RSGB Tonight @ 8 - An Introduction to Meteor Scatter Communications, by Gavin Nesbitt, MM1BXF

[Music] so [Music] [Applause] [Music] [Applause] [Music] [Applause] [Music] [Music] [Applause] [Music] [Applause] [Music] [Music] [Applause] [Music] [Applause] [Music] [Applause] [Music] so [Music] [Music] [Applause] [Music] [Applause] [Music] hello and welcome to tonight at 8 from the rsgb while most radiometers are active on vhf it's most usually used for local or relatively short distance communications but there's a propagation mode called meteor scatter which enables much longer range contacts to be made by bouncing your signals off meteor trails and gavin nesbitt mm1 bxf is here to tell us more about this fascinating mode welcome to tonight at 8 gavin can you give us a quick overview of what you'll be covering this evening david yet tonight i'm just going to cover meet your scatter as a communication mode which you've already pointed out is bouncing your radio signal off major trails this allows much rain much further range of communication and it's used by a lot of stations to work new dxccs or new squares on vhf it's a mode that most people can participate in but don't realize it until they're kind of showing it and it's it's very popular at the moment well we look forward to that and before gavin's presentation a reminder that if you're watching this on monday the 6th of september then this is live and you can add comments and ask questions on either batc or youtube at any time during the presentation or straight afterwards please include your first name and call sign if you have one within each message and also please note that you can make this video stream fill your screen on most devices usually by double clicking on the picture or pressing the full screen button but now it's time to go back to gavin to find out more about meteor scatter communications and good evening again oh i'm just covering an introduction to meteor scatter so i won't go into the full details of all the geometry around how the the major bounces work and there's a lot more detail of that that can be found which i'll cover towards the end so if we get into the basics of it so as is already pointed out it's a propagation mode that exploits the ion the ionized trails of meteors and these are the trails that vaporize in the upper atmosphere good old height so about 70 odd miles in the atmosphere and these allow the reflection of radio waves in the hf and the vhf range and because of their height they are allowed communications of paths around about just over 2 000 kilometers on average one and a half thousand kilometers which in a ways similar to the sporadically propagation that we sometimes experience on vhf as well however unlike spreading key it can be hours of listening for that single ping uh when it's the random meter enters the atmosphere there's a long history of meteor scatter it goes all the way back to 1929 when it was originally noticed on broadcast fm broadcast stations etc and at that point people started to investigate what was going on and in 1954 there was a paper published about using it actually as a propagation method of communication so we've gone back sort of 50 60 70 years of history onto this propagation mode which i've supposed until recently hasn't been used all that much by radio hams or at least not um continuously it's always been used by a fringe number but uh certainly nowadays it's a lot more popular so what makes up a meteor uh interestingly uh the there's probably a lot people know the meters happen all the time into the earth's atmosphere and these can range from anything from a grain of sand uh which is probably the smallest size of meteor we need to generate a ping uh to something the size of a tennis ball of course we have much larger meteors that come in uh chili bins for example being one of those anything smaller than a grain of sand generally just floats down to earth doesn't actually burn up in the atmosphere so it doesn't generate the ionized trail required and as i say anything bigger than a tennis ball rather rare if we were to look at the distribution of matter falling into the earth's atmosphere what you actually find is that it's very um homogeneous so if there's if we take the grain of sand of a ton of material the size of a grain of sand comes to earth every day a ton of material the size of a tennis ball comes into the earth every day there's a lot of reasons behind that which i won't cover into this talk but it's a rather interesting distribution when you look into the details of it although there are major showers in most people are probably familiar with most meteors used for major scatter communications are random so we we can't predict when they're going to come in hence the waiting long times for that pin and that can be uh it can be a long long time believe me so if we look at the vhf band or sorry let's look at the meteor trail it's very popular as as i mentioned on the hf and vhf bands now that that's not to say you can't do meteors on uhf but the reflectivity uh of the the trail is actually sixth law versus frequency so the higher frequency you go if you double the frequency the losses are actually six times as much so although you can get pings at two meters trying to get pings on 70 centimeters for example is actually very difficult unless you're having a very very large array which not a lot of stations have so generally meter scatters limited mainly to six meters four meters and two meters and certainly six meters has many more pings and many more reflections and longer reflections than you get on two meters um and that's i'd say it's down to the sixth floor you also have a path loss which is uh inverse square law where the the loss of your signal is is is um four times the distance and uh with diminishing gains on frequency and reflectivity when you combine these it actually becomes much harder to get any sort of reflections higher than two meters uh on on vhf on uhf so that's generally why you don't see much of this above vhf uh on on on the amateur bands at least going into reflections there are two types of meteors um although you can get it from the same type there are two types of bursts sorry that's probably more accurate to say and these are known as under dense and over dense and these are images of the two and generally what you get with an um an over i'm sorry an under dense burst is a very quick reflection and these are generally the very small meters and actually on this top diagram you can actually see two under dense bursts you can see one just below the 10 second mark which is which is very small and that would probably produce some form of decode and then obviously the very obvious one about 15 and a half and say sorry 15 and a half seconds and you can see the very characteristic fast attack and then the sort of slow diminishing uh loss as the the trail dissipates and then at the bottom you get this over dense bursts and very characteristics of those you get lots of fading these last sort of numbers of seconds and have a very curved sort of reflectivity and the diagram on the right shows why you get these this fading and it's generally because the the signal goes in phase and out of phase and this is very characteristic of a six meter uh propagation where a meter that might be a an under dense or cause an underdense bar some vhf for two meters uh could cause an overdense burst down on six meters so six meters is a far easier band to make major scatter communications on than it is on vhf uh but vhf is always very popular as well uh a real real example of these softwares are this uh which we captured on one of the gs3 pye day expeditions to mull in 2013 at the top waterfall and these run horizontally uh sort of characterized by uh under dense bursts and there's a few of them there there's one about 13 seconds and again one about 15 seconds and you can see a few of them across the whole waterfall and then in the bottom you can see a number of over dense bursts uh where the the ping lasts a number of seconds uh with a bit of fading so these are sort of characteristic of what you would see during decoding uh of major bursts as i mentioned before although um random features are the most likely form of meteors you're going to use for qsos there are times of the year which are far better uh to have the the probability of a ping and these are during the meteor showers which are known and if you come on during those the meteor rates can be three four five hundred an hour for radio meters uh visually they're usually about four times as much as what the visual count is and there's a number of times during the year where you can come on and certainly have a much higher chance of having your qso and i certainly know a number of stations only come on during those times to work new dxecs or new grids and these are the times of the year when you generally find people traveling to to new or rare squares to activate the squares to to allow others to take them off their lists and during the day for the distribution on the left diagram you can see during the day that the rate of measures even changes so early in the morning to late in the evening there's a different distribution of meteors now the reason for that is down to the orientation of the earth on its orbit around the sun if you take six o'clock zulu in the morning if you're on that part of the earth at six o'clock in zulu you're generally at the part of the earth which is traveling forward in the orbit in which case you're traveling into more uh debris which is in that orbit and conversely at six o'clock zulu in the evening you're generally on the lease side of that orbit and meters have to be traveling a little bit faster to catch up with the earth on that orbit and therefore there's generally fewer of them and so if you were to be on at six o'clock in the morning uh during a meet your uh peak of the meteors etc or you know during the showers uh the rates can be significantly higher and certainly we find on the day expeditions for the the stations that really want to work the square uh they're very much asking us to be up early in the morning which is a bit of a conflict when you're on holiday and having a little bit of a relaxing bit of radio but generally we try and do one or two days where we get up early to to satisfy those those sort of stations if we're going to the the geometry of these ping because there's a little bit more to it than that um although amateur comes in to the atmosphere it has to generally be going in a particular direction for a ping to be heard in another particular location the optimal way for a ping is to come in transversely to the direction so if i was beaming due east the the best direction for the meteor is to run north south and that causes this reflective cone as seen in the diagram and uh interestingly if you intersect that cone with the surface of the earth you actually end up with this uh heart-shaped upside down heart-shaped um if you like uh intersection with the at the surface of the earth and that's where you get the maximum uh reflection onto the ground and you can have lots of meteors that will cause you to be heard in other locations and it can be very frustrating during a qso with a specific station where the meteors just aren't falling in the particular orientation you like in other stations outside of the area you're trying to work keep saying they hear you or you know what we're hearing you were hearing you but the station you're trying to complete the qso with is not uh so that can be very frustrating so you have to be very patient uh when it comes to meet your scout certainly when making qsos if you're certainly after work in dxecs or certain squares um it can be very frustrating because normally you'll get halfway through the qso or you'll get to the final and transmission and it's a final transmission it's just not being heard and that that can certainly be very frustrating indeed so that's sort of gone into the background of how our matures work so when we go into the actual procedures there's a number of ways you can actually have qsos using major scatters and i suppose this is sort of going from the history forward you can use cw where they used to run uh on tape machines that's at 1200 words per minute and the reason you have to rescind so fast is because the pings are so short when you're talking sort of 40 milliseconds up to numbers of seconds but if we take an average of sort of 100 milliseconds you have to ensure in that 100 milliseconds that all the data you want to send or all the data that's valid for that qso sorry for that part of the qso is sent during those 100 milliseconds so when it comes to cw you have to be sending the cw fast enough uh that uh your call sign or report or your roger rogers uh gets sent in that time you can also do an ssb generally under showers or on six meters where the ping durations are longer and certainly this can be done during some of the six meter contests where it certainly is when we're contesting a few stations and it can be worked for a major scatter uh it's a italy spain which had good points to your score but it can be hard going because again because of the random nature of features you you have to get these long duration pings for your full call sign or report etc to be sent however in the last number of years uh computers have made a big difference and modes like fsk441 iscap to appoint 6m but less or so and the newer msk144 modes have made a huge difference uh to be able to do meteor scatter with smaller stations and so not only has it made it easier but stations with smaller beams or lower power have started to be able to make six meter so yeah meteor scattered contacts what is before if they were doing it under cw or ssb they would need more power bigger antennas or effectively only been able to do under showers um the qso is split into two sort of time periods known as first and second periods uh the first period is from zero seconds to 30 or from one second to 30 and the second period is from 31 seconds to 20 59 seconds and the west limous station transmits in the second period so that means if i was in the uk and i was beaming at germany i would transmit in the second period which would be your 31 seconds to zero minutes and if i was in germany beaming east i would transmit in the first period and what that means is if you're doing random qsos or call in c2 it just always means that you're always transmitting in a period where the station at the other end is listening in the right period so you're not doubling uh so if there's a station in germany who was also beaming east they would also use the second period so it just means if beam headings are pointing at each other there's a good chance you're transmitting in different periods and listening in different periods so you can hear each other and that's a convention that goes back quite a while in terms of what you actually send your first transmission depends whether you've got a schedule or whether you're doing random if you were random you would call cq with call signing locator or if you're calling a specific station you would send your call sign in their call sign once you've once one end has heard the other you would respond with the two call signs in the report just to say you've heard them i'll cover what the report is in a moment and then once the other station or the second station's also heard the report the answer was roger report which is r27 in this case and then once you've got two reports then you start sending rogers and you can also send seven threes the rogers is the final requirement for the qso and most stations will still send seven threes uh unless uh you have another way of confirming that qso which could be on one for kst which again i'll i'll cover in just a minute and the time it takes as i mentioned before to do a cure so under shower conditions or good conditions can take two minutes outside when you're doing random natures it can take hours and i've certainly had qsos it's taken three or four hours to complete and a lot of that's generally just been one of the last transmissions such as the the rogers sending the rr uh you'll get through the first two or three messages very quickly and then it's just final message it seems to always take forever and anyone that does major scar can very much relate to that i'm sure this is what it looks like if anyone's done fta it's it's a very similar procedure to what fta is and in fact fta procedures effectively have been copied from the major scatter procedures as they've been shown to work very well for data so you send your first message which again as i say is that two stations calling each other in this example uh the second station then sends a report the first station then sends the roger report and then you send the uh the rrs to to roger you've received everything and then you send seven threes and then you go back to either c queuing or you go back to sending to another specific station if you've got a schedule with another specific station so this is reporting this is defined in the region one handbook um and the first digit so in the case of the two seven the number two is a ping and it's duration and then the second digit is a signal strength um in most cases the software you're using and will generate the report based on the db value and the duration of the the ping uh so you don't need to know this table or look up certainly if you're doing ssb or cw then you'll need to know this table because you'll manually be entering those values but when it comes to using the software these values are are automatically put in as mentioned at the bottom the two common reports are two six and three seven and two six is your standard um decode uh nothing special about the decode it was quite short it's relatively strong and if you get certainly if you get a good over dense burst it's generally three seven uh to indicate that it was a very good decode and it was very strong and good in duration when it comes sort of to the station side of things um the antenna can be slightly important um because meteors as i mentioned earlier uh have to sort of be transgender to the to the um the the the two stations different antennas can produce different values and of course larger antennas have much more gain and in theory they would um be a stronger signal at the far end however they've also got a much smaller beam width so we eliminate a smaller section of the sky so therefore meters have to be in that smaller area to to be a good reflection and of course then smaller antennas are generally lower gain but can light up a larger area of the sky so there's there's two ways of thinking of this whether you go for larger rays or whether you go for small arrays and there's there's no real um consensus on this i've i've certainly had arguments from both sides of the camps um some stations will will argue and swear blindly that elevation helps you know sort of like 10 degrees of elevation and don't get me wrong when you come to doing the geometry of paths certainly elevation is part of that or should in theory help but i've seen stations who swear by in the qso rate is is nowhere near higher than what a station without elevation is so it's it's it's a bit of a hit and a miss but it's worth noting that in some cases smaller antennas could in theory be better than larger antennas i've used very large arrays when contest stations and and done very well in first for meteor communications but at the same time i've used three elements and 100 watts and also had very good results and certainly listening with a co-linear i can be decoding lots of stations certainly during showers i i can still be decoding lots and lots of stations and possibly not as many as i would if at a larger or a directional antenna but it's certainly still possible uh so it's it's the jury's still out and i'm sure people will argue both ways still i think a nine element would probably be a good sort of starting place or seven elements and something some of the sort of 40 50 degree of beam width uh would be uh would be a good starting place until you're familiar with everything else and then sort of if you feel like upgrading then by all means upgrade in terms of radios a few seconds just to be aware of where possible run with the agc set to fast or if the radio can support it switch it off this is to allow the under dense burst to be decoded if you have an agc on certainly if it's set to slow when you get these fast attack times of the under dense bursts uh the agc sense to suppress that so it's worth having agc set the faster off to ensure those under dense bursts make it through to the audio stage and therefore into the pc or whichever decoding method you're using uh ensure the noise blanking or a reset off i know a lot of people run the noise blank they're on because of local noise but for meteor scatter it's best to have that off because again for the same reason the noise blanket will try and blanken any underdense bursts uh which again will stop them being decoded and given that they're the most popular type of reflection uh it's it minimizes the number of decodes you get if you're transmitting and you probably want to look at radios that have got high stability um otherwise you end up with lots of frequency drift because you end up transmitting for 30 seconds then receive for 30 seconds and many radios will drift hundreds of hertz uh over those sort of periods so as you transmit you'll start and by the end of the transmission you can be 200 hertz higher and when you start receiving drifts down 200 hertz and part of the decoding is is frequency accuracy certainly if you set the software to be narrower and receive you have the option on receive to set the beam so the bandwidth of receive uh right down to 10 hertz the narrower the bandwidth the more accurate or the more sensitive the decoding and if you've got a radio that drifts you cannot really sensibly do that so if you have the option to get a high stability uh crystal or similar or gps lock your radio then that's certainly worth considering if you're really into meteor scatter modes however if you're just listening just about any radio including an sdr works so i've certainly when i've been monitoring meter scatter i've used fun cube dongles sdr plays eight one sevens nine tens eight one sorry eight five sevens etc they've all decoded on co-linears or beams etc without any trouble uh so that's certainly a good place to start um there's really two pieces of the software that you want to use for from each of your scatter i won't go into the details of them too much i'll cover a little bit of mshv just to show people how to set up should they want to go away and set up for monitoring um but there's a again there's a bit of argument um or opinions about which is best i've found both better at certain times on this example on these images here uh it was running parallel so both softwares were running on the same radio and the mshv window which is the one on the right actually decoded slightly more than what was on the left window which is the ws jta sorry ws jt in this case a wsjtx and it doesn't have the major scatter mode so you have to go to the older ws jt for some of the modes or at least for the fsk 441 mode which is the more popular um the ms 144 is in the wsjtx but it's not always used in this case for those that can see it but for those that can't the uh the station calling cq was actually given a frequency to that they were listening on which in this case was 365 at 144 365 and you can see on the right hand window the text actually has that 365 whereas the the window on the left does not so in this case i wouldn't have known if i was using the mshv sorry if i was using hp i could continue the qso potentially if i was using the wsjt window i wouldn't know which frequency to go and call this other station on um so that's uh although the full call sign isn't there so it's not a valid position to go and call them but you kind of get my my point on that uh in terms of frequencies slight slightly out of order apologies but let's just jump on to this one just now this is probably one you might want to write down if you're looking at it so these are the main frequencies used for meteor scatter uh six meters is 52 280 and generally that's msk144 nowadays jt6m and iscap b is occasionally used but for for the purposes of getting started i would say listen on 280 ms k144 if you've got four meters capability then 70.280 is the same sort of equivalent and on two meters one four four three sixty again msk one four four uh however i've found on two meters and this is slightly down because i mentioned earlier on that on vhf the reflections aren't as good as say six meters and you get a lot more under dense bursts the way msk works is you need a better decode or a longer ping duration for the d code to be successful so a lot of stations still use the older fsk441 mode uh which will decode shorter bursts uh maybe not as accurately but generally it's usually enough still to understand what's going on to continue a qso and that's a 144 370. i i wouldn't be able to say which one is more popular than the other probably 370 fsk441 i would say um so certainly worth monitoring there and uh and if if you find you you're decoding those successfully then it's probably worth going on to 360. uh 144 360 and have a listen to msk uh 144 to see how you're getting on uh so they're the main frequencies used uh for major scatter sorry i mentioned this slide of slightly out because i wanted to jump into the ms hv config for those that wanted to listen and so the only things you really want to configure for here just to get going is the the sound interface one of the options and the sound interface which is the rx and tx if you want to transmit then the interface control which is controlling your ptt and cap for frequency control the macros is where you enter your call sign and then under the network setting you enter your psk reporter and in the middle of the the slide you can see that there's a vertical slider called rx you want to adjust that level so the bar graph of the received signal level which is the the bar graph the horizontal one just at the bottom of the imagery sort of hovers around zero and that's the optimal level for uh for receive and or for the the software to to monitor for pings uh so that's they're the main settings you want to change on mshb i'm using mshv because as a newbie if you're not familiar with me just get out before i i think mshv is slightly easier to use and configure than the wsjt software so i would suggest that's where people start and uh and get going from and these are the settings the minimum settings you need to adjust uh to uh to to to get yourself uh going on receive alongside that the other piece of um or the other tool that's certainly worth using is on 4k st or the kst tv software um anyone that's using vhf frequently will be familiar with this and this is a tool that's used to make schedules and sort of do a talk back in a way on vhf uh so certainly outside of meet your showers and even during meet your showers uh the the one for kst software is very useful for making up um scheds or if you're not even active then just monitoring it just to see who is active to know where to listen uh because you'll see people on here saying i'm listening on a circle and say oh i'm calling another station on a certain frequency so that allows you to sort of listen and sort of monitor on that frequency as well and so if you're not using on4kst then that's certainly a tool i would recommend or you you register with and then if you're certainly if you're using windows then the kst to me um tool is uh is certainly worth using it's a much easier interface to use for uh following for kst um nearing the end of the slides uh psk reporter which i'm again many that use vhf and probably hf are very familiar with and this is a really useful tool just to see what the propagation is like and if you're transmitting it's also a good tool to see where you're being heard um on a particular band or in a particular mode so you can see what the propagation is like on major scatter modes and other modes but um certainly on ms modes if you're calling cq in a particular direction that gives you a feel for what the major accounts are doing and as i mentioned earlier on if you're beaming up sorry if you're trying to have a schedule with a particular station and you're not completing because there's no ping there's no meter in that point of the sky you really need it this might allow you to see if you're being heard elsewhere just to see what the conditions are like and that can determine whether you continue or not uh there's lots of times where you'll decide to give up and move on and try and work another station because you're just getting nowhere so these sort of tools certainly help uh make you decide on what you're going to do with that so getting towards the end as i say these are the useful meter scatter applications i've not covered them all here but most of them so you've got mshb can be downloaded from from well that link ws jtx these are all very easy to google and find the ksd to me one other thing i suppose i should have really covered earlier on with the time period for the first and the second is having a very accurate clock to ensure that everyone's clock is running at the same time if your clock's running fast or slow there's a chance that your first and second period don't align with the other stations and if that's the case then there'll be a point where you'll be transmitting or both of these could be transmitting at the same time or listening at the same time so you're missing out on a few seconds or a number of seconds um where you should be in a qso but you're actually doubling or no one's transmitting at all and the sgo radar at the bottom is a real-time radar the uh the the graph i showed earlier on about the time of day and when the meteor count was the most of the lowest that comes from that sgl radar site and that gives you an idea of how good the radar and so the meteor count is again if you're trying to have a qso with someone and the major accounts really low you may give up because there's just not enough meters but if you're you're an hour or two into a qso and the mutual counts high or it looks like it's getting higher you may decide to continue uh so that's that's worth taking a note of as well so to sort of finish off or to sum up what uh what hopefully is an introduction to meet your scatter for those that are new to it as i mentioned an sdr and a white stick it's certainly good enough to hear and decode ms if you leave it running um if there's nothing to be heard on the hand bands then graves radar on 143.050 down in france is very audible via meters um that's a radar that's used to track space debris so it's it scans sort of a good number of degrees horizontally and then to a good elevation so nature's various heights and distances get illuminated by gray's radar obviously if you're listening to that on say usb tune down at one kilohertz on zero four nine to get a one kilohertz tone and as i mentioned sign up to on for kst and use kst to me to see what the activity levels are and what other stations are up to uh so you can listen to them sometimes there's more activity off the calling frequency than there is on the calling frequency as stations make up scheds and they might call each other on a different frequency from the the calling frequencies are listed earlier on so it might be worth listening to them more than randomly listening on the call frequency um there's loads of material online about this and i've got a little bit of detail that covers more of it on my website under the geekshed website uh john g4 bao had done a great talk as well one of the conventions and there's a huge that was recorded that's available on youtube and his talk what it says talk what makes things go ping it goes into a lot more of the the physics and the detail of how and where pings work so if you're if you're familiar with meteor scattering you just want to know more his talk is fantastic and the reason john knows so much is he done a phd thesis on meteor pings and the geometry of them and his thesis is actually available to download it's 180 megs takes a little while to download but it goes into a lot more of the the the details uh of that and uh it's certainly a good read certainly the appendix towards the end which summarize a lot of these points is worth reading if you want to know more so that's that's pretty much the introduction as it stands so there's a lot more you could go into in detail but hopefully this just a flavor of what mature scatter is as a mode how you get started in it and get you going from uh from the beginning thank you very much gavin well it's uh i mean it was all new to me i must admit and i'm sure many others watching um before we you know we heard from you i mean it was just unbelievable to think how this would happen anyway if you'd like to ask a question to gavin and haven't already done so then you can do it now on either youtube chat or batc messaging and uh please don't forget to include your first name and your call sign if you have one so gavin we've got a few questions already so if it's all right we'll we'll run them to you firstly from torin mm1 stk how often are these qsos pre-arranged and how often are they done to not previously contacted stations um i would probably reckon what depends on the station um i know lots of stations that like to run random probably the same as ssb i know lots of stations that would uh go on hf and call cq and lots of stations might have scads when it comes to meet your scatter and i guess if you're chasing squares or specific countries then the majority of your qsos might be scheduled it could be 100 no one would would say that's a bad thing and other times it could be completely random personally from my point of view i prefer random but then again i don't chase squares or countries i just like the purest side of qsos but i know other stations are after as many squares or as many countries as they can so an answer to that there probably isn't an answer so if anyone wanted to to the same do 100 schedule to take off countries or or squares then that would be seen as is fine but if i was to take a guess i would say 50 50 would be scheduled and 50 would be random i would say okay thanks gavin we've got now mike g4 sjx has asked looking on 144 360 using msk 144 i see some stations staying on 360 and others qsying which is correct he says uh yeah now this is a bit of a bug bear for me i prefer to qsy um although there's no rule that says you should i i personally feel that the call frequencies should be used for calling cq only but not held not for holding qso's on um i i what you've got to remember is if someone was having a qso on the call frequency they generally block that period for another local station although you should all be on the same period would be the argument against that however whenever i call cq and certainly under shower conditions i'll always call c cube with the qsy frequency so i guess i would say i encourage everyone to qsy for a qso whether it's random meters inside a shower or outside a shower so when you call cq you have a you put in which frequency you're going to listen so effectively when you call cq you call cq with a split and when you hear an answer you go simplex on that frequency that is my preference and it's what i would encourage everyone else to do but there's no there's no rule in the band plan to say you must operate like that so i can't tell people to operate like that i can only encourage people to operate like that and that's so that others get the opportunity to use the call frequency as well although in theory everyone let's just say i was located where i am just now in io75 if i was beaming east i would be calling cq in the second period and so would everyone else within my location so that means everyone's transmitting at the same time and receiving at the same time so in theory i shouldn't be transmitting over someone else's receiver or receive free receive period i still believe it's much nicer and more ethical to to have your own frequency certainly for those that are not familiar with nature scatter and may be new to it they may feel they can't transmit at the same time as someone else's so that's one of the reasons i i like to encourage people to to qsy but that's that's just my my personal opinion one question if i may um ask gavin um obviously this is something a little bit random and but does it vary with conditions like when we see lift conditions on bhf does that improve your chances even more with meteor so it's got a communication yes so so the modes used for meteor scatter so fsk4 for one certainly did not like or doesn't like other modes sorry other propagation modes the meter scatter the mode itself is optimized to see very quick rise times as i mentioned before so either over denser under dense type of pings it might not be what you're talking about but if it would say sporadic e or tropo fsk441 is not very good in those conditions because it doesn't see that very quick rise time from from like that zero db value msk441 sort of improved on that somewhat so um if there was a small amount of um tropo uh during a meteor scatter qso then msk 441 will sorry msk144 will decode whereas fsk441 didn't i'll call it fsk and msk without the numbers just to make it a little bit easier um so fsk is only really good during major conditions msk is slightly okay under other propagation modes but there are better modes for that so i would encourage if it spread a key obviously fta or other jt6m other two sort of modes which are slightly better for traditional propagation and fsk and msk are the two modes for meteor scatter lovely okay thank you very much gavin uh jeremy m0rvb asks how do you know a contact has been via ms and not some other method generally the shape of the ping if it was another method you would see a quite a long duration reflection without much fading generally so the if it was aircraft you would get the reflection sorry so if we go back to the under dense and the over dense example the under dense burst which goes really quickly up and down that's very characteristic of a meteor the over dense burst is normally a few seconds long it can be tens of seconds long but you generally get a lot of this fast fading as well you do see that with aircraft reflection but not the fading isn't always as fast and so generally you would know it's mature because there's no other propagation mode around so if there's basically if there's sporadic key around people know the sporadic key around it could be via the odd ionosphere tropical uh or a tropo i suppose in the middle but generally it's going to be mature uh if you're talking on distances 1500 k or more okay thanks kevin martin g0 gmb says it might be useful to mention the virgo app which is very useful tool to ms users to see the best pass path sorry for ms reflections there's i'm not familiar with exact tool i know those i didn't want to go into too much detail this is the one there's certainly a tool by an sm which takes meet your showers into account and the orientation so as many are probably familiar meteor showers are given a name generally based on the constellation they emanate from so if you take the perseids it's generally from the the constellation of persia and the meteor trails all seem to emanate from that single point in the sky as i mentioned earlier on the the best chance of a mature reflection is when the mature is is transgender or at right angles in simple terms to the path you're trying to communicate on and what you find is with a bit of mathematics you can actually calculate what that angle will be and sometimes under certain showers at certain times of the day if i was trying to talk to a station that was due east of me the actual best path is not to be meet but maybe to beam northeast based on the the direction that these majors are emanating from and there's lots of tools out there to to do all that but that's slightly more advanced than just getting started as an introduction sure so i just want to cover this as an introduction rather than going into the details but once you're into it there's an awful lot as i say a lot of math a lot of geometry that you can actually improve uh your qso probability on so you can go into as much as you want really i mean there's a as you've mentioned several times there's some links been in your slides we've also put links on the youtube place where this will be stored and also i've been told that the rsgb 2015 convention is where john g4 bao's convention talk was so if you search for that convention the 2015 rsgb convention then you should find that talk as well so there's plenty out there isn't there to to find out more totally and there's there's an awful lot of tools even the software that i haven't covered there's um there's a concept known as hot a and hot b and that's again what i mentioned depending on the time of day you might be slightly off the direction you're trying to do based on the probability of a meteor not being in the middle of your reflection point but being slightly north and slightly south and that depends on whether you're before midday or after midday so there's an awful lot to this that i just don't want to cover and confuse i just want people to go on and try and receive meet your pings and if they're confident enough try and transmit as well just dip your toe in the water and give it a try yeah but good a good taster good and we've still got a few others to ask you actually as well richard g4 krw says a very interesting talk thanks i noticed that the frequencies you mentioned are not in the band plans are they new and are there any other frequencies in use i certainly don't know of any other frequencies the one four four three seventy has certainly been in use since about 2002 and probably prior to when i started doing major scatter uh six meters changed when the six meter band plan chain i'd like to say was a few years ago but it was probably ten years ago when they replanned it it did change and for a while it used to i think beyond three three zero fifty three thirteen and everything moved slightly lower to 280 and i can't remember exactly when that was interesting they're not in the band planner they'll be in the data section i guess of the band plan and the 360 144 360. is slightly new that's only been used since the msk mode came out again i'd like to say it's a couple years back but it's probably more nearer four years ago now um so it might be something worth i'll raise with the um with the rhgb to maybe see why they're not in there specifically even as a footnote uh whether i don't think would be put in specifically as a as a spot frequency if you like in the the list of frequency certainly as a footnote is the center of activity should probably mentioned sure actually martin g zero gmb comes back and says the norm is certainly not to use the spot frequency for pre-arranged qso skeds yeah i i agree for pre-arranged most people will pick a qsy but i certainly know lots of the big station well any of the stations but certainly the big stations in the experience station so i believe should know better and certainly just run on a single frequency which is the spot free which is i mentioned when as i say my my preference and advice would be to uh to qsy to let others feel as if they can call cq as well sure okay thank you um colin smithers says please explain again slowly the benefits to a newbie of ms hv versus wsjt so i found that mshv is eight so mshv is a single window so the the single window includes the decode um waterfall and also the decode text at the bottom so it's a single window very easy to configure very easy to set up the the receive level the wsjt not the x version comes in two windows i've just found certainly on smaller monitors you don't always fit them on the same screen and it's a little bit although it works it's uh it's a little bit more development-made feeling so if you're a developer it almost feels that's what ws jt feels like so i've when i've run the two of them in parallel as well as mentioned in the example on the presentation i actually found the mshb generally the code's slightly better than the the wsjt i'm sure others might say differently but certainly from my experience i found the wsjt is easier to configure and decode slightly better okay thank you very much actually we've got the link to give you at home uh for the rsgb band plans obviously this only applies to the uk but um you can go to this link now on the bottom of your screen now and you can see the whole band plans for the uh for rsgb which includes some of these for meteor scatter as well communications so a couple more questions for you if we may uh from colin g0 odr you've mentioned antenna needed but what about the transmit power and certainly when i started doing this i had 100 watts from uh for my radio um well 100 watts from an amplifier that couldn't do much more and i was very successful with that i wouldn't have a problem in suggesting 100 watts of course if you go to diminishing returns you know 50 watts is only 3 db down so certainly for 50 watts up the more power you can muster the more um smaller meters you will get a reflection from but certainly with 100 watts you'll be very successful 50 watts you'll be somewhat successful certainly during showers 50 watts would be enough to uh to be certainly keeping you busy uh with qsos random 100 watts i would probably recommend 100 watts and a 9 element would certainly be sufficient to complete almost any qso you endeavor to start i've certainly found when using high power abroad shall i say the more power you use certainly the more pings are heard but it can be very frustrating that you get heard by the other station far more than you hear the station calling you uh but certainly a hundred watts and a nine element equivalent sort of power gain would be sufficient to to to mean that whichever qso you start you should be able to complete and 50 watts certainly during reasonable conditions shouldn't be any trouble lovely okay gavin thank you very much it has been a really good introduction to what is obviously a subject that can be as complex and as challenging as you want to make it really but you've given us a great idea of how to get started how to start listening i guess would be probably the best way um and and i'll summarize with one of our comments here jeff g4 fka says i've made 50 meg ms qsos using msk 144 into a fixed wire dipole at just five meters so it is possible certainly as and as i mentioned i certainly a co-linear with any radio should be enough to receive pings and if you've got the capability to transmit then certainly worth it's worth trying because it's far easier than a lot of people say that it should be um i've never tried it with a wire dipole myself certainly with a v2 000 vertical i've i've made qsos on two meters with 50 watts and a radio with that so it's certainly worth dipping your toe in as i mentioned absolutely well your talk's been very inspirational to many got lots of great comments on there and uh don't forget as well those of you at home now you can do lots of more research online looking at some of the links that gavin gave you another ones as well but once again thank you very much to gavin mm1bxf thank you thanks we hope you've enjoyed this tonight to date and that you'll join us again next time when we'll be finding out all about how repeaters are planned built and commissioned and if you'd like to see details of that and other webinars or to send any comments or feedback please visit rsgb dot o r g forward slash webinars and remember if you subscribe to the rsgb's youtube channel you'll be notified of all upcoming tonight today webinars as well as other new videos and presentations from the society on a wide range of amateur radio topics but until next time this is david g7 erp signing off and clear bye-bye [Music] so [Music] [Music] [Applause] [Music] you

Channel: Radio Society of Great Britain

Views: 959

Rating: 5 out of 5

Keywords: RSGB, meteor scatter communications, Gavin Nesbitt, MM1BXF, amateur radio, radio amateur, Radio Society of Great Britain, propagation

Id: wBTi2nzYOw0

Length: 64min 5sec (3845 seconds)

Published: Mon Sep 06 2021