[Elecraft] K3S USB audio questions

[ab2tc]

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.