Amateur Extra: Gray Code

What is an advantage of Gray code in digital communications where symbols are transmitted as multiple bits?

A. It increases security
B. It has more possible states than simple binary
C. It has more resolution than simple binary
D. It facilitates error detection

Firstly, what the heck is “Gray code” anyway?

The reflected binary code (RBC), also known just as reflected binary (RB) or Gray code after Frank Gray, is an ordering of the binary numeral system such that two successive values differ in only one bit (binary digit). The reflected binary code was originally designed to prevent spurious output from electromechanical switches. Today, Gray codes are widely used to facilitate error correction in digital communications such as digital terrestrial television and some cable TV systems.

From: https://en.wikipedia.org/wiki/Gray_code

To explore the details of Gray Code is just beyond the scope of this simple blog post.  I’ll redirect you to the Wikipedia entry quoted above.   Suffice to say, as you read in the description, the answer is D. It facilitates error detection.

As many of the questions on the test, unless you’re familiar with binary encoding schemes, you will just need to memorize the answer here.  The details of how it gets the job done quite frankly aren’t that important for the new Amateur Extra operator to know.  Doesn’t mean you shouldn’t read up on it in the future, though!


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