Re-wiring the seismic sensor to the logic board with longer wires

Hi Raspberry Shake support team.

I’d like to increase the distance between the geophones and the logic board. Do you foresee any issues with simply replacing the included two wires with longer wires of the same gauge?

This is for the RS1D and RS2D, and RS4D.


I think the first question is going to be, how long?

10 feet (~3 meters).

You are going to have to wait for the RS engineering team to give you a definitive answer, but I would say that this would not work well at all.

The problem is that the signal from the transducer is very low level. Using the same gauge wire would introduce measurable resistive losses, which would mean losing low-end sensitivity. That may, or may not be acceptable for your application. A bigger problem would be the introduction of signals picked up by this long wire acting as an antenna, and possibly inductive coupling from nearby sources.

You could minimize the pickup by using balanced (twisted) pair cable, such as a cat6e pair. Better still, would be a screened and properly grounded cat6e cable. That would deal with the differential signal pick-up. I have no idea how well the RS board deals with common-mode signals though.

I am pretty sure that this would invalidate the calibration data for the device - again, depending upon your application, that may or may not be acceptable.


fa1 In my travels around this board I’ve seen the idea of extending the wires between geophone and signal processing board discussed and its regarded to be a very bad idea. From the signal processor to the rpi is a serial data link which may be extended, I would look at RS485 to ttl converter modules, I don’t recollect what the data rate is but assuming it’s no more than 115kbp/s then the maximum distance should be tens of meters, this being for the RS1D, I don’t know for the others. bonne chance S

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Hello fa1, and welcome to our community!

As Philip and strebor said, that length will cause definite geophone signal degradation, as any distance between the board and the sensor above 20cm or so will see the connecting cables start to act as independent antennas, and capture many unwanted signals.

We recommend not exceeding that distance, and, when (if) possible, put the entire Shake equipment as close as you can to the area that you are interested in investigating.