US 2689346

Patent Overview — US 2,689,346

Title: Long range navigation system

Patent number: US 2,689,346 A

Inventors: John A. Pierce, Donald E. Kerr, Jabez C. Street

Original assignee / current assignee (as listed): US Department of Navy

Application number: US599163A

Filing date / prior art date: 1945-06-13

Publication (grant) date: 1954-09-14

Legal status (as listed): Expired – Lifetime; anticipated expiration 1971-09-14

Classification: G01S1/24 — path-difference systems in which synchronised signals are pulses, with transit times compared by measuring arrival-time differences (e.g., LORAN systems)

Purpose (from the supplied text): The invention "relates to a position indicating system and particularly to a radio pulse type indicating system wherein a plurality of transmitting stations at known points radiate known time related pulse signals, which are detected at a receiver and timed with respect to each other, so as to indicate the difference in their propagation times, whereby the position of the receiver may be determined."

Plain-language scope (from the supplied text): Pairs of radio pulse transmitters emit time-related pulses, each pair at a recurrence rate distinct from the other pairs (starting at, e.g., 25 pulses per second and increasing in cycle steps). Within a pair, one station is the "master" and the other the "slave"; the slave monitors the time relation and corrects deviation. Pulses are emitted alternately so the first emitted is first received, letting the receiver determine which side of the mid-way center line OO' it lies on, since arrival-time difference is greater or less than the emission interval accordingly. The receiver detects, amplifies, and displays pulses on two horizontal cathode-ray-tube sweeps driven by a counter and slow sweep generator from a 100 kc crystal oscillator; the counter output is twice the pulse recurrence rate. Position is fixed by intersecting spherical hyperbolas (constant distance difference to each station pair), with earth-oblateness corrections for global navigation.

Source: https://patents.google.com/patent/US2689346/en

What the excerpt does not establish: It does not establish claim scope or wording, the full specification, the number or exact content of claims, the complete drawing descriptions, or the omitted text (e.g., detailed circuit descriptions of Figs. 3–11). The listing notes the assignee information and legal-status data are not legal conclusions, and the excerpt provides no litigation, ownership-transfer, validity, or prior-art findings.