RE: Blackwidow or Tinywireless radio?
Ben,
Start by listing exactly how far you will fly away from the receiver and whether or not you will doing aerobatics. What is the maximun payload for the video setup? Are you willing to purchase or make different antennas? Are you willing to purchase a receiver antenna amplifier?
900mhz equipment has only one legal channel, 910mhz in the less expensive ($100.00-300.00 range) equipment. It will transmit farther per mw than the higher frequencies, it will transmit the best thru the aircraft, the picture on mine and others I've seen is good, but there is a great deal of equipment near this frequency that could cause interference problems.
1.2ghz equipment, you will need to verify the frequencies it transmits on, should be between 1240-1300mhz. It will transmit twice as far as 2.4ghz of the same power. This equipment will provide good airplane penetration, range, and will not be affected by moisture in the air. The equipment I have seen in this range that is supposed to transmit on legal frequencies seems to overstate the power, a lot.
2.4ghz equipment is the most widely available equipment at this time. It will require over three times the power to transmit the same distance as 900mhz equipment providing that both systems have been optimized. It will provide a clean signal in a straight line to the antenna, it will be affected by moisture in the air, it will not penetrate the aircraft very well. More and more equipment is coming out on this band but inerference should be low do to the low transmittion range.
So to transmit the same distance as 900mhz you need at least 3X the power with 2.4ghz. Most commercial video equipment does not transmit over 700mw of power.
More power is a safety issue. Do not hang around the transmitter antenna with the power on. There are very powerful transmitters being sold in the USA from China that have not been tested by the FCC. I would not recommend these to anyone except someone who has a ham license and has experience with RF radiation. You can't see the radiation, but you may feel microwave radiation, you gunna cook sucka!
People used to freak out about microwave ovens. You will get more radiation from a 1 watt 900-2400mhz transmitter three feet from you on any of these frequencies in one minute than if you sat in front of a microwave oven your whole life!
There are many variables to all this equipment. Power requirements for the same mw output could be double with some equipment.
Most of the equipment that is being sold is having the power output exaggerated by 50-200%. I have not seen a company in China that is advertizing 1500mw, 3000mw, or 5000mw. On the Chinese websites they are listed as 1000mw, 2000mw,and 4000mw.
At this time there is no standards on any of thjis equipment. You need to educate yourself the best you can, talk to some hams and get your license, buy some equipment and check the measured frequency and output. Then check to see how it works in the plane. Move wiring, shielding, antennas around, make dc/dc switching regulators and add rf filters until it all works. Make different types of antennas and try them out.
You are entering into the twilight zone.
Someday there will be a truely RTF system that will work great in most installations, the closest I have seen is the Supercircuits $400.00 system, or for up close slow flying (300ft max) the blackwidow spidermite. I bought my 900mhz 1 watt tx/rx from Microcameras but have not been able to fully evaluate it yet. It seems to work well.