Changes on 03oos_mercator.c

rather than parsing field by field (which is long and error-prone). I recommend you cast the `mercator_vars.uartbufrx` to a variable of type a pointer to `REQ_TX_ht`.

Something like this (not tested):

```
REQ_TX_ht* req_tx;

req_tx = &mercator_vars.uartbufrx[1];
```
Then, to use the fields from the `REQ_TX_ht` structure to, i.e. `req_tx->frequency`