433Mhz : Issues while receiving / sending

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WoodySlum
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Posts: 5
Joined: 01 Apr 2017, 08:57

433Mhz : Issues while receiving / sending

#1 Post by WoodySlum » 15 Dec 2017, 09:48

Hi,

I would like to share my RFLink experience and ask how to improve my process.
I have a 433 RFLink with NRF24L01. The modules has been ordered directly from nodo shop. No hardware issues I guess.

Here is my 2 use cases :
- Lights : When a wall switch is pressed => RFLink transmit to my system => My system ask to RFLink tu turn on some lights. It means that receivers are not associated with senders
- Alarm : When a 433 sensor detected something => RFLink transmit to my system => My system ask to RFLink to turn on siren

That's all, now here is my tests.

1st test : RFLink connected to Raspberry with a short USB cable. The RFLink is next to the WiFI router.
Without 433 presence sensors :
- Switch are working most of the time as expected. No specific issues
- No alarm tested

With 433 presence sensors :
- Switch are not working as expected. The serial instructions are well sent, but sometimes the sending does not work
- Alarm is well triggered, but when my system detects the alarm triggering, it sends the siren 433 code to RFLink and nothing happened, the device doesn't turn on

After digging this forum, I found that it's not advice to place the RFLink next to the raspberry

2nd test : RFLink connected to Raspberry through an ESP8266 with ser2net. The RFLink has been placed in several rooms
With or without 433 presence sensors :
- Switch are not working as expected. The RFLink receives really randomly radio informations. The serial instructions are well sent, but most of the time the sending does not work
- Alarm is not triggered


For the second test, it seems to be worst than 1st test.

So, here is my thoughts :
- Receiving 433 lot of radio informations (from the presence sensor) freezes the RFLink and sending informations in the next seconds doesn't work
- ESP8266 with ser2net causes interferences, or the ESP8266 power reduces the RFLink power and range

I would like to know if anybody has ideas to improve this ?

Thanks for helping

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Stuntteam
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Joined: 27 Jan 2016, 16:46

Re: 433Mhz : Issues while receiving / sending

#2 Post by Stuntteam » 15 Dec 2017, 10:14

Some "433 presence sensors" are transmitting for a long time, like up to 5 seconds.
During this time you can not send any other signal.
This is not an RFlink issue but an issue with sensors that simply transmit too long and doing that block the frequency band for other devices.
They are more like signal jammers than proper devices.
This issue is there no matter what gateway you would use.
It can be solved by using proper sensors.
-=# RFLink Gateway Development Team #=-
Introduction: http://www.nemcon.nl/blog2/
Generic Support forum: http://www.esp8266.nu/forum/viewforum.php?f=8

WoodySlum
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Posts: 5
Joined: 01 Apr 2017, 08:57

Re: 433Mhz : Issues while receiving / sending

#3 Post by WoodySlum » 15 Dec 2017, 10:33

Thanks for the clear answer, that's what I expected. What kind of 433 presence sensors you advice (brands) ?

And is it possible to blacklist some codes to avoid this problem (for example when alarm is not enabled) ?

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Stuntteam
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Posts: 530
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Re: 433Mhz : Issues while receiving / sending

#4 Post by Stuntteam » 15 Dec 2017, 15:52

Blacklisting at RFLink would not help since the sensor is transmitting and occupying the air waves anyway.
If really needed then the only way to use such sensors is to use them at spots where they are rarely triggered and matching actions are send with a reasonable delay to make sure the sensor stopped transmitting.
-=# RFLink Gateway Development Team #=-
Introduction: http://www.nemcon.nl/blog2/
Generic Support forum: http://www.esp8266.nu/forum/viewforum.php?f=8

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