{"product_id":"2940013654648","title":"GPS Made Easy (100 page)","description":"GPS design is based partly on ground-based radio navigation systems developed in the early 1940’s that were used in World War II. These systems were named LORAN and Decca\u003cbr\u003eNavigator and were focused on knowing where the enemy was so they could either attack or\u003cbr\u003eretreat depending on the size of the forces.\u003cbr\u003e\u003cbr\u003eAdditional inspiration for modern day GPS systems came when Sputnik was launched by the\u003cbr\u003eSoviet Union in 1957. A team of scientists monitored Sputnik’s radio transmissions and\u003cbr\u003ediscovered that because of the Doppler Effect, the frequency of the signal being transmitted was high as the satellite approached and lower as it moved away. The Doppler Effect is the change in frequency and wave length of a wave as it is perceived by an observer moving relative to the source of the waves.","brand":"NOOKbooks","offers":[{"title":"Default Title","offer_id":47121215389936,"sku":"2940013654648","price":3.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0737\/7593\/9824\/files\/2940013654648_p0.jpg?v=1763947283","url":"https:\/\/shop-qa.barnesandnoble.com\/products\/2940013654648","provider":"Barnes \u0026 Noble (DEV)","version":"1.0","type":"link"}