A method for protecting a nonmobile work machine driven by an electric motor includes determining, via a measuring unit, at least one measured value of a time-critical parameter of the work machine. The work machine is switched off when the determined measured value of the time-critical parameter is outside a predefined setpoint range. The determined measured value of the time-critical parameter is quantized in a level signal and transmitted as a first signal to an evaluation unit via an interface, and a second signal for further information concerning the work machine, to be transmitted from the measuring unit to the evaluation unit, is modulated to the first signal.

Systems and methods for operating a Unified Security Device (“USD”). The methods comprise: receiving an Electronic Article Surveillance (“EAS”) interrogation signal with an antenna of the USD; processing the EAS interrogation signal using a processor unit of the USD; using the processor unit to generate an EAS response signal that emulates a response signal produced by an Acousto-Magnetic (AM) type of EAS security tag, in response to the EAS interrogation signal; and communicating the EAS response signal from the USD.

A method for protecting a nonmobile work machine driven by an electric motor includes determining, via a measuring unit, at least one measured value of a time-critical parameter of the work machine. The work machine is switched off when the determined measured value of the time-critical parameter is outside a predefined setpoint range. The determined measured value of the time-critical parameter is quantized in a level signal and transmitted as a first signal to an evaluation unit via an interface, and a second signal for further information concerning the work machine, to be transmitted from the measuring unit to the evaluation unit, is modulated to the first signal.

A method for protecting a nonmobile work machine driven by an electric motor includes determining, via a measuring unit, at least one measured value of a time-critical parameter of the work machine. The work machine is switched off when the determined measured value of the time-critical parameter is outside a predefined setpoint range. The determined measured value of the time-critical parameter is quantized in a level signal and transmitted as a first signal to an evaluation unit via an interface, and a second signal for further information concerning the work machine, to be transmitted from the measuring unit to the evaluation unit, is modulated to the first signal.

Methods, techniques, and systems for transmitting a data frame of an electromagnetic (EM) telemetry signal to or from a downhole location can be performed using multi-channel transmissions in which at least two different channels at two different frequencies are used to send a long header and the data frame. At least a portion of the long header is transmitted at a first frequency, and at least a portion of the data frame and any remaining portion of the long header not transmitted at the first frequency are transmitted at one or more additional frequencies different from each other and the first frequency. In one example, only two channels are used: one channel is used to transmit all of the long header, another channel is used to transmit all of the data frame, and either of the channels is used to transmit an identifier identifying the type of the data frame.

Methods, techniques, and systems for transmitting a data frame of an electromagnetic (EM) telemetry signal to or from a downhole location can be performed using multi-channel transmissions in which at least two different channels at two different frequencies are used to send a long header and the data frame. At least a portion of the long header is transmitted at a first frequency, and at least a portion of the data frame and any remaining portion of the long header not transmitted at the first frequency are transmitted at one or more additional frequencies different from each other and the first frequency. In one example, only two channels are used: one channel is used to transmit all of the long header, another channel is used to transmit all of the data frame, and either of the channels is used to transmit an identifier identifying the type of the data frame.

A transmission device includes a first control unit and a signal transmission unit. The first control unit outputs transmission data. The signal transmission unit receives transmission data, converts the data to a first frequency signal and a second frequency signal, and transmits the signals. The reception device includes a signal reception unit and a second control unit. The signal reception unit outputs a first reception signal based on the first frequency signal, and outputs a second reception signal based on the second frequency signal. The second control unit outputs a first control signal in a case where at least one the first reception signal or the second reception signal includes the transmission data. A communication system includes a transmission device and a reception device. A remote operating device includes an input unit, a transmission device, a reception device, and a controlled unit.

A transmission device includes a first control unit and a signal transmission unit. The first control unit outputs transmission data. The signal transmission unit receives transmission data, converts the data to a first frequency signal and a second frequency signal, and transmits the signals. The reception device includes a signal reception unit and a second control unit. The signal reception unit outputs a first reception signal based on the first frequency signal, and outputs a second reception signal based on the second frequency signal. The second control unit outputs a first control signal in a case where at least one the first reception signal or the second reception signal includes the transmission data. A communication system includes a transmission device and a reception device. A remote operating device includes an input unit, a transmission device, a reception device, and a controlled unit.

Methods, techniques, and systems for transmitting a data frame of an electromagnetic (EM) telemetry signal to or from a downhole location can be performed using multi-channel transmissions in which at least two different channels at two different frequencies are used to send a long header and the data frame. At least a portion of the long header is transmitted at a first frequency, and at least a portion of the data frame and any remaining portion of the long header not transmitted at the first frequency are transmitted at one or more additional frequencies different from each other and the first frequency. In one example, only two channels are used: one channel is used to transmit all of the long header, another channel is used to transmit all of the data frame, and either of the channels is used to transmit an identifier identifying the type of the data frame.

Methods, techniques, and systems for transmitting a data frame of an electromagnetic (EM) telemetry signal to or from a downhole location can be performed using multi-channel transmissions in which at least two different channels at two different frequencies are used to send a long header and the data frame. At least a portion of the long header is transmitted at a first frequency, and at least a portion of the data frame and any remaining portion of the long header not transmitted at the first frequency are transmitted at one or more additional frequencies different from each other and the first frequency. In one example, only two channels are used: one channel is used to transmit all of the long header, another channel is used to transmit all of the data frame, and either of the channels is used to transmit an identifier identifying the type of the data frame.