Extend 433mhz coverage ?

[sebitop]

Dear All

currently using domoticz on a rasp Pi + Rfxcom with aurel antenna I still have some issues on some devices when i send orders (modules integrated in walls sometimes miss the signal)

I tried to found a way to amplify the signal ... nothing more than what I have... if you have any idea please let me know

otherwise I was wondering: is there a way to connect 2 RFXCOM or 2 RFLINK and make then communicate to create a kind of 433mhz network ? it will allow to extend the coverage.

please don't answer : add another remote pi I'm trying to just add another tranceiver module on the current pi I have.

thanks for your help !!

[b_weijenberg]

You can use a second Raspberry PI with Domoticz or install ser2net to access the RFXtrx433E over LAN
See also http://www.domoticz.com/forum/viewtopic ... et#p125747

[sebitop]

thanks for your answer bu this is exactly what i'm trying to avoid....

2pi + 2 antennas + + + is too much

i'm looking to put another antena do you think it could be possible ?

in fact the goal is when i send an order on domoticz this order is transmitted on 2 antennas at the same time.
If i use another pi or another rfx over the lan I will have to configure the devices separately on each rfx



thanks

seb

[Timeless]

Unfortunately these 433Mhz protocols are not designed in a "mesh" way. Best you can do is using a antenna with a higher gain, what this does is limit the antennas "visibility" in the bottom/upper direction so it can better "see" in its horizontal direction. This of course only helps if your sensors are placed on the same level as the 433Mhz receiver. But keep in mind that this removes the EC certification of the RFXcom and may/(not) be illegal.

Also if you place those "2" antennas anywhere close to each other will not gain the result your are expecting. splitting a antenna output is never a good idea. And even if those antennas have separate transceivers neither of the 2 will reach the desired sensor if 1 of them is not able to, unless they are at the edge of their range which will be a luck/luck situation. And why do you want to send if out on 2 transceivers? If 1 transceiver is placed somewhere els where it can easily reach the desired sensor, why do you want the other transceiver to send out that same signal? This will only introduce noise.

Domoticz also recently gained rtl_433 support, so if your sensors are also supported by this library you can use a 20USD dongle instead of the 109EUR RFXCom. And use that rtl-sdr on a gl-ar150 and relaying this serial communication over TCP. So you can still use your main Domoticz installation to configure your sensors. this rtl-sdr dongle is only capable of receiving 433Mhz and cannot transmit any data reliably. But since you are also having troubles with sending commands to sensors you could also use a 2nd RFXcom just like b_weijenberg said but instead use the gl.inet router which is cheaper than a raspberry.

You could also change the direction of the 433Mhz antenna you have, Simple saying: maybe the signal bounces inside your house in a way that the polarization changes. So instead of placing the Antenna vertical and receiving vertical signals, the signals in your house becomes horizontal which will reduce the signal when listening for vertical signals. I must say that its not just that simple, wireless signals are not always vertical or horizontal. They can be rotated in a 360° angle. But I hope you understand what I mean.

Similar example:



Hope this helps.
Regards,

[sebitop]

thanks for your detailled answer timeless !really appreciated.

well for the antenna orientation / model and place I think I alrady found the optimal case, it's placed under the ceiling, upside down and it's a ground plane close to the RFXCom. with this I have an excellent reception.

to answer why I want to send the same signal over the 2 transceiver is for simplicity, to explain what i'm looking for : a super simple solution to use only one domoticz easily configured. but maybe used ser2net or another domo is also super simple to configure I don't know as I never experienced it.

for example I have 10 blinds modules accross my house and I would like to be sure that they all receive the order, so in my mind using 2 antenas/tranceiver or any other solution would increse the realiability to receive the signal.


otherwise i'm looking for an enpowered rfxcom or rflink means with an amplifier on the send part, even if it's illegal I don't really care i'm almost alone where i leave I won't disturb my neighbors

cheers

seb

[Timeless]

well for the antenna orientation / model and place I think I alrady found the optimal case, it's placed under the ceiling, upside down and it's a ground plane close to the RFXCom. with this I have an excellent reception.

Ah ok great, I also had such a issue before, thinking that all antennas should be orientated the same. But after testing it with a spectrum analyzer I noticed that the reflections in my house rotated the polarization. But seeing your reply I think you know such a theory already.

to answer why I want to send the same signal over the 2 transceiver is for simplicity, to explain what i'm looking for : a super simple solution to use only one domoticz easily configured. but maybe used ser2net or another domo is also super simple to configure I don't know as I never experienced it.

personally I don't think that it is that simple. Picture it as 2 people yelling through a megaphone, if 1 of the 2 has a slight delay it would be very hard to understand either of the 2 because of interference. And because you're broadcasting over 2 antennas there will always be a signal variation between the 2.

for example I have 10 blinds modules accross my house and I would like to be sure that they all receive the order, so in my mind using 2 antenas/tranceiver or any other solution would increse the realiability to receive the signal.

Same applies here, better would be to create separate networks for each set of blinds.

otherwise i'm looking for an enpowered rfxcom or rflink means with an amplifier on the send part, even if it's illegal I don't really care i'm almost alone where i leave I won't disturb my neighbors

Sorry to be the constant bringer of bad news. But this is against regulations, true the 433Mhz may be used without HAM license, but only with a limited amount of power and duty-cycle(amount of time transmitting). As a example here in the Netherlands its only allowed to send at 10mW (and 1mW) with a duty cycle of < 10%. I don't know the exact specs of the RFXcom but I guess these are as close to these limitation because they are produced in the Netherlands. But that is just a assumption. And if you're alone does not mean anything, 433Mhz is a telementry/alarm band which can reach very var, so It can be used within your area without you even knowing. Thats all I can say, sorry I cannot advise any illegal stuff here because of personal reasons.

And also note that more power does not automatically mean that it can be received better. This line is not linear and more power could create a worse signal. Just like people did with the popular WRT54G back in the day.

Last thing, where are you planning to place these 2 transmitters? are close to each other or at the other side of the house?

[freijn]

What is the lenght of your antenna ?

1/4 wave length ? You made a GP ?

I agree in improving the antenna brings more than increasing TX power....

[sebitop]

@ freijn = already have a GP antenna on this side I've improved a lot and results are there

@ timeless = I think they should be on each side of the house but now the question is :

how could I configure this ? I need another rfx + another pi or just another RFX on the current pi ?

I would like to have a single domoticz and see all my devices on it

[freijn]

Way too much but....... if you give it a lower voltage or lower input ?

price is worth the experiment ?

https://nl.aliexpress.com/item/DC-5-7-2 ... 204.BB78ni

[Timeless]

how could I configure this ? I need another rfx + another pi or just another RFX on the current pi ?
I would like to have a single domoticz and see all my devices on it

Since USB can only reliably extend to a length of 2meters which I assume is not enough , your best bet will be a device that acts as a serial-TCP bridge. Just like I mentioned before. It does not have to be another raspberry Pi. It can be any embedded device which runs a modern operating system, I advise a device that runs LEDE/OpenWRT any of these devices since they are cheap. Especially this one.

And then use ser2net together with (quoted from here)

After installing ser2net and setting .conf-file you can add new hardware into Domoticz -> "RFXCOM - RFXtrx shared over LAN interface" with remote machine IP and .conf-file port.

Install ser2net on LEDE/OpenWRT:

Code: Select all

opkg update && opkg install ser2net

This makes it a somewhat easy and cheap solution. Ofc you could go easier and use a RaspberryPi ZeroW so you could skip OpenWRT/LEDE and instead use a Raspbian image.

[capman]

I have this antenne in use.

Works like charming. For my blinds I give the up or down commands with a pause of 2 seconds. And after 5 minutes a repeat it. I have 11 blinds and they all work fine.
https://www.conrad.nl/nl/antenne-aurel- ... 90073.html

[sebitop]

@ timeless :

idea is good so it means that I would need to split my devices "network" into sub network but at the end it will be transparent and appears the same than today in domotics, the only difference is that the order will be sent via a rfx or another... got it ! thank you for the detailled eexplanation!

for the USB length my pi is 4 to 5 m away from the rfx and i never had a problem between them, 433mhz signal is more challenging


@ freijn :

problem with the RFXcom is that the antenna works both ways to emit and receive, so I don't know what could be the impact connecting this.



@ capman:

thank you for that but this is exactly what I have installed today and I found it better works upside down installed in the ceiling of my house

[Timeless]

@ timeless :
idea is good so it means that I would need to split my devices "network" into sub network but at the end it will be transparent and appears the same than today in domotics

Exactly!

the only difference is that the order will be sent via a rfx or another... got it ! thank you for the detailled eexplanation!

Yes, that's correct. You'll have 2 RFXcom's in your hardware tab, each controlling a subset of your devices.

for the USB length my pi is 4 to 5 m away from the rfx and i never had a problem between them, 433mhz signal is more challenging

Mmh.. that's kinda long, ever measured the voltage drop over that cable? USB is spec'd for 2meters max. Or are you using a powered extension cable?

@ freijn : problem with the RFXcom is that the antenna works both ways to emit and receive, so I don't know what could be the impact connecting this.

I don't believe these things are bi-directional. so receiving would be a problem.

[sebitop]

thanks Timeless

I haven't measured the voltage but never got any issue with the conenction between the RFXcom and the Rasp