FT8 “Taking Amateur Radio By Storm!” By: Jonathan Kayne, KM4CFT

So, what is FT8? FT8 is a weak signal mode that is a variant of JT-65, with the added benefit of having a significantly shorter transmission time. Developed by Joe Taylor, K1JT and Steven Franke, K9AN Will get to more info on JT-65 in a little bit https://microship.com/wp-content/uploads/2018/01/ft8-waterfall.jpg

Joe Taylor, K1JT Joe Taylor is a professor at Princeton University, and obtained the Nobel Prize in Physics back in 1993 for his work in pulsars. Significant research in Moon-bounce (EME) WSJT (Weak Signal Joe Taylor) WSPR (Weak Signal Propagation Reporter, pronounced “Whisper”) FSK441, JT-65, JT-9, FT8 - WSPR is a method used for analyzing propagation, and essentially allows a server to control your rig and by using a network of stations, you can see the effects that prop. has on an area. Similar to PSKreporter or Reverse Beacon Network. FSK441 uses multi-frequency shift keying. https://www.nobelprize.org/prizes/physics/1993/taylor/auto-biography/

Basics of a digital mode Digital modes are simply using a digital interface to carry out a communication. Most Basic: simple binary values: FSK (Frequency Shift Keying) – Radioteletype/RTTY PSK (Phase Shift Keying) – PSK31 Texting using ham radio FSK – alternating between two frequencies, each representing a zero or one PSK – alternating between the sine and cosine wave

How to use a digital Mode You simply need to interface a computer with your radio It is incredibly easy to set up Audio feed (PC speaker to Radio Mic, PC Mic to Radio speaker) A way to key up the radio Software: Fldigi, WSJT-X, HRD, etc. - Duck tape a speaker to your hand microphone…

JT-65 Weak signal mode, QRP Designed for moon bounce Can detect signal well below the noise floor Time dependent ~46s Transmit time 65 tone MFSK Adds redundancy to create Forward error correction Reed-Solomon encoding (often used in DVDs)

Typical JT-65 or FT8 QSO

Disadvantages of JT-65 As you can see there are about 7 cycles per QSO, so a single QSO can take up to 7 minutes! Not very good for contesting or if you want to make a lot of QSO’s in a given time period Meant for basic QSOs, not for “ragchewing” (disadvantage of FT8 too)

FT8 FT8 fixes the problem that JT-65 has by shortening the time period to 13 seconds! This means you can complete a QSO in ~1.5 minutes! It is for this reason that it has become incredibly popular 75 bits of data Uses LDPC (low density parity check) for encoding 8 tones, 6.25 Hz spacing 3 7x7 costas Arrays (start, middle, end)

Statistics from PSKreporter It has become so popular that some hams actually think that it is “destroying” ham radio. Hams said this about AM…then SSB…then FM…then RTTY…then PSK31…then [I’m gonna stop while I’m ahead!]

Using FT8 Requires a properly synced time clock Show the layout Auto-sequence – you have about 3 seconds to respond

FT8CALL A community based mode based off of FT8 More of a ragchew mode

Thanks! Jonathan Kayne KM4CFT jzkmath@vt.edu