I've been fascinated by drones for quite some time, but have recently had the opportunity to join a university engineering team and we're looking to develop some sort of drone component. We've had a few great ideas so far, but we want to do some more research by asking actual thought leaders and seasoned hobbyists.
I want to hear what really pains you about drones. What would make your life easier? How can we build something to fix your problems? Also, I'm very open to having a Skype call!
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Jake Stew, what country are you from? Here in the US, we can legally transmit over a watt on 433 MHz, in fact I think we can do 4 watts legally with a HAM license.
We're not talking licensed operation. Very few here have a HAM license.
Very doubtful you can legally transmit over 10mW here in the US on 433 without a license.
If you're aware of a regulation or loophole that permits more without a license, please post it. In my research I've been unable to find this anywhere, and nobody else has been able to either.
Jake,
as I stated above the legal limits for un licensed operation in the 433 mHz band are 100mW. Actually that figure is a bit dumbed down for the forum. The actual legal limits for unlicensed emission are found in the CFR 47 part 15.209. which is 200 micovolts per meter at a distance of 3 meters. To get this figure you have to know the transmitter power and antenna gain. To simplify this, a 1/4 wave mono pole and and a transmitter of 100mW will be close to this figure thus manufacturers build unlicensed gear to a max power of 100mW.
The 47 CFR contains these regulations under part 15
CFR is a link to a summary of the CFR for this topic the... second link is the actual doc table.
CFR
FCC docs
Its a common fallacy that since you don't know something, it is therefore not known by anybody.
FYI - There is actually a solution available by DroneDeploy that lets you transmit imagery data wirelessly over cellular network from a drone as well as do mission planning over the web browser / tablet / mobile.
www.dronedeploy.com
I know the regs are a mess and seem like they were written by retarded monkeys, so it's hard to fault any misunderstanding.
Looks like the FCC has renumbered and scrambled things up quite a bit since I last looked at the regs.
UNDERSTANDING THE FCC REGULATIONS FOR LOW-POWER, NON-LICENSED TRANS...
The above now seems out of date. Which is kind of immaterial since unless our radio manufacturers got the devices licensed and I missed it then they're not even legal in the first place.
My 3DR radio is certainly illegal since it doesn't have a FCC number on it.
I could certainly be wrong and maybe they've since gotten a certification.
I also think your calculations are wrong...
According to this...
http://www.ti.com/lit/an/swra048/swra048.pdf
200 µV/m = –49.2 dBm EIRP
According to this...
http://sss-mag.com/calcdb.html
–49.2 dBm EIRP = 0.012 mW
To verify...
According to this...
http://www.compeng.com.au/emc_conversion_tables_field_strength_calc...
200 uV/m = .0002 V/m = 46.02 dBuV/m
And according to this...
http://www.compeng.com.au/emc_conversion_tables_power_calculator.aspx
46.02 dBuV/m at 3m = 0.00000732 ERP (mw) (That should be higher than output)
Further, according to this...
http://www.compeng.com.au/emc_conversion_tables_rf_calculator2.aspx
.1W into 0 dBi antenna will produce 5.77e-1 V/m @ 3m
So you're numbers are wrong, or those links/calculators are wrong, or I'm doing something wrong.
I assume you just pulled your numbers out of your you know what, but if you didn't then can you explain this to me and how you come to these conclusions?
With the right set-up, you can definitely get 5miles on 1.2GHz 300mW
Google "video transmitter range calculator"
Sure, if you happen to use a 10 foot satellite dish.
Find me any manufacturer that even claims this range at that power/frequency.
No, I use omni-directionals. Maybe you have a faulty transmitter?
Not sure why you don't believe 5 miles is easily achievable with 300mW 1.2 GHz.
If you are just going off manufacture specs, keep in mind, it is with the non-tuned monopole, and ground-to-ground line of sight. A transmitter in the air is much different than on the ground.
@Steven
That link shows next level gear, experience, and test equipment.
They're using high gain directional antennas mounted on antenna trackers. They also made many antenna designs and are using VERY expensive frequency analyzers to tune them.
A stock 300mW system is going to get you 1/2 mile if you are VERY lucky. Add better/larger standard antennas and you MIGHT get 1 mile max. Add large, high gain directional antennas mounted on antenna trackers and the sky is the limit.
When talking ranges you talk about stock antennas or normal, cheap better antennas, otherwise it makes no sense.
For example did you know a Geo Metro can go 250 mph while towing a 2 ton trailer?
Sure, if you added a supercharger, and nitrous system, and you were going down a 45 degree hill, and you had a tail wind.
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