This section contains operating tips for the WW Digi DX Contest.
Q: What are the proper audio settings for the FT mode?
First, set the audio drive level for zero ALC reading or minimum ALC for those radios that specify minimal ALC is appropriate for digital audio modes.
Second, select “Fake It” in WSJT-X or equivalent software if your radio has CAT control. This allows the software to dynamically adjust your carrier and audio frequencies such that the audio signal is above 500 Hz where there is no low-pass filtering degradation.
Q: What software supports this contest?
Any FT software that exports an ADIF log can be used in WW Digi. The ADIF log can span a greater time period than just the 24 hour contest. An ADIF Converter is available on the website that will convert any ADIF file to the Cabrillo format needed for WW Digi. This converter will not convert QSO data outside the 24-hour contest period, making it easy to input an ADIF file that may contain contacts from before, or after, the contest.
However, some software, e.g., JTDX and MSHV, do not support the shorter message sequence that exchanges Grid Square only. In WSJT-X, this is the "NA VHF Contest" mode, selectable in "Special operating activity" in the Advanced tab of the File/Setting window. See the next question.
Q: What messages do I use for this contest?
When operating in the recommended sub-bands for WW Digi (Rule II.), select "NA VHF Contest" option in "Special operating activity" in the File/Settings menu item In WSJT-X. Other software, e.g., DigiRite, may have different ways of selecting the two message sets. When operating on the standard daily daily FT8 frequencies, de-select "Special operating activity" and use the standard default everyday messages. Although the two different messages sets will inter-operate fine, some QSO partners may be confused if the don't receive a SNR report. Or, they may send Tx 2 instead of Tx 1 and not provide the required Grid Square in their report. (See the next question.)
Q: What if my QSO partner sends the WSJT-X Tx 2 message instead of Tx 1?
The standard WSJT-X Tx 2 message sends a SNR rather than the station’s grid square (Tx 1) as a way of shortening the QSO time. However, this means the other station doesn’t get half the exchange required by the contest rules and therefore no credit for the QSO. The choice is to not respond to Tx 2 callers, or to work them in good will, knowing that they will not contribute to your contest score. This conundrum is similar to working dupes. The QSO time doesn’t increase one’s score, but it gets the duping station out of the way for other QSO partners.
Q: If I call a station who just finished a QSO with a ‘73’ message, how do I get Grid Square?
Your QSO partner will send their Grid Square with their confirmation message (Tx 3) for your report message (Tx 2). The Tx 3 message is designed for exactly this situation.
Q: What is multi-streaming?
The term “multi-streaming” refers to conducting QSOs in parallel where one transmission contains QSO information for 2 or more QSO partners. For example, if two stations answer your CQ, multi-streaming would allow one transmission to contain the signal reports back to each of the two stations. This is a natural consequence of the inherent multi-channel characteristic of the FT mode.
Q: How is multi-streaming done?
As of the 2019 WW Digi DX Contest, there is no satisfactory method available for conducting multiple parallel QSOs in a contest environment.
Q: Isn't the WSJT-X Fox and Hound mode "multi-streaming"?
Yes, but only for a single fox working split frequency. Thus, it is not suitable in a contest where there are many foxes. A large DXpedition is the target user of Fox and Hound mode with the "hounds" being all the DXers striving to work the single DX station.
Q: Why can't there be multiple foxes in a contest?
The current implementation of Fox and Hound mode divides the transmit voltage among 2 or more audio frequencies, one for each QSO partner. This creates two problems in a contest.
First, each contest fox would take up ‘n’ times as much bandwidth as a single audio signal for the ‘n’ parallel QSO partners. In rough terms, this would expand the total contest bandwidth required from a few kHz to over 100 kHz, similar to current RTTY contests. In contrast, FT8 contests to date have used less than 4-6 kHz per amateur band despite high activity.
Second, the on-the-air RF signal is considerably wider than even the multiple audio frequency signal created by the FT8 software. While the multiple audio frequency waveforms are each narrow and distortion free, the RF transceiver creates IMD products from the multiple audio signals, much like the classic Two-Tone SSB transmitter test. The result is a signal with very wide skirts, similar to a typical RTTY signal.
It doesn’t make sense to degrade the clean, narrow FT8 signal into a signal as bad or worse than a RTTY signal. Hopefully, in the future, different implementation techniques will be developed to conduct multiple parallel QSOs while maintaining the inherent clean, narrow signal characteristics of the FT mode.