Your teachings spring forth new brain cells due to your teaching technique, and the warmest sense of humor on all tubes.. I learn stuff here. Cheers. White Board Wednesdays Rule!!!,
RCModelReviews - My nephew (young Quentin) just asked, "What is Arsey Model Reviews? Is is bad tempered fashion models?" I cuffed him over the ear on your behalf Bruce.
A similar thing happens with coaxial cable, a higher loss with higher frequencies. I think it has to do with the magic pixies getting tired more easily as they jump up and down faster on their way down the cable.
A nice highly simplified explanation for us electronic numpties I have found that most hobbyists (or those I know) don't know or even care why lower frequencies go further. All they want to know is how far they go...... which is, given all the variables involved, the same as asking how long is a piece of string. And then there is the vexed question of which frequencies they are ALLOWED to use in their locality which can be a world of hertz. _I have jokes about allowable transmission power to but the normal reaction to them is watt_ ?
brilliant Bruce! thank you for this! i finally understand it. im not horrible at algebra, so i got the equation right away, but the frequency thing was new to me!
Your voice is incredible...the way you speak is amazing....your voice is alot younger than your actual age...i listened to your vedio first time about china ems...and i wished to see you due to your incredible voice....thats why i come to see this vedio so that i can see you..
I came into that formula maybe three or four years ago when i was trying to understand why lower frequencies are better for long range :) I wish you have made that explanation at the time because it implies an expending spherical and also squared representation of the loss signal which is not really fun to understand lol Thank you so much for your hard work Bruce :)
Great video ! i guess in your next video about this, you also will mention that the lower frequencies will have a better penetration "factor" through obstacles or materials. I enjoyed the video ! it is really needed in this hobby, where there are so much things you need to know, to enjoy the hobby to its full potential. btw. the videos are beautifull with the new setup !
'Tis a favorite project of mine, A new value of Pi to define, I would set it at three, For it's simpler you see, Than three point one four one five nine.
Another great explanation Bruce. In the real world not everything is "free space". Some explanation about additional losses caused by things such as trees would also be helpful. I am also looking forward to your review on the Jumper radio, with the new T 12 version having just been released. What are the essential differences between "Open TX" and "Deviation TX".
Yes, I'll be talking more about environmental factors in respect to range and one of the comments I made in my review of the Jumper (which hasn't been published yet) was "this would be a fantastic radio if it had OpenTX". I guess I wasn't the only one who thought that :-)
Let us not forget, that if one can change for "Broad-casting to Directional Transmission" one can project more energy on a single direction decreasing the signal lost....
Oh wow. Even though it is the same technology, I never really associated lower frequencies being better for range with radio control. With IT stuff it makes sense. 2.4Ghz = lower throughput, greater range, 5.8Ghz = higher throughput, shorter range. Fine. You can easily see this if you have a dual band wifi access point. However, when i was a kid, my parents would buy me cheap RC cars from Radioshack. Universally 27Mhz meant the model would have a range of 11 feet, and 49Mhz meant a range of anywhere between 100 feet and a quarter of a mile even if both vehicles were the exact same model. Even to this day i'll unconsciously choose the highest frequency available in a spectrum for really no reason.
Nice Bruce. Great video!!! As you said, Lower the frequency, longer the range. Does that mean that a standard 72Mhz system would give us far more range than 433Mhz LRS? Or a 2.4 GHz system? I guess yes, if the power output of all the systems are equivalent. Why not then we move back to 72Mhz with frequency hopping?
Great explanation, I have learned something new. I previously asked myself, why do drone makers use very short antennas, would a longer antenna have better range? Now I know that extra antenna length has no benefit. Extending the wire to the antenna would weaken the signal. So I’m guessing that ideally the TX should be situated as close to the exterior of a drone as possible, so the antenna is clear of interference from the drone itself with the shortest connection. Am I correct?
Awesome stuff Bruce. I wonder how much range we could get with say the old 27mhz AM or 72mhz with those crazy long antennas paired with spread spectrum frequency hopping.🤔
Great video Bruce, thank you! You have so many great videos for people just starting out and beginners of all kinds but you should consider making a more advanced series of videos for people who have more knowledge and understanding, go deeper in electronics and rf theory, include attenuation, propagation delay, fresnel zones etc. Much love from America buddy
Yes, I just threw that out as an example, I really just wanted to request a video(s) that dives further into the fun world of electronics and rf (as it applies to the hobby and for flying of course). I don't think you would have to be afraid of losing people's interest due to the complexity. I know you're more than capable of doing so and it'd be an awesome video (well series I hope!)
Thanks for the video Bruce. One question, if the frequency loss is all down to the physical length of the antenna, could you not use a 1/2 or full wave antenna on the 2.4ghz system and get more range? I’d guess based on the video that in theory going from a 1/4 wave antenna to a full wave antenna could double the distance in identical circumstances?
I'll be covering how to "get more metal in the game" in an upcoming video. Simply making your 2.4GHz antenna longer won't work for several reasons -- think of it kind of like the extra length receiving a signal that actually cancels out that received by the original length of antenna. For example, a full-wavelength of wire would (in theory) produce *no* output because the signal in one half would cancel the signal in the other -- this is why we use half-wave dipoles or quarter-wave monopoles most often. Another white-board video on this subject coming up soon :-)
Thank you Bruce I had my suspicions when my "pagoda array" 5.8ghz at 150mm started showing promise of outperforming my CPATCH12 1.2ghz at 130mm of "collecting material" What are your thoughts on 5.8ghz parabolic antennas? Say you modify an old satellite dish?
It has more to do with the radiation pattern, and the gain. A dipole is 'somewhat' omni, it does have nulls right off the ends of the antenna. Picture an apple, nulls off the bottom and the top, inline with the stem. A 5/8 is similar, but now squish the apple down a little. it's shorter, the nulls are worse, and fatter, overall gain perpendicular to the stem is higher....
wish to ask about the JST connectors and if there is a common size,? I have a bag full of old cmos sony with 3 pin and 4 pin, I know the pin outs but not the JST connector sizes (3 pin jst) and (4 pin jst) can you help?
Awesome, looking forward to video #2 on long range system tests promised a few years back! Speaking of long lost projects . . . what ever happened with the RC control simulator chair thingy you and Roncam were working on?
The formula is very helpful, but a bit more theory on the subject would be appreciated. The antenna length is a technical feature, not a cause for longer range. Why we use 2.4 Ghz if longer wave is so "awesome" ? Back in the day, we had longer waves for RC, so if the industry switched, then there was a good reason, like less interference and congestion in microwaves. Not everyone in RC have only high school education, some of us love theory too. Thank you for your enthusiasm though.
yes, its about bandwidth, less channels on lower frequencies but this video is only about range and i think the industry switched because of the tight regulations on lower frequencies less and less unlicensed and amateur bands at lower freqs and the other aspect is convenience smaller anntenna and growing number of channels to control more servos and for telemetry not mentioning FPV bc its on its own dedicated video frequency
That's coming... but I wanted to show that antenna performance is about having the most metal in the game. I'll expand on this when I talk about why you can't just use a longer length of wire to get more signal and how the different type of high-gain antennas manage to get more metal in the game anyway.
So the real question of range is how long of an antennae can you mount on your RC unit. For my toys(a boat and a quad) the L9R could easily have had 5-6 times longer antennaes without being an issue.
wavelength is of course literally length. if you change the wavelength, you also change the number of wave *cycles* between Tx and Rx. you could think of it like, more opportunities for something to interfere with the transmission because there are more complete instances of it in the path to corrupt? (with a b/g in audio, i tend to think of all waves similarly, and i think, in audio, it is easier to understand how wavelength relates to transmissiveness). remember to smoke a lot of weed for your health! :)
just woke up, more explain.. a fixed dimension (say 1 cm, or 1ms) translates to more duty cycles of a higher frequency.. so this is how interference of any sort translates to greater loss of shorter wavecycles. acoustically, a high frequency might need to make 100 cycles to pass through a brick wall, whereas the same distance only represents 1/10th of a low wavecycle.
So. Why is 5.8 more common? I am looking into a receiver for my new fatsharks(New to fpv and all things quad) and I see 2.4 and 5.8 receiver modules it the number of channels on 2.4 are far less. Also what is the best setup?.
Smaller antennas can be easier to build in configurations giving more gain (think about the size of a coil antenna for 5.8 GHz vs. 433 MHz). The question is: is this enough to to make up for the path loss? As usual the answer is probably "in some cases" :)
Hi Bruce. Thanks for the video. So in theory , using 2.4 transmitter system and 5.8 video system, we will never be able to have video signals for the entire drone range and we will loose video signal at some stage at the end of the transmitter range . Is that right ? if so , how to fix the issue ? Thanks in advanced
Ehsan Keshtgar for the purposes of an RC craft, you're going to be limited for the receiver antenna for control, it'll need to be onnidirectional. So that'll effectively be fixed. However, you aren't limited(much) for the receiver antenna on the video, so you could effectively get a more sensitive receiving antenna for video and match the range of your control link despite the frequency difference.
The 5.8GHz signal will have a higher path loss than the 2.4GHz signal but the difference can be more than compensated for by either using more power and/or a high gain antenna on the FPV gear. I run 200mW and I can get more video range than RC range with my setup but if I had standard (omni) antennas on both RC & FPV and was running 100mW of power on both then I'd expect the video to disappear before control was lost.
Thanks for your reply . I have 600mW video transmitter and RF632 receiver with diversity which is a decent video receiver but I don't know what type of antenna would give me the best range . I'm thinking of Pagoda. May I ask what rang should I expect with this setup ?
Good day Bruce, I don't know how else I can contact you. I am also in NZ and I have over the years accumulated lots of RC parts (ESCs, motors, frames, servos etc) and since CAA changed their rules I practically haven't touched them since...Is there a way you can send me a message and I shall arrange to maybe deliver these parts to you personally so they can maybe contribute towards what you do? Thanks. Gordon
Both 4 and Pi combine (ie: 4 x Pi) to create a value which effectively reduces the effect that d and f have on the result. The bigger the "other" factors on that line, the less effect distance or frequency has. Think of it as a scaling effect. For the purposes of this video they're not important because I only wanted to show that changes to d (distance) and f (frequency) have an effect on the path loss and how going up in down in in d or f affects that.
The formula for calculating the surface area of a sphere is 4πr², the r in this case is represented by d and thus, after factoring in frequency and the speed of light, more of that later, 4πr² represents the loss of signal due to the expanding sphere. f/c is also 1/λ (lambda) the wavelength of the frequency. As the frequency increases its wavelength decreases, 1/λ increases the loss inversely proportional to the wavelength, and directly proportional to the frequency, of the signal. .... and then it's squared, bugger. Edit: ain't math/algebra fun.
Why couldn't you put multiple higher frequency antennas in parallel? Of course, attention to the length of the coax to where the 2 antennas join would need to be taken to prevent issues with phasing, and the placement of antennas to prevent destructive interference due to wavelength. As well as the fact that 2 50 ohm loads in parallel results in a 25 ohm impedance, so some impedance matching network would be needed as well. But other than that, it should double the gain in theory?
superdau I guess I was thinking more along the lines of an actual dipole. Yagi antennas are cool, too! But is there a way to make is have an isotropic radiation pattern, at least as good as a normal wire antanna?
Hi, my comment is off topic, because I did'nt know where to contact you for this. If you could direct me to your video or make a video on how to figure out how much draw is on a set of servos (say Hitech 430BH) and how much battery power is needed. P.s. I fly internal combustion engines only, and not electrics, I use Futaba T-HSS 8 channel receiver, with 6.6V Li-fe 1900mah, with 7 servos.
Hi Bruce. ive seen claims that some fpv tx antenna can cause bleed through to other channels. doesnt seem right. Is that true or just an old wives tale?
Yes, they used frequencies right down in the high-tens to low hundreds of KHz (from memory) and even in the cold-war era, were using this as a way of globally communicating with underwater vehicles.
Because a smaller antenna is better if you want to keep things compact. Have you seen a 2.4GHz CP antenna? Not good on a racing quad, especially if you consider you want your control frequency lower than your video frequency. 5.8GHz is king for miniquads because the antenna size is so small. Really there's no other reason.
I'll be covering this more in the next video on long-range systems but basically higher frequencies are usually associated with more bandwidth and more space in the band. The 2.4GHz band (for example) offers us 85MHz of space but on 900MHz we're down to about 15MHz and on 72MHz we had less than 1MHz. This is why we can have heaps of people simultaneously flying RC on 2.4GHz but already I see that some of the 900MHz and 433MHz RC systems are having issues trying to support more than a handful of simultaneous users.
So why did the whole hobby move to higher frequency from the 27 35and 40mhz; apart from the business concerning crystals. I presume 2.4ghz is not good for rc. submarines being under water.
s tanner good question, money is one answer , 2.4ghz chips are cheap and easily available now compared to old frequency ones, size of antenna is another and also number of pilots flying at once is increased with higher frequencies. Trouble now is 2.4ghz band is swamped because of routers etc etc..... Here is the UK 35mhz is the RC air frequency but is not used much any more apart from a few flyers. I must say that I had more trouble with 35mhz losing control than I ever had with 2.4ghz (apart from spektrum dsm2 lol ) but might have been because other flyers did not follow the rules about turning on their txs without checking the peg board first lol..... Though sometimes if a train went past it would interfere with my 35mhz control...
Bruce I would like for you to revisit video frequency. I'm getting some pretty good results on 5.8ghz. Flying out 20km. I believe the F zone of 5.8 makes a big difference if you know how to setup it your equipment correctly and fly in the receiving beam. Check out my channel for ground station setup and long range flights please.
this is pi: 3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117067982148086513282306647093844609550582231725359408128481117450284102701938521105559644622948954930381964428810975665933446128475648233786783165271201909145648566923460348610454326648213393607260249141273724587006606315588174881520920962829254091715364367892590360011330530548820466521384146951941511609433057270365759591953092186117381932611793105118548074462379962749567351885752724891227938183011949129833673362440656643086021394946395224737190702179860943702770539217176293176752384674818467669405132000568127145263560827785771342757789609173637178721468440901224953430146549585371050792279689258923542019956112129021960864034418159813629774771309960518707211349999998372978049951059731732816096318595024459455346908302642522308253344685035261931188171010003137838752886587533208381420617177669147303598253490428755468731159562863882353787593751957781857780532171226806613001927876611195909216420198938095257201065485863278865936153381827968230301952035301852968995773622599413891249721775283479131515574857242454150695950829533116861727855889075098381754637464939319255060400927701671139009848824012858361603563707660104710181942955596198946767837449448255379774726847104047534646208046684259069491293313677028989152104752162056966024058038150193511253382430035587640247496473263914199272604269922796782354781636009341721641219924586315030286182974555706749838505494588586926995690927210797509302955321165344987202755960236480665499119881834797753566369807426542527862551818417574672890977772793800081647060016145249192173217214772350141441973568548161361157352552133475741849468438523323907394143334547762416862518983569485562099219222184272550254256887671790494601653466804988627232791786085784383827967976681454100953883786360950680064225125205117392984896084128488626945604241965285022210661186306744278622039194945047123713786960956364371917287467764657573962413890865832645995813390478027590099465764078951269468398352595709825822620522489407726719478268482601476990902640136394437455305068203496252451749399651431429809190659250937221696461515709858387410597885959772975498930161753928468138268683868942774155991855925245953959431049972524680845987273644695848653836736222626099124608051243884390451244136549762780797715691435997700129616089441694868555848406353422072225828488648158456028506016842739452267467678895252138522549954666727823986456596116354886230577456498035593634568174324112515076069479451096596094025228879710893145669136867228748940560101503308617928680920874760917824938589009714909675985261365549781893129784821682998948722658804857564014270477555132379641451523746234364542858444795265867821051141354735739523113427166102135969536231442952484937187110145765403590279934403742007310578539062198387447808478489683321445713868751943506430218453191048481005370614680674919278191197939952061419663428754440643745123718192179998391015919561814675142691239748940907186494231961567945208095146550225231603881930142093762137855956638937787083039069792077346722182562599661501421503068038447734549202605414665925201497442850732518666002132434088190710486331734649651453905796268561005508106658796998163574736384052571459102897064140110971206280439039759515677157700420337869936007230558763176359421873125147120532928191826186125867321579198414848829164470609575270695722091756711672291098169091528017350671274858322287183520935396572512108357915136988209144421006751033467110314126711136990865851639831501970165151168517143765761835155650884909989859982387345528331635507647918535893226185489632132933089857064204675259070915481416549859461637180270981994309924488957571282890592323326097299712084433573265489382391193259746366730583604142813883032038249037589852437441702913276561809377344403070746921120191302033038019762110110044929321516084244485963766983895228684783123552658213144957685726243344189303968642624341077322697802807318915441101044682325271620105265227211166039666557309254711055785376346682065310989652691862056476931257058635662018558100729360659876486117910453348850346113657686753249441668039626579787718556084552965412665408530614344431858676975145661406800700237877659134401712749470420562230538994561314071127000407854733269939081454664645880797270826683063432858785698305235808933065757406795457163775254202114955761581400250126228594130216471550979259230990796547376125517656751357517829666454779174501129961489030463994713296210734043751895735961458901938971311179042978285647503
Wonderful! I love the technical whiteboard discussions you produce. I sure have missed them. Welcome back, Bruce!
Your teachings spring forth new brain cells due to your teaching technique, and the warmest sense of humor on all tubes.. I learn stuff here. Cheers. White Board Wednesdays Rule!!!,
RCModelReviews - My nephew (young Quentin) just asked, "What is Arsey Model Reviews? Is is bad tempered fashion models?"
I cuffed him over the ear on your behalf Bruce.
I've said it before Bruce, this is what you do best. You are a born teacher who can make anything easy to understand.
I could watch your whiteboard videos all day. Thanks Bruce
Excellent. Great explanation. I will now refer to you as professor.
Great explanation. Don't forget about attenuation. Lower frequency RF will propagate further than higher frequency RF. Love these videos.
A similar thing happens with coaxial cable, a higher loss with higher frequencies. I think it has to do with the magic pixies getting tired more easily as they jump up and down faster on their way down the cable.
isnt it due to the coaxial coating? the mesh mb cant isolate losses from higher frequencies
great video Bruce - clear and simple
looking forward to the next white board session
Simplifying the algebraic equation blew my mind on a whole new level.
A nice highly simplified explanation for us electronic numpties
I have found that most hobbyists (or those I know) don't know or even care why lower frequencies go further. All they want to know is how far they go...... which is, given all the variables involved, the same as asking how long is a piece of string.
And then there is the vexed question of which frequencies they are ALLOWED to use in their locality which can be a world of hertz.
_I have jokes about allowable transmission power to but the normal reaction to them is watt_ ?
watt the freq kenneth?
kenneth: i saw flying saucers, i think they are alien RC models
Very nice job Bruce! I always enjoy you tutorials.
brilliant Bruce! thank you for this! i finally understand it. im not horrible at algebra, so i got the equation right away, but the frequency thing was new to me!
Your voice is incredible...the way you speak is amazing....your voice is alot younger than your actual age...i listened to your vedio first time about china ems...and i wished to see you due to your incredible voice....thats why i come to see this vedio so that i can see you..
Another good job Bruce !! You look good , and happy !!
Thanks for your enthusiasm about this. I learned something!
Excellent explanation, love the whiteboard episodes :)
This may all be for RC but this really helps me learn more about Amateur Radio.
The same transmit power at different frequencies has a definite effect. I think this important to he discussion.
Thanks for the info. You make it so simple to understand even for me. Your great.
More white board more white board yes yes yes. I look forward to your test results Bruce. Far out man.
Nicely explained Bruce
4 = 4 = 4 all day... It's not good when we can't comprehend constants...! :o
Thanks for "breaking it down" Bruce!
Excellent Bruce. Elephants and Whales cottoned on to this, they'd be good at fpv
I came into that formula maybe three or four years ago when i was trying to understand why lower frequencies are better for long range :)
I wish you have made that explanation at the time because it implies an expending spherical and also squared representation of the loss signal which is not really fun to understand lol
Thank you so much for your hard work Bruce :)
Excellent way of explaining it! Thank You!!
Really good stuff should do more of this.
Good video I liked your explanation , but no one I know teaches about the theory of ether anymore that is old school but I still remember it.
Excellent! Excellent, Excellent! Looking forward to the videos.
Have always enjoyed your videos. Thanks for all that you share.
Great video ! i guess in your next video about this, you also will mention that the lower frequencies will have a better penetration "factor" through obstacles or materials.
I enjoyed the video ! it is really needed in this hobby, where there are so much things you need to know, to enjoy the hobby to its full potential.
btw. the videos are beautifull with the new setup !
'Tis a favorite project of mine,
A new value of Pi to define,
I would set it at three,
For it's simpler you see,
Than three point one four one five nine.
Another great explanation Bruce. In the real world not everything is "free space". Some explanation about additional losses caused by things such as trees would also be helpful. I am also looking forward to your review on the Jumper radio, with the new T 12 version having just been released. What are the essential differences between "Open TX" and "Deviation TX".
Yes, I'll be talking more about environmental factors in respect to range and one of the comments I made in my review of the Jumper (which hasn't been published yet) was "this would be a fantastic radio if it had OpenTX". I guess I wasn't the only one who thought that :-)
Thanks Bruce!
Let us not forget, that if one can change for "Broad-casting to Directional Transmission" one can project more energy on a single direction decreasing the signal lost....
The skin effect also plays a part as lower frequency penetrates more obsticals.
Thanks for the awesome explanation!
Oh wow. Even though it is the same technology, I never really associated lower frequencies being better for range with radio control. With IT stuff it makes sense. 2.4Ghz = lower throughput, greater range, 5.8Ghz = higher throughput, shorter range. Fine. You can easily see this if you have a dual band wifi access point. However, when i was a kid, my parents would buy me cheap RC cars from Radioshack. Universally 27Mhz meant the model would have a range of 11 feet, and 49Mhz meant a range of anywhere between 100 feet and a quarter of a mile even if both vehicles were the exact same model. Even to this day i'll unconsciously choose the highest frequency available in a spectrum for really no reason.
I wish I'd knew you when I was young. You always make dumbs like me understand everything.
a video on why, how and when different frequencies are used.
Nice Bruce. Great video!!!
As you said, Lower the frequency, longer the range. Does that mean that a standard 72Mhz system would give us far more range than 433Mhz LRS? Or a 2.4 GHz system?
I guess yes, if the power output of all the systems are equivalent. Why not then we move back to 72Mhz with frequency hopping?
Great explanation, I have learned something new. I previously asked myself, why do drone makers use very short antennas, would a longer antenna have better range? Now I know that extra antenna length has no benefit. Extending the wire to the antenna would weaken the signal. So I’m guessing that ideally the TX should be situated as close to the exterior of a drone as possible, so the antenna is clear of interference from the drone itself with the shortest connection. Am I correct?
Great explanation. But could we not get more range from high freq.s like 5.8ghz if we used full wave antennas?
Awesome stuff Bruce. I wonder how much range we could get with say the old 27mhz AM or 72mhz with those crazy long antennas paired with spread spectrum frequency hopping.🤔
Don't know if 27MHz will allow the fast data that is used/needed... MW/FM :)
Great video Bruce, thank you! You have so many great videos for people just starting out and beginners of all kinds but you should consider making a more advanced series of videos for people who have more knowledge and understanding, go deeper in electronics and rf theory, include attenuation, propagation delay, fresnel zones etc. Much love from America buddy
I think I did a video on the Fresnel zone a while ago.
Yes, I just threw that out as an example, I really just wanted to request a video(s) that dives further into the fun world of electronics and rf (as it applies to the hobby and for flying of course). I don't think you would have to be afraid of losing people's interest due to the complexity. I know you're more than capable of doing so and it'd be an awesome video (well series I hope!)
Thankyou for the video. It's nice to know stuff about my hobby
Thanks for the video Bruce. One question, if the frequency loss is all down to the physical length of the antenna, could you not use a 1/2 or full wave antenna on the 2.4ghz system and get more range? I’d guess based on the video that in theory going from a 1/4 wave antenna to a full wave antenna could double the distance in identical circumstances?
I'll be covering how to "get more metal in the game" in an upcoming video. Simply making your 2.4GHz antenna longer won't work for several reasons -- think of it kind of like the extra length receiving a signal that actually cancels out that received by the original length of antenna. For example, a full-wavelength of wire would (in theory) produce *no* output because the signal in one half would cancel the signal in the other -- this is why we use half-wave dipoles or quarter-wave monopoles most often. Another white-board video on this subject coming up soon :-)
Thank you Bruce I had my suspicions when my "pagoda array" 5.8ghz at 150mm started showing promise of outperforming my CPATCH12 1.2ghz at 130mm of "collecting material"
What are your thoughts on 5.8ghz parabolic antennas? Say you modify an old satellite dish?
what if you use half wave or 3 quarter wave antenna for 2.4Ghz radio link, will it make any difference?
it will, if i remember correctly, it has to do with impedance matching
It will, dipoles are a half wave, but I will let Sir Bruce explain properly. It becomes a matter of what you can fit into your aircraft.
I was wondering as well, thanks for the info! :)
It has more to do with the radiation pattern, and the gain. A dipole is 'somewhat' omni, it does have nulls right off the ends of the antenna. Picture an apple, nulls off the bottom and the top, inline with the stem. A 5/8 is similar, but now squish the apple down a little. it's shorter, the nulls are worse, and fatter, overall gain perpendicular to the stem is higher....
wish to ask about the JST connectors and if there is a common size,? I have a bag full of old cmos sony with 3 pin and 4 pin, I know the pin outs but not the JST connector sizes (3 pin jst) and (4 pin jst) can you help?
Sir
Please make a video on the aerodynamics of an ornithopter.
A question: Is it correct, that the EU-868MHz offers a little advantage over the US-915MHz on the Crossfire/R9 systems?
Awesome, looking forward to video #2 on long range system tests promised a few years back! Speaking of long lost projects . . . what ever happened with the RC control simulator chair thingy you and Roncam were working on?
Still waiting to be finished... but Ron keeps nagging me so it'll be done this spring.
The formula is very helpful, but a bit more theory on the subject would be appreciated. The antenna length is a technical feature, not a cause for longer range. Why we use 2.4 Ghz if longer wave is so "awesome" ? Back in the day, we had longer waves for RC, so if the industry switched, then there was a good reason, like less interference and congestion in microwaves. Not everyone in RC have only high school education, some of us love theory too. Thank you for your enthusiasm though.
yes, its about bandwidth, less channels on lower frequencies
but this video is only about range
and i think the industry switched because of the tight regulations on lower frequencies
less and less unlicensed and amateur bands at lower freqs
and the other aspect is convenience
smaller anntenna and growing number of channels to control more servos and for telemetry
not mentioning FPV bc its on its own dedicated video frequency
can't remember a ton of digit of pi? -> unsubscribe :) Thanks for the good work
Love it!
35MHZ RC ah the days ... I was pretty sure that l.o.s. reception wasn't the problem back then. Even if it only was PPM
This needs the atmospheric absorption taken into account, too. ;)
Can you explain why loss is proportional to frequency squared rather than just frequency?
Hooray math! Thanks for the helpful info, Bruce. Now how about that Part 2 on Antenna Theory :)
That's coming... but I wanted to show that antenna performance is about having the most metal in the game. I'll expand on this when I talk about why you can't just use a longer length of wire to get more signal and how the different type of high-gain antennas manage to get more metal in the game anyway.
So the real question of range is how long of an antennae can you mount on your RC unit. For my toys(a boat and a quad) the L9R could easily have had 5-6 times longer antennaes without being an issue.
Could you make a video explaining NACA Ducts
wavelength is of course literally length. if you change the wavelength, you also change the number of wave *cycles* between Tx and Rx. you could think of it like, more opportunities for something to interfere with the transmission because there are more complete instances of it in the path to corrupt? (with a b/g in audio, i tend to think of all waves similarly, and i think, in audio, it is easier to understand how wavelength relates to transmissiveness). remember to smoke a lot of weed for your health! :)
just woke up, more explain.. a fixed dimension (say 1 cm, or 1ms) translates to more duty cycles of a higher frequency.. so this is how interference of any sort translates to greater loss of shorter wavecycles. acoustically, a high frequency might need to make 100 cycles to pass through a brick wall, whereas the same distance only represents 1/10th of a low wavecycle.
So. Why is 5.8 more common? I am looking into a receiver for my new fatsharks(New to fpv and all things quad) and I see 2.4 and 5.8 receiver modules it the number of channels on 2.4 are far less. Also what is the best setup?.
Because there are laws what frequencies you can use and how wide those bands are. That dictates how many channels you can fit.
nice videos !
Thanks amazing videos
thanks for solving my algebra homework
Although a valid theoretical principle, reality means that range is determined by many other factors.
Smaller antennas can be easier to build in configurations giving more gain (think about the size of a coil antenna for 5.8 GHz vs. 433 MHz). The question is: is this enough to to make up for the path loss? As usual the answer is probably "in some cases" :)
Where does this equation come from Bruce? I'd like to read up more about it.
thank you sir!
is very helpful !
:)
Hi Bruce. Thanks for the video. So in theory , using 2.4 transmitter system and 5.8 video system, we will never be able to have video signals for the entire drone range and we will loose video signal at some stage at the end of the transmitter range . Is that right ? if so , how to fix the issue ? Thanks in advanced
Ehsan Keshtgar for the purposes of an RC craft, you're going to be limited for the receiver antenna for control, it'll need to be onnidirectional. So that'll effectively be fixed. However, you aren't limited(much) for the receiver antenna on the video, so you could effectively get a more sensitive receiving antenna for video and match the range of your control link despite the frequency difference.
The 5.8GHz signal will have a higher path loss than the 2.4GHz signal but the difference can be more than compensated for by either using more power and/or a high gain antenna on the FPV gear. I run 200mW and I can get more video range than RC range with my setup but if I had standard (omni) antennas on both RC & FPV and was running 100mW of power on both then I'd expect the video to disappear before control was lost.
Thanks for your reply . I have 600mW video transmitter and RF632 receiver with diversity which is a decent video receiver but I don't know what type of antenna would give me the best range . I'm thinking of Pagoda. May I ask what rang should I expect with this setup ?
Bruce!
The antenna is vertical but the wavelength is horizontal. Can you explain what's happening here?
Good day Bruce,
I don't know how else I can contact you. I am also in NZ and I have over the years accumulated lots of RC parts (ESCs, motors, frames, servos etc) and since CAA changed their rules I practically haven't touched them since...Is there a way you can send me a message and I shall arrange to maybe deliver these parts to you personally so they can maybe contribute towards what you do? Thanks.
Gordon
As always an interesting bit. However, being a "Constant" is well and good, but what does the Constant "4" represent?
Both 4 and Pi combine (ie: 4 x Pi) to create a value which effectively reduces the effect that d and f have on the result. The bigger the "other" factors on that line, the less effect distance or frequency has. Think of it as a scaling effect. For the purposes of this video they're not important because I only wanted to show that changes to d (distance) and f (frequency) have an effect on the path loss and how going up in down in in d or f affects that.
The formula for calculating the surface area of a sphere is 4πr², the r in this case is represented by d and thus, after factoring in frequency and the speed of light, more of that later, 4πr² represents the loss of signal due to the expanding sphere. f/c is also 1/λ (lambda) the wavelength of the frequency. As the frequency increases its wavelength decreases, 1/λ increases the loss inversely proportional to the wavelength, and directly proportional to the frequency, of the signal. .... and then it's squared, bugger.
Edit: ain't math/algebra fun.
Good stuff , keep it up.
Thanks for your reply. I get the inverse-square stuff from studying light. I just don't get why the number 4. Why not 3, or 5?
It's halfway to supplying the answer to "the meaning of life, the universe, and everything"??????
We think we have advanced on board flight Control Systems now look what the future has to hold
Why couldn't you put multiple higher frequency antennas in parallel? Of course, attention to the length of the coax to where the 2 antennas join would need to be taken to prevent issues with phasing, and the placement of antennas to prevent destructive interference due to wavelength. As well as the fact that 2 50 ohm loads in parallel results in a 25 ohm impedance, so some impedance matching network would be needed as well. But other than that, it should double the gain in theory?
Congratulations, you just built a yagi. In use since the dawn of radio.
superdau I guess I was thinking more along the lines of an actual dipole. Yagi antennas are cool, too! But is there a way to make is have an isotropic radiation pattern, at least as good as a normal wire antanna?
Perhaps we should have stuck to 35Mhz in the UK
Hi, my comment is off topic, because I did'nt know where to contact you for this. If you could direct me to your video or make a video on how to figure out how much draw is on a set of servos (say Hitech 430BH) and how much battery power is needed. P.s. I fly internal combustion engines only, and not electrics, I use Futaba T-HSS 8 channel receiver, with 6.6V Li-fe 1900mah, with 7 servos.
Hey Bruce why can the 2.4 gigahertz on your wifi only go 500 m but get the 2.4 gigahertz on your controller can go away further
So how does Voyager communicate with earth at 2.1 GHz?
Very slowly!
Hi Bruce. ive seen claims that some fpv tx antenna can cause bleed through to other channels. doesnt seem right. Is that true or just an old wives tale?
So why then don't just use bigger 2.4ghz antennas?
Wasn't ULF used in WW2 for Morse Code transmission to the Submarine Fleets?
Yes, they used frequencies right down in the high-tens to low hundreds of KHz (from memory) and even in the cold-war era, were using this as a way of globally communicating with underwater vehicles.
Interesting but why then, would you use high frequency rather than low frequency?
its cheaper i believe and easier to licence with the fcc
Because a smaller antenna is better if you want to keep things compact. Have you seen a 2.4GHz CP antenna? Not good on a racing quad, especially if you consider you want your control frequency lower than your video frequency. 5.8GHz is king for miniquads because the antenna size is so small. Really there's no other reason.
I'll be covering this more in the next video on long-range systems but basically higher frequencies are usually associated with more bandwidth and more space in the band. The 2.4GHz band (for example) offers us 85MHz of space but on 900MHz we're down to about 15MHz and on 72MHz we had less than 1MHz. This is why we can have heaps of people simultaneously flying RC on 2.4GHz but already I see that some of the 900MHz and 433MHz RC systems are having issues trying to support more than a handful of simultaneous users.
Ummm... We should sync everyone up and use *_time division multiplexing_* !!!
So why did the whole hobby move to higher frequency from the 27 35and 40mhz; apart from the business concerning crystals.
I presume 2.4ghz is not good for rc. submarines being under water.
s tanner good question, money is one answer , 2.4ghz chips are cheap and easily available now compared to old frequency ones, size of antenna is another and also number of pilots flying at once is increased with higher frequencies.
Trouble now is 2.4ghz band is swamped because of routers etc etc.....
Here is the UK 35mhz is the RC air frequency but is not used much any more apart from a few flyers.
I must say that I had more trouble with 35mhz losing control than I ever had with 2.4ghz (apart from spektrum dsm2 lol ) but might have been because other flyers did not follow the rules about turning on their txs without checking the peg board first lol.....
Though sometimes if a train went past it would interfere with my 35mhz control...
thanks thanks thanks 谢谢老师。。。
So why not go back to 72mhz. For long range for with a auto backup? Solve many problems and much lower so video doesn't interfere with the system
Bruce I would like for you to revisit video frequency. I'm getting some pretty good results on 5.8ghz. Flying out 20km. I believe the F zone of 5.8 makes a big difference if you know how to setup it your equipment correctly and fly in the receiving beam. Check out my channel for ground station setup and long range flights please.
I see u had a large earthquake. Hope u are safe. Post any info you may have.
this is pi:
3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117067982148086513282306647093844609550582231725359408128481117450284102701938521105559644622948954930381964428810975665933446128475648233786783165271201909145648566923460348610454326648213393607260249141273724587006606315588174881520920962829254091715364367892590360011330530548820466521384146951941511609433057270365759591953092186117381932611793105118548074462379962749567351885752724891227938183011949129833673362440656643086021394946395224737190702179860943702770539217176293176752384674818467669405132000568127145263560827785771342757789609173637178721468440901224953430146549585371050792279689258923542019956112129021960864034418159813629774771309960518707211349999998372978049951059731732816096318595024459455346908302642522308253344685035261931188171010003137838752886587533208381420617177669147303598253490428755468731159562863882353787593751957781857780532171226806613001927876611195909216420198938095257201065485863278865936153381827968230301952035301852968995773622599413891249721775283479131515574857242454150695950829533116861727855889075098381754637464939319255060400927701671139009848824012858361603563707660104710181942955596198946767837449448255379774726847104047534646208046684259069491293313677028989152104752162056966024058038150193511253382430035587640247496473263914199272604269922796782354781636009341721641219924586315030286182974555706749838505494588586926995690927210797509302955321165344987202755960236480665499119881834797753566369807426542527862551818417574672890977772793800081647060016145249192173217214772350141441973568548161361157352552133475741849468438523323907394143334547762416862518983569485562099219222184272550254256887671790494601653466804988627232791786085784383827967976681454100953883786360950680064225125205117392984896084128488626945604241965285022210661186306744278622039194945047123713786960956364371917287467764657573962413890865832645995813390478027590099465764078951269468398352595709825822620522489407726719478268482601476990902640136394437455305068203496252451749399651431429809190659250937221696461515709858387410597885959772975498930161753928468138268683868942774155991855925245953959431049972524680845987273644695848653836736222626099124608051243884390451244136549762780797715691435997700129616089441694868555848406353422072225828488648158456028506016842739452267467678895252138522549954666727823986456596116354886230577456498035593634568174324112515076069479451096596094025228879710893145669136867228748940560101503308617928680920874760917824938589009714909675985261365549781893129784821682998948722658804857564014270477555132379641451523746234364542858444795265867821051141354735739523113427166102135969536231442952484937187110145765403590279934403742007310578539062198387447808478489683321445713868751943506430218453191048481005370614680674919278191197939952061419663428754440643745123718192179998391015919561814675142691239748940907186494231961567945208095146550225231603881930142093762137855956638937787083039069792077346722182562599661501421503068038447734549202605414665925201497442850732518666002132434088190710486331734649651453905796268561005508106658796998163574736384052571459102897064140110971206280439039759515677157700420337869936007230558763176359421873125147120532928191826186125867321579198414848829164470609575270695722091756711672291098169091528017350671274858322287183520935396572512108357915136988209144421006751033467110314126711136990865851639831501970165151168517143765761835155650884909989859982387345528331635507647918535893226185489632132933089857064204675259070915481416549859461637180270981994309924488957571282890592323326097299712084433573265489382391193259746366730583604142813883032038249037589852437441702913276561809377344403070746921120191302033038019762110110044929321516084244485963766983895228684783123552658213144957685726243344189303968642624341077322697802807318915441101044682325271620105265227211166039666557309254711055785376346682065310989652691862056476931257058635662018558100729360659876486117910453348850346113657686753249441668039626579787718556084552965412665408530614344431858676975145661406800700237877659134401712749470420562230538994561314071127000407854733269939081454664645880797270826683063432858785698305235808933065757406795457163775254202114955761581400250126228594130216471550979259230990796547376125517656751357517829666454779174501129961489030463994713296210734043751895735961458901938971311179042978285647503
not exactly of course
I was going to say... you missed a few digits off the end :-)
RCModelReviews XD
the speed of light is not a constant
C, the speed of light IN FREE SPACE, is a constant
Chris Balmforth in a vacuum yeah
hey wheres dick gibson then>?
pewdie who ?
Thats a snot load better!!!!!!🤣🤣