Hi Take, In generating SSB, (the filter method) DSB is fed to a filter which shifts the phase
of the signals, all over the place so I doubt one could "fix" this without knowing the exact filter phase changes. Then change to another SSB rig and it's all wrong. Can the experts comment on this? Alan VK2ZIW On Thu, 18 Jun 2020 00:50:26 +0000, Tsutsumi Takehiko wrote > Hi Glen, > > What is your position of Single-carrier FDMA or LP-OFDMA technology compare > to PARP reduction scheme which you have rich experience in your memo? > > I wonder why radio amateur society leaves PARP issue untouched when they > adopt OFDM technology. > > Does it comes from SSB experience which has about 5dB PARP? > > Regards, > > take > > de JA5AEA > > Windows 10 $BHG$N(B$B%a!<%k(B$B$+$iAw?.(B > > > $B:9=P?M(B:Glen English > $BAw?.F|;~(B: Wednesday, June 17, 2020 8:09 AM > $B08@h(B: [email protected] > $B7oL>(B: Re: [Freetel-codec2] FreeDV Tx power > > Hi David > I've been across OFDM PAPR reduction development for many years. > Most successful simple schemes involve some sort of selective mapping or bit > flipping. > -IE the PAPR is computed and an alternative trajectory is generated . > -These can be either tweaking the source bitstream slightly (many methods) > -and also providing overmapping of the constellation (say 64 QAM points might > only map to 48 unique symbols, giving the system a choice of some other point > that can convey the same data. > -and also deliberate FEC violation (modify the most encoded code and > remove/reduce the offenders) > -and also selective bit flipping - easy and fast. > I would encourage some form of PAPR reduction for any ham OFDM development. > Without it, OFDM is often and (and ignorantly) overdriven creating spectrum > headaches for adjacent channel users > > -glen > > On 17/06/2020 07:33, David Rowe wrote:Hello List, I've been working with Peter, VK3RV on the surprisingly tricky problemof measuring FreeDV Tx power. Over the weekend I built an inline "sampler" and tried a few averagingoptions to measure the power of a 700D waveform on my spec-an. I amusing my IC7200 with the drive adjusted so that the ALC just moves. Iam sampling the power between the IC7200 and my ATU, which is connectedto a dipole on 40M. > --------------------------------------------------- Alan Beard OpenWebMail 2.53
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