2 ms·
FT8 and other weak signal modes can work with more noise and less signal than conventional modes. Which makes possible to communicate with the current poor HF p
by ianburrell 8y ago
FT8 and other weak signal modes can work with more noise and less signal than conventional modes. Which makes possible to communicate with the current poor HF propagation, or with lower power devices and longer distances. It does this by using low bandwidth (50 Hz), low bit rate (6 bit/s), and error correction.
The other special thing about FT8 is that it only does contacts, with binary messages for doing the exchange.
- jpmattia 8y ago> FT8 and other weak signal modes can work with more noise and less signal than conventional modes I'm a little surprised that FT8 is better S/N than conventional mode of morse code, but then I didn't think in terms of S/N back when I was active in the 70s/80s (btw: Straight key! I finally build a keyer after 5 years of straight key, and then went off to college and didn't have another QSO for many years. :( Edit: Regard QSO, Do folks even use Q signals anymore?
- tasty_freeze 8y agoThese low bandwidth / low power modes are mathemagic, extracting signals that are well below the noise floor. Redundancy, forward error correction, and low baud rates are the key. In morse, the baud rate is low, but you get one chance at each symbol and that is it. With these new modes a small set of bits is sent in a highly redundant fashion such that you can recover the whole message even if you capture only, say, 30% of the bits, not necessarily contiguous.
- deleted 8y ago[deleted]
- hatsunearu 8y agomorse CW is pretty bad in terms of BER because it's hard to create a robust automatic decoder, not to mention OOK (which is morse essentially is for this purpose) is very poor against multipath interference.