Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Using radiant energy
Reexamination Certificate
2001-08-15
2003-06-17
Oda, Christine (Department: 2858)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Using radiant energy
C324S685000, C324S076360, C359S199200
Reexamination Certificate
active
06580263
ABSTRACT:
CLAIM OF PRIORITY
This application makes reference to and claims all benefits accruing under 35 U.S.C. Section 119 from an application entitled “Bit Rate Discrimination Device with Temperature Compensation Function,” filed in the Korean Industrial Property Office on Aug. 22, 2000 and there duly assigned Ser. No. 2000-48502.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a light transmission system, and, in particular, to a bit rate discrimination device for use in a light transmission system.
2. Description of the Related Art
A light transmission system can adopt various protocols, such as FDDI (Fiber Distributed Data Interface), ESCON (Enterprise Systems Connectivity), Fiber Channel, Gigabit Ethernet, and ATM (Asynchronous Transfer Mode) for high-bandwidth and high-bit-rate communications. Fiber optics technology can adopt various bit rates of 125 Mb/s, 155 Mb/s, 200 Mb/s, 622 Mb/s, 1062 Mb/s, 1.25 Gb/s, and 2.5 Gb/s to supply the capacity to meet the demand for multimedia applications. In operation, the light transmission system adopts one set of the protocols as a multiplexing format for using any number of bit rates. In this type of light transmission system, the bit rate of an optical signal is set previously to a specific rate, such that an optical receiver can be designed to match the incoming bit rate. The function of an optical receiver is to convert an input optical signal into an electric signal, and thereafter restores the electric signal to the original data that is noise-free.
FIG. 1
illustrates a conventional bit rate discrimination device, which includes a photoelectric converter
110
; a signal processor
120
; a bit rate detector
130
; a DC (Direct Current) amplifier
140
; and, a bit rate discriminator
150
.
During operation, the photoelectric converter
110
converts an input optical signal into an electric signal
112
. A photodiode is typically used for the photoelectric converter
110
. The signal processor
120
amplifies the electric signal
112
into a standardized electric signal
122
, such that a level “0” and a level “1” of the electric signal
122
have predetermined values, respectively. The bit rate detector
130
outputs a discrimination signal
132
, representing the number of pulses proportionate to the bit rate of the standardized electric signal
122
. The DC amplifier
140
outputs a bit rate detection signal
142
by amplifying the discrimination signal
132
, wherein the voltage level of the bit rate detection signal
142
is linearly increased according to the bit rate. The bit rate discriminator
150
discriminates the bit rate of the optical signal between a “1” and a “0” from the voltage level of the bit rate detection signal
142
.
However, the DC amplifier
140
of the conventional bit rate discrimination device, as described in the preceding paragraph, is very susceptible to variations in the operating temperature, making it difficult to stabilize its output. Hence, the bit rate discriminator
150
tends to inaccurately determine the bit rate of the optical signal depending on the unstable voltage level of the bit rate detection signal
142
. As a result, it is difficult to accurately discriminate the bit rate by means of a bit rate discriminator.
SUMMARY OF THE INVENTION
The present invention is directed to a device that is capable of accurately discriminating the bit rate regardless of variations in the operating temperature.
The present invention provides a bit rate discrimination device with a temperature compensation function. The device includes a photoelectric converter for converting an input optical signal into an electric signal; a bit rate detector for detecting the bit rate of an optical signal from the electric signal and for outputting a discrimination signal indicating the bit rate; a DC amplifier for outputting a bit rate detection signal by amplifying the discrimination signal; a temperature detector for detecting the operating temperature of the DC amplifier and outputting a temperature signal indicating the detected operating temperature; a variation amplifier for outputting a temperature compensation signal by amplifying the voltage level difference between the temperature signal and a predetermined reference signal, so as to cancel variations in an output voltage of the DC amplifier according to the operating temperature; a voltage adder for outputting a temperature-compensated bit rate detection signal by combining the bit rate detection signal with the temperature compensation signal; and, a bit rate discriminator for determining the bit rate of the input optical signal according to the voltage level of the temperature-compensated bit rate detection signal.
According to another aspect of the present invention, a signal processor standardizes the electric signal output from the photoelectric converter, such that the voltage levels of “0” and “1” of the electric signal have predetermined values, respectively, thus providing the standardized electric signal to the bit rate detector.
According to another aspect of the present invention, the DC amplifier has a characteristic in which the voltage level of the bit rate detection signal is increased in proportion to an increase in the operating temperature. In addition, the variation amplifier has a characteristic in which the voltage level of the temperature compensation signal is decreased in proportion to an increase in the operating temperature of the DC amplifier.
REFERENCES:
patent: 5933265 (1999-08-01), Nagarajan
patent: 6091531 (2000-07-01), Schwartz et al.
Choi Jeong-Seok
Doh Hee-Chan
Oh Yun-Je
Park Gil-Yong
Park Tae-Sung
Cha & Reiter
Kerveros James
Oda Christine
Samsung Electronics Co. LTD
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