FR519308A - Improvements to underground signaling systems - Google Patents

Improvements to underground signaling systems

Info

Publication number
FR519308A
FR519308A FR519308A FR519308DA FR519308A FR 519308 A FR519308 A FR 519308A FR 519308 A FR519308 A FR 519308A FR 519308D A FR519308D A FR 519308DA FR 519308 A FR519308 A FR 519308A
Authority
FR
France
Prior art keywords
underground
signaling systems
signaling
systems
underground signaling
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
FR519308A
Other languages
French (fr)
Inventor
Lee De Forest
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Application granted granted Critical
Publication of FR519308A publication Critical patent/FR519308A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B13/00—Transmission systems characterised by the medium used for transmission, not provided for in groups H04B3/00 - H04B11/00
    • H04B13/02—Transmission systems in which the medium consists of the earth or a large mass of water thereon, e.g. earth telegraphy

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Organic Insulating Materials (AREA)
  • Selective Calling Equipment (AREA)
FR519308A 1917-06-16 1920-07-07 Improvements to underground signaling systems Expired FR519308A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US175119A US1424805A (en) 1917-06-16 1917-06-16 Subterranean signaling system
FR519308T 1920-07-07

Publications (1)

Publication Number Publication Date
FR519308A true FR519308A (en) 1921-06-08

Family

ID=22638986

Family Applications (1)

Application Number Title Priority Date Filing Date
FR519308A Expired FR519308A (en) 1917-06-16 1920-07-07 Improvements to underground signaling systems

Country Status (3)

Country Link
US (1) US1424805A (en)
FR (1) FR519308A (en)
GB (1) GB145476A (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4030032A (en) * 1960-04-05 1977-06-14 Westinghouse Electric Corporation Radio transmission system

Also Published As

Publication number Publication date
GB145476A (en) 1921-06-30
US1424805A (en) 1922-08-08

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