RFXTrx433 - Extremly poor reception from WT450H temp sensor

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haklis
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RFXTrx433 - Extremly poor reception from WT450H temp sensor

Post by haklis »

Hello!
Can someone confirm that WT450H (ESIC / Clas Ohlson) works ok with RFXTrx433 from more than 40cm distance?

I have just bought and tested RFXTrx433 and several of NEXA's magnetic switches remote controls and motion sensors. Everything works at a range of 5-10m when tested.
That is not true for the three WT450H temperature/humidity sensors I have bought. They have to be within 40cm to show up in RXFMngr. I have tested with only the necessary protocol enabled.

I have several other wireless temperature sensors around the house (and even out in the garage) that works perfectly OK with a weather station so I do not think it should be RF noise present.
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Hakon
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b_weijenberg
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Re: RFXTrx433 - Extremly poor reception from WT450H temp sensor

Post by b_weijenberg »

Several users have reported that the range of UPM sensors is terrible. This is a known problem.
The range could be improved a little by adjusting the blue variable capacitor on the loop antenna but the range is still low with a maximum of about 8 meter with one brick wall in between.

I have done a few tests with the UPM sensor. See the results below.

17,5cm wire antenna connected to the UPM transmitter.
upm1.jpg
upm1.jpg (7.57 KiB) Viewed 17371 times
The UPM transmitter replaced by a small transmitter module and the performance is much better.
upm2.jpg
upm2.jpg (16.05 KiB) Viewed 17371 times
D=Data, G=GND, +=+3Volt
The transmitter used is not a good one because it needs minimum 3V. If the battery voltage drops a little bit it will stop working.

If you want to replace the transmitter module I suppose this one can be used: Aurel TX-SAW MID/3V module (http://www.conrad.com ordernr 191511)
This transmitter accepts 1.8 to 3.5Volts. The 17.5cm wire antenna for this transmitter can be folded in the sensor or for a better result drill a 2mm hole in the sensor and position the antenna wire vertical.

Or even better use the more expensive Oregon sensors which have a much better range.
haklis
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Re: RFXTrx433 - Extremly poor reception from WT450H temp sensor

Post by haklis »

Thank you for your reply. I will certainly try the antenna modification. Even if it is a cheap sensor a max distance 40cm is waay to short. There must be some other problem present as well.
Hakon
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b_weijenberg
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Re: RFXTrx433 - Extremly poor reception from WT450H temp sensor

Post by b_weijenberg »

Are other sensors received with normal distance?
haklis
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Re: RFXTrx433 - Extremly poor reception from WT450H temp sensor

Post by haklis »

I have a Rubicson and Oregon temp sensor also. They are received from farther away, but maybe all of them should work from an even greater distance. The Oregon sensor did not work from just outside our house. Since my other weather station works perfectly from the other side of the garage I guess it is not RF noise present. Is it possible the RFXTrx433 is bad? What is the expected operating distance with an Oregon THGR810?
Hakon
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b_weijenberg
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Re: RFXTrx433 - Extremly poor reception from WT450H temp sensor

Post by b_weijenberg »

To increase the receiving range you can connect another antenna for example the conrad 190073 antenna.
This adapter can be used for SMA- to BNC http://www.ebay.com/itm/BNC-female-SMA- ... 2a03ea8391
Another antenna is not allowed for transmit because the RFXtrx433 is certified with the supplied antenna and the antenna will also increase the transmit distance!
To have max sensitivity disable all protocols not used! There are also some protocols that influence receive sensitivity of other protocols, see the RFXtrx User Guide.
This document has also an explanation on RF range reduction by walls and the angle.

Try the RFXtrx433 also on another system and do not use an USB hub. We have seen degraded receiving on some systems and USB hubs due to RF noise present on the USB interface!

Soon I hope to have test results with another transmitter in the UPM sensor
haklis
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Re: RFXTrx433 - Extremly poor reception from WT450H temp sensor

Post by haklis »

Today I made a simple whip antenna with four radials ( I work as a R&D electronics engineer and had SMA-BNC adapter, coax cable etc. lying in my office. :), so I brought it home yesterday) The result was an additional 10m+wall for my Oregon sensor. Now it is placed inside my garage while the antenna is in my house on the opposite side from the garage. Signal :6. That is good! My NEXA switches also has the same or better range.

When it comes to my WT450H's it has maybe improved from ~50cm to 2m. This thread (in swedish) confirms that the WT450H's are extremly bad. Some people are lucky and get a unit that works better though. I think I do not want to spend more time on these sensors. I will go and by more Oregon sensors instead! :wink: Maybe I keep one and try to improve it a little bit. Or just wait to see the result on the results from the transmitter swap b_weijenberg is planning.

Thanks!
Hakon
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Re: RFXTrx433 - Extremly poor reception from WT450H temp sensor

Post by Striffster »

Which protocol do you use in the RFX? I think I have tried all of them but it doesn't show up. I have tried to plac the WT450H 20cm from the RFX but with no success.
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Re: RFXTrx433 - Extremly poor reception from WT450H temp sensor

Post by b_weijenberg »

It is better not to use UPM/ESIC sensor because the packet format used is very bad for the RFXtrx433!
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