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CW copying Improvement
Andy writes:
A recent thread from a ham with a hearing disability who was looking for a way to make CW easier to copy caused me to think about something I had seen that might help. I will try to describe it... The audio output was applied to an amplifier that had an artificial "threshold", like putting diodes in SERIES with the input so that no signal would reach the amplifier until the total level was high enough to break down the diodes .......... only the threshold was more precise and not "soft".............. easy to do with op amps..... The audio was adjusted to the point where NO signal would not produce and output and YES signal would simply amplify and cause an output... ..... much like adjusting a relay to click in at a given threshold.... Note that this does NOT increase the SNR because that has to be measure with a signal, and when the signal is present the noise is riding on top of it...... However it would produce more "abrupt" contrast between YES signal and NO signal..... much like the FM quieting phenomena that one of the posters in CW Remodulator referred to....... It might improve the ability to copy for someone with a hearing disability.. I haven't tried it, but I can't see why it wouldn't help. If a reader has built it up, or something similar, I would appreciate hearing about it..... or possibly where the original article describing it appeared.... I'm sure it was either the ARRL handbook or an old issues of QST.... Just wanted to throw this in the mix. Good luck. Andy W4OAH |
CW copying Improvement
Over 30 years ago I designed and built something similar to what you're
describing. I ran the CW signal through a sharp audio filter, detected it with a diode, and used that to key an audio oscillator (rather than amplifying the original signal as you describe). It was interesting, but worked only for a rock-solid signal which was simple to copy anyway. It didn't take much QRN or QRM to cut holes in the output signal which made copy impossible. The brain is an amazing signal processing mechanism. It's really hard to beat. If I had a hearing disability, I'd look into various amplifying and frequency shaping devices and perhaps some types of audio signal processing. But in my opinion it's best to send more-or-less the original signal to the brain and let it do what it's good at. If that's not feasible, then use a digital mode that's specifically designed for easy detection with electronic circuits and let them do all the work. Roy Lewallen, W7EL AndyS wrote: Andy writes: A recent thread from a ham with a hearing disability who was looking for a way to make CW easier to copy caused me to think about something I had seen that might help. I will try to describe it... The audio output was applied to an amplifier that had an artificial "threshold", like putting diodes in SERIES with the input so that no signal would reach the amplifier until the total level was high enough to break down the diodes ......... only the threshold was more precise and not "soft".............. easy to do with op amps..... The audio was adjusted to the point where NO signal would not produce and output and YES signal would simply amplify and cause an output... ..... much like adjusting a relay to click in at a given threshold.... Note that this does NOT increase the SNR because that has to be measure with a signal, and when the signal is present the noise is riding on top of it...... However it would produce more "abrupt" contrast between YES signal and NO signal..... much like the FM quieting phenomena that one of the posters in CW Remodulator referred to....... It might improve the ability to copy for someone with a hearing disability.. I haven't tried it, but I can't see why it wouldn't help. If a reader has built it up, or something similar, I would appreciate hearing about it..... or possibly where the original article describing it appeared.... I'm sure it was either the ARRL handbook or an old issues of QST.... Just wanted to throw this in the mix. Good luck. Andy W4OAH |
CW copying Improvement
Roy Lewallen wrote:
Over 30 years ago I designed and built something similar to what you're describing. I ran the CW signal through a sharp audio filter, detected it with a diode, and used that to key an audio oscillator (rather than amplifying the original signal as you describe). It was interesting, but worked only for a rock-solid signal which was simple to copy anyway. It didn't take much QRN or QRM to cut holes in the output signal which made copy impossible. The brain is an amazing signal processing mechanism. It's really hard to beat. If I had a hearing disability, I'd look into various amplifying and frequency shaping devices and perhaps some types of audio signal processing. But in my opinion it's best to send more-or-less the original signal to the brain and let it do what it's good at. Hi Roy, So much depends on the nature of the hearing problem. I have a lot of holes in my hearing, as well as a different tone of tinnitus in both ears. It took me over 6 months/3 hours per day to learn CW to 5 wpm. And it still had to be crystal clear signal. I learned a lot of things during this time. The main thing is that my brain gives equal weight to all sounds, whether the CW I am trying to copy, or whatever happens to be around it. Turns out that the same is true for multiple people speaking, or one person speaking with an air conditioner on in the room. This is probably related to the length of time that I have been hard of hearing (started at 7 with a bad case of the mumps, then the tinnitus started at 18) If that's not feasible, then use a digital mode that's specifically designed for easy detection with electronic circuits and let them do all the work. Yup, I'm a big fan of PSK31. - 73 de Mike KB3EIA - |
CW copying Improvement
On Mon, 06 Nov 2006 19:51:47 -0500, Mike Coslo
wrote: Roy Lewallen wrote: Over 30 years ago I designed and built something similar to what you're describing. I ran the CW signal through a sharp audio filter, detected it with a diode, and used that to key an audio oscillator (rather than amplifying the original signal as you describe). It was interesting, but worked only for a rock-solid signal which was simple to copy anyway. It didn't take much QRN or QRM to cut holes in the output signal which made copy impossible. The brain is an amazing signal processing mechanism. It's really hard to beat. If I had a hearing disability, I'd look into various amplifying and frequency shaping devices and perhaps some types of audio signal processing. But in my opinion it's best to send more-or-less the original signal to the brain and let it do what it's good at. Hi Roy, So much depends on the nature of the hearing problem. I have a lot of holes in my hearing, as well as a different tone of tinnitus in both ears. It took me over 6 months/3 hours per day to learn CW to 5 wpm. And it still had to be crystal clear signal. I learned a lot of things during this time. The main thing is that my brain gives equal weight to all sounds, whether the CW I am trying to copy, or whatever happens to be around it. Turns out that the same is true for multiple people speaking, or one person speaking with an air conditioner on in the room. This is probably related to the length of time that I have been hard of hearing (started at 7 with a bad case of the mumps, then the tinnitus started at 18) If that's not feasible, then use a digital mode that's specifically designed for easy detection with electronic circuits and let them do all the work. Yup, I'm a big fan of PSK31. - 73 de Mike KB3EIA - Hi Roy and Mike, Ten Tec made a device similar to the one Roy is describing back in the 1970's. It was called the S-20 Signalizer and I don't think that Ten Tec sold very many. I still have mine and use it quite frequently. As Roy said, it was not for weak signal work and most everyone who bought one seemed to think it was just another filter or Q-multiplier that would help dig out weak signals. On the contrary, the Signalizer works best when you have a strong signal and you just want to get rid of some annoying background sound, like a heterodyne or static crashes. I use mine primarily on 80 meters when there is QRN and I feed its audio to one side of my stereo headphones. The other side of the headphones goes directly to the audio from the receiver so I can hear the raw signal without any AGC action. The advantage of this arrangement is that I can turn the receiver audio down a bit lower than I usually would and still pick up those characters that I would miss completely with the signalizer. It is definitely more comfortable than listening to the raw receiver audio for a long period of time when QRN is present. Of course, the above arrangement only works because the brain is in fact "an amazing signal processing system", and can selectively insert the weaker signal from the raw receiver audio into the stream of perfect audio coming from the Signalizer. Mike, I might add that the product review of the Signalizer in QST said that the effect of turning it on was "like closing the door" to shut out the noise from an adjacent room. When I try to describe the effect of the Signalizer to others ("Its a re-keyer, not a filter"), I often use the very analogy that you mentioned, namely that its like being able to lower your voice when someone turns the air conditioner off or other people stop speaking in a crowded room. You occasionally see a signalizer on e-bay, often misdescribed as a CW filter or amplified speaker. A couple of months ago one went for about fifty dollars as I recall. -- Dave WB4JTT |
CW copying Improvement
I helped my CW hearing ability by making a long speaker
box which allowed the speaker element to slide up and down the length of the box, changing the resonant pitch of the box, which allows an audio "peaking" effect. This has the effect of amplifying the cw sidetone at different pitches and also increasing the S/N ratio. Usually, the QRN gets lost in the longer travel up the wooden box. Dave N4DAG "AndyS" wrote in message oups.com... Andy writes: A recent thread from a ham with a hearing disability who was looking for a way to make CW easier to copy caused me to think about something I had seen that might help. I will try to describe it... The audio output was applied to an amplifier that had an artificial "threshold", like putting diodes in SERIES with the input so that no signal would reach the amplifier until the total level was high enough to break down the diodes ......... only the threshold was more precise and not "soft".............. easy to do with op amps..... The audio was adjusted to the point where NO signal would not produce and output and YES signal would simply amplify and cause an output... ..... much like adjusting a relay to click in at a given threshold.... Note that this does NOT increase the SNR because that has to be measure with a signal, and when the signal is present the noise is riding on top of it...... However it would produce more "abrupt" contrast between YES signal and NO signal..... much like the FM quieting phenomena that one of the posters in CW Remodulator referred to....... It might improve the ability to copy for someone with a hearing disability.. I haven't tried it, but I can't see why it wouldn't help. If a reader has built it up, or something similar, I would appreciate hearing about it..... or possibly where the original article describing it appeared.... I'm sure it was either the ARRL handbook or an old issues of QST.... Just wanted to throw this in the mix. Good luck. Andy W4OAH |
CW copying Improvement
On Mar 31, 7:56 pm, "DaveS" wrote:
I helped my CW hearing ability by making a long speaker box which allowed the speaker element to slide up and down the length of the box, changing the resonant pitch of the box, which allows an audio "peaking" effect. This has the effect of amplifying the cw sidetone at different pitches and also increasing the S/N ratio. Usually, the QRN gets lost in the longer travel up the wooden box. Dave N4DAG - Dave, that's genius. |
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