What about something like Winlink? Don't they use a proprietary modem that one has to purchase in order to encode/decode? Isn't that essentially encryption?
Not exactly.. The Pactor 3 modulation and coding standards are published. The problem would be if you wanted to go build something to implement them, in which case you'd be violating the patents underlying it. However, the meaning isn't obscured, which is what encryption is all about.
The same thing applies to D-star voice, which uses a patented voice encoding technique. The technique is published, but if you were to implement and use it, you'd need a license from the patent assignee, which they're not obligated to sell you.
With WiFi, the algorithms are published, but there's also the secret key, which is not.
Ah, makes sense.