FS: BHI

[K7TV]

On the subject of BHI, I once had an ambitious project to build a switch box incorporating some SO2R functions plus two BHI DSP single channel units. Before I had finished wiring the unit (starting with just one BHI channel unit) my understanding of SO2R requirements grew to the point that I abandoned my build and went with a commercial MicroHam SO2R box. At this point I am no longer motivated to get a second BHI unit and deploy them. If anyone is inerested in buying the one I have, please email me directly and we can discuss a deal. To be clear: This is a unit for integration in other equipment, and not a standalone box ready to place on your desk. It does incorporate an AF power amp for driving a speaker, and the input may be driven from the radio speaker output.
73,
Erik K7TV

-----Original Message-----
From: [hidden email] <[hidden email]> On Behalf Of Erik Basilier
Sent: Saturday, January 12, 2019 1:11 PM
To: 'Walter Underwood' <[hidden email]>; 'Elecraft Reflector Reflector' <[hidden email]>
Subject: Re: [Elecraft] Query for new DSP features

The noise level at my QTH is not nearly as bad as many of you have. The K3 S-meter tends to read around S4 on the background noise noise (SSB bandwidth, 20m preamp off, atten off). When it comes to engaging NR, like many others I have in the past tended to crank up the aggressiveness etc and noted a loss of apparent volume on the wanted signal, and apparent loss of the higher frequency voice components. I have compensated by cranking up the volume and widening the passband (which helped little as the received station had insufficient boost of highs). I have admired the apparently better results from other DSP implementations such as BHI and other radios. Lately I have modified my approach to using the K3 DSP, and found much better results. For ssb I now have NR engaged full time and like it. The setting is the least aggressive possible: F1-1. I used to have the impression that this setting did little to help, but I have changed my opinion. The sound with this weak NR on now s
 eems very normal and comfortably intelligible. If I turn NR off, I can still read the signal, but it sounds harsh and tiring. I can't say the NR makes an unreadable signal readable, but it makes the copy more comfortable. My old brain seems to, slowly, adjust its own filtering to fit what is being heard, not just to focus on the wanted cw signal in a wider passband, but also when listening to voice when switching between NR on/off. This may be just my speculation, but subjectively, even with no radio involved, I seem to need an adjustment period also when listening to different adult voices, and especially when going between an adult voice and that of a small child. The existing K3 DSP seems to be optimized based on objectively measurable criteria that are somewhat at odds with the strange workings of the human auditory system. Perhaps the addition of a tone control that alters the low/high tonal balance would be a helpful new resource for those who feel the NR makes signals
  sound weak or too bassy. The tone control setting could be automatically engaged with an emphasis on the highs when NR is engaged. It could also be helpful as a manual control for adapting to stations that have not adjusted their transmit equalizer to fit the operator's voice. Besides a low/high tilt, a peak/notch function might be helpful.
73,
Erik K7TV
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