I have been looking for ways to increase the range on the Moteino RF69HW. Even though it has a 100mw RF power output, I would really like it to extend its range for several miles.
One possibility is to use one of these high 7w power amplifiers:
(http://www.flytron.com/1061-large_default/7w-booster-for-uhf-lrs-openlrs.jpg)
from here: http://www.flytron.com/1061-large_default/7w-booster-for-uhf-lrs-openlrs.jpg
or this one with 3 to 5 W:
(http://i.ebayimg.com/images/g/ULEAAOSwRLZT8LcT/s-l500.jpg)
from here: http://www.ebay.com/itm/433MHz-FSK-digital-radio-input-amplifier-19dBm-Output-3-5W-half-duplex-/141378920638?hash=item20ead720be:g:ULEAAOSwRLZT8LcT
The first one is unidirectional and the second is half duplex, with the receive/transmit switching being done by sending 01 or 10 to two pins on the board.
But I found that Hope has a higher power radio, also controlled by SPI, just like the RFM69HW.
It has +30db output power, which is 1W!!! The RFM69HW has 0.1W, 10 times less power.
Of course this is achieved with a very high current consumption of 550mA, which is not the core reason for the Moteino to exist. The idea, I think, is to have a low or even very low power (current consumption) device. However, I think that if it is at all possible, having this option would be a major bump on the available devices for long range telemetry.
You can check the Open LRS site to check what is already being done on this field with the RFM23BP:
http://openlrsng.org
And here:
http://www.itluxembourg.lu/site/hobbyking-orangerx-433mhz-modules-faq/
A 40km range was achieved here:
http://www.itluxembourg.lu/site/ultimate-lrs-40-km-setup/
There is a mod to the transceiver where it can be upgraded up to 2.5W!!!!
http://diydrones.com/profiles/blog/show?id=705844%3ABlogPost%3A2186094&commentId=705844%3AComment%3A2187925&xg_source=activity
This radio can be powered up to 5 Volts for high wattage, and even up to 10V as shown on the last link but at the SPI level it must keep working at 3.3V.
So if there is a question in this long post, it is: is there ever going to be a Moteino with a RFM23BP?
If not, can an Arduino Mini Pro be loaded with the Optiboot and work as a Moteino with this radio? Of course the library would have to be changed.
I would suggest the LoRa radios instead. 20dBm, are designed for long range.
With more elevated antennas, or perhaps Yagi antennas I am sure you will get many miles of range.
Even with RFM69 you can achieve 160km at 600bps if proper elevation is used. Guys that deploy high altitude baloons achieved that range with RFM69. But of course from 2 ground units you cannot do that since you cannot raise it high enough to make it above the earth curvature.
Anyway, 7W is surely very illegal to say the least. You will need a license to operate even at 1W in most places.
So I guess te answer is no... No Moteinos with the RFM23BP :'(
Quote from: luisr320 on February 25, 2016, 05:10:57 PM
So I guess te answer is no... No Moteinos with the RFM23BP :'(
I don't know... maybe if you offer Felix enough money to cover the cost of custom development, international approvals, legal fees for any violations, and a handsome profit, he'll reconsider.
Tom
@luisr320 Comparing the spec sheets, at least to me it looks like you'd get better range out of the LoRa Moteino, fresh out of the box, than you would with your more expensive RFM23BP rigged to transmit at 7 watts. Try comparing the link budgets possible with each and see if you don't agree.
I thought the LoRa were +20db (100mw), just like the HW. That's still 10 times less power then the 23BP which is +30db (1000mw). What are you suggesting that I compare? (Couldn't understand it). Not hopping to get 10 times more range, of course, but a significant increase would be expected.
I know that the FCC has very strict rules in the USA regarding transmitting power, but since the power output is adjustable, I guess it would be a question of good judgment to only use the maximum allowed power. And regarding profitability, there is a whole industry looking for stuff like this: RC telemetry. Look up those LRS links I have posted. People are poking holes to hack regular RC transceivers just because there are no alternatives.
Best receive sensitivity of the RFM23B: -121dBm
Transmit power at 7 watts: 38.45dBm
So, Link Budget is: 159.45
Best receive sensitivity of the LoRa: -148dBm
Transmit power at 100mw: 20dBm
So, Link Budget is 168.
168 > 159.45. QED
Well, at least that's my understanding of how to do the comparison. If there's a better way to compare, I hope someone here will point it out. Also, there may be other factors to consider, like the relative ability to reject interference from adjacent channels, that might be important to you.
AHHH, major epiphany.
Thank you the "Budget" clarification.
It makes sense then. If the receiver sensitivity is higher, the transmitting power doesn't need to be that high.
Hummm....
You can get cheap 328p+RFM23B from HobbyKing under the OrangeLRS 1W transmitter modules name.
There are a few topics about them on rcgroups, most interesting is FlipFlap's alternative firmware which I use for long range FPV flight with MavLink support.