Update Console/Transmitter/Usage_Transmitter.md

Console/Transmitter/Usage_Transmitter

-

Console/Transmitter/Usage_Transmitter.md

+# Programming the transmitter 
+
+The .c files programs the transmit cards. The script implements the functions for the m4i.6622 transmit functions. The ‘m4iset_8ch.c’ file initiates the card for 8-channel transmit operation using 400 MHz sampling frequency (297MHz output, please see the paper for the reasoning about transmit frequency selection [1]). For 123 MHz (3T). The sampling frequency can be changed to 625MHz. The main function is named ‘m4iset’ takes three arguments as follows:
+
+```c
+/**
+ * Set two m4i transmitter cards
+ *
+ * @param pvData   16-bit data pointer for the first transmit card (each card has 4 transmitter)
+ * @param pvData1  16-bit data pointer for the second transmit card 
+ * @param lMemsize 32-bit memory length for the transmit data    
+ * @Return void
+*/
+
+void m4iset_(int16 *pvData, int16 *pvData1, int32 *lMemsize)
+    {
+
+    drv_handle hDrv;    //The instance of the first card
+    drv_handle hDrv1;   //The instance of the second card
+    drv_handle hSync;   //The instance of the star-hub
+    ...
+    ...
+    ...
+    }
+
+```
+
+The Fortran codes implements the .c code and generates the transmit data. Therefore, the .c code and fortran code must be compiled first. For example,
+
+```console
+gfortran pex_m4i_8ch_CP.f m4iset_8ch.c /usr/lib64/libspcm_linux.so -o pex_m4i_CP 
+```
+
+where pex_m4i_8ch_CP.f is the fortran routine m4iset_8ch.c is the code for card programming and libspcm_linux.so is the library for the m4i driver cards that needs to be pre-installed from the manufacturer's website. The name of the output file is pex_m4i_CP. To run the cards, this file needs to be used with two parameters 
+
+```console
+pex_m4i_CP $mode $att
+# The variable $mode determines the mode of operation. This can be either 0 or 1 as integer. The mode 0 prepares and transmits a composite pulse. 
+# The composite pulse is composed of 1 millisecond long signals. The 1 millisecond signals are subsequently transmitted for each channel. 
+# The second mode transmits a parallel transmit pulse that is generated based on a mode. The total power is normalized. 
+# The length of the pulse is approximately 1 ms.
+
+# $att parameter adjusts the attenuation level for the output. It can take floating values between [0,1].
+```
+
+
+