DE2362274

• Main Authors: POSTL, WOLFGANG., 8191 HOEHENRAIN, BAUCH, HELMUT, MOEHRMANN, KARL HEINZ
• Format: Patent
• Language: English
• Published: 10.07.1980
• Edition: 3
• Subjects: BASIC ELECTRONIC CIRCUITRY; ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS; TRANSMISSION; TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHICCOMMUNICATION

1484910 Data transmission SIEMENS AG 6 Dec 1974 [14 Dec 1973] 52768/74 Heading H4P In order to shape the transmitted signals in a PCM data transmission system such that signal to noise ratio is optimized transversal filters are provided at both the transmitter and receiver, which together provide attenuation/frequency and phase/frequency characteristics such that at the receiver a partial response signal of class IV is produced (i.e. amplitude frequency response is given by /H(jw)/ = 2/sin wT/; phase frequency response by arg(H(jw)) = #/2sign[sin wT], where T represents the pulse duration of the PCM pulses for frequencies below an upper cut off, while above this cut off the filters block the signals. The required attenuation/frequency characteristic is produced conjointly, e.g. equally between the filters, whereas the required phase/frequency characteristic is produced by only one of them. The filters at transmitter and receiver may respectively be as shown at SF, EF, Fig. 1. The filters incorporate delay elements V, weighting elements B and adders S to combine the delayed and weighted versions of the signal applied to each filter in accordance with the required response. The phase response is effected only in the transmitting filter SF, by means of the arrangement and sign of the weighting units. Simple low pass filters TP1 and TP2 ensure that high frequency signals outside the required band are not transmitted. In one particular embodiment, a tapped delay line with closed circuit termination is used as the transmitting filter (Fig. 2, not shown). This enables the weighting units to be doubly effective and provide an improved approximation to the required characteristic. At the receiver a tapped delay line with a buffer termination feeding a further weighting unit is used (Fig. 3, not shown), the buffer being highly ohmic to provide an in phase reflection which enables the weighting units connected to the taps to be doubly effective, and provides a pure attenuation response.