Signal system employing polarized light
United States Patent 2457502
US Patent References:
/0891339.html
- - 0891339

/0923170.html
- - 0923170

/1009309.html
- - 1009309

Light telephony
- - 1642011

Safety device for railroad operation
- - 1791938


Inventors:
O'd, Shepherd Judson
Publication Date:
12/28/1948
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Assignee:
O'd, Shepherd Judson
Primary Class:
340/906
Other Classes:
398/140, 340/902, 398/152, 398/184
International Classes:
G08G1/087; H04B10/10; G08G1/07
US Patent References:
1849488Multiplex transmission
2100348Light beam transmission system
2131042Radio traffic control system