All max ranges assume 100mw setting. 1/4 the power goes 1/2 as far (e.g. 25mw goes half as far as 100mw), so you can figure out ranges for lower power levels. 1/64th the power goes 1/8th as far.
Any one with similar or different experiences please post.
There are reports of 7km on other omnidirectional antennas. This was probably under ideal conditions and should not be expected. I've gotten easily 2km on other good antennas (at 100mw ... that translates to about 250m at 1.6mW) without doing any of the extended range things:
- mounting the base station antenna on a pole
- directional base station antenna
- flying at a high angle above base
but doing the minimum:
- both antennas vertical
- aircraft always high enough to be in line of sight
Beware that simply banking the aircraft can cause loss of reception when at long range. This is an antenna polarization issue. Two antennas like this | | work well but like this | _ do not work well.
The wire dipole antennas that come with OpLinks and Revos are good antennas
if configured and mounted correctly. I would put their performance as about as good as you will get. These wire dipoles should be mounted like ---| with the dashes being the coax coming out sideways and the two wires being vertical (one up, one down). A ferrite bead on the coax at the antenna wire junction probably helps.
Here is a post I did testing many antennas:
https://forum.librepilot.org/index.php?topic=4199.msg28510;topicseen#msg28510My guess is that anyone who has decent antennas mounted/held correctly can hope for 2km LOS when both antennas are vertical but your RF environment may be different (noisy): You really
really should either:
- have a working failsafe RTB
- fly with base antenna held in a non-optimal way (low or pointing toward the aircraft) so that when it goes out of range you can just raise the transmitter above your head with antenna vertical and know you can get control back.
You should also fly in attitude mode. Loss of FPV vision or RC control when banking in Rate mode will cause a crash.
Careful base station antenna mounting (high and clear of obstruction) and you might get 4km, but you should assume it will fail at any time until proven otherwise. Again, RTB should be considered a requirement.
Experts can replace the RFM22B with an RFM23BP (requires soldering rework station, expert soldering, electronics knowledge to add an additional clean 5.5V or 6V power supply for only the RFM23BP, possibly additional licensing depending on your country) which runs at basically 1000mW only until you measure/verify the lower power settings (which for the RFM23BP are undefined). There is a reason those lower power levels are undefined (the amplifier design doesn't throttle well/cleanly).
Be careful of switching power supplies, such as switching BECs. They can produce a lot of RF noise and greatly affect range. I had an issue before, so now I run linear BECs or at least test. The 3rd harmonic of 433 is 1299, which is really close to 1280. 433 will affect 1280 FPV reception on the ground (but 1280 shouldn't hurt 433).
Test test test. Use min power for tests. Do not set it on the ground for a test. Keep metal away. Turn things off (fpv cameras sometimes have switching regulators) or use linear power supplies for the test to see what range you can get with accessories on/off and using linear/switching power supplies. I get hundreds of meters on 1.6mW. When you get that your antennas are good and your noise level is good.