Rick, I can see where the approach in the paper could be a solution to existing transmitting systems. Unless the semantics of pre-distortion have eluded me, a closed loop which is integral to the design of the complete amplifier is a much better solution; as it is hands-off. In every case, whether or not it is a calibrated lookup table or an active correction method, a sample of the output is needed (at some point) to pre-distort the input to the amplifier stages as much as possible. Simple negative feedback that has been used in tube and transistor circuits is really not much more than a gain controller to stabilize the amplifier stage(s). It doesn't know how the input waveform has to be 'shaped' to cause a less undistorted output signal.
Jim - KR9U ~~~~~~~ We can measure the characteristics of the amplifier by using the receiver of our SDR to receive the amplifier's output and then comparing the signals going into and coming out of the amplifier. Note, however, that receiving the amplifier's output signal requires a feedback path to be established from the amplifier output to the receiver input during the time that we are transmitting. Clearly this must be done with a directional coupler/attenuator or sampler/attenuator so as to deliver ONLY the required amount of power back into the receiver input. ~~~~~~~ -----Original Message----- From: Richard (Rick) Karlquist [mailto:[email protected]] Sent: Saturday, August 02, 2014 11:11 PM To: [email protected]; [email protected] Subject: Re: Topband: Rig Comparisons On 8/2/2014 7:53 PM, James Wolf wrote: > Rick, > > Is the report public? Do you have a link to it? > > Jim - KR9U > This is the report I read; it was at the top of the Google search results: http://www.wavenode.com/PureSignal.pdf Maybe I didn't read the right paper. Like I said, this paper is clearly not on the same page with what Paul C. said. Paul, can you point us to the correct paper to read? Rick N6RK _________________ Topband Reflector Archives - http://www.contesting.com/_topband
