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RFMB12 (433) Excessive CRC errors

Added by Rob over 5 years ago

Hi,

I did recently acquire a new Jeenode with a RMFB12 433MHz module.
This new module is working, but compared with an old one it is showing excessive CRC errors at reception, even if close to the sender.
Any ideas of how to tune the receiver signal level (using different RF rate doesn’t help, and length of the antenna is correct)?
Is it possible that the module is failing (I mean, does other had the same experience)?

Thanks in advance
Robert


Replies (4)

RFMB12 (433) Excessive CRC errors - Added by martynj over 5 years ago

Rob,

Does the older module have  metal can crystal?

RFMB12 (433) Excessive CRC errors - Added by Rob over 5 years ago

Marty,

I have 3 modules withe the same type of crystal (a small one), but it look that only one is not working properly.
Robert

RE: RFMB12 (433) Excessive CRC errors - Added by martynj over 5 years ago

Robert,

If you have the luxury of access to a frequency meter, probe the CLK pin on the RF module with the JeeNode held in reset (this prevents any init code running - the default 1MHz will show on that pin after power comes on). I suspect the nominal 10MHz crystals are not in agreement.

Alternatively, use one of the ‘good’ ones to run up NRfMon and visualise where the other two signals appear in the band.

If there is a significant skew between the notionally equal carriers, that will make the reception marginal.

RE: RFMB12 (433) Excessive CRC errors - Added by Rob over 5 years ago

Martyn,

Thanks for your feedback, but unfortunately I don’t have a frequency meter or a scope.
Now something did happen, I did removed (painful!) the RFMB module from the JeeNode and add a 2mm socket/header, in order to be able to swap it with several other modules.
Connecting the module back with the header, (and important; with an antenna), the problem seems to be gone, so I suspect a bad contact somewhere!.

At the other hand I am interesting to verify the signal with nrfmon, however I am working on a MAC OSX, and I do not know how to run / start, this program
(I have tried the Window version on a windows virtual machine, that starts without problem; however I have a problem to map the USB port).
So any idea of how to start nrfmon an a MAC (something double click on the file or ./nrfmon from a terminal session doesn’t work)
Robert

On 04 Dec 2014, at 12:49, redmine@jeelabs.net wrote:

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