[WriteLog] Interfacing WL to Elecraft K3

[Joe Subich, W4TV]

> The stuttering comes from (maybe) the OS handling for the USB side of
> a USB to serial converter. So far, I haven't found any USB to serial
> converters that don't have that problem, although others people
> insist they work fine.

Much of the USB related stuttering is caused by timing in the USB
system.  USB is a slot based protocol with the default slot being
16 milliseconds.  If one has multiple devices connected to a "Root
Hub" (think bus controller) each device gets 16 ms out of N x 16 ms.
If one has two radio interfaces, a sound card, two CW/PTT and two
FSK/PTT interfaces connected to a single "root hub", the CW or FSK
line gets services 16 ms of every 112 ms if each device is passing
data although every device does not have data on every slot and
unused time is released.  On the other hand, if one adds a USB memory
device to that root hub, (e.g. a memory stick for back-up, 
"Ready/Boost," etc.) storage read/write can take several "slots"
depending on the driver configuration.

JA7UDE looked at jitter in RTTY with both EXTFSK and EXTFSK2 ...
comparing the MMTIMER (EXTFSK) and HPTIMER (EXTFSK2) and single
USB converter vs. USB converter with USB storage using a high
performance CPU (2.8 GHz, i7).  His results are here:
    http://www.qsl.net/ja7ude/extfsk/jitter.html

While the absolute error will be less significant with the lower
baud rates encountered with CW, the trends are clear.  A single
USB converter with CAT, CW and PTT should be relatively clean but
add sound (for CW decoder), multiple radios and real-time back-up
and/or Ready/Boost on an old (single/dual core < 2 GHz) CPU, the
quality of CW and/or RTTY can go to pot in a hurry.

73,

    ... Joe, W4TV


On 2014-12-04 12:06 PM, Victor A. Kean, Jr. wrote:
> On Thursday, December 04, 2014 8:09:46 AM Ed Muns wrote:
>> Yes, it functionally works but the CW timing stutters or is off in some way
>> frequently.
>
> In my experience, keying the K3 from the PC works perfectly when an actual
> hardware serial (com) port is used.  I've used 3 different computers since
> I've had my K3, including an old Compaq laptop used just for Field Day.
>
> The stuttering comes from (maybe) the OS handling for the USB side of a USB
> to serial converter.  So far, I haven't found any USB to serial converters
> that don't have that problem, although others people insist they work fine.
> So maybe performance varies with OS loading.
>
> I used a homebrew SO2R box this past weekend for the CQ WW CW.  The box
> includes a USB to serial adapter implemented with custom code running on
> a USB capable microcontroller chip.  This particular USB to serial converter
> stuttered only about 10 times over the process of logging 2800 QSOs.
>
> Victor, K1LT
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