GB2244877A - Control of oscillators - Google Patents
Control of oscillators Download PDFInfo
- Publication number
- GB2244877A GB2244877A GB9018896A GB9018896A GB2244877A GB 2244877 A GB2244877 A GB 2244877A GB 9018896 A GB9018896 A GB 9018896A GB 9018896 A GB9018896 A GB 9018896A GB 2244877 A GB2244877 A GB 2244877A
- Authority
- GB
- United Kingdom
- Prior art keywords
- frequency
- oscillator
- temperature
- microprocessor
- operating temperature
- 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.)
- Granted
Links
- 239000013078 crystal Substances 0.000 claims abstract description 15
- 238000005070 sampling Methods 0.000 claims abstract description 6
- 238000000034 method Methods 0.000 claims description 10
- 238000009795 derivation Methods 0.000 claims 1
- 230000001131 transforming effect Effects 0.000 claims 1
- 238000012360 testing method Methods 0.000 abstract description 3
- 238000006243 chemical reaction Methods 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 4
- 230000032683 aging Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L1/00—Stabilisation of generator output against variations of physical values, e.g. power supply
- H03L1/02—Stabilisation of generator output against variations of physical values, e.g. power supply against variations of temperature only
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
- H03D7/00—Transference of modulation from one carrier to another, e.g. frequency-changing
- H03D7/16—Multiple-frequency-changing
- H03D7/161—Multiple-frequency-changing all the frequency changers being connected in cascade
- H03D7/163—Multiple-frequency-changing all the frequency changers being connected in cascade the local oscillations of at least two of the frequency changers being derived from a single oscillator
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
- H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
- H03L7/08—Details of the phase-locked loop
- H03L7/10—Details of the phase-locked loop for assuring initial synchronisation or for broadening the capture range
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L1/00—Stabilisation of generator output against variations of physical values, e.g. power supply
- H03L1/02—Stabilisation of generator output against variations of physical values, e.g. power supply against variations of temperature only
- H03L1/022—Stabilisation of generator output against variations of physical values, e.g. power supply against variations of temperature only by indirect stabilisation, i.e. by generating an electrical correction signal which is a function of the temperature
- H03L1/023—Stabilisation of generator output against variations of physical values, e.g. power supply against variations of temperature only by indirect stabilisation, i.e. by generating an electrical correction signal which is a function of the temperature by using voltage variable capacitance diodes
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
- Oscillators With Electromechanical Resonators (AREA)
Abstract
There is provided a system for automatically and integrally calibrating an oscillator 10 to achieve frequency accuracy and stability in a radio, particularly a radio where the temperature of an oscillator can be set. For calibration or setting up of an oscillator 10 subject to error in output frequency, the radio is tuned to a calibration frequency received from a transmitted frequency standard or a precision test instrument. The frequency error of 10 is multiplied as a result of conversion to the baseband via mixers 14, 16 and a demodulator 20. The baseband frequency is measured by digital frequency sampling in a microprocessor included in a processor 18. The microprocessor applies frequency control signals to the oscillator 10 via a D/A converter until the frequency deviation measured at the demodulator 20 output disappears. The final output of D/A converter is stored in a non-volatile memory. The oscillator 10 may be an oven temperature controlled crystal oscillator. <IMAGE>
Description
AUTOMATICALLY SELF-CALIBRATING OSOILLATORS
IN HETERODYNED RADIO RECEIVERS
Field of Invention
This inventIon relates to automatic calibration of oscillators. More particularly, this invention relates to temperature and frequency calibration of oscIllators in ig Frequency Single Side Band (HF SSB) heterodyned radio receivers to achieve frequency accuracy and stability.
3ack-round of the Invention
Frequency accuracy and stability are major problems radio communications, particularly in HF SSB. The oscillating frequency of oscillator components (and especially the oscillating crystal) for radios are particularly sensitive to temperature variatIon and are, therefore, commonly isolated from ambient temperature conditions by being maintained at a constant temperature within oven enclosures.
The dominant frequency contribution of the oscillator comes from the crystal. A typical frequency deviation vs temperature characteristic for a crystal is illustrated in
Figure 1. Thus, substantial frequency stability can be achieved by regulating the temperature of the crystal aboLt the point of minimum frequency deviation for given changes in temperature (i.e., zero slope). Also, any method that regulates the operating temperature of the entire oscillator according to the basic characteristics of the crystal itself will achieve substantial frequency stability.
This optimum temperature for maximum frequency stability varies considerably from crystal to crystal and migrates in each crystal over time due to aging. Thus, although the oven temperature is orinarily individually set within a certain tolerance by the use of precision instrumentation at the factory for each oscillator before being assembled into the radio and then individually frequency adjusted once assembled, each will require adjustment throughout its lifetime in the field and as it ages.
What is needed, then, is a method -- integral to the radio itself -- for Individually regulating the temperature of the oscillator according to its prevailing temperature vs frequency characteristics and subsequently adjusting the frequency for maximum accuracy.In modern HF SSB radios, it is now possible to do automatic calibration within the radIo Itself in the field, without the use of precision test instrumentation but simply using elements of the radio itself, because the frequency error is multiple in the radio reciever such that it can easIly be measured at the audio output with conventional microprocessors using known methods of digital signal processing/frequency sampling.
It Is, therefore, one object of te invention to provide a method for automatically and integrally calibrating the temperature and frequency of the oscillato according to the basic prevailina characteristics of the oscillator to achieve appreciable freau'ency stability, using only an external frequency reference signal.
Summary of the Invention
According to the present invention, there is provided a system for automatically and integrally calibrating the temperature of an oscillator to achieve frequency stability in a system where the temperature of an oscillator can be set. The temperature calibration is performed by Integrally determining the present optimal operating temperature for the oscillator and integrally resetting the temperature 0 the oscillator to that optimal temperature. Thus, frequency vs. temperature stability is achieved; frequency calibration may follow.
Brief Description of the Drawings
An exemplary system in accordance with the present invention Will now be described, by way of example only, with reference to the accompanying drawings, in which:
Figure 1 is a graph that illustrates a typical frequency deviation vs temperature characteristic for a crystal.
Figure 2 is a block diagram of a synthesized radio incorporating the present invention.
Figure 3 is a block dIagram of the Processing Unit of
FIgure 2 and ccnstr'cted according to the present invention.
Detailed Description of the Invention
ure 2 is a block diagram of a synthesized radio incorporating the present invention. The synthesized radio includes a frequency oscillator providing a reference frequency, a synthesizer providing a first and second injection frequency for the fIrst and second Intermediate
Frequency mixers and whose progra=able frequency dividers are loadable from the processor, and a demodulator, whose ordinary audio output is advantageously used in accordance with the present invention to provide frequency deviation and calibration information to the processor.
The oscillator of this synthesized radio can be accurately calibrated because the frequency error between the external reference frequency recieved by the radio reciever and Its internal reference frequency is trans formed to the base-band and multiplied by the ratio of the recieved frequency to the reference frequency.Thus, wit an internal reference frequency of 11.4 XE:z and with the reciever tuned to a 10 MHz and an external frequency of 10.001 EHz, a tone of approximately 1 Rev will be produced at the audio output -- a 0.1 ppm oscillator error is reflected in the audio output as a 1000 ppm deviation. This multiplication of the frequency error is then easily measured in the audio output by modest microprocessors clocked by low cost crystals.
Figure 2 is a block diagram of the Processor of @ igure 2 and constructed according to the present invention. The Processor includes a microprocessor coupled to the audio output of the reciever and is used in accordance with the resent invention to provide frequency deviation and calibration information to the processor and further includes digital-to-analogue converters to supply temperature and frequency calibration information to the oscillator.
to calibrate the oscillator, the reciever is tuned to a calibration frequency (recieved from a calibrated transmitter, from an external precision test instrument or frcm a transmitted f-ezzency standard -- t me and frequency reference sIgnals are commonly available in the HF band for navigation and time distribution purposes). Next, the voltage generated using the Temperature Digital-to-Anologue converter (D/A-2) is varied to drive the oven temperature of the oscillator across its design range from its minimum temperature to its maximum temperature. After sufficient time has passed for the oven temperature to stablize following each change in voltage, the change in frequency deviation at the audio output is measured and noted (a microprocessor is utilized to note said resultant frequency deviations using digital frequency sampling techniques).
Once a sufficient number of frequency/temperature points have been noted (for example, a minimum of three is required for the parabolic curve approximation of Figure 1), the oven temperature at which the least frequency deviation exists can be determined.Again, for the basic parabolic characteristic of Figure 1, this optimum temperature (where the slope is zero) is determined from coefficients of the parabola f=At**2+Bt+C where:
Tcalibration = B/2A and where
A=[(fl-fo) (t2-t0)-(f2-f0) (t1-t0)] / (t1-t0) (t2-t0) (t1-t2)
and
B=[f2-f0-A (t2**2-t0**2)]/t2-t0 from the temperature/frequency pairs (t0, f0), (t1, f1) and (t2,f2) Finally, the voltage corresponding to the optimum temperature calibration is generated through the
Temperature D/A and the Frequency Tuning D/A is adjusted (varying the voltage on varicap diodes in the oscillator) until the frequency deviation measured at the audio output disappears. The calibration is complete when the values of both the Temperature and the Frequency TunIng 3/As are stored in non-volitile memory.
Thus, what has been provided is a system for automatically and integrally calibrating the temperature of an oscillator to achieve frequency accuracy and stability in a synthesized radio where the temperature of an oscillator can be set. The temperature calibration is performed by integrally determining the present optimal operating temperature for the oscillator and Integrally resetting the temperature of the oscillator to that optimal temperature.
Thus, f-evaency vs. temperature stability is achieved; frequency calibration may follow.
This method of calibration is suitable for use with any oscillator where frequency accuracy and stability is a concern, Including those that are not oven temperature controlled. It is particularly advantageous for field frequency adjustments to compensate for crystal aging.
While the preferren embodiment of the invention has been descried and shown, it ill be understood by those skilled In n the art that other variations and modifications of this invention may be implemented.
Claims (4)
- CLAIMS:tYMat we claim and desire to secure by Letters Patent is: 1. A method of automatically and integrally calibration the temperature of an oscillator to achieve frequency stabilltv in a synthesized radio where the temperature of an oscillator can be set, characterized by: integrally determinIng the present optimal operating temperature for the oscillator and integrally resetting the temperature of the oscillator to that optimal temperature, whereby frequency vs. temperature stabilIty is achieved.
- 2. As claimed immediately above, further characterizec v calibrat ng the operating frequency of saia oscillator following said temperature calibration, whereby frequency accuracy is achieved.
- 3. As claimed i=ediately above, wherein said frequency calibration is further characterized by notIng the resultant frequency deviation following said temperature calibration and adjustIng the frequency of said oscillator to eliminate said frequency deviation.
- 4. A radio according to any one of the preceding claims, wherein a microprocessor-driven digital-toanalogue converter is provided to adjust the frequency of the oscillator by altering the voltage supplied to varicap diodes in a frequency generator of the oscillator.4. As claimed anywhere above, wherein a microprocessor-driven digital-to-analogue converter is utilized to adjust the frequency of the oscillator by altering the voltage supplied to varicap diodes in the frequency generator of the oscillator.As claimed anywhere above, wherein said integral determination is further characterized by: deriving the specific frequency vs temperature characteristic of said oscillator and calculating the optimal operating temperature where relative temperature differentials result in relatively minimal frequency deviations.6. As claimed i=.ediately above, wherein said derivation is further characterized by: adusting the operating temperature of the oscillator across its operating temperature range, noting the resultant frec-uenoy deviations and calculating the coefficients of a repressentative polynomial e~- atlon and calculating the relative minima of said polynomial equation, whereby said relative minima represents the optimal operating temperature of said oscillator.7. As claimed immediately above, wherein three frequency vs temperature pairs are noted to resolve the coefficients and to calculate the relative minima of a parabolic quadratic equation representative of a crystal oscillator.8. As claimed anywhere above, wherein a microprocessor-driven digital-to-analogue converter is utilized to adjust the operating temperature of the oscillator by altering the voltage supplied to the temperature control of an oscillator.9. As claimed anywhere above, wherein a microprocessor is utilized to note said resultant frequency deviations using digital frequency sampling techniques.10. As claImed above wherein a microprocessor-driven dIgItal-to-analogue converter is utilized to generate a current proportional to the optimal operating temperature and to supply said voltage to the temperature control of an oscillator.11. A method of automatically and integrally calibrating an oscillator to achieve frequency stability in a synthesIzed radio where the oven temperature of a crystal oscillator can be set, characterized by: Integrally determining the present optimal operating temperature for the oscillator by: deriving the specific frequency vs temperature characterIstIc of said oscillator and calculating the optimal operating temperature where relative temperature differentials result in relatively minimal frequency deviations by:: adjusting the operating temperature of the oscillator across its operating temperature range, noting the resultant frequency deviations calculating the coefficients of a representative polynomial equation and calculating the relative minima of said polynomial equation (whereby said relative minima represents the optimal operating temperature of said oscillator), by:: noting three frequency vs temperature pairs to resolve the coefficients an to calculate the relative minima of a parabolic quadratic equation representative of a crystal oso- a integrally resetting the temperature of the oscillator to that optimal temperature by: utilizing a microprocessor-driven tal-to-analogue converter to adjust the operating temperature of the oscillator bv altering the voltage supplied to the temperature control of an oscillator by:: utilizing a microprocessor-driven digital-to-analogue converter to generate a voltage proportional to the optimal operating temperature and to supply said current to the temperature control of an oscillator and calibrating the operating frequency of said oscillator following said temperature calibration by: noting the resultant frequency deviation following said temperature calibration and adjusting the frequency of said oscillator to eliminate said frequency deviation by: : utilizing a microprocessor-driven dIgital-to-analogue converter to adjust the frequency of the oscillator by altering the voltage supplied to varicap diodes in the frequency generator of the oscillator, wherein a microprocessor is utilized to note said resultant frequency deviations using digital frequency sampling techniques and whereby fre'-'ency vs. temperature stabilIty is achieved and whereby frequency accuracy is achieved.CLAIMS: 1. A radio comprising an oscillator for generating an internal reference frequency signal, means for transforming the internal reference frequency error to the radio baseband, multiplied by the ratio between the received frequency and the reference frequency and by the ratio between the received frequency and the baseband and calibrating means for measuring this error in the baseband and adjusting the internal reference frequency to the desired value.2. A radio according to claim 1, wherein the calibrating means comprises a microprocessor for carrying out digital frequency sampling to measure the frequency of the baseband.3. A radio according to claim 1, wherein the frequency error of the reference frequency signal gives rise to an error at least 1000 greater in the baseband.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9018896A GB2244877B (en) | 1988-05-28 | 1990-08-30 | Automatically self-calibrating oscillators in heterodyned radio receivers |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8812773A GB2220317B (en) | 1988-05-28 | 1988-05-28 | Automatically self-calibrating oscillators in heterodyned radio receivers |
| GB9018896A GB2244877B (en) | 1988-05-28 | 1990-08-30 | Automatically self-calibrating oscillators in heterodyned radio receivers |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9018896D0 GB9018896D0 (en) | 1990-10-17 |
| GB2244877A true GB2244877A (en) | 1991-12-11 |
| GB2244877B GB2244877B (en) | 1992-07-22 |
Family
ID=10637774
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8812773A Expired - Lifetime GB2220317B (en) | 1988-05-28 | 1988-05-28 | Automatically self-calibrating oscillators in heterodyned radio receivers |
| GB9018896A Expired - Lifetime GB2244877B (en) | 1988-05-28 | 1990-08-30 | Automatically self-calibrating oscillators in heterodyned radio receivers |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8812773A Expired - Lifetime GB2220317B (en) | 1988-05-28 | 1988-05-28 | Automatically self-calibrating oscillators in heterodyned radio receivers |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JP2814638B2 (en) |
| KR (1) | KR900702657A (en) |
| GB (2) | GB2220317B (en) |
| HK (2) | HK87695A (en) |
| SG (2) | SG22795G (en) |
| WO (1) | WO1989011756A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4209843A1 (en) * | 1992-03-26 | 1993-11-18 | Telefunken Microelectron | Temp. compensated oscillator circuit - stores tuning element setting signal and corresponding temp. signal during calibration phase for subsequent provision of correction signal |
| GB2291751A (en) * | 1994-07-25 | 1996-01-31 | Nec Corp | PLL receivers |
| US6954625B2 (en) | 2001-04-28 | 2005-10-11 | Zarlink Semiconductor Limited | Tuner and method of aligning a tuner |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2273405B (en) * | 1992-12-10 | 1996-12-04 | Motorola Israel Ltd | A communications device and method of calibration therefor |
| US6606009B2 (en) * | 2001-03-08 | 2003-08-12 | Schlumberger Technology Corporation | Self-compensating ovenized clock adapted for wellbore applications |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2007049A (en) * | 1977-10-26 | 1979-05-10 | Philips Nv | Receiver having a frequency synthesising circuit |
| GB2064248A (en) * | 1979-11-21 | 1981-06-10 | Philcom Electronics Blackburn | Temperature compensated crystal oscillators |
| GB1600393A (en) * | 1977-09-23 | 1981-10-14 | Racal Res Ltd | Correcting oscillator output frequency for temperature variations |
| US4373209A (en) * | 1980-03-10 | 1983-02-08 | Trio Kabushiki Kaisha | Method and circuitry for controlling the intermediate frequency of an FM receiver to lessen phase distortion |
| EP0182982A1 (en) * | 1984-11-12 | 1986-06-04 | Hagenuk Gmbh | Oscillator circuit |
| WO1986005637A1 (en) * | 1985-03-21 | 1986-09-25 | H. U. C. Elektronik Hansen & Co. | Circuit for automatic tuning of sharpness in fm receivers |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2856320A1 (en) * | 1978-12-27 | 1980-07-17 | Roehm Gmbh | ENZYMATIC STICKING PROCESS |
| JPS5977259A (en) * | 1982-10-25 | 1984-05-02 | Matsushita Electric Ind Co Ltd | Solar heat collector |
| JPS61220527A (en) * | 1985-03-26 | 1986-09-30 | Fujitsu Ltd | Crystal oscillator |
| JPS623527A (en) * | 1985-06-29 | 1987-01-09 | Nec Corp | Piezoelectric oscillator with constant temperature oven |
| DE3526363A1 (en) * | 1985-07-19 | 1987-01-22 | Siemens Ag | METHOD FOR PRODUCING AN ADJUSTABLE FREQUENCY GENERATOR |
| JPS62116003A (en) * | 1985-11-15 | 1987-05-27 | Fujitsu Ltd | Oscillator |
| US4746879A (en) | 1986-08-28 | 1988-05-24 | Ma John Y | Digitally temperature compensated voltage-controlled oscillator |
-
1988
- 1988-05-28 GB GB8812773A patent/GB2220317B/en not_active Expired - Lifetime
-
1989
- 1989-05-25 WO PCT/US1989/002285 patent/WO1989011756A1/en unknown
- 1989-05-25 JP JP1506396A patent/JP2814638B2/en not_active Expired - Lifetime
-
1990
- 1990-01-23 KR KR1019900700124A patent/KR900702657A/en not_active Application Discontinuation
- 1990-08-30 GB GB9018896A patent/GB2244877B/en not_active Expired - Lifetime
-
1995
- 1995-02-11 SG SG22795A patent/SG22795G/en unknown
- 1995-02-11 SG SG22895A patent/SG22895G/en unknown
- 1995-06-01 HK HK87695A patent/HK87695A/en not_active IP Right Cessation
- 1995-06-01 HK HK87595A patent/HK87595A/en not_active IP Right Cessation
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1600393A (en) * | 1977-09-23 | 1981-10-14 | Racal Res Ltd | Correcting oscillator output frequency for temperature variations |
| GB2007049A (en) * | 1977-10-26 | 1979-05-10 | Philips Nv | Receiver having a frequency synthesising circuit |
| GB2064248A (en) * | 1979-11-21 | 1981-06-10 | Philcom Electronics Blackburn | Temperature compensated crystal oscillators |
| US4373209A (en) * | 1980-03-10 | 1983-02-08 | Trio Kabushiki Kaisha | Method and circuitry for controlling the intermediate frequency of an FM receiver to lessen phase distortion |
| EP0182982A1 (en) * | 1984-11-12 | 1986-06-04 | Hagenuk Gmbh | Oscillator circuit |
| WO1986005637A1 (en) * | 1985-03-21 | 1986-09-25 | H. U. C. Elektronik Hansen & Co. | Circuit for automatic tuning of sharpness in fm receivers |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4209843A1 (en) * | 1992-03-26 | 1993-11-18 | Telefunken Microelectron | Temp. compensated oscillator circuit - stores tuning element setting signal and corresponding temp. signal during calibration phase for subsequent provision of correction signal |
| GB2291751A (en) * | 1994-07-25 | 1996-01-31 | Nec Corp | PLL receivers |
| US5706315A (en) * | 1994-07-25 | 1998-01-06 | Nec Corporation | Automatic frequency control device for tuning an intermediate frequency signal to a target frequency |
| GB2291751B (en) * | 1994-07-25 | 1999-07-21 | Nec Corp | Automatic frequency control device for tuning an intermediate frequency signal to a target frequency |
| US6954625B2 (en) | 2001-04-28 | 2005-10-11 | Zarlink Semiconductor Limited | Tuner and method of aligning a tuner |
Also Published As
| Publication number | Publication date |
|---|---|
| SG22895G (en) | 1995-06-16 |
| GB2244877B (en) | 1992-07-22 |
| GB2220317A (en) | 1990-01-04 |
| KR900702657A (en) | 1990-12-08 |
| WO1989011756A1 (en) | 1989-11-30 |
| JPH04504035A (en) | 1992-07-16 |
| JP2814638B2 (en) | 1998-10-27 |
| HK87695A (en) | 1995-06-09 |
| SG22795G (en) | 1995-06-16 |
| GB9018896D0 (en) | 1990-10-17 |
| GB2220317B (en) | 1992-07-22 |
| GB8812773D0 (en) | 1988-06-29 |
| HK87595A (en) | 1995-06-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19990528 |