GPS

Left at the big tree, right at the second red barn, then go bit and swing another right...

Episode Transcript

Speaker 1 (00:00):
Hello, listeners. I cannot thank you enough for stopping by.
It's time for another episode of the What They Did
Before podcast? What Did We Do Before? Anything? So easy
to take most things for granted. They're just right there
and always are, always have been. I pretty sure as

(00:20):
long as I can remember. Need to go some place
you don't know where it is, Yes, up in the car,
put in a g P S and well it tells
you how to go. What did we do before GPS?
It's hard to imagine. Navigation has historically been done with

(00:44):
celestial bodies, that is, using heavenly bodies to determine latitude
and eventually longitude. Tools used were the astrolabe, this measures
the altitude of celestial bodies above the horizon, and a sextant,

(01:08):
which measures the angle between a celestial object and the horizon.
It's more precise quadrant and cross staffs were earlier tools.
To measure star altitudes, Mariners used known star positions called

(01:30):
navigational stars, particularly Polaris in the northern hemisphere, to estimate
their position. Lunar distance method compared the Moon's positioning to
stars to calculate Greenwich time, and Polynesian star charts used

(01:52):
shells and sticks to represent wave patterns in star paths.
Navigators memorized entire night skies and use environmental cues like
birds and cloud shapes. None of those sound very exact.

(02:13):
The quite possibly old is and tried and true method
is just dead Reckoning. Determining your position by calculating direction
and distance traveled from a known point. You'll need to
know your speed. It's typically measured with a long rope

(02:36):
or a sand glass. Time is measured using hour glasses
or marine chronometers, and direction is maintained, usually with a
magnetic compass or by sun position. Errors accumulate quickly with
these systems, and over time, without fixed references, you won't

(03:00):
really be navigating at all. It was especially used in
overcast or cloudy weather when celestial navigation was impossible. For
those trying to navigate on land, there were terrestrial landmarks.
These visual landmarks were used by early navigators and used

(03:24):
recognizable land features such as mountains, peaks, rivers, coastlines. Traders
in deserts followed oasis and rock formations. The vikings navigated
using coastal silhouettes, whales, sea birds, and even the smell

(03:46):
of land on wind. You had to have a nose
for that. Indigenous knowledge included familiarity with the exact placement
of trees, stones, and animal trails, which were passed through
generations orally. By the thirteenth century, Portolin charts emerged in

(04:15):
the Mediterranean. These were focused on coastlines and harbors with
precise compass bearings. It contained room lines radiating from compass
roses for easy course plotting. Later Ptolemaic maps used gridded

(04:37):
coordinates but relied on often inaccurate data. To maps were
medieval symbolic maps based on religious views, not used for
real navigation. Chinese maps used compass and detailed early cartography. Next,

(05:01):
let's talk about wind and ocean currents. Mariners utilize the
trade winds east to west and the westerlies west of
east to travel between the continents. Knowledge of Atlantic and
Pacific guyers was key for round trip voyages, and early

(05:24):
European navigators discovered the Gulf Stream's power in the Atlantic
for a rapid return to Europe. Polynesians memorized seasonal wind patterns,
bird migrations, and wavery forractions near land for Pacific voyaging. Next,

(05:44):
let's dive into commercial and military navigation. They had all
the fun toys long before we could just dial up
our cell phone. Marine chronometers allowed for accurate longitude measurement,
which required knowing precise time had a reference location like Greenwich.

(06:04):
John Harrison invented the first accurate marine chronometer in the
eighteenth century. You would compare local noon via the sun
to Greenwich meantime. Each hour of time difference equals fifteen
degrees of latitude. This hugely improved naval and commercial sea travel,
especially for empires. Some early radio navigation systems include the

(06:30):
low RAN that's the long range navigation. It was developed
in World War II and used synchronized radio signals from
a fixed towers. It provided distance from multiple stations and
its accuracy was within a few hundred feet. The Decca
navigator system used a phase comparison of signals. It was

(06:53):
common in European waters. The Omega system was operated until
nineteen nine twenty seven. It was one of the first
global systems using very low frequency signals VLF. Inertial navigation
systems i INS calculates position using internal sensors, celerometers, and gyroscopes.

(07:20):
The advantage is as these don't rely on external signals. However,
error is builed up over time that equal drift. Some applications, though,
include submarines which can't use GPS, underwater military aircraft, or
early space travel such as the Apollo missions. Radar and

(07:43):
sonar made navigation much easier. Radar measures distance and bearing
to nearby land masses or ships. It's widely used by
naval vessels and aircraft from the nineteen to forties onward.
Sonar is used by submarines and ships to detect ocean
floor and obstacles. Echo sounding helped determine depth and detect

(08:06):
undersea obstacles. Next, let's take a look at some map
grid systems and recon Military grids include the MGRS, the
Military Grid Reference System, and the Universal Transverse Mercader UTM.
These allowed precise map reading and targeting. Manual reconnaissance relied

(08:30):
on scout reports and spy photography before satellite imagery and
aerial surveys were created. Detailed maps before satellite cartography. Some
early Cold War satellites included the Corona program in the
nineteen sixties. These secretly mapped huge areas using film return satellites.

(08:57):
US normal folk had to rely on paper maps and
atlases with brands like Rand McNally, Michelin, Triple A and USGS.
Maps were staples. You had to have a glove box
full of them. Should have been called a map box.
Road atlases were full color, spiral bound books with indexed

(09:21):
cities and topographic maps showed elevation and terrain. It was
used for hiking and camping. Usually. These, of course, were
a navigational challenge, as you had to know where you
were to begin with. We always had landmark based directions
turned left at threadbarn. These were common in rural or

(09:44):
unfamiliar areas. You could always reference local institutions churches, diners
and gas stations, et cetera. But hazards include unreliable landmarks
they can change over time, and mental mapping you must
write it down. People memorize city layouts and roots. There

(10:04):
were trip planners and guide books such as the Triple
A Trip Dicks and which provided custom strip maps with
route markings and notes, and the Thomas Guide was popular
in the US West Coast, which gave you street level
map books. The hitchhiker's maps often anted tooted by hand
with landmarks and tips, and the railway and a bus

(10:25):
timetables which required careful planning before GPS transit apps folks. Unfortunately,
that's all the time that we've got for today's episode
of What did We do before? In? This episode has
been dedicated to the GPS. I can't thank you enough
for listening, and until next time, we'll dive a little deeper.

(10:45):
Until then,