Highplains and Abel,

Let me see if I can nut shell what you two have said.

The system picks any two available channels out of 80 channels available. It picks two channels due to antenna orientation problems presented by an aircraft.

Within each 1 MHz channel the data is spread 1 MHz wide.

Questions.

If 4.2 billion codes are available, who assigns these codes?

Since the system picks two of 80, does that not mean that there are actually 40 times 4.2 billion or 160 billion possibilities?

Since two receivers are used to receive the two channels, why didn't they use only one frequency if it was just an antenna orientation problem?

I am not trying to bore anyone or be a smart A.., I am just trying to learn.
I was within a few days of buying the AeroSpectra scanner, but if SS is real close then I don't want to waste $900.