Hi, On item 4:
The audio level seen by, say a recording program on the PC depends on the LINE OUT setting on the K3. I left that as the default, 10, and used the Windows mixer to adjust the level. My audio is now reading approximately -6dB below clipping which is probably a little high, but I have set my AGC SLP to the flattest possible setting (highest number). If you prefer a considerable slope on the AGC curve above threshold, you will need a lower LINE OUT setting. Remember that even when throwing away 3 bits, you still have far more resolution than you can use with an HF receiver. AB2TC - Knut Matt Zilmer-3 wrote > Hi Richard, > > Some answers, below. --matt > > > On 11/5/2016 9:38 AM, Richard Lamont wrote: >> A few questions about the K3S internal audio interface: >> >> 1. Is the internal connection between the USB audio interface and the >> 2nd IF analogue or digital? If digital, how is the sample rate >> conversion implemented? > > The KIO3B uses a codec (digital on its USB side, analog one the audio > side (line in/out). The codec's USB D+/- nets are connected to a USB hub. > > >> >> 2. It seems to support sampling rates of 32000, 44100 and 48000 Hz, but >> not higher or lower values. Is this correct? > > These are the sample rates the codec supports. Yes. > >> >> 3. What determines the clock frequency for this sampling? Is it a >> free-running crystal? If so, what is its frequency tolerance? Or is it >> locked to the main TXCO and/or external 10 MHz reference? > > The clock is an XO: 12 MHz, +/- 100 ppm as rated. The XO's output is > buffered and feeds the codec. > >> >> 4. When listening to SSB audio at S9+, with slow AGC, the output level >> via this interface seems to be -22 dBFS true peak. Why is it throwing >> away three bits of resolution? Or is this amount of headroom >> necessary/useful? > > You can find a copy of the data sheet here: > http://www.digikey.com/product-search/en?keywords=PCM2901E%2F2K > > 73, > matt W6NIA > >> >> TIA. >> > > -- > Always store beer in a dark place. - R. Heinlein > > Matt Zilmer, W6NIA > [Shiraz] > <snip> -- View this message in context: http://elecraft.365791.n2.nabble.com/K3S-USB-audio-questions-tp7623845p7623848.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ 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]
