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{{Short description|Frequency shift keying digital mode}} {{Short description|Frequency shift keying digital mode}}
] ] showing FT8 in use on the ].]]
'''FT8 '''or '''Franke & Taylor 8''' is a ] digital ]. Following release on June 29, 2017, by its creators ], and Steve Franke, K9AN, along with the software package ],<ref name=":0">Burmester, Dale March 12, 2019. Amateur Radio Digital Communications Mode FT8. http://site.ieee.org/msn/files/2019/04/FT8-KA9SWE.pdf</ref> FT8 was adopted rapidly and, in little over two years, it became the most popular digital mode on spotting networks such as ].<ref>{{Cite web |last=Barron |first=Robert |date=2020-02-08 |title=PSK Reporter |url=http://www.ka5wss.com/posts/psk-reporter/ |access-date=2022-10-06 |website=KA5WSS |language=en-US}}</ref> '''FT8 ''' (short for Franke-Taylor design, 8-FSK modulation) is a ] digital ] used by ] operators worldwide. Following release on June 29, 2017, by its creators ], and Steve Franke, K9AN, along with the software package ],<ref name=":0">{{cite web |last=Burmester |first=Dale |date=March 12, 2019 |title=Amateur Radio Digital Communications Mode FT8 |url=https://site.ieee.org/msn/files/2019/04/FT8-KA9SWE.pdf |access-date=2024-11-11}}</ref> FT8 was adopted rapidly, becoming the most popular digital mode recorded by automatic spotting networks such as ]<ref>{{Cite web |last=Barron |first=Robert |date=2020-02-08 |title=PSK Reporter |url=http://www.ka5wss.com/posts/psk-reporter/ |access-date=2022-10-06 |website=KA5WSS |language=en-US |archive-date=2022-10-06 |archive-url=https://web.archive.org/web/20221006195106/http://www.ka5wss.com/posts/psk-reporter/ |url-status=live }}</ref> within 2 years.


==Introduction== ==Introduction==
FT8 is a popular form of digital weak signal communication used primarily by amateur radio operators to communicate on ] with a majority of traffic occurring on the ] amateur bands.<ref>{{Cite web |last=Luscre |first=Anthony |date=2019-10-11 |title=FT8—What Is It and How Can I Get Started? |url=https://www.onallbands.com/ft8-what-is-it-and-how-can-i-get-started/ |access-date=2022-08-17 |website=OnAllBands |language=en-US}}</ref> The mode offers operators the ability to communicate in unfavorable environments such as during low ], high RF noise, or during ].<ref>{{Cite web |title=FT8 – Signal Identification Wiki |url=https://www.sigidwiki.com/FT8 |access-date=2022-08-17 |website=www.sigidwiki.com}}</ref> With advances in signal processing technology FT8 is able to decode signals with a signal to noise ratio as low as −20&nbsp;dB, which is significantly lower than ] or ] transmissions.<ref>{{Cite web |title=FT8 Mode is Latest Bright Shiny Object in Amateur Radio Digital World |url=http://www.arrl.org/news/ft8-mode-is-latest-bright-shiny-object-in-amateur-radio-digital-world |access-date=2022-08-17 |website=www.arrl.org |language=en}}</ref> FT8 is a popular form of digital weak signal communication used primarily by amateur radio operators to communicate on ] with a majority of traffic occurring on the ] amateur bands.<ref>{{Cite web |last=Luscre |first=Anthony |date=2019-10-11 |title=FT8—What Is It and How Can I Get Started? |url=https://www.onallbands.com/ft8-what-is-it-and-how-can-i-get-started/ |access-date=2022-08-17 |website=OnAllBands |language=en-US |archive-date=2022-10-01 |archive-url=https://web.archive.org/web/20221001035847/https://www.onallbands.com/ft8-what-is-it-and-how-can-i-get-started/ |url-status=live }}</ref> The mode offers operators the ability to communicate despite unfavorable conditions such as during low ], high RF noise, or with ].<ref>{{Cite web |title=FT8 – Signal Identification Wiki |url=https://www.sigidwiki.com/FT8 |access-date=2022-08-17 |website=www.sigidwiki.com |archive-date=2022-08-17 |archive-url=https://web.archive.org/web/20220817030846/https://www.sigidwiki.com/FT8 |url-status=live }}</ref> With advances in signal processing technology, software can decode FT8 signals with a signal-to-noise ratio as low as −20&nbsp;dB in a 2500&nbsp;Hz bandwidth, which is significantly lower than conventional ] or ] transmissions.<ref>{{Cite web |title=FT8 Mode is Latest Bright Shiny Object in Amateur Radio Digital World |url=http://www.arrl.org/news/ft8-mode-is-latest-bright-shiny-object-in-amateur-radio-digital-world |access-date=2022-08-17 |website=www.arrl.org |language=en |archive-date=2022-05-28 |archive-url=https://web.archive.org/web/20220528155358/http://www.arrl.org/news/ft8-mode-is-latest-bright-shiny-object-in-amateur-radio-digital-world |url-status=live }}</ref>


==Opearation== ==Operation==
FT8 works by sending signals in 15-second-blocks with 12.64&nbsp;seconds of transmission time and 2.36&nbsp;seconds of decode time, this gives the mode five words per minutes effective transmission.<ref name=":0" /> The mode requires both sending and receiving computers to be synchronised so, while manual time setting is possible, most users make use of automatic online time servers using ] or by receiving broadcast time signals from the ] to ensure their transmissions fall in the proper windows. FT8 involves 77-bit message blocks transmitted in regular 15-second periods, consisting of 12.64&nbsp;seconds of transmission time and 2.36&nbsp;seconds of decode time, giving a digital data rate of 6.09&nbsp;bits/sec. Source encoding gives an effective message throughput equivalent to about 5 words per minute. The required signal-to-noise ratio in a 2500&nbsp;Hz bandwidth is &minus;21&nbsp;dB, so the corresponding ] is 10 log<sub>10</sub>(2500/6.09) = 26.1&nbsp;dB greater, or &minus;21&nbsp;dB + 26.1 = 5.1&nbsp;dB.<ref name=":0" />


Although FT8 transmissions occur within fixed time windows, the software can cope with discrepancies between sending and receiving systems of up to a second or two. Provided that they are manually set to the correct time every so often (for example, by using ] or other time standard broadcasters), conventional computer Real Time Clocks are usually adequate. However, most FT8 users take advantage of online time servers using ] or time signals from the ] to achieve and maintain better time accuracy, automatically.
Each FT8 transmission can support up to 13 text characters, coded using ] to ensure proper transmission and decoding despite common radio effects such as fading, interference or poor signal propagation conditions, or low power operation with compromised antennas in restricted urban spaces. As the mode is quite limited in the number of words that it can send, it only sends enough information to ensure a contact with each station.

] helps achieve reliable communication despite common RF issues such as fading and interference, and weak/noisy signals due to marginal propagation paths, low power operation and inefficient antennas (e.g. in restricted and overcrowded urban locations). If anticipated messages are missed or not acknowledged, the software can re-send them in the next time-slot.

The 77 bits are sufficient for free text messages of up to 13 text characters, reminiscent of ] (TXT) messages or ], while a clever data compression scheme reduces the number of digital bits required to pass structured messages containing conventional callsigns, reports and locators. Long or unusual callsigns are problematic for the protocol, however, despite using hashing to pass condensed representations. Decoding errors and hash collisions occasionally generate false 'callsigns' creating puzzlement or excitement if they appear to be rare but genuine calls.


==Applications== ==Applications==
]
⚫ There are multiple uses for FT8 including contesting,<ref>{{Cite web |title=FT8/FT4 from a contester's perspective – VA7ST.ca |url=https://va7st.ca/2020/10/ft8-ft4-from-a-contesters-perspective/ |access-date=2022-08-17 |language=en-US}}</ref><ref>{{Cite web |title=ARRL Surveying Field Day Participants |url=http://www.arrl.org/news/arrl-surveying-field-day-participants |access-date=2022-08-17 |website=www.arrl.org |language=en}}</ref> testing antennas,<ref>{{Cite web |title=FT8 |url=https://www.rtl-sdr.com/tag/ft8/ |access-date=2022-08-17 |website=www.rtl-sdr.com}}</ref> and for scientific research.<ref>{{Cite web |last1=Erickson |first1=P. |last2=Liles |first2=W. |last3=Miller |first3=E. |last4=Miller |first4=E. |date=2020 |title=Amateur digital mode based remote sensing: FT8 use as a radar signal of opportunity for ionospheric characterization |url=https://hamsci.org/publications/amateur-digital-mode-based-remote-sensing-ft8-use-radar-signal-opportunity-ionospheric |access-date=2022-08-17 |website=hamsci.org}}</ref>
] ]
⚫ There are multiple uses for FT8 including contesting,<ref>{{Cite web |title=FT8/FT4 from a contester's perspective – VA7ST.ca |url=https://va7st.ca/2020/10/ft8-ft4-from-a-contesters-perspective/ |access-date=2022-08-17 |language=en-US |archive-date=2022-08-17 |archive-url=https://web.archive.org/web/20220817030847/https://va7st.ca/2020/10/ft8-ft4-from-a-contesters-perspective/ |url-status=live }}</ref><ref>{{Cite web |title=ARRL Surveying Field Day Participants |url=http://www.arrl.org/news/arrl-surveying-field-day-participants |access-date=2022-08-17 |website=www.arrl.org |language=en |archive-date=2022-08-17 |archive-url=https://web.archive.org/web/20220817075953/http://www.arrl.org/news/arrl-surveying-field-day-participants |url-status=live }}</ref> testing antennas,<ref>{{Cite web |title=FT8 |url=https://www.rtl-sdr.com/tag/ft8/ |access-date=2022-08-17 |website=www.rtl-sdr.com |archive-date=2022-09-30 |archive-url=https://web.archive.org/web/20220930170306/https://www.rtl-sdr.com/tag/ft8/ |url-status=live }}</ref> and for scientific research.<ref>{{Cite web |last1=Erickson |first1=P. |last2=Liles |first2=W. |last3=Miller |first3=E. |last4=Miller |first4=E. |date=2020 |title=Amateur digital mode based remote sensing: FT8 use as a radar signal of opportunity for ionospheric characterization |url=https://hamsci.org/publications/amateur-digital-mode-based-remote-sensing-ft8-use-radar-signal-opportunity-ionospheric |access-date=2022-08-17 |website=hamsci.org |archive-date=2022-08-17 |archive-url=https://web.archive.org/web/20220817030846/https://hamsci.org/publications/amateur-digital-mode-based-remote-sensing-ft8-use-radar-signal-opportunity-ionospheric |url-status=live }}</ref>
]

== Further information ==
is a popular club dedicated to this digital mode.

The gives pragmatic advice on using FT8 for HF communications.


== References == == References ==
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{{Telecommunications|state=collapsed}} {{Telecommunications|state=collapsed}}


] ]
] ]
] ]

Latest revision as of 19:02, 12 November 2024

Frequency shift keying digital mode
A waterfall display showing FT8 in use on the 40-meter band.

FT8 (short for Franke-Taylor design, 8-FSK modulation) is a frequency shift keying digital mode of radio communication used by amateur radio operators worldwide. Following release on June 29, 2017, by its creators Joe Taylor, K1JT, and Steve Franke, K9AN, along with the software package WSJT, FT8 was adopted rapidly, becoming the most popular digital mode recorded by automatic spotting networks such as PSK Reporter within 2 years.

Introduction

FT8 is a popular form of digital weak signal communication used primarily by amateur radio operators to communicate on amateur radio bands with a majority of traffic occurring on the HF amateur bands. The mode offers operators the ability to communicate despite unfavorable conditions such as during low solar activity, high RF noise, or with low transmit power. With advances in signal processing technology, software can decode FT8 signals with a signal-to-noise ratio as low as −20 dB in a 2500 Hz bandwidth, which is significantly lower than conventional CW or SSB transmissions.

Operation

FT8 involves 77-bit message blocks transmitted in regular 15-second periods, consisting of 12.64 seconds of transmission time and 2.36 seconds of decode time, giving a digital data rate of 6.09 bits/sec. Source encoding gives an effective message throughput equivalent to about 5 words per minute. The required signal-to-noise ratio in a 2500 Hz bandwidth is −21 dB, so the corresponding Eb/N0 is 10 log10(2500/6.09) = 26.1 dB greater, or −21 dB + 26.1 = 5.1 dB.

Although FT8 transmissions occur within fixed time windows, the software can cope with discrepancies between sending and receiving systems of up to a second or two. Provided that they are manually set to the correct time every so often (for example, by using WWV or other time standard broadcasters), conventional computer Real Time Clocks are usually adequate. However, most FT8 users take advantage of online time servers using NTP or time signals from the GPS to achieve and maintain better time accuracy, automatically.

Forward error correction helps achieve reliable communication despite common RF issues such as fading and interference, and weak/noisy signals due to marginal propagation paths, low power operation and inefficient antennas (e.g. in restricted and overcrowded urban locations). If anticipated messages are missed or not acknowledged, the software can re-send them in the next time-slot.

The 77 bits are sufficient for free text messages of up to 13 text characters, reminiscent of SMS (TXT) messages or Tweets, while a clever data compression scheme reduces the number of digital bits required to pass structured messages containing conventional callsigns, reports and locators. Long or unusual callsigns are problematic for the protocol, however, despite using hashing to pass condensed representations. Decoding errors and hash collisions occasionally generate false 'callsigns' creating puzzlement or excitement if they appear to be rare but genuine calls.

Applications

FT8 blocks on 20 meters
Recording of FT8 transmissions on 20 meters

There are multiple uses for FT8 including contesting, testing antennas, and for scientific research.

Further information

FT8DMC is a popular club dedicated to this digital mode.

The FT8 Operating Guide gives pragmatic advice on using FT8 for HF communications.

References

  1. ^ Burmester, Dale (March 12, 2019). "Amateur Radio Digital Communications Mode FT8" (PDF). Retrieved 2024-11-11.
  2. Barron, Robert (2020-02-08). "PSK Reporter". KA5WSS. Archived from the original on 2022-10-06. Retrieved 2022-10-06.
  3. Luscre, Anthony (2019-10-11). "FT8—What Is It and How Can I Get Started?". OnAllBands. Archived from the original on 2022-10-01. Retrieved 2022-08-17.
  4. "FT8 – Signal Identification Wiki". www.sigidwiki.com. Archived from the original on 2022-08-17. Retrieved 2022-08-17.
  5. "FT8 Mode is Latest Bright Shiny Object in Amateur Radio Digital World". www.arrl.org. Archived from the original on 2022-05-28. Retrieved 2022-08-17.
  6. "FT8/FT4 from a contester's perspective – VA7ST.ca". Archived from the original on 2022-08-17. Retrieved 2022-08-17.
  7. "ARRL Surveying Field Day Participants". www.arrl.org. Archived from the original on 2022-08-17. Retrieved 2022-08-17.
  8. "FT8". www.rtl-sdr.com. Archived from the original on 2022-09-30. Retrieved 2022-08-17.
  9. Erickson, P.; Liles, W.; Miller, E.; Miller, E. (2020). "Amateur digital mode based remote sensing: FT8 use as a radar signal of opportunity for ionospheric characterization". hamsci.org. Archived from the original on 2022-08-17. Retrieved 2022-08-17.
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