GB2304478A - Direct broadcasting satellite tuner with negative feedback circuit to filter for tracking if image signal - Google Patents
Direct broadcasting satellite tuner with negative feedback circuit to filter for tracking if image signal Download PDFInfo
- Publication number
- GB2304478A GB2304478A GB9517255A GB9517255A GB2304478A GB 2304478 A GB2304478 A GB 2304478A GB 9517255 A GB9517255 A GB 9517255A GB 9517255 A GB9517255 A GB 9517255A GB 2304478 A GB2304478 A GB 2304478A
- Authority
- GB
- United Kingdom
- Prior art keywords
- signal
- intermediate frequency
- frequency
- circuit
- amplifier
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/16—Circuits
- H04B1/26—Circuits for superheterodyne receivers
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
- H03D3/00—Demodulation of angle-, frequency- or phase- modulated oscillations
- H03D3/001—Details of arrangements applicable to more than one type of frequency demodulator
- H03D3/003—Arrangements for reducing frequency deviation, e.g. by negative frequency feedback
- H03D3/005—Arrangements for reducing frequency deviation, e.g. by negative frequency feedback wherein the demodulated signal is used for controlling a bandpass filter
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/3052—Automatic control in amplifiers having semiconductor devices in bandpass amplifiers (H.F. or I.F.) or in frequency-changers used in a (super)heterodyne receiver
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
- H03J7/00—Automatic frequency control; Automatic scanning over a band of frequencies
- H03J7/02—Automatic frequency control
- H03J7/04—Automatic frequency control where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant
- H03J7/08—Automatic frequency control where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant using varactors, i.e. voltage variable reactive diodes
Description
2304478 DIRECT BROADCASTING SATELLITE TUNER WITH NEGATIVE FEEDBACK CIRCUIT
FOR TRACKING IF IMAGE SIGNAL
BACKGROUND OF THE INVENTION (a) Field of the Invention
The present invention relates to tuners, and relates more particularly to a direct broadcasting satellite tuner with negative feedback circuit for tracking IF image signal in which demodulated baseband frequency signal is fed back to the variode of an intermediate frequency bandpass tracking filter by a reverse feedback amplifier, so that the intermediate frequency bandpass filter circuit needs only a bandwidth of 1OMHz to enable the IF amplifier to track the instantaneous deviation of the intermediate frequency image signal, and therefore the signal-to- noise ratio can be greatly increased, the noises can be eliminated, and the threshold can be reduced when the intermediate frequency image signal enters the demodulator circuit.
(b) Description of the Prior Art
During the transmission of direct broadcasting satellite, audio and video (baseband frequency) signals are properly arranged at the ground transmitting station through a multiplexer, then 1 modulated to intermediate frequency signal and then amplified and turned into a radio signal for transmitting through a transmitting antenna. The ground receiving station has a low-noise broad-band radio frequency receiver to receive radio signals. Upon receipt of a radio signal, the signal is amplified and turned into an intermediate frequency signal, and then the intermediate frequency signal is further demodulated by a demodulator circuit to a baseband frequency signal, containing a video signal and an audio signal. When the ground receiving station receives a useful electromagnetic wave signal from the atmosphere, interference waves and noises from the atmosphere may interfere with the receiving of the signal or pass into the signal, causing the reliability of the communication affected.
Furthermore, in regular broadband satellite receiving tuners with demodulator means, the intermediate frequency bandwidth is already set, and an IF bandpass filter shall be used if to change the bandwidth of the frequency. However, using an IF band pass filter to adjust the bandwidth of the frequency tends to cause a receiving signal loss and an image distortion. Besides, the use of an IF bandpass filter 2 gives little improvement on threshold. In addition, SAW filters are commonly used as intermediate frequency filters. However, because the bandwith of a regular SAW filter is not adjustable, noises tend to enter the filter and then the demodulator circuit to affect the threshold when the carrier-to-noise ratio is low. An intermediate frequency filter with two-stage switch may be used to eliminate noises by a narrower bandwidth. However, this measure tends to cause a partial loss of the intermediate f requency image signal. When a partial loss of the intermediate frequency image signal occurs, a picture distorsion will happen.
SUMMARY OF THE INVENTION
The present invention has been accomplished to provide a direct broadcasting satellite tuner with negative feedback circuit for tracking IF image signal means which eliminates the aforesaid drawbacks.
It is one object of the present invention to provide a direct broadcasting satellite tuner with negative feedback circuit for tracking IF image signal in which the demodulated baseband frequency signal is fed back to the variode of an intermediate frequency bandpass tracking filter by a reversing amplifier, so 3 that the intermediate frequency bandpass filter circuit can effectively eliminate noises, improve threshold, and increase signal-to-noise ratio with a bandwidth of 1OMHz.
It is another object of the present invention to provide a direct broadcasting satellite tuner with negative feedback circuit for tracking IF image signal which is simple in structure, and can be set subject to different satellite transmission band widths to maintain the quality of the image.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be described by way of example with reference to the annexed drawings, in which:
Fig. 1 is a circuit block diagram according to the present invention; and Fig. 2 is a circuit diagram of the radio frequency input device according to the present invention; Fig. 3 is a circuit diagram of the frequency converter according to the present invention; Fig. 4 is a circuit diagram of the intermediate frequency amplifier unit, the demodulator 4 circuit, and the negative feedback amplifier circuit according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to Figure 1, a direct broadcasting satellite tuner with negative feedback tracking circuit for tracking IF image signal in accordance with the present invention is generally comprised of radio frequency input device 1, frequency converter 2, intermediate frequency amplifier unit 3, demodulator circuit 4, and negative feedback amplifier circuit 5.
Referring to Figures 1, 2, 3, and 4, radio frequency input device 1 is comprised of low-pass filters 11 and 111, radio frequency amplifiers 12 and 121, and switching circuit 13. The input terminals of radio frequency amplifiers 12 and 12' are respectively connected to output terminals of low-pass filters 11 and 111, and the output terminals thereof are respectively connected to a respective input end at switching circuit 13. The output end of switching circuit 13 is connected to frequency converter 2.
The radio frequency signal (950 MHz-2050 MHz) from the satellite antenna is received by low-pass filters 11 and 11' through terminal A or B by means of the control of switching circuit 13. Switching circuit 13 is comprised of A/B terminal option switch SW1, transistors 02 and Q3, diodes D3 and D4, resistors R44, R53 and R45, and capacitors C70 and C71. When A/B terminal option switch SW1 of switching circuit 13 is at high potential, transistor Q2 and diode D4 are electrically connected, transistor Q3 and diode D3 are electrically disconnected, and therefore low pass filter 11 receives the radio frequency signal (950-205OMHZ) and eliminates signal frequency over 205OMHz to let impedance be matched. Low pass filter 11 consi.sts of capacitors C60, C61, C62, C63, C64 and C65, inductor Ll and microstrip line circuit SU and SL5. The output signal from low pass filter 11 is sent to radio frequency amplifier 12 for amplification. Radio frequency amplifier 12 consists of coupling capacitor C66, transistor Q1, diode D1, bias resistors R49, R50, and R51, ground capacitor C67, decoupling circuits R52 and C69, and microstrip line circuit SL7. The amplified signal from radio frequency amplifier 12 is then sent to frequency converter 2 through capacitor C70 and diode D4. Decoupling circuits R52 and C69 of radio frequency amplifier 12 prohibit high-frequency signal from passing through resistor R53 to diode D4.
6 Similarly, when A/B terminal option switch swl of switching circuit 13 is at low potential, transistor Q3 and diode D3 are electrically connected, transistor Q2 and diode D4 are electrically disconnected, and therefore radio signal is inputted into radio frequency input device 1 through terminal B and then sent to low pass filter 11', which consists of capacitors C43, C45, C46, C47, C48 and C49, inductor L12 and microstrip line circuit SL4 and SL6, permitting frequency over 205OMHz to be removed and impedance matched. The output signal from low pass filter 11' is then sent to radio frequency amplifier 121 for amplification, which radio frequency amplifier 12' consists of coupling capacitor C52, transistor Q4, diode D2, bias resistors R39, R41 and R43, ground capacitor C53, decoupling circuit R42 and C54, and microstrip line circuit SL8.
The amplified output signal from radio amplifier 12' is then sent to frequency converter 2 through capacitor C71 and diode D3. Decoupling circuit R42 and C54 of radio frequency amplifier 12' prohibits high-frequency signal from passing through resistor R44 to diode D3.
7 Frequency converter 2 consists of tracking filter 21, attenuation circuit 22, and microwave monolithic integrated circuit (MMIC) 23. The input terminal of tracking filter 21 is connected to the output terminal of radio frequency input device 1, and its output terminal is connected to the input terminal of attenuation circuit 22. The output terminal of attenuation circuit 22 is connected to the input terminal of microwave monolithic integrated circuit 23. The output terminal of microwave monolithic integrated circuit 23 is connected to intermediate amplifier unit 3.The internal circuit of frequency attenuation circuit 22 is connected with automatic gain control Tracking filter 21 which consists of inductor C15, (AGC). L3, resistors R70 and R24, capacitors C13, C14, C73 and C12, variodes VD8 and VD9, and microstrip line circuit SL9, SLIO, SL11 and SL12, receives the output signal from radio frequency input device 1 and removes image frequency from the signal. The output signal from tracking filter 21 is then sent to attenuation circuit 22, which consists of coupling capacitor C17, diode D10, resistors R27, and R28, capacitors C19, C32 and C22, and matching circuit C20, C21 and SL13. Matching circuit C20, C21 and SL13 is to constrain low frequency signal form gaining. Attenuation circuit 22 8 attenuates the output signal from tracking filter 21 so as to eliminate interference of noises during high intensity of signal. By means of the control of automatic gain control 5, attenuation circuit 22 controls the gaining or reducing of the signal passing through. The attenuated signal from attenuation circuit 22 is then sent to microwave monolithic integrated circuit 23, which is composed of radio frequency amplifier 231, frequency mixer 232, and voltage control oscillator 233, for amplification.
Microwave monolithic integrated circuit 23 comprises integrated circuit Icl, resistors R58 and R59, capacitors C81, C96 and C112, microstrip circuits SL16 and SL14, variodes VD6 and VD7. Microstrip circuit SL16 is connected to variode VD6. The opposite end of variode VD6 is connected to variode VD7, and connected through resistor R58 to power supply VT to control the oscillating frequency of voltage control oscillator 233. The opposite end of variode VD7 is connected to resistor R59, and connected to IC1 through capacitor C96. The output terminal of IC1 is connected to intermediate frequency amplifier unit 3. Microwave monolithic integrated circuit 23 receives the output signal from attenuation circuit 22 and processes the signal into an intermediate frequency signal by superheterodyne by 9 means of the operation of radio frequency amplifier 231, voltage control oscillator 232 and frequency mixer 233, for output to intermediate frequency amplifier unit 3 for amplification.
Intermediate frequency amplifier unit 3 consists of first stage intermediate frequency amplifier 31, IF bandpass tracking filter 32, and second stage intermediate frequency amplifier 33. The input terminal of first stage intermediate frequency amplifier 31 is connected to the output terminal of frequency converter 2. The output terminal of first stage intermediate frequency amplifier 31 is connected to the input terminal of IF bandpass tracking filter 32. The output terminal of IF bandpass tracking filter 32 is connected to the input terminals of second stage intermediate frequency amplifier 33. The output terminal of second stage intermediate frequency amplifier 33 is connected to the input terminal of demodulator circuit 4. The internal circuit of first stage intermediate frequency amplifier 31 is connected with automatic gain control (AGC). First stage intermediate frequency amplifier 31 consists of MOSFET, bias resistors R32, R33, R34, R35, R36 and R69, ground capacitors C25 and C38, and matching circuit, which consists of inductor L4, resistor R37, capacitors C35, C36, C41, and C24. First stage intermediate frequency amplifier 31 receives the intermediate frequency output signal from frequency converter 2 and then amplifies the signal, and also controls the gaining or reducing of the signal passing through by means of the operation of automatic gain control circuit. The output signal from first stage intermediate frequency amplifier 31 is then sent to IF bandpass tracking filter 32, which consists of helical filter HF1, variodes VD201 and VD202, ground capacitors C204 and C205. Variode VD202 is connected to a +12V power supply through resistor, R210, capacitor C206, and variable resistor VR1. Through the control of a +12V power supply, the direct current level of the interncediate frequency signal is changed.
IF bandpass tracking filter 32 filtrates the signal from first stage intermediate frequency amplifier 31 with frequency bandwidth of 1OMHz and then sends the filtrated signal to second stage intermediate frequency amplifier 33, which consists of integrated circuit IC3, ground capacitor C105, and coupling capacitors C104 and C108. Amplified signal from second stage intermediate frequency amplifier 33 is then sent to demodulator circuit 4.
11 The input terminal of demodulator circuit 4 is connected to the output terminal of intermediate frequency amplifier unit 3. The internal circuit of demodulator circuit 4 is coupled to automatic gain control. The output terminal of demodulator circuit 4 is connected to IF bandpass tracking filter 32 of the intermediate frequency amplifier unit 3 through negative feedback amplifier circuit 5. Demodulator circuit 4 is comprised of integrated circuit IC4, capacitors C5, C8, C128 and C129, resistor R21,... etc. It receives and demodulates the output intermediate frequency signal from intermediate frequency amplifier unit 3, and controls the gaining or reducing of the signal demodulated by means of automatic gain control, so as to obtain a satisfactory baseband frequency signal. The baseband frequency signal from demodulator circuit 4 is outputted in two paths. In one path, the image signal of the baseband frequency signal is sent to the subscriber. In the other path, the baseband frequency signal is sent to the negative feedback amplifier circuit 5, which is a reverse amplifier circuit consisting of transistors Q51, resistors R51, R52 and R53, variable resistor VR54, capacitor C51, zener diode VD51.
12 Negative feedback amplifier circuit 5 amplifies the output signal from demolulator circuit 4, then feeds back the amplified signal to the negative terminals of variodes VD201 and VD202 of IF bandpass tracking filter 32 through resistor 207, capacitor 203, and resistors R208 and R209, permitting intermediate frequency amplifier unit 3 to track instantaneous deviation of image of the intermediate frequency signal, so as to eliminate noises, improve threshold, and increase signal-to-noise ratio. Therefore, a high quality picture is obtained. When the image modulating signal of the radio frequency signal is deviated upwards upon the loading of a load, the frequency of the intermediate frequency signal obtained from the mixing of the deviated radio frequency signal and the frequency of the local oscillation will be deviated downwards relatively (the frequency of intermediate frequency signal (IF) is equal to the frequency of local oscillation (L.O.) minus the frequency of radio frequency signal (RF), i.e., IF = L.O. - RF). The intermediate frequency signal will be then filtered and amplified by intermediate frequency amplifier unit 3, and then sent to demodulator circuit 4 for demodulating into a baseband frequency signal, permitting it to be further amplified by negative feedback amplifier circuit 13 and then fed back to variodes VD201 and VD202. Therefore, intermediate bandpass tracking filter 32 can track downwards the instantaneously deviated intermediate frequency image signal. On the contrary, when the image modulating signal of the radio frequency signal is deviated downwards upon the loading of a load, the frequency of the intermediate frequency signal obtained from the mixing of the deviated radio frequency signal and the frequency of the local oscillation will be deviated upwards relatively. The intermediate frequency signal will be then filtered and amplified by intermediate frequency amplifier unit 3, and then sent to demodulator circuit 4 for demodulating into a baseband frequency signal, permitting it to be further amplified by megative feedback amplifier circuit 5 and then fed back to VD201 and VD202. Therefore, intermediate bandpass tracking filter 32 can track upwards the instantanceously deviated intermediate frequency image signal.
As indicated above, any deviation of the image of intermediate frequency signal can be effectively tracked, so that the band width of 10 MHz is sufficient to cover the information of the intermediate frequency signal. Therefore, the signal-to-noise ratio 14 can be greatly increased, the noises can be eliminated, and the threshold can be reduced when the intermediate frequency image signal enters demodulator circuit 4, i.e., the image distortion problem is eliminated.
While only one embodiment of the present invention has been shown and described, it will be understood that various modifications and changes could be made without departing from the spirit and scope of the invention.
Claims (6)
1. A direct broadcasting satellite tuner comprising: radio frequency input means for receiving and amplifying the radio frequency signal transmitted from a satellite antenna; frequency converting means for converting and amplifying the signal outputted from said radio frequency input means into an intermediate frequency signal by means of the operation of a microwave monolithic integrated circuit thereof; intermediate frequency amplification means comprising a primary intermediate frequency amplifier, an intermediate frequency bandpass tracking filter, and a secondary intermediate frequency amplifier, wherein said primary intermediate frequency amplifier receiving and amplifying the output intermediate frequency signal from said frequency converting means, said intermediate frequency bandpass tracking filter tracking and filtering the signal from said primary intermediate frequency amplifier with an intermediate frequency signal of 1OMHz bandwidth, said secondary intermediate frequency amplifier receiving and amplifying the output signal from said intermediate frequency bandpass tracking filter; 16 demodulator circuit means for receiving and demodulating the output signal from said intermediate frequency amplification means so as to obtain a satisfactory baseband frequency signal through the control of an automatic gaining control circuit; and negative feedback amplification means for receiving and amplifying the output signal from said demodulator circuit means, and feeding back the amplified signal to said intermediate frequency band pass tracking filter, enabling said intermediate frequency amplification means to track the instantaneous deviation of image signal of the intermediate frequency signal so as to eliminate noises, reduce threshold, and improve signal-to-noise ratio.
2. The direct broadcasting satellite tuner of claim 1 wherein said radio frequency input means comprises:
a first low-pass filter to receive the radio frequency signal (950M HZ-2050M HZ) from said satellite antenna, and to remove frequency of bandwidth over 2050 M HZ from the signal; a first radio frequency amplifier to amplify the output signal from said first low-pass filter; a second low-pass filter to receive the radio 17 frequency signal (950M HZ-2050M HZ) from said satellite antenna and to remove frequency of bandwidth over 2050 M HZ from the signal; a second radio frequency amplifier to amplify the output signal from said second low-pass filter; and a switching circuit controlled to let said first low- pass filter or said second low-pass filter receive the radio frequency signal from said satellite antenna.
3. The direct broadcasting satellite tuner of claim 1 wherein said frequency converting means comprises: a tracking filter to receive the output signal from said radio frequency input means, and to remove the image frequency from the signal; an attenuation circuit to receive the output signal from said tracking filter and to attenuate it, so as to eliminate the interference of noises when the intensity of the received signal is high; and a microwave monolithic integrated circuit to receive the output signal from said attenuation circuit and to process it into an intermediate frequency signal through a superheterodyne process by means of the operations of the radio frequency amplifier and voltage 18 control oscillator thereof.
4. The direct broadcasting satellite tuner of claim 3 wherein said attenuation circuit of said frequency converting means is coupled to an automatic gain control circuit to control the gaining and reducing of the output signal from said tracking filter.
5. The direct broadcasting satellite tuner of claim 1 wherein said first stage intermediate frequency amplifier of said intermediate frequency amplification means is coupled to an automatic gain control circuit to control the gaining and reducing of the intermediate frequency signal passing through.
6. A direct broadcasting satellite tuner substantially as hereinbefore described and as illustrated in the accompanying Figures.
19
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9517255A GB2304478A (en) | 1995-08-23 | 1995-08-23 | Direct broadcasting satellite tuner with negative feedback circuit to filter for tracking if image signal |
| DE19531032A DE19531032A1 (en) | 1995-08-23 | 1995-08-23 | Tuner for direct reception of satellite transmission |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9517255A GB2304478A (en) | 1995-08-23 | 1995-08-23 | Direct broadcasting satellite tuner with negative feedback circuit to filter for tracking if image signal |
| DE19531032A DE19531032A1 (en) | 1995-08-23 | 1995-08-23 | Tuner for direct reception of satellite transmission |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9517255D0 GB9517255D0 (en) | 1995-10-25 |
| GB2304478A true GB2304478A (en) | 1997-03-19 |
Family
ID=26017932
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9517255A Withdrawn GB2304478A (en) | 1995-08-23 | 1995-08-23 | Direct broadcasting satellite tuner with negative feedback circuit to filter for tracking if image signal |
Country Status (2)
| Country | Link |
|---|---|
| DE (1) | DE19531032A1 (en) |
| GB (1) | GB2304478A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008064994A1 (en) * | 2006-11-29 | 2008-06-05 | Stmicroelectronics S.R.L. | Circuit for the generation of pulse-width modulation signals, particularly for a satellite reception system |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0064819A1 (en) * | 1981-04-28 | 1982-11-17 | Oki Electric Industry Company, Limited | An FM signal demodulation system |
| US4792993A (en) * | 1985-10-30 | 1988-12-20 | Capetronic (Bsr) Ltd. | TVRD receiver system with automatic bandwidth adjustment |
| GB2222332A (en) * | 1988-08-25 | 1990-02-28 | Nec Corp | Radio receiver receiving voice and data signals |
| GB2270223A (en) * | 1992-08-29 | 1994-03-02 | Motorola Israel Ltd | Radio with adjustable filter controlled in dependence on received reference frequency |
-
1995
- 1995-08-23 DE DE19531032A patent/DE19531032A1/en not_active Withdrawn
- 1995-08-23 GB GB9517255A patent/GB2304478A/en not_active Withdrawn
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0064819A1 (en) * | 1981-04-28 | 1982-11-17 | Oki Electric Industry Company, Limited | An FM signal demodulation system |
| US4792993A (en) * | 1985-10-30 | 1988-12-20 | Capetronic (Bsr) Ltd. | TVRD receiver system with automatic bandwidth adjustment |
| GB2222332A (en) * | 1988-08-25 | 1990-02-28 | Nec Corp | Radio receiver receiving voice and data signals |
| GB2270223A (en) * | 1992-08-29 | 1994-03-02 | Motorola Israel Ltd | Radio with adjustable filter controlled in dependence on received reference frequency |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008064994A1 (en) * | 2006-11-29 | 2008-06-05 | Stmicroelectronics S.R.L. | Circuit for the generation of pulse-width modulation signals, particularly for a satellite reception system |
| US8013638B2 (en) | 2006-11-29 | 2011-09-06 | Stmicroelectronics S.R.L. | Circuit for the generation of pulse-width modulation signals, particularly for a satellite reception system |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9517255D0 (en) | 1995-10-25 |
| DE19531032A1 (en) | 1997-02-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |