Method and apparatus for frequency division multiplex system
First Claim
1. A method for digital conversion of signals into signals of a frequency-division multiplex system, comprising the steps of limiting the band width of signals to be converted to a specific band width, and selecting a basic operating rate for generating samples of said signals having a frequency equal to six times said specific band width, selecting further operating rates which are entire multiples of said basic operating rate, forming a 12-channel group given a channel width of 4 kHz and a basic PCM sampling rate of 8 kHz, the operating rate for 12 channels is increased by the factor 3 to 24 kHz, traversing an identical filter, inverting each second scanning sample in its operational sign for some channels, increasing the operating rate for all channels by the factor 5 to 120 kHz and combining the individual channels into a 12-channel group after passing through modulators and filters at an operating rate of 120 kHz.
0 Assignments
0 Petitions
Accused Products
Abstract
A method for digital frequency conversion of audio signals or PCM signals into signals of a frequency-division multiplex system in which the original signals exist in a channel of limited band width. All channels are brought into their desired frequency ranges through simplified multiplication processes, using a basic operating rate having a frequency of six times the channel band width.
-
Citations
20 Claims
-
1. A method for digital conversion of signals into signals of a frequency-division multiplex system, comprising the steps of limiting the band width of signals to be converted to a specific band width, and selecting a basic operating rate for generating samples of said signals having a frequency equal to six times said specific band width, selecting further operating rates which are entire multiples of said basic operating rate, forming a 12-channel group given a channel width of 4 kHz and a basic PCM sampling rate of 8 kHz, the operating rate for 12 channels is increased by the factor 3 to 24 kHz, traversing an identical filter, inverting each second scanning sample in its operational sign for some channels, increasing the operating rate for all channels by the factor 5 to 120 kHz and combining the individual channels into a 12-channel group after passing through modulators and filters at an operating rate of 120 kHz.
-
2. Apparatus for digital conversion of signals into signals of a frequency division multiplex system, comprising;
- means for forming a 2-channel sub-group at an operating rate of 8 kHz, means for increasing the operating rate for the two channels by the factor 3 to 24 kHz;
each channel having a filter whose pass band lies between 4 kHz and 8 kHz, one of said channels having an inverting circuit which inverts the operational sign of every second sample, means for subsequently increasing the operating rate by the factor 2 to 48 kHz in both channels, a plurality of further filters which are identical to one another connected in both channels, a modulator with 16 kHz modulation frequency connected to said channels, and a further circuit for inverting the operational sign for each respective second sample connected to the filter in one said channel, and means for supplying both channels to a summing circuit at an operating rate of 48 kHz. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20)
- means for forming a 2-channel sub-group at an operating rate of 8 kHz, means for increasing the operating rate for the two channels by the factor 3 to 24 kHz;
-
19. Apparatus for digital conversion of signals within a 4 kHz band width into signals of a frequency division multiplex system, comprising;
- means for producing PCM signal samples at 8 kHz, means for increasing the operating rate to 24 kHz, an identical filter in each channel, means in at least one channel for inverting the operational sign of every second scanning sample, means for increasing the work rate to 120 kHz, a plurality of modulators connected individually in said channels, a plurality of filters connected individually with said modulators, and combining means for summing said channels into a 12-channel group, said combining means including a directional filter for combining two of said channels.
Specification