Patents by Inventor Helmut Ullrich

Helmut Ullrich has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 4467141
    Abstract: A mobile subscriber station served by a telephone network is coupled by a radio link with an individually associated stationary relay station directly connected to that network. The tow stations are able to communicate with each other, over a radius of about 50 meters, on any of 40 channels available to all the posts of subscriber and relay stations in the neighborhood. Each station of a post includes a transmitter and a receiver operating at about 900 MHz; in the idle state of the post, the receivers of both stations continuously scan the available channels to determine their free or busy condition. A person wishing to make an outgoing call causes the transmitter of the subscriber station to send out a predetermined code word which is picked up by the receiver of the associated relay station in its scanning operation and, upon verification by a code comparator, initiates the emission of a handshake signal to the subscriber station whereupon the channel is seized to let the call proceed over the network.
    Type: Grant
    Filed: September 7, 1982
    Date of Patent: August 21, 1984
    Assignee: Portaphone AG
    Inventors: Heinz Resch, Franz Machl, Klaus Kerschbaumer, Helmut Ullrich