Reading and processing real-time data

I have to read an input signal continuously and process (some filter operations) the data. It can’t be done using one arduino since it takes a long time to process the data and hence interferes with reading the signal. Also a large amount of data had to be read which can’t be stored in the arduino’s SRAM. So I decided to use 2 arduinos and an SD card module to write and read the data. This again didn’t work since it wasn’t possible to connect an SPI device to 2 arduinos simultaneously.

Can anybody tell how this can be achieved? I am at wits end.

Regards
Bharath

Describe your setup in more detail, like what data are you reading & how fast. How much data. What processing is needed. What do you do with the resultant processed data.

An Arduino Mega has more SRAM (8K) and if your system is 3.3V tolerant then maybe a Teensy3.1 would be suitable as it has even more memory and runs a lot faster.