Those DT Blues

[Richard-6]

HARDWARE:
K3s, Mac mini, SignaLink USB (unable to use just an A/B USB cable).

The Mac mini is dedicated to WSJT-X; it isn’t asked to do anything else.

When running FT8 via WSJT-X 1.9.1, I see a wide variety of DT numbers of transmitting stations, everything from minus 1 to plus 2. A friend who is perfection personified reported that my DT is a consistent 0.4 into his gear at his station.

The numbers I see most are 0.0, 0.1, and 0.2. Mister Perfection tells me I’m fine and I shouldn’t worry about it. Is he on target?

If 0.4 means my transmitter begins transmitting 0.4 seconds AFTER the “official” start of each 13-second transmit segment, does that put me at a disadvantage when calling the same DX along with several others?

When I think about the “Call 1st” feature of WSJT-X, I wonder — does that mean the DX’s decoder will process my 0.4 signal AFTER processing all the 0.0, 0.1, and 0.2 signals which it “sees first?” How does the decoder decide whom to decode and in what order?

Richard Kunc - W4KBX
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[Jim Brown-10]

On 10/1/2018 3:38 PM, Richard wrote:
> When running FT8 via WSJT-X 1.9.1, I see a wide variety of DT numbers of transmitting stations, everything from minus 1 to plus 2. A friend who is perfection personified reported that my DT is a consistent 0.4 into his gear at his station.

That DT number is the difference between your clock and his. If it were
off by a second or two, you would see almost all stations off by that
amount, and in the same direction. If it were off by more than that, you
would see few decodes at all. 99.9% of my WSJT-X work is on 6M, and I
rarely see DTs greater than a half second -- most are 0.1 - 0.2. You
WILL see occasional DTs greater than 1 second.

For many years, I've used this nice little clock utility. Works great.
Free. http://www.timesynctool.com/

73, Jim K9YC


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