the static with no digital artifacts and making the signal more pleasant for long-term listening. And you can use the high cut filter and low cut filter to tailor the sound to suit your ears, and they work quite well for that purpose.

On weaker signals, however, the GNR1 did not provide as much help in reducing noise or sometimes could not hear the signal at all.

For example, at my location east of Troy, NY, I can hear the Canadian time station CHU on 3330 nearly all the time. Today I could hear the time “pips” but down in the noise. I plugged in the BHI Compact In-Line Noise Eliminating Module (which I reviewed elsewhere), and I could hear the time station better, along the with the trickling water sound that is an artifact of the BHI noise reduction algorithm. But with the GNR1, it was as if the CHU time station had disappeared, no matter what adjustments I made to the device.

Bottom line, I can provisionally recommend the GNR1for reducing noise with no artifacts and tailoring audio on strong shortwave broadcast signals, but not for weak signals.

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Horizontal Loop Antenna Experiments

Man-made RF noise levels have increased dramatically at my place in the past six months. It has become much harder to hear weaker shortwave signals. Even the stronger stations are getting covered in all types of hash from all manner of electrical appliances.

So, I have been looking at ways to reduce the noise problem. I’m currently researching a few possible solutions, including trying a different antenna.

The HF horizontal loop has been around for many years now, but it’s a new antenna for me. I’ve never had a need to try one…..until now! There is some documentation out there praising this antenna’s low noise capabilities. So, it was time to find out for myself and start building an experimental version. So far, the results have been really quite pleasing!

I have prepared a YouTube video (below) in which I discuss the reasons for looking at this antenna, its design, and its installation. I also do some on-air comparisons of my experimental rectangular (!) version of the horizontal loop against my three regular double bazooka (coax) dipoles and the Par SWL End-Fed antenna.

Have you tried this antenna before? Your thoughts and feedback would be most appreciated.

73 and good DX to you all,

Rob VK3BVW

Rob Wagner, VK3BVW, is the author of this post and a regular contributor to the SWLing Post. He also blogs at the Mount Evelyn DX Report.

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Testing SDR#’s noise reduction in a London park

LondonShortwave-ParkSDR

Yesterday, SWLing Post reader London Shortwave took his laptop, FunCube Dongle Pro+, and 6 meter long wire antenna to a local park where he tested SDR#‘s new IF noise reduction.

He made the following screencast/video where he toggles the IF noise reduction feature while receiving the BBC World Service’s Pashto language service on shortwave:

Most impressive! Indeed, I believe SDR#’s noise reduction might rival that of OEM applications. While I’m not the biggest fan of noise reduction for everyday use (due to inherent digital artifacts) it is a valuable tool when noise levels are high.

 Click here to follow @LondonShortwave on Twitter.

If you would like to experiment with SDR#, click here to download your free copy. SDR# has a number of additional plugins and dedicated users/developers who communicate via this this Yahoo! Group.

Many thanks to @LondonShortwave.

Any other readers using SDR#? Please comment.

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