Sentinel Ridge

Sentinel Ridge is a small West Coast defense-adjacent shop operating out of a low industrial park five miles inland from the San Diego naval bases. Nine engineers, two of whom served in joint cybersecurity roles before retiring early and discovering that retirement was, as one put it, “actively uninteresting.” Their badge readers still work. Their badges have not been issued anywhere since they left.

The product line is signal-classification models — radar disambiguation, acoustic anomaly detection, the kind of work that requires knowing what an ordinary maritime environment looks like in order to flag the things that don’t fit. Their customers are mid-tier defense contractors who subcontract to the primes. The contracts settle in the mid-five-figure Cu range — quiet, regular, never visible on procurement disclosure registers. The food chain is long. The contracts are quiet.

The office has a coffee machine the staff treat with a reverence usually reserved for working defense hardware. It was installed early in the firm’s history. It has never failed.

One of Sentinel Ridge’s founders maintains a hobbyist interest in distinguishing organic from synthetic radio signal patterns. He insists this is irrelevant to his day job and has nothing to do with any specific project. He has also, over the past three years, quietly purchased six high-end signal-processing GPUs through personal channels.