Defending Continuous values using Error Correction Codes Say I'd like to transmit, using FSK modulation, a 100-bit packet which has a continuous field. I'd like to protect this value with an error correction code but an error in the MSB of this value is much more catastrophic than an error in the LSB, so how do I have to design the code so that it will be optimal by means of protection (more redundant bits for the important parts)?

For example, let's assume my continuous field is Temperature. My problem is that the temperature is represented by X bits but they are not equally important. If the temperature is 23.452298 degrees than I can't risk an error in the integer part (23) but if I'll get an error in the fractional part I'll be able to live with it (though I prefer protecting it too, with less "protection" bits).
In communications engineering this problem is called "Unequal error protection" and you can find many references on google. It can be a very involved topic. 

However, a simple method is to group your bits of each sample into N groups (e.g. if you hve a 16-bit sample, you have N=4 groups, of 4 bit each). Then, you can encode each group with a different code rate (e.g. by puncturing the bits) and form a frame from these bits. Since the code performance increases with its length, you can increase performance when you sacrifice latency. Though, this really depends on your particular application.