Tekade Felten & Guilleaume Fernmeldeanlagen Gmbh

Karlheinz Parras

Edgar Bader

Helmut Dupont

A data transmission path comprises a first and a second station, a first data transmission channel operative for synchronously transmitting data from the first to the second station in synchronism with a predetermined clocking schedule and at a respective first maximum data transmission rate, and a second data transmission channel for asynchronously transmitting data from the second to the first station at a respective second maximum data transmission rate, the first maximum data transmission rate being equal to a multiple p of the second maximum data transmission rate. A test waveform is applied to the first station for transmission to the second station along the first data transmission channel, the test waveform presenting a data transmission rate at least approximately equal to said first maximum data transmission rate. The test waveform, as received at the second station, is applied to a selector circuit whose output waveform is applied to the transmitting input of the second station for transmission back to the first station along the second channel. The selector circuit transmits to its output only every p-th one of the waveform elements applied to its input, relying on clock signals which the second station produces one per waveform element of the synchronously transmitted test waveform. The shortest waveform-element duration of the waveform produced at the output of the selector circuit at least approximately corresponds to said second maximum data transmission rate.

Loopback test for data transmission paths

A loopback testing system for an asynchronously operating fully duplex data transmission path comprising proximate and remote stations, a proximate-to-remote data transmission channel for transmitting data to the remote station at a relatively high maximum data transmission rate, and a remote-to-proximate data transmission channel for transmitting data to the proximate station at a relatively low maximum data transmission rate. A test-waveform generator applies to the proximate station, for transmission along the proximate-to-remote channel, a test waveform presenting a data transmission rate at least approximately equal to the aforementioned higher maximum data transmission rate. A loopback circuit at the remote station receives the thusly transmitted test waveform and reapplies it at the remote station for transmission back to the proximate station along the remote-to-proximate channel. However, the loopback circuit includes a digital frequency divider which reduces the waveform-element transmission rate presented by the test waveform to such a level that the waveform-element duration of the test waveform, as transmitted back to the proximate station, at least approximately corresponds to the aforementioned lower maximum data transmission rate.

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Nuremburg, Germany

Karlheinz Parras