| 摘要 |
The invention relates to a method for transmitting a binary digital transmit signal over an optical transmission link. The method includes the steps of creating a differential optical duobinary signal (SdODB(t)), supplying the differential optical duobinary signal SdODB(t)) to a first end of the optical transmission link, transmitting the differential optical duobinary signal SdODB(t)) to a second end of the optical transmission link, and receiving the differential optical duobinary signal SdODB(t)) as receive signal (SRX(t)) at the second end of the optical transmission link by detecting the optical power of the differential optical duobinary signal SdODB(t)) and creating a binary digital receive signal (SbRX(t)) corresponding to the binary digital transmit signal (SbTX(t)) by decoding the receive signal (SRX(t)). The differential optical duobinary signal SdODB(t)) may be created by pre-coding the binary digital transmit signal (SbTX(t)) having a given bit interval (T) into an intermediate pre-coded digital signal (Spi(t)), the pre-coding operation being identical with or equivalent to applying a non-XOR operation to the binary digital transmit signal (SbTX(t)) and the intermediate pre-coded digital signal delayed by a single bit interval (Spi(t−T)), again pre-coding the intermediate pre-coded digital signal (Spi(t)) into a pre-coded digital signal (Sp(t)), this second pre-coding operation being identical with or equivalent to applying a non-XOR operation to the intermediate pre-coded digital signal (Spi(t)) and the pre-coded digital signal delayed by a single bit interval (Sp(t−T)), duobinary encoding the pre-coded signal (Sp(t)) into a differential duobinary signal (SdDB(t)), and modulating an optical light source of an optical modulator device (15) having the predetermined optical wavelength using the differential duobinary signal (SdDB(t)) as modulate signal. Alternatively, the differential optical duobinary signal SdODB(t)) may be created by directly pre-coding the binary digital transmit signal (SbTX(t)) into the pre-coded digital signal (Sp,alt(t)), the pre-coding operation being identical with or equivalent to applying a non-XOR operation to the binary digital transmit signal (SbTX(t)) and the pre-coded digital signal delayed by twice the bit interval (Sp,alt(t−2T)), duobinary encoding the pre-coded signal (Sp,alt(t)) into the differential duobinary signal (SdDB(t)), and modulating the optical light source of the optical modulator device (15) using the differential duobinary signal (SdDB(t)) as modulate signal. Further, the invention relates to a transmitter device (1) and a receiver device (17, 17′) for realizing the transmission method according to the invention. |
| 主权项 |
1. Method for transmitting a binary digital transmit signal over an optical transmission link, characterized by the steps of:
(a) creating a differential optical duobinary signal SdODB(t)) by
(i) pre-coding the binary digital transmit signal (SbTX(t)) having a given bit interval (T) into an intermediate pre-coded digital signal (Spi(t)), the pre-coding operation being identical with or equivalent to applying a non-XOR operation to the binary digital transmit signal (SbTX(t)) and the inter-mediate pre-coded digital signal delayed by a single bit interval (Spi(t−T)),(ii) again pre-coding the intermediate pre-coded digital signal (Spi(t)) into a pre-coded digital signal (Sp(t)), this second pre-coding operation being identical with or equivalent to applying a non-XOR operation to the inter-mediate pre-coded digital signal (Spi(t)) and the pre-coded digital signal delayed by a single bit interval (Sp(t−T)),(iii) duobinary encoding the pre-coded signal (Sp(t)) into a differential duobinary signal (SdDB(t)), and(iv) modulating an optical light source of an optical modulator device (15) having the predetermined optical wavelength using the differential duobinary signal (SdDB(t)) as modulate signal, or (b) creating a differential optical duobinary signal SdODB(t)) by
(i) directly pre-coding the binary digital transmit signal (SbTX(t)) into the pre-coded digital signal (Sp,alt(t)), the pre-coding operation being identical with or equivalent to applying a non-XOR operation to the binary digital transmit signal (SbTX(t)) and the pre-coded digital signal delayed by twice the bit interval (Sp,alt(t−2T)),(ii) duobinary encoding the pre-coded signal (Sp,alt(t)) into the differential duobinary signal (SdDB(t)), and(iii) modulating the optical light source of the optical modulator device (15) using the differential duobinary signal (SdDB(t)) as modulate signal, (c) supplying the differential optical duobinary signal SdODB(t)) to a first end of the optical transmission link and transmitting the differential optical duobinary signal SdODB(t)) to a second end of the optical transmission link, and (d) receiving the differential optical duobinary signal SdODB(t)) as receive signal (SRX(t)) at the second end of the optical transmission link by detecting the optical power of the differential optical duobinary signal SdODB(t)) and creating a binary digital receive signal (SbRX(t)) corresponding to the binary digital transmit signal (SbTX(t)) by decoding the receive signal (SRX(t)), (e) wherein the binary digital receive signal (SbRX(t)) is created by
(i) interpreting the receive signal (SRX(t)) as ternary digital signal, sampling and recovering the receive signal (SRX(t)) using a first and a second decision threshold and creating a first binary digital recovered signal (SRX1,rec(t)) revealing a “1” level, if the sampled values are above the first decision threshold, and a “0” level, elsewise, and creating a second binary digital recovered signal (SRX2,rec(t)) revealing a “1” level, if the sampled values are above the second decision threshold, and a “0” level, elsewise, and(ii) applying a non-XOR operation onto the first (SRX1,rec(t)) and second (SRX2,rec(t)) binary recovered receive signal for creating the binary digital receive signal (SbRX(t)), and (f) wherein the receive signal (SRX(t)) or the optical differential duobinary signal SdODB(t)) is low-pass filtered in such a way that the bandwidth of the respective low-pass filtered signal is within the range of 0.25 to 0.35 times the bit rate of the binary digital transmit signal (SbTX(t)). |
