How to increase range of transmitter? Other antenna, increase transmit power? [SOLVED]

[bassie127]

I bought an RFLink set at nodo shop (including stick antenna), and have connected it to my RPI-1 with Domoticz installed.
Everything works fine, except that some of my devices (Promax switches from Action) seem to be too far away from the RFlink (signal has to go through a concrete floor, and is at the other side of the house (about 10 meters away).

The on and off-switching is not reliable for the switches far away. The switches less far away function 100% correctly.
I have also exchaned some switches, and the problem stays at the location that is farest away.
The logging in Domoticz is not showing strange things.

Are there possibilities to increase the range of the (Aurel)transmitter on RFlink? For instance another kind of antenna, or can the transmit power be increased? Or can I repeat the signal (for instance 20 times) easily?

[RidingTheFlow]

Maybe bad assembly/soldering? This is very common cause of signal integrity issues and bad overall performance.

Also, which antenna did you use? Stubby one or dipole? The short stubby one is a coil antenna and I won't recommend it since it highly dependant on transceiver's ground plane (which is modest to say the least).

I use my aurel-based RFlink to receive sensor located at ~30 meters in the garden on the other side of house through 3 walls just fine, and another one inside fridge again on the other side of house through 2 walls.
I use this internal dipole antenna - http://www.ebay.co.uk/itm/272021293532? ... EBIDX%3AIT

But generally the rule "bigger antenna = better" does not work, simply because antenna will amplify noise along with useful signal. All antenna needs to be is to be decent enough - at which point performance will be bottlenecked by transceiver SNR limitations.

*Edit: if in your case you are limited by receiver on endpoint device (and you sure your transmitter working at 100% performance), the only three things you may do is:
- improve receiver on endpoint device or change endpoint device to one with better receiver
- improve signal path, e.g. relocate transmitter so signal does not have to go through walls/floors *along them* (when signal path is almost parallel to floor/wall - this will attenuate signal greatly, much more than simply "piercing" the wall/floor straight)
- increase transmit power. This will help technically, but this is highly illegal if you will exceed allowed power limits for IMA band - you have to be *very* careful, and if you don't have proper measuring equipment I recommend staying away from this.

[bassie127]

Thanks; I will check soldering tomorrow.
I am using this antenna: http://www.nodo-shop.nl/nl/antennes/12- ... -nodo.html
How can I determine whether this is a coil or dipole antenna?

[RidingTheFlow]

Thanks; I will check soldering tomorrow.
I am using this antenna: http://www.nodo-shop.nl/nl/antennes/12- ... -nodo.html
How can I determine whether this is a coil or dipole antenna?

This looks like coil antenna. But only way to be 100% sure is to x-ray or break it
Internal dipole is longer and have thicker bottom half.
BTW I think nodo shop also sells "classic" (center-connection) dipole.

[proza]

Thanks; I will check soldering tomorrow.
I am using this antenna: http://www.nodo-shop.nl/nl/antennes/12- ... -nodo.html
How can I determine whether this is a coil or dipole antenna?

As an ex-Nodo user I also using this antenne, and experienced the same problems. Now I'm using a simple wire of 17cm in lenght. This is working great

[RidingTheFlow]

From my experience lot of people who had problems with (SMA) antenna, but improved things with piece of wire (kind of stick antenna) simply didn't solder SMA connector properly, or damaged SMA connector by overheating while soldering it.
I would not know if coil antenna from Nodo is bad, but I wouldn't it expect to be worse than stick. But stick/wire also depends on ground plane and dipole antenna still should better.

[DomoUHT]

I use the center-connection antenna from Nodo Shop which looks like to function better then the small standard SMA antenna.

Too Bad that RFlink doesn't show reception signal strength like RFXcomm. Then you could use the ProMax remote control from long distance and see which antenna gives maximum reception signal. When reception is better, transmission should also be better.

I also have the ProMax switches from Action and found that reception is very poor. The former Action switches (Eurodomest) are a lot better. I've read that heterodyne (with a crystal) receivers are the best (receiving only 433Mhz signals). The Eurodomest switches have crystals and a neat coil antenna, while the ProMax switches have a cheap receiver board without crystal and without a proper antenna.

These cheap receivers I also found in Flamengo (FA500S) and DI.O (correct me if I'm wrong) receivers. ProMax switches appear in RFlink as FA500S.

[Truff]

Its also worth checking you've screwed the antenna on tight enough. I had poor range initially but then tightened the antenna bit and now its all good.

[RidingTheFlow]

You may also try to extra shield transceiver, so it does not get so much side noise and more signal just from antenna.
This is my customized RFLink connected to Pi:

Cropped.jpg (275.84 KiB) Viewed 7599 times

I've used generic tall-ish acrylic case from eBay (http://www.ebay.co.uk/itm/251568457337? ... EBIDX%3AIT), cut extra holes in it for transceiver & antenna, glued extra piece of ~8mm thick plastic with hollowed out "gap" for transceiver to slide in, and covered this plastic bit in self-adhesive copper foil. This helped signal processing quite a bit.

[georgesattali]

Hello, proza, could you post a photo of your antenna and how you mounted it on your rfx/rflink ? I would be very interrested in you diy.

About the dipole antenna from nodo shop. it's fine and goes outside my house at least 20m from antenna.

Thanks

[bassie127]

I checked a redid some soldering -> no effect
I made a DIY coil antenna from some wire (see http://www.instructables.com/id/433-MHz ... d-antenna/) and put in loose in the antenna connector on the RFLINK => seems to work great.

[Bighouse]

I have a full DIY RFLink build, without a neat PCB.

I soldered the SMA connector to my superheterodyne RXB12 receiver



I soldered the middle pin of this thing:


To the antenna hole (most left one of the RXB12).

Do I need to do something with the ground connections from the SMA connector?

It's working now, but didn't test anything range-related yet.