Look at the entries here — Page 389, Lesson 389

This is the index of the book — the alphabetical listing of topics and where they appear. I want to walk you through how to read this, because it tells you exactly where everything lives in the syllabus. Look at the entries here. We have DME listed at pages 148, 149, 174, 243, 265, and 285. That tells you DME — Distance Measuring Equipment — is covered in multiple places, each time from a different angle. Page 148 is where the main treatment starts, page 174 is where DME/P appears — that's the precision version of DME used for approaches — and page 285 is where it shows up again, likely in the context of aircraft systems or certification. You'll also see D-layer and E-layer at page 25 — those are the ionospheric layers that affect radio wave propagation. The D-layer is the lowest, and it absorbs high-frequency signals during the day; the E-layer is above it and can reflect signals. Both matter for understanding why certain navigation signals behave the way they do. Now look at the Doppler entries. Doppler Principle at page 67, Doppler Shift at 67, Doppler Frequency at 67, and Doppler Navigation Systems at 70. The Doppler principle is the change in frequency of a wave when the source and observer are moving relative to each other — that's the Doppler shift. Doppler VOR, or DVOR, is at pages 116 and 118 — that's a VOR that uses the Doppler effect to improve accuracy. DVOR is listed separately at 116 and 118, and DOC — which is the Document, likely ICAO Doc 8168 or similar — appears at 116 and 265. You'll also see DOP at page 318 — that's Dilution of Precision, a measure of satellite geometry quality in GNSS. And Downlink Aircraft Parameters at page 237 — that's data sent from the aircraft to the ground. Moving to E: EASA CS-25 at page 285 — that's the European certification specification for large aeroplanes. Echo at 188, Echo Principle at 186 and 211, and Echo Protection Circuit at 251 — these relate to radar and transponder systems where reflected signals matter. Effect of Aircraft Manoeuvre at 318 — that's how aircraft movement affects navigation accuracy. EFIS at 207 and 285 — Electronic Flight Instrument System. EGNOS at 305 and 320 — the European Geostationary Navigation Overlay Service. EHSI at 285 — Electronic Horizontal Situation Indicator — with EHSI Colour Coding at 290, EHSI Controller at 285, and EHSI Symbology at 291. And finally Electromagnetic Radiation at page 3, EM Energy at page 4, and Emission Designators — which is cut off here but continues on the next page. So this index is your map. When you're studying DME, you know to go to page 148 for the core material, and you know the related topics — Doppler, Echo, EHSI — are all interconnected. That's how you build a complete picture of radio navigation.