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So, I’ve had this device for about two years now and have mentioned it to several people on the air, describing just how effective it is.

What is it? This is an active DSP audio noise eliminator filter manufactured by BHI Ltd.. As simply as possible, it wipes out background hash band noise. It isn’t a pulse noise eliminator like a noise blanker, though it will drastically soften the edge of pulse noise as well.

This is an AF (audio frequency stage) DSP unit. It plugs into the audio output of _anything_ you want to feed through it and you in turn loop it’s output into the speaker or other destination audio feed of your choosing.

The unit has either 4 or 8 steps of increasing DSP elimination effects. In stronger conditions you can back it off easily so it isn’t as heavy handed on processing the signals, or in lousy conditions with weaker signals, you can really clamp it down for the maximum effect.

The best way to show you what this does is simply an mp3 file I created to demonstrate its effectiveness.

Here is a 40m SSB clip with the filter being toggled in and out

The clip was made with some high noise levels and relatively low signal levels at or below the noise peaks, using my vertical on 40m SSB.

The DSP setting was on maximum 8/8 so there is some minimal artifact on the audio signal and a very slight audio level drop. Keep in mind the completely annoying original signal. With the DSP engaged it would be easily possible to maintain a pleasant extended contact with any of the stations in the recording, vs only wanting a brief ‘in and out’ style contact before getting sick and tired of the noise level. A slight bit of the ‘under water’ artifact is much more tolerable.

These units are available in a few configurations from BHI Ltd.. They come in built-in modules designed to be hard wired into the audio circuit of a radio or to be built-in to the internal of a speaker cabinet. They also come in self contained powered speakers with the module included internally. Lastly and my personal favorite are the ‘universal’ inline modules. These allow you to use whatever source or speaker you choose by simply plugging in different inputs and outputs to the unit. It’s the most flexible option.

These modules aren’t cheap, but they are worth every cent if you like to spend a lot of time listening.

W4RT.com is one source in the US for this product.

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This map shows ham station beacons and the trails of moving vehicles on APRS

Well my IF tap worked great for a few hours and after I shut down my rig….signals were not right. I learned what seems to be a fundamental lesson about JFETs…they don’t like static much. I’m 99% sure that I zapped the JFETs in the buffer amp I installed after doing some reading on how static sensitive they are. At least my rig is just fine otherwise.

So I got an alternative design buffer amp that’s sitting here waiting for me to pop the hood again and install it. This one doesn’t use JFETs, so my gorilla paws without a static mat won’t be as likely to cook it.

In other news, I’ve rewired myself again for packet radio and APRS operations. Using Xastir on Ubuntu linux, I’ve had APRS up and running a few days consecutively here and there. Pretty neat stuff and can be _very_ handy for any mass deployment events.

In a nutshell, APRS takes GPS coordinates or other information and sends it out as a beacon via radio. So if I’m running the mapping and client software and you are in the field with a handheld running APRS, I can see your position as it is beaconed every few minutes overlaid on a map.

If you are providing event support over an entire marathon course as an example, as the control operator or other field station, at a glance you would be able to see the location of all your operators. This becomes important when you get a call that a runner or rider has been injured and needs first-aid. The closest support vehicle can be instantly located. Not only that, but you can follow that vehicle on the map and know when it arrives at the hospital or control point.

You can beacon most any data up to a limit of 40 characters per beacon. Commonly people beacon their position and then a frequency they are listening to. This way when you see them up close, if you see them you know how to reach them. It can be fun while traveling around just to make contacts as you ‘run into’ them.

Generally this is all done on the 2m ham band for local coverage. But even with that system, there are facilities to repeat or ‘digipeat’ the traffic a station hears. So if I beacon, a station within range will hear it, and then transmit again. Yet another station further out will pick that up and repeat it again, and so on. Add that it is also possible to send the data out to the internet from home stations and you can reach pretty much anyone on the network, world wide.

There are even low frequency links that will broadcast the traffic hundreds or thousands of miles in a single hop. This can all be incredibly useful in the even of a major disaster that knocks out telecommunications services. Hams have the ability to set up field stations with these capabilities in a matter of hours. It’s something not often remembered about this ‘hobby’ as witnessed here ARRL article about the Haiti earthquake

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It’s indeed been a scanner day here at the shack. After having it annoy the hell out of me for several years, I finally got around to replacing the EL (electroluminescent) back light for the display on my old Radio Shack Pro-2006 scanner.

Found the tips on how to do it at Radio Reference thanks to one of their forum users. The part was all of $3.50 from All Electronics one of my favorite quick grab parts-bin sites.

Now it’s as bright, if not a bit better than it was new, 15+years ago.

The surgery to do it was a bit deeper than I’d expected with a few annoying ribbon connectors to un-wedge and the usual myriad of small retaining screws, but once the adhesive blob was cut and the two leads desoldered, it was a piece of cake getting the new EL panel in there. Worth doing.

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