analog multichannel shielded cable

[Alexander_Sobolev]

We need to connect a multichannel sensor to our intermediate board (before NI xseries digitizer). The intermediate board will be custom designed, it can have virtually any connector.

Sensor has 32 channel connector (mating is MS3116F20-41S). We could not find a good cable for it (see signal description below), so we need to make a custom connection.

Our idea is to take a good cable, cut it and solder a connector for the sensor on free end. 

Signal from the sensor: 0.5 us, pulses 30uV -  5 mV amplitude with ~1 V bias offset, up to 10 kHz rate.

Sensor is a ~100 Ohm resistance, so current is 10 mA average on each channel. 

Signal is AC coupled, amplified, integrated on our board, so pulse shape change is not important. Distance is up to 1 m (3 feet). We can not place ac coupling and amplifier closer to the sensor.

Pulses on all channels happen at the same moment, cable should not allow cross-talk at least up to 1/1000. 

Surrounding environment is pretty noisy.

The questions are: what type of shielding is recommended, should each channel be individually shielded?

What cable would you recommend?

Thanks in advance!

[johnsold]

Alexander_Sobolev,

Sounds like a challenging measurement problem!

I would probably use a multi-pair twisted cable with each pair individually shielded.  Something like Alpha Wire 6019C.  Since your cable is short and the currents are small, you could probably use a cable with smaller wires than that example.  Apparently the sensor outputs share a common or ground since the connector does not have enough contacts for a pair of conductors per channel.  I would probably ground one wire of each pair  at both ends and ground the shields only at one end.  If ground loops are a possibility, build some isolation into the intermediate board.

At the intermediate board I might use a DB-50 connector with a metal shell.  Ground as many of the pins as you can and connect the shell to the shields.  Put good mechanical supports on the connector on the board and use jack screws to hold the cable to the board.

Lynn