diff --git a/Console/Receiver/Spectrum Instrumentation m4i.4451/instructions.md b/Console/Receiver/Spectrum Instrumentation m4i.4451/instructions.md
index 466dc54d0e9144933c34d1f4a8165ae8fde71498..c9fc4048600394bc920cf20b9b91114b02e403e8 100644
--- a/Console/Receiver/Spectrum Instrumentation m4i.4451/instructions.md	
+++ b/Console/Receiver/Spectrum Instrumentation m4i.4451/instructions.md	
@@ -1,2 +1,18 @@
 # Software instructions
 
+These folders includes .c code for the digitizer m4i.4451 [1] and Fortran code that implements .c code as c-routines. 
+
+The compilation of the codes can be done using the first line of each Fortran files. Everything is implemented under Cent-OS system. Compatibility to other Linux distributions or windows has not been investigated.
+
+It is also possible to use other software platforms for the digitizer cards such as MATLAB and Python. The function names to control the cards are the same throughout different environments. Hence, mitigation to other software platforms should be relatively straightforward. For more information, please see the documentation and examples from the manufacturer’s website [1]. In addition, please follow the manufacturer’s website to install corresponding libraries because they differ by the OS. 
+
+## ADC
+The file **m4iset_extrig_rms.c** contains the functions for the ADC card setup and receiver operation. The routine uses 3 arguments:  
+- _*pvData_ 16-bit data pointer for the received data
+- _*lMemsize_ 32-bit memory length for the received data
+- _*posttr_ 32-bit post trigger pointer to adjust the time window of the ADC. Please see manufacturer’s documentation for more information about post trigger. 
+
+The other two scripts **rec_m4i_fifo_tdfilter.f** and **rec_m4i_tdfilter_rms.f** implement the c routine. They need to be compiled with a Fortran complier. The first line in these files can be taken as an example i.e. copy and paste it into the OS terminal using the working folder. 
+
+## References
+[1] M4i.4451-x8 | Spectrum Instrumentation https://spectrum-instrumentation.com/de/m4i4451-x8