by Burgerman » 23 Mar 2014, 13:47
Well you have just 500mw RF power and a narrow data bandwidth. And just one frequency. You wont get 5 miles from that without a super sensitive long range receiver. And they pick up noise equally well... You may get 1 or a bit more miles reliably in ideal conditions. I have seen almost 2 miles on 35mhz maximum. Tested via many FPV flights and watched the failsafe kick in. So called Long Range systems on 430mhz that are hopping, with very sensitive specialist dual diversity receivers get 2 to 6 miles. And are less reliable than 2.4ghz as far as interference or shared frequencies.
I have 2.4ghz, and its working on 2 different frequencies at once all the time. And is also hopping both of these channels across the whole band of around 80 "channels". What's more 2.4ghz only needs to transmit and receive for around 1 to 3 percent of the time to fully communicate as at this frequency you can send a lot of data fast in a small "packet" of encoded encrypted data. As such its almost immune to the sort of interference that 35, 37, 40, 70, 72mhz is shot down by. You can literally have 100s of transmitters on at once on the same frequencies, or Wi-Fi, radar, etc. Its just not an issue.
And I also have some 32x the power output of a "normal" 2.4ghz RC transmitter @ 3.2watts Radiated. Or 6x the power of your 37mhz system.
I guarantee that apart from being way less prone to interference by the very nature of how the 2.4ghz stuff works, than the xx mhz systems. Due to being frequency agile, and using 2 different frequencies at any one time, multiple receivers in different positions, and at different polarizations, and massive data bandwidth. It also has at least 3x the range, and is BETTER through walls and trees than your 37mhz is too just because of the silly power output I chose to use.
I have tested my own 500mw 35mhz RC gear against my boosted 12x transmitter, and its got nowhere near the transmitting capability through walls or trees. The 2.4 simply works better here through any amount of obstacles than the 35mhz systems. And they have about 1/4 the range at best before failsafe kicks in.
I swapped my powerchairs over to 3200mw of hi-bandwidth frequency hopping 2.4ghz with 4 satellite receivers, from the old PCM Futaba 500mw of 35mhz, precisely because it works much BETTER through the walls of my house, garage, van, etc. There are now never any "failsafe" events as I used to get on occasion with the old low frequency 35mhz RC system.
Yes 35 (37) MHz penetrates walls etc better theoretically. BUT the system as a whole is worse, you need one channel to yourself, and with no diversity you can be shut down by dead null spots, reflected signals, RF noise etc too easily.