How do you estimate TAM for a niche defense electronics segment?

For defense electronics TAM, I'd start with SIPRI and USASpending.gov for procurement data, then layer in IHS Markit Jane's or Forecast International for segment-specific forecasts — they're pricey but worth it for niche defense work. If budget is tight, comb through 10-K filings from players like Raytheon or L3Harris and back into segment revenue from their disclosures. From there, a bottom-up build using unit counts × ASP usually gets you closer to reality than top-down in a niche like radar components.