K4 Sound Card, used for Weak Signal Digital Modes.

[Elecraft mailing list]

If available at this early stage, any specs on the upcoming K4 sound card,
or likewise, its internal chip model number, would be of interest here.
Perhaps it will be the same as the carefully chosen TI chip used in the
K3-S.   Thank you.

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[ANDY DURBIN]

"Perhaps it will be the same as the carefully chosen TI chip used in the K3-S"

What is the part number of that carefully chosen TI chip?  Various versions of the PCM2903 are used in amateur radio equipment.  Did Elecraft use something better in the K3S?

73,
Andy, k3wyc
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[ANDY DURBIN]

"The TI PCM2901, I am told by a Watsonville rep, was used in the K3-S."

Thanks.

The PCM2901 and PCM2903 appear to be be very similar.  The only obvious difference I found is in support of S/PDIF.  It was interesting to see that the shared data sheet shows even the latest version of the PCM2903 is not recommended for new designs.

I didn't see anything that suggests the performance of the PCM2901 is better than the PCM2903 but I never was good at "spot the differences".

73,
Andy, k3wyc



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[ANDY DURBIN]

"It was interesting to see that the shared data sheet shows even the latest version of the PCM2903 is not recommended for new designs"

Well, the PCM2903C seems to be the latest version of the PCM2903 and it does not have the NRND designation.  The PCM2901 datasheet reference to PCM2903E is puzzling (at least to me).

http://www.ti.com/lit/ds/symlink/pcm2903c.pdf

73,
Andy, k3wyc


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[Jim Brown-10]

To put this in context, WSJT-X works at 16-bit 48 kHz. The spec that
matters is the linearity of the A/D at the extremes of the dynamic range.

73, Jim K9YC

On 7/12/2019 8:02 AM, Andy Durbin wrote:
> "It was interesting to see that the shared data sheet shows even the latest version of the PCM2903 is not recommended for new designs"



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[ANDY DURBIN]

"The spec that matters is the linearity of the A/D at the extremes of the dynamic range."

Jim,

A bit more information please.  Are you talking about TX or RX?  Are you talking about the A/D that is typically in the TX path between the CODEC and DSP of a modern transceiver or perhaps an A/D that may be used in an outboard analog sound interface?

Why wouldn't a smart new rig accept USB audio and feed it directly to DSP rather than converting to analog and back to digital before reaching the DSP.

73,
Andy, k3wyc



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[Jim Brown-10]

I'm talking about feeding detected audio to the computer for decoding.
And not all digital formats are the same -- going from one to another
takes time and processor power, and, depending on how data is encoded,
may be problematic.

73, Jim K9YC

On 7/12/2019 12:49 PM, Andy Durbin wrote:

> "The spec that matters is the linearity of the A/D at the extremes of the dynamic range."
>
> Jim,
>
> A bit more information please.  Are you talking about TX or RX?  Are you talking about the A/D that is typically in the TX path between the CODEC and DSP of a modern transceiver or perhaps an A/D that may be used in an outboard analog sound interface?
>
> Why wouldn't a smart new rig accept USB audio and feed it directly to DSP rather than converting to analog and back to digital before reaching the DSP.
>
> 73,
> Andy, k3wyc
>
>
>

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