Device for wireless transmission of digital data, in particular of audio data, by infrared light in headphones
First Claim
Patent Images
1. A process for the wireless transmission of digital audio data, comprising the steps of:
- based on digital stereo sampling values (audio data
3) having a word length of 16 bits in each instance and based on a system clock rate of 256-times the sampling rate (transmitter base clock
1), forming a data frame having a bit length of 128 bits for the transmission data (9, 20,
47), wherein the data frame contains three stereo sampling values (3) at the sampling rates of 48 kHz (A) and 44.1 kHz (B) or two stereo sampling values (3) at the sampling rate of 32 kHz (C) and, instead of the third stereo sampling value (3), contains a filling pattern and coded information about the current sampling rate;
sending the transmission data (9, 20,
47) at a transmission data rate which is obtained from the transmission base clock (1) by integral division;
feeding the transmission data (9, 20,
47) after transmission to a receiver parallel to a decoding device (24, 25,
26) and to a clock pulse recovery (21);
regenerating a clock pulse (22,
45) which is an integral multiple of (N-times) the transmission data rate by the clock pulse recovery (21); and
deriving by integral division the clock pulses required for a channel decoder (block decoder
25) for decoding the data stream of the data frames of 128-bit length, by a receiver base clock (22) and the transmitter base clock (1) which is 256-times the sampling rate.
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Abstract
Infrared light is used in a device for wireless transmission of digital data, e.g. in headphones. In order to satisfy the strict requirements regarding compactness and power consumption, it is proposed that three digital stereo sampling values are encoded in data frames of 128-bit length for channel coding. Control characteristics and synchronizing characteristics are added to these data frames. A special coding rule is used for the sampling value coding.
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Citations
13 Claims
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1. A process for the wireless transmission of digital audio data, comprising the steps of:
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based on digital stereo sampling values (audio data
3) having a word length of 16 bits in each instance and based on a system clock rate of 256-times the sampling rate (transmitter base clock
1), forming a data frame having a bit length of 128 bits for the transmission data (9, 20,
47), wherein the data frame contains three stereo sampling values (3) at the sampling rates of 48 kHz (A) and 44.1 kHz (B) or two stereo sampling values (3) at the sampling rate of 32 kHz (C) and, instead of the third stereo sampling value (3), contains a filling pattern and coded information about the current sampling rate;sending the transmission data (9, 20,
47) at a transmission data rate which is obtained from the transmission base clock (1) by integral division;feeding the transmission data (9, 20,
47) after transmission to a receiver parallel to a decoding device (24, 25,
26) and to a clock pulse recovery (21);regenerating a clock pulse (22,
45) which is an integral multiple of (N-times) the transmission data rate by the clock pulse recovery (21); andderiving by integral division the clock pulses required for a channel decoder (block decoder
25) for decoding the data stream of the data frames of 128-bit length, by a receiver base clock (22) and the transmitter base clock (1) which is 256-times the sampling rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. The process according to claim 16, wherein the transmission data (9, 20, 47) are modulated to a HF carrier.
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12. A device for carrying out a process for the wireless transmission of digital audio data, comprising the steps of, based on digital stereo sampling values (audio data 3) having a word length of 16 bits in each instance and based on a system clock rate of 256-times the sampling rate (transmitter base clock 1), forming a data frame having a bit length of 128 bits for the transmission data (9, 20, 47), wherein the data frame contains three stereo sampling values (3) at the sampling rates of 48 kHz (A) and 44.1 kHz (B) or two stereo sampling values (3) at the sampling rate of 32 kHz (C) and, instead of the third stereo sampling value (3), contains a filling pattern and coded information about the current sampling rate, sending the transmission data (9, 20, 47) at a transmission data rate which is obtained from the transmission base clock (1) by integral division, feeding the transmission data (9, 20, 47) after transmission to a receiver parallel to a decoding device (24, 25, 26) and to a clock pulse recovery (21), regenerating a clock pulse (22, 45) which is an integral multiple of (N-times) the transmission data rate by the clock pulse recovery (21), and deriving by integral division the clock pulses required for a channel decoder (block decoder 25) for decoding the data stream of the data frames of 128-bit length, by a receiver base clock (22) and the transmitter base clock (1) which is 256-times the sampling rate,
with channel coding taking place in a coding device (63) and based upon a transmitter base clock (1) and with decoding talking place in a decoding device (68), said device comprising that: -
said decoding device (68), for the purpose of clock pulse recovery (21) containing a phase control loop (PLL 40, 42, 44,
46) with a flank detector (46) for signaling the change in level, a filter (42), and a voltage-controlled oscillator (VCO
44);said phase control loop (PLL 40, 42, 44,
46) containing a state machine (40) which operates in frequency-selective mode as well as in phase-selective mode as a frequency comparator and phase comparator for clock pulse recovery and multiplication by the factor N;said state machine (40) being coupled on an input side with said flank detector (46) and voltage-controlled oscillator (44) and on an output side with said filter (42); and said state machine (40) remaining in a basic state of a first, frequency-selective work cycle with a quantity of possible recurring states until the incoming data stream has a change in level, is then switched farther at every clock pulse by one state in this first work cycle and, when no further change in level occurs, returns to the basic state of this first work cycle after passing through the quantity of possible repeating states, but passes into the state following the basic state when a change in level occurs and, in so doing, transmits a positive control pulse (41) to the filter (42) if less than N clock pulses have occurred since the last change in level, or transmits a negative control pulse (41) to the filter (42) if more than N clock pulses have occurred since the last change in level, or, finally, jumps to a second, phase-selective work cycle with N possible repeating states if exactly N clock pulsers have occurred since the last change in level; and said state machine being then switched farther at every clock pulse by one state in the second work cycle, wherein a negative control pulse (41) is sent to the filter (42) whenever a change in level occurs in the region between the state (16) before the jumping point (17) until the state N/4 (third state 20, where N=12,
20) after the jumping point (17), or a positive control pulse (41) is sent to the filter (42) whenever a change in level occurs in the region between the state N/2 (sixth state 23, where N=12) after the jumping point (17) until the state 5/6 N (tenth state 27, where N=12) after the jumping point (17), or jumps back into the basic state (0) of the first work cycle without initiating a control pulse (41 ) when a change in level occurs in the region between the state N/3 (fourth state 21, where N=12) and state 5/12 N, (fifth state 22, where N=12) after the jumping point (17), i.e., when there is an excessive divergence in frequency between the Nth of the receiver basic clock (22,
45) and the transmission data rate. (FIGS. 4, 5 and
6). - View Dependent Claims (13)
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Specification