Where the W and H are the dimensions of the photo in pixels. Time(sec) = W * H / 1000 for black and white To calculate the transmit time for an image use the following formula: Images should be carefully selected for size before beginning a transmission. It can provide excellent photo transmission on a really good path. The data is transmitted as an FM modulated signal and is subject to burst and phase noise on the transmission path. The preamble reads as "Pic:The successful reception of a MFSKpic is highly dependent on s/n conditions. The MFSKpic transmission has a preamble sent which will be visible on the text screen. Reception of an MFSKpic transmission is fully automatic. The transmission mode for MFSKpic is similar to FAX. The program can send and receive MFSK images in both black and white and in 24 bit color. When operating with other modem programs you should limit sending pictures to the MFSK-16 baud rate. This is an example of properly tuned MFSK16 signal with a s/n of approximately 9 dB.įldigi can send and receive images using all MFSK baud rates. These are very useful for send large documents or files when some transmission errors are can be tolerated. MFSK-32 and MFSK-64 are high baud rate and wide bandwidth modes designed for use on VHF and UHF. MFSK8 has improved sensitivity, but is very difficult to tune, and suffers more from Doppler. The mode was designed for long path HF DX, and due to its great sensitivity is one of the best for long distance QSOs and skeds. Tuning must be very accurate, and the software will not tolerate differences between transmit and receive frequency. The mode has full-time Forward Error Correction, so it is very robust. The tones selected are set by the transmitted (4 or 5 bit) bit pattern and a gray-code table. As a result, no unwanted sidebands are generated, and no special amplifier linearity requirements are necessary. A single carrier of constant amplitude is stepped (between 16 or 32 tone frequencies respectively) in a constant phase manner. MFSK16 and MFSK8 are multi-frequency shift keyed (MFSK) modes with low symbol rate.
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