The "mixing" of two (or more) sine waves of different frequencies to create sum and difference frequency components is a well-known phenomenon. It is called
heterodyning. It
only occurs if the "mixing" is performed with a non-linear device, such as a human ear which has a logarithmic response. In electronics, mixing occurs when one signal is modulated by another signal. This can be modulation of amplitude, frequency, or phase and the result is the production of sideband frequencies. For amplitude modulation, there are two sidebands equally spaced above and below the frequency of the signal (called the carrier) that is modulated.
For frequency and phase modulations the sidebands are similar, but are described by more complicated functions and the sidebands are repetitive and theoretically infinite. However, that is not the topic under discussion. In this context, modulation means to vary some characteristic of a signal, such as its amplitude, frequency or phase as a function of some other signal, which may also vary in amplitude, frequency or phase.
Linear processing of two (or more) sine waves DOES NOT result in the production of sum and difference frequencies. The term "high fidelity" was applied originally to very linear audio amplification because "hi-fi" devices did not deliberately produce sum and difference frequencies from the audio input. That is, hi-fi tried to produce an output that was faithful in reproduction of the input, without adding or subtracting anything, or creating new frequency components sounds not present in the original. The same applies to RF: linear amplifiers are used to avoid the production of sum and difference frequencies or
intermodulation distortion.
What
any of this sum and difference frequency stuff has to do with generating truly random numbers from outer space is a mystery to me. As I may have mentioned before, any number from a set of finite numbers stored in any sort of finite memory device, such as a flash drive, is NOT a random number. It is simply a member of a finite set of numbers, however derived from a set of infinite possibilities. In other words, trying to squeeze random numbers (space noise) into a finite-sized box destroys the randomness by making it specifically finite. The probability of any number stored in the flash drive being truly random is exactly zero.
Are you ever going to tell us what you are trying to do? No one here is going to design your "analog" front end without knowing what it is supposed to do, or how it is supposed to do it. One of our moderators,
@davenn, is quite well-versed in microwave electronics. Perhaps you should send him a private message explaining what you are trying to do, and WHY you are trying to do it, instead of wasting our time here in the forums.
Hop - AC8NS
BTW: I LOVE your website!