Going back to the original question as for now it seems there is no concrete information available on "predistortion" with the K4. Maybe further information will materialize over the next weeks/months which could be a valid platform for discussions.
73 Roger, DL5RBW -----Original Message----- From: W2xj [mailto:w...@w2xj.net] Sent: Sunday, May 19, 2019 11:56 AM To: Roger Cc: j...@audiosystemsgroup.com; elecraft@mailman.qth.net Subject: Re: [Elecraft] K4 and Predistortion With EER a class C or D amplifier can deliver an IMD of at least -80 DB but with pre-distortion it could be even better. Sent from my iPad > On May 19, 2019, at 3:38 AM, Roger <ro...@mulzer.de> wrote: > > As pointed out "PreEmphasis/DeEmphasis" and "PreDistortion" are two > different things. So it is important to keep this in mind. To describe > the process a little bit better it the introduction of "DeDistortion" > would help. While DeEmphasis was done at the receiver end DeDistortion > is done at the transmitter end by the amplifier. Just using one part > of Distortion (or > Emphasis) would really not reflect the true signal that is going into > the microphone. As any amplifier stage is adding distortion it is > appropriate to call the procedure done in the SDR (the ones that are > capable of) PreDistortion. The DeDistortion in the amplifier gives you > a much better approximation of a true linear amplification. Just > ADDING Predistortion and not adding or better SUBTRACTING the proper > amount of Dedistortion sure would make and leave the signal distorted. > > 3rd order IMD in the range of -60 dB and with careful design even more > is possible. > > Consider this: the best receiver doesnt help if a lot of average or > below average quality signals are around and splattering into your > "communication channel". The same is true if someone with a radio that > creates a lot of phase noise is next to you - your radio can have a > clean oscillator signal with low phase noise but still the other dirty > signal will go into the equation. > > So after it has been acknowledged that high phase noise oscillators > are a NO GO these days the next consequent step would be to clean up > the transmit signal in terms of intermodulation. > > If someone tuning a motorcycle or a car he better not only tunes the > engine for power but also adapt the brake system the chassis and > everything else affected to handle the more power. > > 73 Roger, DL5RBW > > -----Original Message----- > From: elecraft-boun...@mailman.qth.net > [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Jim Brown > Sent: Sunday, May 19, 2019 2:09 AM > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] K4 and Predistortion > >> On 5/18/2019 4:01 PM, Phil Kane wrote: >> Those >> of us with engineering backgrounds knew that what I was referring to >> as "pre-distortion" was the pre-emphasis / de-emphasis curves >> commonly used in FM broadcast audio chains. > > All of which emphasizes the need for using the right words to describe > things. The word "distortion" is most commonly used to describe > non-linearity, not frequency response. And, BTW, that > pre-emphasis/de-emphasis is a Standard, not just "commonly used." You > know the Regs far better than I, but I suspect it's there too. > > As I'm sure you know, it was also common practice to go FAR beyond > that, with multi-band dynamics processing and the tricky stuff that > Bob Orban was doing. The engineering "rule of thumb" was that if you > could see the modulation monitor needle move, you weren't doing > enough.:) > > I did some research on the Orban FM processor, which I published as an > AES Paper in 1986. http://k9yc.com/AESPaper-TDS.pdf > > 73, Jim K9YC > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net Please help support this email > list: http://www.qsl.net/donate.html > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net Please help support this email > list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
