L14 Pre-flight

L14 Pre-flight#

Block 2: RF Electronic Warfare — Lesson 14: Triangulation and Fusion Work this before L14. Pre-flights are never collected — in class, anyone may be cold-called to present any question at the board, and that recitation is the participation grade.

Assumed pre-class reading#

  • L13 wrap-up

  • The Jupyter Book Reading page for L14 — lines of position and triangulation, the crossing-angle effect on accuracy, multi-receiver fusion, and the RWR signal-processing chain.

Quiz questions (5 items, ~5 minutes)#

Q1. (Multiple choice) A single receiver measures the bearing to an emitter. By itself, that measurement gives you:

  • [ ] (a) A position fix, once the bearing is plotted from the receiver’s own location

  • [ ] (b) A line of position running out from the receiver along that bearing

  • [ ] (c) The range to the emitter, from the strength of the received signal

  • [ ] (d) The emitter’s velocity, from the Doppler shift on its pulses

Q2. (Multiple choice) Two identical receivers cross their bearings on an emitter. What most strongly sets the accuracy of the resulting fix?

  • [ ] (a) The emitter’s transmit power, which sets the intercept strength

  • [ ] (b) The crossing (“cut”) angle at which the two bearing lines intersect

  • [ ] (c) The receivers’ noise figure, which sets how faint a pulse each can hear

  • [ ] (d) The emitter’s PRI, which fixes how often each receiver reports a bearing

Q3. (Multiple choice) An emitter moves far downrange so the two bearings cross at a shallow angle. The position fix:

  • [ ] (a) Improves, because the longer range averages the two bearing errors

  • [ ] (b) Holds its size, since \(\sigma_\theta\) alone sets the ellipse

  • [ ] (c) Degrades, with the error stretched along the range direction

  • [ ] (d) Degrades, with the error stretched across the line of sight

Q4. (Multiple choice) Why fuse bearings from three or more receivers instead of just two?

  • [ ] (a) Three bearings always meet at one exact point, removing the noise

  • [ ] (b) A third bearing measures range directly, which two bearings cannot

  • [ ] (c) The fix is overdetermined, so a least-squares solution fits them all

  • [ ] (d) Each receiver can then run a narrower bandwidth and hear fainter pulses

Q5. (Short answer) Before you cross two receivers’ bearings into a fix, what must be true about the two measurements, and what do you create if you cross bearings from different emitters?

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