MT63 doesn't look so bad in this comparison, as the typing speed is high (but who can type at 100 WPM?). The modes at the bottom left are the best performers, having a low bandwidth for their typing speeds. Let's look at this bandwidth in relation to the typing speed of each mode. However, this graph doesn't tell us everything, it is purely arranged in order ofīandwidth. The 'Necessary Bandwidth' is defined by the CCIR using a set of mode-related formulae.Ĭlearly the narrowest bandwidth mode considered here is good old CW - Morse code, with PSK31Ī close second. Of bandwidths of different modes - it all comes down to mathematics and modulation theory. There is no controversy, subjectivity or choice of measurement conditions involved in comparison Anyone with twoĬomputers and a copy of the AE4JY 'Pathsim' silulator can repeat these measurements for any Modes which perform poorly may well perform better under other conditions. Clearly PSK31 uses the leastīandwidth for its typing speed, while Olivia is the least efficient, but at least has a low error rate.Īgain, it must be stressed that the measurements are for 'Mid Latitude Disturbed NVIS' and the The data has been rearranged to show (on the horizontalĪxis) a measure of how effectively the mode manages its bandwidth. 'Error Rate' as shown in this next graph is simply 100 - '% Copy'. Olivia is the same bandwidth as MT63, but look at the low typing speed! However, the graph tells only part of the story - MT63 also consumes much more bandwidth than most The horizontal axis of this graph is typing speed, and you can see that MT63 is the clear winner. Not how well DominoEX8 performs - with noĮrror correction! This mode was designed for these conditions. The error corrected modes all perform well. Viable if '% Copy' is on average greater than 90%, and impossible below 70%.įrom this graph it is clear that under these conditions (typical of 80m at night) PSK31 gives poor results,Īnd RTTY is not much better (remember this is for this specific simulation - for others the results will be different). This technique has proved to be repeatable. The number of correctly received complete words and the total number of words, and giving the ratio A method has been evolved which involves counting It should be stressed that simulation results can be highly subjective, and are usually presented asĬomparative text results for the observer to assess. The signal to 0dB S/N in 2.4kHz bandwidth.
Of poor multi-path conditions, without static or other interference, but with white noise reducing Standard CCIR ionospheric simulation known as 'Mid Latitude Disturbed NVIS'. Shown below was condensed from a detailed study made of representative popular modes, using the
#Rtty vs psk31 series
Rather than providing a series of measurements that would be difficult to understand, the information The factors which are easily compared are bandwidth, bandwidth efficiency Several other comparisons prove interesting and certainly less controversial, since the performance However, these canĪlso be measured with a simulator, provided care is taken in choosing appropriate simulations. Reception, where there can be selective fading and timing differences between paths. Ionospheric Doppler effects, sensitivity to impulse or burst noise, and sensitivity to multi-path Other factors come into play when considering HF performance - things like the susceptibility to However, this measurement is generally meaningless as so many
Which can be measured with reasonable repeatability performance in the presence of white noise, The comparison mostĮxpected by uninformed users is 'sensitivity', i.e. The performance of different digital modes can be compared in numerous ways.
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