Hi Bob, Viewing pink noise with an oscilloscope, it is continuous, where as speech has breaks.
The web page is evaluating both expected power to a load and compression gain. Using a little over six second recorded speech. Recording contains fast spoken words, mostly numbers and a few "this is a test" etc, for maximum power over time. Evaluating scope shoot, about 25 words during six second recording. Not even close to pink noise. John KN5L On 6/20/19 11:27 AM, Bob McGraw K4TAX wrote: > To evaluate speech use a pink noise source. That is the standard source > signal for acoustic measurements. > > Bob, K4TAX > > > Sent from my iPhone > >> On Jun 20, 2019, at 10:34 AM, John Oppenheimer <[email protected]> wrote: >> >> Hi Don, >> >>> On 6/20/19 9:21 AM, Don Wilhelm wrote: >>> John, >>> >>> That connection is OK if you realize that your scope is reading the DC >>> voltage developed by rectifying the RF from 1/2 of the load. You still >>> have to use the power formula that is in the DL1 manual. >> >> Well yes, power references are DCV^2 / 25 >> >> DdB ratios computed using voltage ratios in the form of >> 20 * Log(v1/v2). For example, 0 compression Pep/Pav dB = >> 20 * log(15.3/5.24) = 9.3. I do need to flip the table title to Pav/Pep >> for proper negative dB values, Done. >> >>> I prefer to allow the 'scope to read the full peak RF voltage. Connect >>> the 'scope probe to the side of one resistor which is connected to the >>> BNC jack (one of the leads closest to the BNC), and the 'scope ground >>> probe to one or the resistor leads furthermost away from from the BNC jack. >> >> Using detected RF envelope for oscilloscope average RF measurement at >> each digitized point during long, six second, trace. This will result >> with increased accuracy when measuring modulated speech. >> >> John KN5L >> >>>> On 6/20/2019 9:38 AM, John Oppenheimer wrote: >>>> Using DL1 with Oscilloscope to measure KX3 SSB RMS power: >>>> >>>> https://www.kn5l.net/ssbpower/ >>>> >>>> Question, is this technique correct? ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
