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Mark Allyn
2026-04-21 08:38:18 -07:00
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CLAUDE.md
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@@ -641,3 +641,243 @@ settings.h — tunable constants:
- Rain clutter filter: default (0.0 = off), minimum (0.0), maximum (1.0), keyboard step size
- Wave clutter filter: default (0.0 = off), minimum (0.0), maximum (1.0), keyboard step size
- Key-hold acceleration for gain, rain clutter, and wave clutter keys
==================================================================
LEFT PANEL TEXT — ONE ENTRY PER SCOPE
==================================================================
Note: Each left panel renders its description text followed immediately by its
control table. Every panel also states the next scope name so the visitor knows
what pressing s will show. The s / S advance note appears in every panel.
------------------------------------------------------------------
PANEL 1 — EXHIBIT INTRODUCTION
------------------------------------------------------------------
Header (all caps, large):
WELCOME TO THE MUSEUM VINTAGE RADAR EXHIBIT
Body:
Welcome! This exhibit lets you experience how radar worked from the 1940s
through the 1960s — technology that changed the course of World War 2 and
shaped modern aviation and maritime safety.
Radar works by sending out short bursts of radio energy and listening for
the echo that bounces back from ships, aircraft, and terrain. By measuring
the time it takes for the echo to return, the radar calculates how far away
the object is. Rotating the antenna builds a map of everything around it.
This exhibit features six radar displays. Explore each one at your own pace.
Press s at any time to jump to the next display — do not wait for the
automatic 120-second advance. Press S (shift+s) to go back.
Pressing any key or control resets the 120-second timer.
Next: Marine A-Scope →
┌─────┬───────────────────────┐
│ KEY │ FUNCTION │
├─────┼───────────────────────┤
│ s │ Next display │
│ S │ Previous display │
└─────┴───────────────────────┘
------------------------------------------------------------------
PANEL 2 — MARINE A-SCOPE
------------------------------------------------------------------
The A-Scope was one of the earliest radar displays, used aboard ships and
in coastal stations in the 1950s. Unlike the circular display you may have
seen in movies, the A-Scope sweeps left to right: distance (range) runs
along the bottom axis, and the height of each spike shows how strong the
echo is from that direction.
To look in a different direction, the operator physically rotates the
antenna by hand. Use c and v to rotate the antenna on this display.
The green glow is the P1 phosphor coating on the inside of the cathode ray
tube. In a real radar room this was often the only light in the space.
The glass panel in front of the screen is the graticule — an etched,
back-lit calibration scale for measuring range. When you change the maximum
range setting, watch the operator swap the graticule panel by hand — just
as it was done in the period.
Location: Bellingham Bay, WA — a fictional 100-foot mid-bay platform.
Press s to advance. Press S to go back. Auto-advance in 120 seconds.
Any key press resets the timer. Next: Chain Home A-Scope →
┌──────┬──────────────────────────────┐
│ KEY │ FUNCTION │
├──────┼──────────────────────────────┤
│ s/S │ Next / previous scope │
│ c/v │ Bearing clockwise / CCW │
│ u/d │ Max range up / down (2,4,6) │
│ 1/2 │ Gain increase / decrease │
│ 3/4 │ Rain filter increase / dec │
│ 5/6 │ Wave filter increase / dec │
└──────┴──────────────────────────────┘
------------------------------------------------------------------
PANEL 3 — CHAIN HOME A-SCOPE
------------------------------------------------------------------
Chain Home was Britain's early warning radar network, built in the late
1930s and critical during the Battle of Britain (1940). Instead of a
rotating dish, it used a fixed array of tall transmit towers that flooded
the sky over the English Channel with radio energy — a technique called
floodlighting. Aircraft crossing the Channel reflected this energy back
to separate receive antennas, sometimes at ranges up to 100 miles.
FINDING DIRECTION — THE GONIOMETER
Because there was no rotating dish, finding the bearing and altitude of a
target required a technique called nulling. A device called a goniometer
electronically combined signals from several receive antennas. The operator
slowly turned the goniometer dial while watching the screen. In most
positions the signal was strong. But at one precise setting the signal
suddenly disappeared — this was the null. When nulled, the goniometer was
pointing directly at the aircraft. Think of it like tuning a radio: you
search for the silent spot between two stations. Press [ to switch the
goniometer between bearing (horizontal) and elevation (vertical) modes.
Use keys 9 and 0 to tune — turn slowly, the null appears suddenly.
CALIBRATOR PIPS
Early electronics drifted, stretching or compressing the range scale.
The crystal calibrator injects tiny spikes at exact 10-mile intervals.
Use n to shrink and m to stretch the trace until the pips line up with
the 10-mile marks on the glass graticule.
This display is set at the Chain Home station at Poling, East Sussex,
facing the English Channel. All targets are simulated German aircraft.
Press s to advance. Press S to go back. Auto-advance in 120 seconds.
Any key press resets the timer. Next: Marine PPI →
┌──────┬─────────────────────────────────┐
│ KEY │ FUNCTION │
├──────┼─────────────────────────────────┤
│ s/S │ Next / previous scope │
│ [ │ Goniometer mode: bearing / elev │
│ 9/0 │ Goniometer tune left / right │
│ . │ Toggle PRF: 25 Hz / 12.5 Hz │
│ n/m │ Calibrator shrink / stretch │
│ 1/2 │ Gain increase / decrease │
│ 3/4 │ Rain filter increase / dec │
│ 5/6 │ Wave filter increase / dec │
└──────┴─────────────────────────────────┘
------------------------------------------------------------------
PANEL 4 — MARINE PPI SCOPE
------------------------------------------------------------------
The PPI (Plan Position Indicator) became the standard radar display for
ships from the late 1950s onward. The antenna rotates clockwise and the
sweep line rotates with it, painting a map of everything within range.
Targets glow bright blue the instant the sweep passes over them, then
fade through green to yellow before the sweep returns — this is the P7
phosphor persistence that keeps the picture visible between sweeps.
The dotted range rings give distance reference. The incandescent bearing
scale shows True direction (0 = North, clockwise to 359).
The yellow overlay is a mechanical cursor — a plastic ring and crosshair
mounted in front of the screen. Use the cursor keys to position it over a
target; range and bearing read out below the scope.
Location: Bellingham Bay, WA — a fictional 100-foot mid-bay platform.
Targets: AIS-equipped vessels and simulated traffic.
Press s to advance. Press S to go back. Auto-advance in 120 seconds.
Any key press resets the timer. Next: ATC PPI →
┌──────┬────────────────────────────────────┐
│ KEY │ FUNCTION │
├──────┼────────────────────────────────────┤
│ s/S │ Next / previous scope │
│ u/d │ Max range up / down (2, 4, 6 mi) │
│ r/l │ Cursor bearing right / left │
│ t/y │ Cursor range increase / decrease │
│ k/j │ Antenna offset right / left │
│ │ (boat heading correction — zero │
│ │ means antenna faces True North) │
│ 1/2 │ Gain increase / decrease │
│ 3/4 │ Rain filter increase / decrease │
│ 5/6 │ Wave filter increase / decrease │
└──────┴────────────────────────────────────┘
------------------------------------------------------------------
PANEL 5 — AIR TRAFFIC CONTROL PPI SCOPE
------------------------------------------------------------------
This is the Airport Surveillance Radar (ASR) display used by air traffic
controllers at regional airports in the 1960s. It works on the same
principle as the marine PPI but covers a larger area (up to 20 miles) and
is optimised for tracking aircraft rather than ships. The S-Band frequency
(3 GHz) gives a good balance of range, resolution, and resistance to
weather clutter for airspace surveillance.
Controllers used this display to sequence arriving and departing aircraft,
identify potential conflicts, and provide navigation guidance to pilots
flying in low visibility conditions.
Location: Bellingham International Airport (BLI), dedicated radar tower.
Targets: ADS-B equipped aircraft and simulated traffic.
Press s to advance. Press S to go back. Auto-advance in 120 seconds.
Any key press resets the timer. Next: Precision Approach Radar →
┌──────┬──────────────────────────────────────────┐
│ KEY │ FUNCTION │
├──────┼──────────────────────────────────────────┤
│ s/S │ Next / previous scope │
│ u/d │ Max range up / down (5, 10, 15, 20 mi) │
│ r/l │ Cursor bearing right / left │
│ t/y │ Cursor range increase / decrease │
│ k/j │ Antenna offset right / left │
│ 1/2 │ Gain increase / decrease │
│ 3/4 │ Rain filter increase / decrease │
└──────┴──────────────────────────────────────────┘
------------------------------------------------------------------
PANEL 6 — PRECISION APPROACH RADAR (PAR)
------------------------------------------------------------------
The Precision Approach Radar was developed during World War 2 and refined
through the 1950s. It gives a controller a precise picture of exactly where
an aircraft is on its final approach to the runway — both its left-right
position and its altitude.
Unlike instrument landing systems that require special equipment on the
aircraft, PAR needed nothing from the pilot's plane. The controller watched
the display and talked the pilot down over the radio: "You are slightly
right of centerline, begin correcting left. You are above the glide path,
begin a slightly steeper descent." This made PAR invaluable when a plane's
own instruments failed or when visibility dropped to near zero in heavy fog.
TOP DISPLAY — AZIMUTH (left-right)
Shows whether the aircraft is left or right of the runway centerline.
The centerline runs horizontally through the middle of the display.
BOTTOM DISPLAY — ELEVATION (up-down)
Shows whether the aircraft is above or below the correct glide slope.
The ideal descent path runs through the center of the display.
Both displays expand the inner 5 miles to 70% of the screen width —
giving maximum precision during the critical final approach phase.
Location: South end of Runway 16/34, Bellingham Airport (BLI).
Active runway: 34 (aircraft landing northbound). All traffic is simulated.
Press s to advance. Press S to go back. Auto-advance in 120 seconds.
Any key press resets the timer. Next: Exhibit Introduction →
┌──────┬──────────────────────────────┐
│ KEY │ FUNCTION │
├──────┼──────────────────────────────┤
│ s/S │ Next / previous scope │
│ 1/2 │ Gain increase / decrease │
│ 3/4 │ Rain filter increase / dec │
└──────┴──────────────────────────────┘