Tag Archives: BHI Compact In-Line Noise Elimination Module

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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Sometimes the right tools lead to agreeable results

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By Jock Elliott, KB2GOM

Listening to the HF ham bands can be a lot of fun. All you need is a shortwave receiver capable of receiving single sideband (SSB) transmissions and a chart of the amateur bands. You can find downloadable PDF charts of the United States Amateur Radio Band Plan here or a detailed explanation of the band plan here.

Tuning around to hear what people are talking about can be enlightening. You might hear hams chatting about ham radio equipment, house repair projects, religious discussions, news and views or the state of the country, disaster response communications, or almost anything.

Recently I was tuning through the 80 meter ham band when, at 3605 LSB, I encountered a group having a conversation. I couldn’t tell if this group had a formal “Net” name, but I did get the impression that they met regularly in the early morning on that frequency, so I made a note to revisit the frequency.

Yesterday, I did so. With the horizontal room loop hooked to my Grundig Satellit 800, all I could hear was noise. The same with the whip antenna on the Satellit 800.

But when I engaged the MFJ 1886 loop antenna I could clearly hear the group talking above the noise . . . but the noise was still pretty bad. So I tried bringing the MFJ 1045C active preselector online, to no avail. The 1045C did not make the conversation easier to hear.

The noise was like a hum, not a nice gentle hum like a bumble bee flying by; no this was a nasty, raspy hum, like a circular saw trying to get purchase on a particularly tough piece of wood. Listening to the chat group on 80 meters with that noise under it would be tiring on the ears.

Soooo, what to do? Then I plugged in the BHI Compact In-line Noise Eliminating Module into the headphone socket of the Satellit 800 and then plug headphones into the BHI device.

Turning on the BHI module, I adjusted the level of noise reduction, and – tah dah! – the noise just melted away. I could hear the conversation clearly, and all that was left of the noise was the trickling water sound that is an artifact of the noise reduction algorithm.

Sometimes, the right gear just works.

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Frans experiments with the MFJ-1026 Noise Canceling Signal Enhancer

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Many thanks to SWLing Post contributor, Frans Goddijn, who writes:

“Last week I purchased the MFJ-1026 ‘noise canceling signal enhancer’ and I posted two blogs with video about it. Initially the device seemed as useless as it is good looking but then I found a configuration where the device is not only pleasant to have but also useful for radio listening.”

Here are Frans’ reports which he kindly shares from these two posts originally published on his blog, Kostverlorenvaart:

Part 1: MFJ-1026 deluxe noise canceling signal enhancer

Using a GRAHN antenna, (a VENHORST wire antenna for noise reference), the iCOM R8600 radio and optional bhi DSP audio noise canceling, trying to see what’s the best way to cancel noise — on the antenna entry point of the radio or at the speaker output end.

In this case the MFJ-1026 seems ineffective. The DSP at the audio output end works well and easy.

I have also tried two GRAHN antennas on the MFJ-1026, one for MAIN and one for AUX but that was also not noticeably effective yet.

I will also try the little whip antenna that MFJ supplied with the box. Further tweaking may turn out to be helpful on some other frequencies / signals.

Before installing the MFJ i used the little TECSUN H-501x to scan the room for any devices producing radio noise. It turned out that the two Apple Homepods sit in a dense cloud of radio noise, the Macbook Pro also radiates noise, EVE smart plugs controlling lights also produce radio noise, two little label printers s well and the HP printer/scanner too. So I moved those to the other end of the toom or to another room. Continue reading →

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Jock explores “The Essential Listening Post”

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Many thanks to SWLing Post contributor, Jock Elliott, who shares the following guest post:

The Essential Listening Post

By Jock Elliott, KB2GOM

Listening to shortwave radio (or any radio, for that matter) is just plain fun.

So what do you need to get in on the fun?

A radio. With today’s crop of portable SW radios, many of which have search and store capabilities, a newbie SWL can get started quickly without a lot fuss and bother and no extra stuff. Just hit the search and store function (it has different names on different radios), let the search function do its thing, and step through the memories to see what’s out there. If your radio doesn’t have search and store, you can just tune around to see what’s currently broadcasting or, if you have a computer or smart phone, use it to explore one of the online directories like https://shortwaveschedule.com/

What follow next are some things that I’ve found increase my enjoyment of SWLing. Continue reading →

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Jock reviews the BHI Compact In-Line Noise Eliminating Module

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Many thanks to SWLing Post contributor, Jock Elliott, who shares the following guest post:

The noise, the neighbor, and the box

By Jock Elliott, KB2GOM

Imagine the annual meeting of an international corporation called SWLing Inc. (or SWLing LTD). The CEO, looking splendid in his custom-tailored suit, is addressing the assembled multitudes. On the giant screen is an equation showing signal-to-noise ratio. The CEO aims his laser pointer at the word “signal.” We want ALL of this, he says. Then he points at the word “noise,” and says, “and NONE of this.”

Then he looks at the audience and says, “Got it?” And he walks off the stage.

That, whether they want to admit it or not, is the mindset of every single SWL, international music fan, overseas program listener, and DXer. Period. They want as much signal as they can get, and as little noise as possible. That’s what drives radioheads to buy amplified loops, to string long wires, to build towers and yagi antenna arrays, to lay out beverage antennas hundreds of feet long, and to build ferrite sleeve loop antennas . . . it’s all about the signal to noise radio. More signal, less noise.

And it was noise that was bothering me . . . a kind of hiss, hash, eggs-frying sound. It was that noise that prompted me to create the horizontal room loop to try to boost the signal coming into my Grundig Satellit 800 over the noise normally received on the Satellit’s whip antenna.

And it worked; there was more signal on top of the noise . . . but that hiss, hash, whatever you want to call it, was still there. I could hit the attenuator, and some of the noise would go away, but it was still there. After a while, it was just plain tiring on the ears. Poking around the internet, the wisdom seemed to be that the source of the noise was likely electric/electronic gear in my radio room. So I killed the power to everything in my radio room, powered the Satellit 800 off internal batteries, and the noise was still there.

So I called my neighbor. He’s (a) a really good neighbor, (b) a ham with a serious station, and (c) technically knowledgeable. I explain the problem. He says, “Meet me outside.”

We meet between the yards, and he has a Sony 7600 portable shortwave radio in his hand. He switches it on. “Is this the noise you’re talking about?”

“Yup,” I say. “That’s the atmosphere,” he says. Well, nuts.

More poking around the internet reveals that an amplified receive-only magnetic loop antenna might be significantly quieter, and there are several manufacturers of them. I’m thinking about one of those loops when I run across a review of a relatively inexpensive ham transceiver that is reported to be excellent at pulling difficult signals out of the noise because of the superior “digital signal processing” (DSP) that is built into the transceiver.

Digital signal processing . . . that sounds promising . . . after all, if you take a step back and think about it, there are two ways to improve signal-to-noise ratio. One way is to improve the signal with better antennas and the like. The other way is to reduce the noise, and one way to achieve that might be through digital signal processing.

So, are there any companies that make external digital signal processors that could be used with an HF receiver? There are several, it turns out. Some of the units are large, studded with knobs and look complicated to operate, and almost all of the offerings require an external power supply.

But I wanted something that could be easily transferred between receivers and might even be used with a portable receiver when I was doing my horizontal DXing in bed. A big box that requires an external power supply was going to be awkward, cumbersome, and inconvenient. And that’s when I ran into a British company called BHI. They make noise cancellation products, gizmos that use digital processing to remove noise from an audio signal. They serve amateur radio, commercial, marine, medical, and even covert surveillance markets.

One of their products is the Compact In-line Noise Eliminating Module. It can be run off AA batteries and isn’t much bigger than a deck of cards (in fact, its footprint is almost exactly the same as my CCrane Skywave SSB). It has just two knobs and is easy to set up: you just plug it in between your HF receiver and your headphones or external speaker. It even comes with a cable to connect your receiver to the Noise Eliminating Module.

I order one from DX Engineering in Ohio. The cost, delivered to my door, including tax, is just over $260 American dollars. It arrives two days later, just in time for the bands to be sizzling with noise (apparently) produced by a solar coronal mass ejection (CME). The amount of noise is brutal, about as bad as I have ever heard in decades of hamming and SWLing.

Plugging the BHI in-line module into my Satellit 800 and clamping the headphones over my ears, I begin tuning the 20-meter ham band. Part way up the band, I run into a Canadian ham chatting with someone. His signal is barely above the noise and copyable, but the noise is really annoying. I punch the button for the BHI device, and . . . the noise disappears. Wow! I press the right-hand button (to bypass the BHI device), and the noise comes back full force.

Quickly, I grab my Tecsun PL-880, extend the whip antenna, tune to the same frequency, and plug the BHI in-line module into the 880. The noise sounds even worse on the 880 (the Canadian ham is barely copyable), probably because of the shorter antenna. But when I engage the BHI device, the result is even more dramatic; a very pleasant signal emerges as the BHI unit suppresses the noise, with just a bare hint of hiss still audible.

Then I take hold of my CCrane Skywave SSB to see how the BHI in-line module will behave with that. It doesn’t take long to realize that, apparently because of the solar activity, all the bands are noisy on the Skywave. Not just shortwave, but AM, FM, weather, and Air were all uncharacteristically affected by hiss or noise. The BHI Compact In-line Noise Eliminating Module reduced the noise and made each of them more pleasant to listen to, without exception. I am “officially” impressed.

As I experiment with the BHI device in following days, during which atmospheric conditions improve, I continue to be impressed. Why? Because the BHI Compact In-line Noise Eliminating Module is effective at substantially reducing noise without a lot of fuss and bother.

As good as the BHI module is, though, it is not a miracle device; it does have some limitations. Sometimes it will not eliminate all the noise, even though the noise will be reduced substantially. If you crank up the level of filtering/noise cancellation too high, it can distort speech and make tuning single sideband difficult. Further, you sometimes hear artifacts of the digital signal processing. These artifacts sound to me like trickling water, and, frankly, I don’t find these sounds objectionable (they sure beat the heck out of the atmospheric noise), but some people, I suppose, might not like them.

Image via DX Engineering

The module is easy to operate. There are two knobs. Press the left one in to power up the unit, then turn the knob to adjust the volume. Press the right knob to activate noise reduction and then turn the knob to adjust the level of noise reduction. Sometimes, I find, the sweet spot for listening is with the noise substantially reduced – perhaps 85-90 percent – but not completely gone. Press the right knob again to bypass noise reduction and hear what the signal sounds like without the BHI module online.

Because the two knobs on the face of the BHI module are also push-buttons, if you are going to pack the device in your luggage, remove the batteries to prevent the unit from inadvertently turning on and draining the batteries.

Bottom line

The BHI Compact In-line Noise Eliminating Module is highly effective at reducing or eliminating noise. It works on international broadcasters, ham single-sideband signals, and utility stations, as well as AM, FM, and even NOAA weather radio when conditions are horrible. It can make weak signals easier to hear and strong signals more pleasant for long-term listening. It reduces audio fatigue. It is not a cure-all for all signal-to-noise or audio problems, but it is a big help. Further, it can be readily moved from location to location and from radio to radio and adds a new capability to receivers that do not have built-in digital signal processing.

I think it is a worthwhile addition to any shortwave listening post.

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Advice on cancelling locally generated noise

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An SWLing Post reader recently contacted me with the following question:

“What devices work well to cancel out local RFI? I’ve been told that both the Timewave ANC-4 and a number of BHI products are all worth considering.”

Unfortunately (or fortunately, for me) I’ve no experience with outboard DSP or noise cancelling devices because I live in such an RFI-free area.

I know this reader already has a Wellbrook Loop, but he’s looking for a way to even increase noise mitigation further at his home listening post.

Post Readers: Can you help guide him? Please comment with your experience. Is a product like the Timewave or BHI the next logical step? If not, what is?

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Guest Post: More Anti-Noise Ideas

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In a previous guest post, SWLing Post contributor TomL, shared his “Evolving, Morphing, SW Listening Station” where he detailed the many ways he’s trying to fight heavy radio interference at his listening post. The following post is TomL’s update:

More Anti-Noise Ideas

(Continuing the hunt for better reception in a foul RFI environment)

by TomL

I have made the following changes:

Created a prototype mini-loop based on a crossed-parallel idea from VE1ZAC (Jeff).
Added a balun from LNR Precision (Parfitt’s EF-SWL) in an experimental configuration.
Added to the balun, an outdoor amplifier – Wellbrook ALA-100M.
Added a noise canceling unit (MFJ-1026).
Added 2 preselectors, an old Grove TUN-3 connected to the main loop feed and an MFJ-1046 connected to the ground connection of the balun. Both feeds go into the MFJ-1026.
Added BHI Compact In-Line DSP filter and two switch boxes to cut it in/out as needed.
Added a medium wave noise canceling unit that I have not figured out how to use yet. (Quantum Phaser). The MFJ unit does not work on medium wave without modification.
Purchased from eBay a used Grundig Satellit 800, a somewhat more robust fixed-station receiver to replace my aging Sony ICF-2010.
Other non-related (not shown): Whistler digital scanner + UHF over-the-air TV + FM broadcasts + an AM/FM HD digital radio + high pass filters from MiniCircuits.com – (audio from all these sources is passed to an existing high fidelity stereo power amp and NHT Super One speakers on the computer desk for near-field monitoring). Associated antennas are also hidden on the outside deck (shhhhh!).
Large charge card balance!!

So, here are some pics for the crossed-parallel loop. VE1ZAC web site has all the references if you want to explore further or google him. Mine is purely a prototype and not finished. And should eventually be placed on a rotor (but how to keep my Nazi-like condo association from finding out?!?!?!?).

It is three 14 inch quilters hoops from Joann Stores plus some 1-inch copper strips cut from a small 2 meter roll of thin copper from eBay. Then, it is wired in parallel with silver-plated aviation wire on each side with a feed in the middle. Not an optimal placement of the feed, (should go straight down along the pipe). Will fix things up whenever I get some more time.

Seems to be an efficient way to prototype small loops. It is now mounted on a short ¾” inside diameter PVC pipe into a cheap plastic sand-filled deck-umbrella stand. Loops are light and somewhat flimsy, so I mounted the three loops on a plastic triangle ruler and dowel sticks glued to the sides for some extra strength. Good enough for now.

The EF-SWL balun is also in an experimental configuration. Since I read somewhere that loop antennas have a very low impedance at the feed point (like, 10 ohms or lower), I thought I might try a balun that is meant to lower the impedance and mount it backwards. I don’t have a picture of it but the SO-239 output is facing the loop and the screw terminals are facing the direction of the radio. My feeble brain thinks since it is a passive device of coils on ferrite, it should work bidirectionally for receive only applications like this. It seems to work but I have the excuse that I really don’t know what I am doing! 🙂

BHI unit in action.

The BHI DSP filter is useful in some circumstances but I find it fatiguing to listen to. The audio from the Sattelit 800 is so nice, I mostly like it without the DSP. The DSP narrows the bandwidth significantly, somewhere around 4 kHz or less from my hearing. I like that the Grundig has two tone controls. And it also has a stable SSB and on very strong signals with clear audio, I like to listen with SSB lower or upper sideband. But the DSP is useful at times for hash-like noisy signals; it is not quite as good on buzzing noise and I wish the Satellit 800 had a noise blanker, but that would have been a more costly purchase, like a Drake R8A.

So, in a nutshell, I have a discovery about noise here: it is all around me and ubiquitous, like the air I breathe!

I find it hard to null and also worry about peaking a station signal at the same time. However, I do have a lower noise floor with the experimental loop sitting outdoors, especially on medium wave (the Wellbrook amp + loop works great on the lower frequencies – am able to get eight different medium wave stations carrying Major League Baseball games at night – it would be nine to get WFAN for the New York Mets but the local Chicago Cubs station covers the adjacent frequency with horrible digital hash! ***Bleeping*** digital junk!).

Also, the signal level is noticeably lower using the loop. Then, add in the effect of the MFJ Noise Canceling unit, the usable signal gets even weaker.

The bottom line is, I can now finally enjoy listening to many SW broadcasts, BUT only the strongest signals. Anything else is still hopelessly lost in the noise. So, gains are limited.

On the other hand, and something else I learned by doing is that, any 1 or 2 dB signal/noise ratio improvement will help with the final audio output in the end product. Using low-noise amps, loops, noise canceler, preselectors, grounded connections, ground isolators at the input of every receiver, high quality stereo amplifier and speakers, tone controls, SSB vs. AM Sync, weird antenna configurations, etc, etc. It all helps in the end to some degree.

Tinkering is an art that involves a lot of thinking/doing iterations! And high quality parts must be used all along the chain or it could degrade the signal.

Below are some audio samples, not very well recorded, but can give some idea of the incremental improvement with each enhancement (turn up the volume). NOTE: other people may get better or worse results depending upon individual situations, type of antennas used, etc, etc.

Recording 1: R. Marti. First 10 seconds an indoor antenna with no noise reduction, second 10 seconds the outdoor loop without the MFJ-1026, the third 10 seconds with the MFJ-1026, then switched off and on to hear the difference.

Recording 2: R. Marti. MFJ -1026 is ON. Last 15 seconds is SSB, very thin sounding. Really only good for strongest signals. I liked the AM Sync better (Satellit 800 is really a Drake SW8 in disguise with a quality AM Sync). But, SSB can sound excellent with very clear voices with a steady and strong signal (The Satellit 800 does NOT have IF-shift or a BFO to fine tune an SSB reception, so the station must be exactly transmitting on the kHz mark, which most are nowadays).

Recording 3: R. Marti. MFJ-1026 is ON. Last 20 seconds you hear me switch in the two audio switches and the BHI DSP is on its lowest setting. Narrower and clearer with some reduction of background noise. I find I only like going up to about 4 on the DSP dial, after that the audio fidelity starts getting more choppy with digital artifacts that sound like dripping water. I tend to like higher fidelity. One nice thing about the BHI DSP is a faux-stereo that helps a little with voice intelligibility by helping the brain naturally filter the noise. Faux-stereo is ON even when the noise reduction circuit is manually turned off (power must be on and bandwidth still sounds narrowed).

Recording 4: R. Nacional Brazilia. First without MFJ-1026, then ON, then OFF, then ON, then with the BHI kicked for the last 20 seconds.

Recording 5: Greece. Switching the MFJ-1026 on and off every 5 seconds. In this particular case, the signal was weak and fading a lot. The MFJ OFF was also weaker than with it turned ON. That is interesting behavior, usually it is opposite. It pays to play with the settings a little. At other times, and less frequently, the MFJ unit turned OFF sometimes sounds better than with it ON and tuned for less noise. Go figure!

After all the tweaking is done, and I cannot get any more performance out of this, I will probably have to move to a nice, quiet neighborhood and setup a nice antenna farm!!

In the meantime, I do enjoy listening to the stronger stations from North America, Cuba, Brazil, Europe, and Australia with less noise than before.

73’s

TomL from NOIZEY Illinoiz

Once again, Tom, thanks for sharing your RFI elimination journey!

I love how you take on this noisy problem by experimenting and seeing it more as a challenge than an obstacle to enjoying your hobby. Great job!

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