ZS2EZ FT8 HF OPERATIONS

INTRODUCTION

On 11 July 2017 the WSJT Development Group announced the Beta Release of WSJT-X Version 1.8.0 (RC1). Included in this release was a new mode : FT8

From the release notes:

Brief Description of the FT8 Protocol
-------------------------------------

WSJT-X Version 1.8.0 includes a new mode called FT8, developed by K9AN
and K1JT. The mode name "FT8" stands for "Franke and Taylor, 8-FSK
modulation". FT8 uses 15-second T/R sequences and provides 50% or
better decoding probability down to -20 dB on an AWGN channel. An
auto-sequencing facility includes an option to respond automatically
to the first decoded reply to your CQ. FT8 QSOs are 4 times faster
than those made with JT65 or JT9. FT8 is an excellent mode for HF
DXing and for situations like multi-hop E_s on 6 meters, where deep
QSB may make fast and reliable completion of QSOs desirable.

Some important characteristics of FT8:

- T/R sequence length: 15 s
- Message length: 75 bits + 12-bit CRC
- FEC code: LDPC(174,87)
- Modulation: 8-FSK, tone spacing 6.25 Hz
- Constant-envelope waveform
- Occupied bandwidth: 50 Hz
- Synchronization: 7x7 Costas arrays at start, middle, and end
- Transmission duration: 79*1920/12000 = 12.64 s
- Decoding threshold: -20 dB; several dB lower with AP decoding
- Multi-decoder finds and decodes all FT8 signals in passband
- Optional auto-sequencing and auto-reply to a CQ response
- Operational behavior similar to JT9, JT65

We plan to implement signal subtraction, two-pass decoding, and use of
a priori (AP) information in the decoder. These features are not yet
activated in v1.8.0.

We haven't yet finalized what the three extra bits in the message
payload will be used for. Suggestions are welcome!

-- Joe, K1JT, for the WSJT Development Team
Whilst this mode was primarily aimed at Sporadic E on 6m, it was VERY rapidly adopted on the HF bands. In a mere matter of weeks it became a runaway phenomenon. Huge numbers of operators flocked to the new mode, and it very quickly became supported by the companion program JTAlert. Major logging programs such as DXKeeper, Log4OM and HRD also rapidly provided support for the mode, and eQSL were very quick to accept uploads of FT8 QSOs. Only LoTW lagged behind, insisting on waiting for ADIF to "approve" the mode. This led to chaos as operators mapped their contacts to the ubiquitous "DATA" in TQSL in order to upload, only then having to RE-UPLOAD with the mapping removed once ADIF FINALLY got around to approving FT8.... the chaos and confusion continued more than a month later - this was a mistake that many LoTW users (myself included) have vowed NEVER to make again!!!

On 2 September 2017 WSJT-X 1.8.0 RC2 was released. To quote the release notes : "Implementation of FT8 and its auto-sequencing feature is now more capable and more polished. The decoder is faster and better: it now includes signal subtraction, multi-pass decoding, and the use of accumulated "a priori" information as a QSO progresses. Sensitivity extends downward as far as -24 dB in some circumstances. Overlapping
signals 2 and 3 deep are frequently decoded at essentially the same frequency. On a crowded band we sometimes see more than 30 decodes in a single 15-second interval, over a 2 kHz window. The North American VHF Contesting Mode has been extended to include both FT8 and MSK144 modes.The "RC2" release also includes many minor bug fixes and an extensively updated WSJT-X User Guide."

The "development releases" of WSJT-X continue to display as version 1.7.1 (this will change to 1.8.0 once the final General Release of 1.8.0 is issued). These releases require users to compile ("build") their own installer files. Detailed instructions for doing this can be found here. These development releases include bug fixes to issues found in the Release Candidate versions.

FT8 has significantly changed the Digital landscape - HF Digital will never be the same again!

SOME CONSIDERATIONS FOR USING FT8 ON HF:
The most CRITICAL aspect of FT8 operation is EXACT time calibration. Due to the short 15 second periods being any more than 1 second out can result in other stations being unable to decode your signal. ACCURATE time-synchronisation software such as Meinberg NTP (recommended) or Dimension 4 are a necessity.  Avoid ALC action if possible - much like any other audio input to an SSB transmitter FT8 can generate a poor signal if over driven. FT8 is a weak signal mode, NOT a low power mode. Its primary design purpose is to facilitate Sporadic E communications on VHF. For use on HF there is no issue with using as much power as is needed to establish a contact with a DX station, PROVIDED YOU DO NOT OVERDRIVE YOUR AUDIO!

MY ACTIVITY
ZS2EZ has been active in FT8 on the HF bands since it's release in the WSJTX-1.8.0-RC1 package on 11 July 2017. My first QSO in this mode was with YT1XN on 20m on 13 July 2017. [Before starting operations I had to make some changes to my logging program to accept the new mode]. Within a VERY short time I had in excess of 100 QSOs logged, and found the rapid pace of the mode very well suited to my operating style.  Due to poor propagation towards NA it took a while to log my first few American stations, but have now completed my WAS on FT8 (with confirmations via LoTW) when logging WC0G in ND on 30m (13/10/2017). I have also logged in excess of 1 000 QSOs with more than 100 DXCC entities!!

I will gladly respond to sked requests for any band in FT8!!

Below is my table of US States worked and needed in my quest for WAS via FT8!

WAS on FT8 : My contacts table: (all confirmed via LoTW)

STATE QSO
Alabama
WG8S
Alaska AL7TC
Arizona
WW7B
Arkansas
KG5COF
California
WI6K
Colorado
K0ARG
Connecticut
KA1J
Delaware W3WTE
Florida
N4TB
Georgia
WF4W
Hawaii
KH6FHI
Idaho
W7MEM
Illinois
NA9RB
Indiana
WB9DLC
Iowa
N0JR
Kansas
WB0NRV
Kentucky
K4OP
Louisiana
W5TZX
Maine
W1OWL
Maryland
W3JX
Massachussets
W1PFZ
Michigan
KD8ZQZ
Minnesota
K0XB
Mississippi
W5THT
Missouri
N0IAI
Montana
KB7Q
Nebraska
KA0UNB
Nevada
N7XCZ
New Hampshire
N2CVS
New Jersey K3EL
New Mexico
K6LIE
New York
AC2QH
North Carolina
W4CHI
North Dakota
WC0G
Ohio
KC8YDS
Oklahoma
N5AQ
Oregon
W7YAQ
Pennsylvania
K3UA
Rhode Island
K1RI
South Carolina K4ADB
South Dakota
KE0HQZ
Tennessee
WD4T
Texas
KC9FFV
Utah
N5LZ
Vermont
KC1APK
Virginia
K1HTV
Washington
N7QT
West Virginia
KB8BIP
Wisconsin
KE9LZ
Wyoming
KC7UBS

LAST UPDATED : 13 OCTOBER 2017

 

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