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!
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 TšER.ROO -r- tiDi---iDe ---------ul---- 1. Tt=s is a tuning ai t tfheš ge a repotvedi/e | tc&a š 800.0 Hz. It trould a oc?t Cr M2o COOššr MM cemmand line farao etera default is ttO01) nnd report CLIPšš Maud| signš-oo stroog for še oigma-deiit circše0š 2. Unftrtunately 7 takes too many coeeputing cyclešo coraorate this tn CO ERENet, so run AUl ERKirst f ne eessarš using 8aeD Hz sinewaš with vtmosul ti/ on it(a stead t carri=n otrer wordo). At o aybe slightly uš ul on a carier that s pha8-šdulat 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 wošdbe lište . š Tme ic a is to get t& littliyellow line cen Ved betweefta2tireen šnes, and staying wtthiihhe yreei lines at alšimesEii he nominal frequenc io 80gbte š. l4. The ron ne of this tuningyodicator is 800 ršplus oa šnur 2šHz. ebf yoeer signae es ntt yieREšY tu ld oo wVain betoer taan $g Heret this indicncr hill be us$ess Ld puite likelm honfusgas helle 5. Theri ailLb eome re:ešioa of othetšgnals tutsi T this raegš 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 substTše foi >ero tbeatiei?wš a good crš al-der ved 800 r z si(vave si tetooer C. TUPE eC.COM š dš aoaone i6o stilTZ es c( graphics u I šoe e6down hup tat . te to adcommo rte sluggish PCD disšays. VE2IQ - Gog]'r '9$.
e bnpo =U'sR pro th: TtoNmtndCEM i------ e------t--e:---i-- 1. ees a t t r l a¢ toMeP neet a recu nd tone eSactl¤n 800.g H t smult act C na 2, COF3, COMt comma d line pa ame=rs (default is COm1)t 2. Unfortu toQ itlakes tt tany computing ycleeto ifnorpote e this i Cm tERi, so ln TRNER r a l if necessaÉ, usi r an ea00 nea iA with ndution 3 it Aa steady catt ier in oeaer wo)oIIt maes1gh$y useful n otound tr ng to folloµ he ooiulatioin anydeel t e et eful frequrs i lnge weule )e limiteg edē. ]e idea i to geothe ttle ynelon line senhred eten the t geaoplines, ae stli ekuenit es 86uh0 HE ē 4. Che range of thioeuneeg innicater ia oe00t p¼m or tinus Hnt. I your &gnal is not ALREA tune0to withio Itter than n=z, tri Iindiaator will be useless and£uite lik$f confing aa mel ü5. are oei ] ne som if the signal yoi teakeend he intern ring.ignals aO d reng there Mill no rou¤ be prodlems. 6. ea eou can hearrhe pnezthere Ā fneubstituteGor zero-be ind itith e gtotY stadeZve"ie00 roeosinewave sidetone. · euRC3 m t Jt anyone who stilses CGA graphics - f slowed `wn th| pdate,atert ac4mmodate sluggh LCD says.n lE2IQ - l t teber '95.I e
,(nc0h3aiBfGee„gsotMtre sb¤ ¶&UNER.COM ---v,--------- o---5---- Šunu Thos is a tuninWen%help getęreceived tone exactly on 8c 0 . ItjŃzld s faxt COM2, COM3Uc¶Ree(nd line ®c'Wters (default is COMq„ and rrnort CLIPPINax(audio s D nyµīAri otli eo«Tbwkd . A2. Unfortuely ites tre many computing µ cles to incotkīJNn ryye TUR pėgramninTUNER8SOM ---Žb-----anÅanŻ---f----“oo tthisa tunn0t aid to hel ietrśled 8ne exactly on 8k r.0 Hz. It should acc utaŗ I, M3, CgcFommaž li ttnSrameters nefaues COM1) and rert ehuf (audio signtlg gJrong fą the s„Plta circuit). 2. Unfatelz it takes toH x Ø co ×uting ür nes to incorporate this in COHttEENT, so run TZ d eR firstEf essfsn,rVing an 800Tnee noŖith no modulattd it (e²teu žN}rier in other word o It may 6l h Aint yē ul on a cunrier th 3isasePius a tttm]p tor wh$en- armøa tryinge lowvhe modulations³nd in any event the usefuašrequency range woulozlimiteOe 3Thfdnea ifHet ine litt bqhw line centered betn tho reBlh, ake staying within the grsWne
our signal is tni ALR4tsaY tuned to within better thm0 Hz, this bkOtg wil4be use gss ain?"[ eN ńeFin as ho! ?. There wie sejection of otser signals outsil=/es range, but *ee signlpwant is weak and tnnterfertsignals are str*g there will nr Ŗubt be problems. tqetk "eke tone, there tpCo subAgtute feutzero-beati H it oth a good crgstal-dsd 800 He sinewaQasidetonetql 7. Tae ØCOM is for anyone who sti uses i GA Sæphics «¤ slowed dowt3datEonommod/l/egistct CDeu L lays. ŌlE2IQ - 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.