The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 06, 1994
Filed:
Sep. 17, 1993
Applicant:
Inventor:
Antti Berg, Kiiminki, FI;
Assignee:
Outokumpu Oy, Helsinki, FI;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04B / ; H04B / ;
U.S. Cl.
CPC ...
375-6 ; 375-7 ; 375 88 ; 455 19 ; 455 40 ; 455 82 ; 455 83 ; 343741 ;
Abstract
The invention relates to an apparatus which is desiged for underground use in order to facilitate a two-way communication. The apparatus is operated within the frequency band 0.1-2 MHz, in order to make the electromagnetic waves propagate advantageously by utilizing the metal structures installed in the underground facilities and the bedrock itself. According to the invention, the transmitter/receiver unit is provided with an analog to digital converter (5) and respectively a digital to analog converter (20) in order to transmit the intermediate signal coded in digital form in between the two units of the apparatus.