zanthor Dirt Dobbins Thread OP

Mini-HowTo Freaking Freq's and FPV Racing



The Problem

I've shown up at a hand full of meets now, and each time the story was the same... "What channel are you on?" "I don't know?" "Fatshark 7" "Boscom 12" "I use AOMWAY?!?!" "I'm not even sure this is 5.8ghz..."



So after some discussion, we all power up, figure out who's stomping on who, move some people around, figure out who's stomping on who, move people back, figure we can take turns flying, and in the end someone still ends up powering up a vTX 10mhz off band and because they are close enough in channel it screws up the pilot who's 1000 feet away...



Channels, Bands and Frequencies and Bandwidth

So vTX and RX come in 7, 8 and 32 channel varieties. I'm sure there are more, but those are the ones I've come across. They almost all name their channels differently, which means saying I'm on channel 7 is absolutely meaningless unless we all have matching gear. The same goes for "I'm on band 7 channel 5" because again, the bands are named differently AND in different orders.



Frequencies however are reality. Over at FPVLab there is talk about how some vTX aren't compatable with some RX because of technobabble... the gist being that instead of being XXXX frequency +/-8 they are XXXX frequency -16... so there's an offset which will impact performance. For the sake of clarity lets assume everyone has a vTX that works with their vRX when they are in a field and alone.



To exacerbate this problem, the bandwidth used by these 32 frequencies used are NOT evenly spaced out. They vary from 1mhz apart to 20mhz apart... since the video signal uses 16mhz that means we can be on different frequencies and still stomping all over each other. In the right scenario we can even appear to be fine when both of our quads and RX are back at the launch point, but when I'm 1000 feet away and your 100 feet away, my vTX may decide your video signal is "Better" than mine and switch to it, even though it's 8mhz off mine...



The Solution

So enter my favorite tool in the world... Google! Which lead me to many articles on the topic, the best being



So I did some digging, I did some thinking, and I've come up with a variant of their work which allows 4 or 5 pilots in the air at the same time. If you don't live in the USA, or don't care if the FCC comes and takes your ham license and lots of money, then you can fly 6 at a time.



Why 4 or 5? Because the majority of FPV hardware I've come across in actual use is



So here's what I came up with...





In both scenarios the closest channels are 60mhz apart, which leaves room to shift as needed. If your hardware doesn't support 5840 but does support 5845 you can use that safely, because you are far enough away from your neighbors. That said people should do their ready best to stay as close to the "Golden" channel as possible.



Event Administration

When running an event you should encourage all participants to come prepared to change their frequency. This means when they build, they need to do so without burying their vTX. If they are unable to do this, they fly when no one else is going to be impacted by it. This may mean they get slotted in with a group that happens to have good spacing.



I personally think it's a good idea for event organizers to be willing to put in the extra time to help their fliers. We want people to come out and have a good time, and we want them to understand what they are doing and why.



With that in mind I've been building a



Theory vs Reality

In this journey I've been told that real life never works out like a spreadsheet on the internet, and that it's absolutely pointless for me to try and improve on the "show up, manually find and resolve conflicts" method. I disagree with this entirely. A little prep on the part of event management, and a little knowledge shared with the participants goes a long ways. I'm not asking people to memorize the 32 channels available on their dip switch panel... I am however asking that they be prepared to look them up (print them out ahead of time and bring them with, we all carry a box of stuff to fly!)



More than anything I think it's important that everyone keep a good attitude and work together to have fun, because otherwise why are we out here? Being the new guy on the block I'm finding new information every single day. And as I do I like to pontificate about it, because often in discussing a topic with someone else, or even just writing down my thoughts, I learn something new.I've shown up at a hand full of meets now, and each time the story was the same... "What channel are you on?" "I don't know?" "Fatshark 7" "Boscom 12" "I use AOMWAY?!?!" "I'm not even sure this is 5.8ghz..."So after some discussion, we all power up, figure out who's stomping on who, move some people around, figure out who's stomping on who, move people back, figure we can take turns flying, and in the end someone still ends up powering up a vTX 10mhz off band and because they are close enough in channel it screws up the pilot who's 1000 feet away...So vTX and RX come in 7, 8 and 32 channel varieties. I'm sure there are more, but those are the ones I've come across. They almost all name their channels differently, which means saying I'm on channel 7 is absolutely meaningless unless we all have matching gear. The same goes for "I'm on band 7 channel 5" because again, the bands are named differently AND in different orders.Frequencies however are reality. Over at FPVLab there is talk about how some vTX aren't compatable with some RX because of technobabble... the gist being that instead of being XXXX frequency +/-8 they are XXXX frequency -16... so there's an offset which will impact performance. For the sake of clarity lets assume everyone has a vTX that works with their vRX when they are in a field and alone.To exacerbate this problem, the bandwidth used by these 32 frequencies used are NOT evenly spaced out. They vary from 1mhz apart to 20mhz apart... since the video signal uses 16mhz that means we can be on different frequencies and still stomping all over each other. In the right scenario we can evenwhen both of our quads and RX are back at the launch point, but when I'm 1000 feet away and your 100 feet away, my vTX may decide your video signal is "Better" than mine and switch to it, even though it's 8mhz off mine...So enter my favorite tool in the world... Google! Which lead me to many articles on the topic, the best being Solving the Frequency Dilemma by DroneX. Unfortunately even their excellent article and handy spreadsheet didn't do the trick for me, because they use 3 frequencies that are out of the legal range for the USA ! (5650-5925 MHz is legal, two of their bands are clearly outside, the 3rd sits on 5925mhz which is the midpoint for the band, thus using it is outside.)So I did some digging, I did some thinking, and I've come up with a variant of their work which allows 4 or 5 pilots in the air at the same time. If you don't live in the USA, or don't care if the FCC comes and takes your ham license and lots of money, then you can fly 6 at a time.Why 4 or 5? Because the majority of FPV hardware I've come across in actual use is ImmersionRC or FatShark So here's what I came up with...In both scenarios the closest channels are 60mhz apart, which leaves room to shift as needed. If your hardware doesn't support 5840 but does support 5845 you can use that safely, because you are far enough away from your neighbors. That said people should do their ready best to stay as close to the "Golden" channel as possible.When running an event you should encourage all participants to come prepared to change their frequency. This means when they build, they need to do so without burying their vTX. If they are unable to do this, they fly when no one else is going to be impacted by it. This may mean they get slotted in with a group that happens to have good spacing.I personally think it's a good idea for event organizers to be willing to put in the extra time to help their fliers. We want people to come out and have a good time, and we want them to understand what they are doing and why.With that in mind I've been building a DropBox Folder with assorted documentation in it. It's my goal to be able to help any pilot who shows up get their gear setup in a timely fashion.In this journey I've been told that real life never works out like a spreadsheet on the internet, and that it's absolutely pointless for me to try and improve on the "show up, manually find and resolve conflicts" method. I disagree with this entirely. A little prep on the part of event management, and a little knowledge shared with the participants goes a long ways. I'm not asking people to memorize the 32 channels available on their dip switch panel... I am however asking that they be prepared to look them up (print them out ahead of time and bring them with, we all carry a box of stuff to fly!)More than anything I think it's important that everyone keep a good attitude and work together to have fun, because otherwise why are we out here?