MFSK 2000
Ionospheric Simulation
Ionospheric simulation has been used for some time now to accurately model the ionosphere, in order to test new modems and other communications equipment.
One of the experts in this field is Johan Forrer, KC7WW, who kindly offered to test MFSK16 in the same way as other amateur radio modes he has assessed.
Johan has sophisticated digital signal processing equipment which he uses commercially to accurately model the ionosphere. Unfortunately the ionosphere is quite random in its effects, and while the models are as well, the results obtained cannot be used to provide a "figure of merit" for the mode or modem under test. You need to look at the result of sending a standard file and assess the performance for yourself.
A standard series of test conditions has been specified by the CCIR, and Johan has tested many amateur radio modes using the CCIR POOR standard and his equipment. CCIR POOR represents one of many possible scenarios, and is perhaps not as "poor" as conditions we sometimes try to use!
See Johan's Simulator web page for more details and results from other modes than those shown here. The results do not imply that any one mode is necessarily better than any other under other simulated conditions, or on air.
The TUNER program - TUNER.COM ----------------------------- 1. This is a tuning aid to help get a received tone exactly on 800.0 Hz. It should accept COM2, COM3, COM4 command line parameters (default is COM1) and report CLIPPING (audio signal too strong for the sigma-delta circuit). 2. Unfortunately it takes too many computing cycles to incorporate this in COHERENT, so run TUNER first if necessary, using an 800 Hz sinewave with no modulation on it (a steady carrier in other words). It may be slightly useful on a carrier that is phase-modulated, but the indicator will jump around trying to follow the modulation, and in any event the useful frequency range would be limited. 3. The idea is to get the little yellow line centered between the 2 green lines, and staying within the green lines at all times. The nominal frequency is 800.0 Hz. 4. The range of this tuning indicator is 800 Hz plus or minus 20 Hz. If your signal is not ALREADY tuned to within better than 20 Hz, this indicator will be useless and quite likely confusing as hell! 5. There will be some rejection of other signals outside this range, but if the signal you want is weak and the interfering signals are strong there will no doubt be problems. 6. If you can hear the tone, there is no substitute for zero-beating it with a good crystal-derived 800 Hz sinewave sidetone. 7. TUNERC.COM is for anyone who still uses CGA graphics - I slowed down the update rate to accommodate sluggish LCD displays. VE2IQ - November '95.
The UNER0 on ramD TðER.ROO -r- tiDi---iDe ---------ul---- 1. Tt=s is a tuning ai t tfheð ge a repotvedi/e | tc&a ð 800.0 Hz. It trould a oc?t Cr M2o COOððr MM cemmand line farao etera default is ttO01) nnd report CLIPðð Maud| signð-oo stroog for ðe oigma-deiit circðe0ð 2. Unftrtunately 7 takes too many coeeputing cycleðo coraorate this tn CO ERENet, so run AUl ERKirst f ne eessarð using 8aeD Hz sinewað with vtmosul ti/ on it(a stead t carri=n otrer wordo). At o aybe slightly uð ul on a carier that s pha8-ðdulat d, but the iodiahto ai oa juee]arount trying-f lrow the modllation, and in any even th u eeul frequ ncy r a ae woðdbe liðte . ð Tme ic a is to get t& littliyellow line cen Ved betweefta2tireen ðnes, and staying wtthiihhe yreei lines at alðimesEii he nominal frequenc io 80gbte ð. l4. The ron ne of this tuningyodicator is 800 rðplus oa ðnur 2ðHz. ebf yoeer signae es ntt yieREðY tu ld oo wVain betoer taan $g Heret this indicncr hill be us$ess Ld puite likelm honfusgas helle 5. Theri ailLb eome re:eðioa of othetðgnals tutsi T this raegð but im hlsia nal you wtnhis geak and the interferinte signalalrst tng therqwill no doubt be problems. a. f yol can hea e the eone, thite iDno substTðe foi >ero tbeatie i?wð a good crð al-der ved 800 r z si(vave si tetooer C. TUPE eC.COM ð dð aoaone i6o stilTZ es c( graphics u I ðoe e6down hup tat . te to adcommo rte sluggish PCD disðays. VE2IQ - Gog]'r '9$.
e bnpo =U'sR pro th: TtoNmtndCEM
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ycleeto ifnorpote e this
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otound tr ng to folloµ he ooiulatioin
anydeel t e et eful frequrs i lnge weule )e limiteg edç. ]e idea i to geothe ttle ynelon line senhred et en the t geaoplines, ae stli
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if the signal yoi teakeend he intern ring.ignals aO d reng there Mill no rou¤ be prodlems.
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ind itith e gtotY…stadeZve"ie00 roeosinewave sidetone.
· euRC3 m t Jt anyone who stilses CGA graphics - f slowed `wn
th| pdate,atert ac4mmodate sluggh LCD says.n lE2IQ - l t teber '95.I
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,(nc0h3aiBfGee¥gsotMtre sb¤ ¶&UNER.COM ---v,--------- o---5---- Ðunu Thos is a tuninWen%help getæreceived tone exactly on 8c 0 . ItjÑzld s faxt COM2, COM3Uc¶Re“e(nd line ®c'Wters (default is COMq¥ and rrnort CLIPPINax(audio s D nyµîAri otli eo«Tbwkd . A2. Unfortuely ites tre many computing µ cles to incotkîJNn ryye TUR pëgramninTUNER8SOM ---Þb-----anÅanÝ---f----´oo tthisa tunn0t aid to hel…ietrúled 8ne exactly on 8k r.0 Hz. It should acc utaº I, M3, CgcFommaþ li ttnSrameters nefaues COM1) and rert ehuf (audio signtlg gJrong fà the s¥Plta circuit). 2. Unfatelz it takes toH x ¨ co ×uting ür nes to incorporate this in COHttEENT, so run TZ d eR firstEf essfsn,rVing an 800Tnee noªith no modulattd it (e²teu þN}rier in other word o It may 6l h Aint yç ul on a cunrier th 3isasePius a tttm]p tor wh$en- arm¸a tryinge lowvhe modulations³nd in any event the usefuaðrequency range woulozlimiteOe 3Thfdnea if’Het ine litt bqhw line centered betn tho reBlh, ake staying within the grsWneour signal is tni ALR4tsaY tuned to within better thm0 Hz, this bkOtg wil4be use gss ain?"[ eN ñeFin as ho! ?. There wie sejection of otser signals outsil=/es range, but *ee signlpwant is weak and tnnterfertsignals are str*g there will nr ªubt be problems. tqetk "eke tone, there tpCo subAgtute feutzero-beati H itŒ oth a good crgstal-dsd 800 He sinewaQasidetonetql 7. Tae ¨COM is for anyone who sti uses i GA S¿phics «¤ slowed dowt3datEonommod/l/egistct CDeu L lays. ÔlE2IQ - November '95. "ai
p The Tp>ER program - TUNER.COM --------------P»----------- 1. This is a tuning aidtZFelp get a received tone ec oEiilint0cEK. It should accept COM5, COM3, CIM4 command rine param ttsw (default isto ei6 dort CLIPPING (audio signal too strong for the sigma-delta circuit). 2. Unfortunately it takes too many compuieng cycles toncorporate this in CO$]iENT, so run TUNER first if necessary, using an 800 Hz sinewave with no modulation on it (a steady carrier in other words). It may be slightlp useful on a carrier that if zulated, but the indicator will jump around trying to follow the modulation, and ino any event the useful frequency range would be limitedx³ 3. Theo.ea is to get the little yellow line centered between the 2 green lines, and staying within the greecTinesIres. The nominal frequency is 800.0 Hz. 4. † t nge of this tuning indicator is 800 Hz plus or minus 20 Hz. If your signal is not ALREADY tuned to within betRr than 20 Hz, this indicator will be hseless and quite likely confusing as hell! 5. There will be some rejection o,R her signals outside this esetpFbjea \ the signal you want is weak and the interfering signals are strong there will no doubt be problems. 6. If you can hear the tone, th 1rReedt f« ute for zero-beating it with a good crystal-derived 800 Hz sined§ e sidetone. 7. TUNE¥ COM is for anyone whos eill uses CGA graphics - I slowed down the update rate to accommodate sluggish LCD displ.VE2i Q - November '95.
Make your own assessment - the results are all different! Which is the most readable? Grateful thanks to Johan for the above results.
