KX3 - dBV question
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Hi,
I have been playing around with the "dBV-Feature" of my KX3 for some time. I understood how to use it and that it measures a relative input level into the AF stage of the KX3, but my question is if there is any kind of "data processing" involved, in other words: the display is updated roughly once in a second, and my question is if is the input level to the AF stage just being sampled once a second, is the value being displayed something like the peak level that occured during this one second interval between two updates of the value or is something like the average of the signal level during this second being displayed? We have been discussing the "system advantage" of CW compared to SSB in the german QRP facebook group, I tried to measure my personal ability to copy weak SSB and CW signals by using this dBV display, but am not sure, if I can compare the values directly, since I do not know how the data is being generated and processed. Maybe someone on the list or at Elecraft can help me out. Vy 73 Ralf, DL6OAP |
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The DSP uses audio samples at a 12 kHz rate and performs a true RMS calculation on the samples. The result is computed over the display update time (1 second?) the buffer flushed and the process repeated..
73, Lyle KK7P > ... but am not sure, if I can > compare the values directly, since I do not know how the data is being > generated and processed. Maybe someone on the list or at Elecraft can help > me out. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Hi Lyle,
So I actually measure a quantity that is proportional to the energy (signal + noise) that has been "collected" in the display update time, am I getting this right? Greetings Ralf, DL6OAP Am 20.10.2014 um 14:31 schrieb Lyle > The DSP uses audio samples at a 12 kHz rate and performs a true RMS calculation on the samples. The result is computed over the display update time (1 second?) the buffer flushed and the process repeated.. > > 73, > > Lyle KK7P > >> ... but am not sure, if I can >> compare the values directly, since I do not know how the data is being >> generated and processed. Maybe someone on the list or at Elecraft can help >> me out. Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by DL6OAP
Hi Ralf,
Lyle explained how the dBV value is derived. It's a pretty useful measurement. One way to use it is to disable AGC, then measure different signal levels. This makes dBV a linear measurement, up until the signal level causes hardware AGC to activate. Be cautious with your hearing when AGC is disabled. 73, matt W6NIA On Mon, 20 Oct 2014 01:45:24 -0700 (PDT), you wrote: >Hi, > >I have been playing around with the "dBV-Feature" of my KX3 for some time. I >understood how to use it and that it measures a relative input level into >the AF stage of the KX3, but my question is if there is any kind of "data >processing" involved, in other words: the display is updated roughly once in >a second, and my question is if is the input level to the AF stage just >being sampled once a second, is the value being displayed something like the >peak level that occured during this one second interval between two updates >of the value or is something like the average of the signal level during >this second being displayed? > >We have been discussing the "system advantage" of CW compared to SSB in the >german QRP facebook group, I tried to measure my personal ability to copy >weak SSB and CW signals by using this dBV display, but am not sure, if I can >compare the values directly, since I do not know how the data is being >generated and processed. Maybe someone on the list or at Elecraft can help >me out. > > >Vy 73 > >Ralf, DL6OAP -- "Give me six hours to chop down a tree and I will spend the first four sharpening the axe." -A. Lincoln ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by DL6OAP
Hallo Ralf!
Yes. The measurements are taken post-filter and post-AGC. 73, Lyle KK7P > Hi Lyle, > > So I actually measure a quantity that is proportional to the energy (signal + noise) that has been "collected" in the display update time, am I getting this right? > > Greetings > > Ralf, DL6OAP > > > > Am 20.10.2014 um 14:31 schrieb Lyle > >> The DSP uses audio samples at a 12 kHz rate and performs a true RMS calculation on the samples. The result is computed over the display update time (1 second?) the buffer flushed and the process repeated.. >> >> 73, >> >> Lyle KK7P >> >>> ... but am not sure, if I can >>> compare the values directly, since I do not know how the data is being >>> generated and processed. Maybe someone on the list or at Elecraft can help >>> me out. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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