Need just a small increase in range

[Sergegsx]

Hello,

I am finding myself with 2 nodes which are barely in the range to reach the gateway.
I have tried:
- adding a vertical wire from ground downwards to increate ground plane
- changing the antenna for the pcb dipole antenna
- tested several antennas sold on ebay (which look great but give lower performance than a simple wire).

I dont know what else to do to increase my range a little bit as this nodes manage to transmit but from time to time I have lost packages.

¿any idea?


Thank you very much.

[TomWS]

I assume you are already using an HW radio so either of two things that should work, but both are somewhat complicated:
1. Lower the bit rate (but this requires a network wide change since the gateway would have to match it),
2. Add a simple dedicated repeater, move your nodes to a different network ID (the repeater's) and then code the repeater to relay between that network and the gateway's.

Tom

[Sergegsx]

Indeed I am using HW radios of the 915 Mhz.

I have thought of added a repeater, I even started to code it but never finished it. (is there any code you know about doing this?)

Could you point me to how to lower the bit rate? I dont need massive transmission of information so I guess this is a very good option.

thank you tom.

[Felix]

You could also use a better tuned antenna, a dipole, or a directional antenna. This perhaps is a more "expensive" approach.

[Sergegsx]

I have tried several ones sold on ebay, all meant to be used for 915mhz

The kind shown in the picture below. (pictures from google but same items)
But performance was worst than a simple wire.
I would mind spending a bit more money, I have already done by buying several antennas but none with good results.


Tom, to reduce the bit rate, does it imply modifying the library? or do i need to add something to the sketch?

thank you both.

[TomWS]

Indeed I am using HW radios of the 915 Mhz.

I have thought of added a repeater, I even started to code it but never finished it. (is there any code you know about doing this?)

I don't have code, but it should be relatively easy if the link is unidirectional, ie, the node only sends to the gateway, not the other way around (excepting ACKs, of course).   Bear in mind that a repeater may have to be mains powered unless it can predict when the nodes will be sending.

Could you point me to how to lower the bit rate? I dont need massive transmission of information so I guess this is a very good option.

I haven't personally done it on Moteinos, but there have been discussions on the forum about this so a search should yield some direction on this.  The library can accommodate bit rate changes, although it may require changing or extending the initialization code.

[ssmall]

Check out this post
https://lowpowerlab.com/forum/rf-range-antennas-rfm69-library/working-bitrate-configs-for-1-2kbps-(1200bpsbaud)/msg7710/?topicseen#msg7710

[Felix]

I have tried several ones sold on ebay, all meant to be used for 915mhz

The kind shown in the picture below. (pictures from google but same items)
But performance was worst than a simple wire.

I'm not surprised at all. The simple wire monopole is really hard to beat in most cases. All my own motes have wire monopoles, some are bent and twisted in the mote boxes and still work great.
When I got an antenna analyzer, I realized just how terrible some of these ebay antennas are, not even close to their claimed center frequencies, this includes 915mhz, 2.4ghz antennas.
It's a hit or miss, you never know what you will get.

[perky]

I have actually done an all battery repeating design (under NDA unfortunately so can't release the code). The principles are well known though, which is basically to synchronize the transmitter to the receiver so they 'lock', and use the time of arrival of a packet to make minor timing changes on the receiver so they stay in lock. This is best done if you have a 32kHz watch crystal on each radio device and use a permananely counting asynchrous counter that's progammed to wake at defined times.

A watch crystal based Moteino would be a really useful design, it opens up a whole world of possibilities from frequency hopping to all battery mesh networks once it has the ability to time accurately even when asleep, and generate accurately timed interrupts.

[doppler]

How about a two-moteino repeater - receive on one, software serial to the second one, setup as a transmitter.  I am doing something like that for my weather station, only I am using a Picaxe in between them for legacy reasons I.e., I replaced my old radios with what I think of as Arduino/rfm69hcw "communication modules".

[Sergegsx]

How about a two-moteino repeater - receive on one, software serial to the second one, setup as a transmitter.  I am doing something like that for my weather station, only I am using a Picaxe in between them for legacy reasons I.e., I replaced my old radios with what I think of as Arduino/rfm69hcw "communication modules".

what do you think are the benefits over a unique moteino sending and receiving?

I'm not surprised at all. The simple wire monopole is really hard to beat in most cases. All my own motes have wire monopoles, some are bent and twisted in the mote boxes and still work great.
When I got an antenna analyzer, I realized just how terrible some of these ebay antennas are, not even close to their claimed center frequencies, this includes 915mhz, 2.4ghz antennas.
It's a hit or miss, you never know what you will get.

I was really surprised in my case, I expected better results. So lesson learned. I guess the best solution right now is to add a repeater. I will post code if I manage to get it working correctly.

[doppler]

what do you think are the benefits over a unique moteino sending and receiving?

In my case, as an old ham radio guy, I don't have the Arduino coding skills to easily whip up a single-radio solution - I'm at my best winding toroids and such :-).  i have done a lot with Picaxe chips and use Arduino's when I can find other's code to hack.  I started by adding an Arduino/rfm69hcw to my remote Picaxe based weather station, and did the same for a receiving setup in the house.  It worked well and I was amazed at the range:  -80db @ 100m with a metal barn in the path.  I posted my solution a while back at .....

https://lowpowerlab.com/forum/moteino/moteinorfm69-as-a-uart-transfer-device/

I decided that I wanted to do a repeater in my workshop, which is next to the metal barn, so that I could use the live data to develop other weather tools at my workbench e.g., a baraograph.  A promiscuous mode receiver would work for that, but I also decided to add my barometer and humidity readings at the barn.  The HIH-4000 humidify sensor is on the  workshop porch, protected from the extremes, and the Sure Electronics barometer module is part of the repeater.  These two sensors have worked well for several years, and give good, reliable data - I want to protect them.

I switched the remote transmitter and repeater receiver to 433Mhz, and the repeater transmitter & house receiver to 915Mhz.  I did this because I don't know how susceptible these radios are to "back dooring" (receiver getting overloaded from close proximity transmission).

For the radio board, I am using cheap 5V Arduino Nano clones, 5v/3.3v logic level shifters, and rfm69hcw radios.  The board draws ~60mah continuously (radio packets come in every 10 seconds, 24/7), which could be a problem if running off battery alone.  I am using Mains power, but have a 3000mah battery UPS implemented.  My whole repeater uses ~110mah, not counting the displays, which are only powered by the Mains.  I feel certain that I could run a Moteino based repeater using solar power alone.  My remote instruments, with just a transmitter, use 25mah, and my (2x) 6v/1w solar panels charging a 2200mah lipo are an overkill, even through multiple overcast days.

Hopefully this wasn't too long, but maybe it will help you in your planning.  Attached is a picture of my radio board.

Greg

[Felix]

I just released some new Dipoles which should be well matched from 868 to 915mhz.

https://www.youtube.com/watch?v=p-15QFaMQSA