Hi. Was just wondering if you have carried out any range tests with the antenna you supply and the optional antenna you sell that has some extra gain. While transmit power and speed will also effect distance, planning to buy a few to remotely monitor a few beehives about 300m away.

I may need to upgrade to the rfm95 variant for a bit of extra distance or maybe a Yagi for transmitting may help if rssi is low.

Thanks. Paul.

Hi Paul,

Yes we did some real tests during the product development using the standard antenna shipped together with the Whisper Node. Please have a look on the results below:



Note that the tests were performed in a semi-populated area with a few trees, roads and obstructions in many directions. The "base" station was placed about 2 meters from the ground and the remote node was normally around 1.5 meters from ground.

It's important to note that we didn't have line-of-sight on all tests above. Also the speed and modulation used during the tests where: 125Kbps and FSK.

If you're after a solution to cover only 300m in line-of-sight or with little obstructions like small trees, a RFM69W (standard version) should be more than enough. You still can reduce the communication speed down to a few Ks/s to increase the receiving signal and get extra distance or better reliability.

Regarding the external antenna available in the Store, it offers a 3dBi gain, while the shipped antenna has 2dBi, both are omni-directional. In terms of gain it might give you a few extra dozen of meters, but one of the bigger advantages of the 3dBi antenna is that you can easily place it in a higher position, or above obstruction, or away from the ground, etc. This makes a good option of the base station or when the Whisper Node needs to be enclosed in a "shielded" area.

In practical terms we have customers in a rural property successfully communicating with nodes over 2Km away using the 3dBi antenna as base. Also, a YouTuber recently post a range test using the RFM69 (Whisper Nodes) and RFM95 (LoRA) - the tests showed the range is very similar between both: https://www.youtube.com/watch?v=9qcghiz246E. In my personal opinion I would only use LoRA if I need to connect to an already available network, like "The Things Network", otherwise the costs and possible complexity to build a LoRA network can be prohibitive. Remember you can always built a node as a repeater to overcome, for example, a hill.

Another RFM69 posts on the Internet show some interesting results: https://plus.google.com/113289611175907 ... LMpdDVLEeL and http://jdesbonnet.blogspot.com.au/2014/ ... gital.html

Finally, we're working to perform and document additional range tests in different situations and with different hardware. Including tests using 7dBi yagi and a big 1.2m 8dBi omni antenna to cover customer with real long-range requirements (over 5-10Km). It's just important to consider the legal limits when using high-gain antennas when transmitting.

Thanks Heaps, I think its time to purchase a few nodes and do some testing.

I will also have to read up on the AMCA website about the 25mW limit and antenna size.

Look forward to your test results with other antennas.

Cheers Paul

Hi Paul,

If you're in Australia here the document explaining the rules: https://www.legislation.gov.au/Details/F2015L01438

Note for 915MHz you have the general category but also have a dedicated section for digital modulation and/or frequency hopping. There's also the general use 433MHz band and the not very popular 470MHz for telemetry and telecommand.

Cheers,
Mike M.

Thanks.

I'm in Tasmania, so by default yes Australia. . I see that the different bands 433, 470 and 915 all have different max eirp. 25mW, 100mW and 3mW respectively.

Obviously You only sell 433 and 915, but as they sit in different areas of the spectrum the different max eirp will have different range/ benefits. At home I currently use rfm12b on 433 MHz. As it is a totally different radio and will be used for a different purpose and location not sure if 915 will fit the use better.


But maybe I should research a bit more on antenna theory, does the type of antenna/ gain effect the eirp of the device. ??

Regards Paul

Actually, the 915Mhz the limit is only 3mW for general transmitters. But if you look to section 58 you'll see 1W:

58
Digital modulation transmitters
915–928
1 W

Now, the module have a wide band, for example, the 433MHz module can work from 424MHz to 510MHz; and the 915MHz can work from 890MHz to 1020MHz. So you have option to cover the 470MHz if you wish.

In my experience the 915MHz is more popular, mostly because external antenna size, which is normall smaller. Again, any option should be ok to reach over 300m line-of-sight without any effort.

Cheers,
Mike M.

I ran some distance tests with the RFM69H in a very densely populated city setting today.

Setup:
- Base Station, only about 1.5m off the ground on my back patio that is covered and surrounded on 2 sides. GPS module good to +/- 3m
- Transmitter, sitting on dash in my van, with GPS module good to +/- 3m, again at about 1.5m off the ground.

I drove a loop around my area with transmitter broadcasting out ever 5s.

Hitting the end of the street, about 120m from the base station and turning the corner it lost contact. (base station on back side of my house). So made it 120m coming through my house, but as soon as it tried to make it through about 6 houses, it was done.

I picked it back up as I made my loop about 150m from my house on a different street. A park is behind me in that direction and just had to make it through/bounce between 2 houses.

Long term application for me is out in the country with decent LOS between locations, but with no tweaking so far and with lousy LOS, 120-150m in a urban area with lots of other noise isn't too shabby. Will be looking to pick up a 3db or greater antenna in the future for the base station though to see how that helps.

Hi xnih13,

Thanks for posting your test results. Dense areas without line-of-sight is very challenging indeed, the signal lost heaps of power when bouncing or going through different materials.

You can try to lower the speeds, have a look at http://www.airspayce.com/mikem/arduino/ ... _RF69.html, just need to use the "setModemConfig" and the speed/modulation.

In terms of antenna, the most important is to have at least one (normally the base station) as high as possible.

Thanks,

Yes, speed and height are the next part of the testing for urban area. As I'm in the US I need to double check laws on transmit power next too before I start tweaking that as well.

I have tested up to 3.4KM in flatter farmland terrain. Mike has the image I sent him. He can share, if he wants.
This was in the North American winter, and I expect lower distance once deciduous trees and crops begin cutting down on distance.

I considered RFM95 LoRa option also. I don't know of a ready to use option with such low power capabilities.
I'm most likely to remote my RPI3 base and power via battery and solar options or "ask a neighbor for hosting the RPI3 to link to the internet."

A case or two of brew, goes a long way for these type of requests of neighbors!