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A waterfall plot for FT8 signals (bandwidth 50 Hz) in the 40-meter band and for JT65 on the right (bandwidth 180 Hz) Joe Taylor, K1JT, announced on June 29, 2017, the availability of a new mode in the WSJT-X software, FT8. [11] FT8 stands for "Franke-Taylor design, 8-FSK modulation" and was created by Joe Taylor, K1JT and Steve Franke, K9AN.
Synchronization is via a 162 bit pseudo-random sync vector. Each channel symbol conveys one sync bit (LSB) and one data bit (MSB). Duration of transmission is 162 × 8192 ⁄ 12000 = 110.6 s. Transmissions nominally start one second into an even UTC minute: e.g., at hh:00:01, hh:02:01, etc.
The required signal-to-noise ratio in a 2500 Hz bandwidth is −21 dB, so the corresponding E b /N 0 is 10 log 10 (2500/6.09) = 26.1 dB greater, or −21 dB + 26.1 = 5.1 dB. [1] 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.
The 64-bit binary fixed-point timestamps used by NTP consist of a 32-bit part for seconds and a 32-bit part for fractional second, giving a time scale that rolls over every 2 32 seconds (136 years) and a theoretical resolution of 2 −32 seconds (233 picoseconds). NTP uses an epoch of January 1, 1900. Therefore, the first rollover occurs on ...
Fldigi (short for Fast light digital) [4] is a free and open-source program which allows an ordinary computer's sound card to be used as a simple two-way data modem.The software is mostly used by amateur radio operators who connect the microphone and headphone connections of an amateur radio SSB or FM transceiver to the computer's headphone and microphone connections, respectively.
The High Precision Event Timer (HPET) is a hardware timer available in modern x86-compatible personal computers.Compared to older types of timers available in the x86 architecture, HPET allows more efficient processing of highly timing-sensitive applications, such as multimedia playback and OS task switching.
IEEE 1588v2 PTP GPS Smartgrid clocks from Tekron [70] IPITEK MSP-1588 [71] Open Time Server : 1GbE, Rubidium IEEE 1588 PTP, NTP, SyncE, PPS GNSS grandmaster clock from Timebeat.app [72] Open Time Server : 10/25GbE, Rubidium IEEE 1588 PTP, NTP, SyncE, PPS GNSS grandmaster clock from Timebeat.app [73]
The Time Stamp Counter was once a high-resolution, low-overhead way for a program to get CPU timing information. With the advent of multi-core/hyper-threaded CPUs, systems with multiple CPUs, and hibernating operating systems, the TSC cannot be relied upon to provide accurate results — unless great care is taken to correct the possible flaws: rate of tick and whether all cores (processors ...