US20020070878A1 - Radio frequency transmitter having switched mode power supply - Google Patents
Radio frequency transmitter having switched mode power supply Download PDFInfo
- Publication number
- US20020070878A1 US20020070878A1 US09/970,574 US97057401A US2002070878A1 US 20020070878 A1 US20020070878 A1 US 20020070878A1 US 97057401 A US97057401 A US 97057401A US 2002070878 A1 US2002070878 A1 US 2002070878A1
- Authority
- US
- United States
- Prior art keywords
- radio frequency
- power supply
- oscillator
- mode power
- switched mode
- 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.)
- Abandoned
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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
- H04B1/1607—Supply circuits
-
- 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
- H04B1/02—Transmitters
- H04B1/04—Circuits
Definitions
- the invention relates in general to radio frequency transmitters and, in particular, to a switched mode power supply for a radio frequency transmitter.
- Hand-held radio transmitters are energized by a battery and it is desirable to maintain as long a battery life as possible. However, it is also important for hand-held radio transmitters to be inexpensive, while still conforming with requirements of the Federal Communications Commission for center frequencies, bandwidth limitations, power limitations and the like.
- hand-held radio transmitters particularly of the type disclosed in U.S. Pat. No. 4,806,930 to Wojciak, Jr., were directed to battery operated systems wherein a radio transmitter might include a code generator as well as an oscillator having an output modulated in some fashion by a code generator for producing a modulated radio frequency output. The transmitter was energized by a battery E.
- Such a transmitter was relatively bulky, in part because relatively large batteries, such as 9-volt and 12-volt batteries were used to energize the transmitters.
- batteries such as 9-volt and 12-volt batteries were used to energize the transmitters.
- 3-volt lithium batteries do suffer from voltage drop-off with battery life and the initial voltage of the batteries as received from the supplier varies to some extent.
- the transmitter radio frequency generating section will not always receive the same energizing voltage and this may lead to the transmitter drifting in frequency and possibly having its electrical characteristics affected greatly by the change in the battery voltage that it will be unable to oscillate at all and, hence, will be unable to generate a radio frequency signal.
- a hand-held radio frequency transmitter includes a switch mode power supply for delivering a pre-selected potential to a radio-frequency oscillator.
- the switched mode supply is controlled by a microprocessor or other digital logic device, such as an application-specific integrated circuit or a custom integrated circuit and includes a switch controlled by the microprocessor, which switch enables or disables current from flowing through an inductor coupled to a storage capacitor.
- a feedback loop is coupled to the storage capacitor for signalling the microcontroller when the storage capacitor has reached a preselected voltage.
- a radio frequency oscillator is connected to be energized from the storage capacitor and includes an input for receiving a modulating code. The modulating code causes the oscillator to be switched on and off, thereby producing a pulsed carrier wave which may be supplied to a garage door operator or other device to be operated.
- FIG. 1 is a schematic diagram of a hand-held radio frequency transmitter embodying the present invention.
- FIG. 2 is a flow chart showing operation of a microcontroller of the radio frequency transmitter shown in FIG. 1.
- a hand-held radio frequency transmitter embodying the present invention is generally shown therein and is identified by numeral 10 .
- the transmitter 10 includes a switch mode power supply 12 coupled to a radio frequency oscillator 14 .
- a microcontroller 16 produces a modulating code on an output line 18 which is supplied to the oscillator 14 for causing the oscillator 14 to generate radio frequency energy which is emitted by an antenna 20 and which may be received by a garage door operator or other device to be operated.
- a plurality of switches are connected in parallel to a ground 36 and to three inputs 40 , 42 and 44 of the microcontroller 16 . Closure of switches 30 , 32 or 34 each will respectively cause a different modulation code stream to be produced by the microcontroller 16 on the line 18 .
- each of the switches may be dedicated to a particular garage door so that three garage doors could be operated separately from the three switches. In the alternative, one of the switches might be dedicated to sending the code, which would cause a light to be illuminated within the garage even when a garage door is not being operated.
- the modulation output is supplied on line 18 to a resistor 50 which ultimately feeds to the oscillator 14 .
- the oscillator 14 must be energized in order to provide an output.
- a battery 52 is coupled to VCC pin of the microcontroller 16 to energize it at all times.
- the microcontroller 16 may, for instance, be a CMOS 8-bit microcontroller such as a Zilog Z86C03.
- One of the pins of the microcontroller 16 provides a pulsed output at pin 54 which is fed through a 470-ohm resistor 56 to an NPN transistor 58 which receives the pulses at its base 60 , transistor emitter 62 is connected to ground and its collector 64 .
- Current from the battery 52 may be supplied to a one millihenry inductor 70 coupled to the battery 52 and to the collector 64 .
- a pulse on the line 54 switches the transistor 58 off uncoupling the inductor 70 from ground and causing current to flow through a diode 80 to a 10 microfarad electrolytic capacitor 82 and charging the 10 microfarad electrolytic capacitor 82 until the point that it reaches a voltage which is equal to the breakdown voltage of a Zener diode 84 connected to the capacitor 82 .
- a 100 kilohm resistor 86 is connected between the Zener diode 84 and ground and a feedback line 88 couples the junction of the Zener diode 84 and resistor 86 to a feedback input terminal on the microcontroller.
- the microcontroller drives the pulsed output 54 high, biasing the transistor 58 on and interrupting current flow to the capacitor 82 .
- the capacitor 82 has received sufficient potential to energize the oscillator 14 as will be seen hereinafter.
- step 100 an interrupt occurs every 50 milliseconds.
- step 102 a test is made to determine whether the pulsed output pin connected to the line 54 is high. If it is high, the switched mode output on the line 54 is set low in a step 104 . If the test of step 102 is negative, a test is made in a step 106 to determine whether the feedback input on line 88 is high. If it is, control is transferred to the step 104 , causing the pin connected to line 54 to switch low. If it is not, control is transferred to a step 110 , causing the switch mode output line connected to line 54 to switch high, turning on transistor 58 .
- a test is made to determine whether the period for the modulation bit timing for the modulation generated on line 18 has expired. If the period for modulation bit timing has expired, the routine is exited in a step 114 . If it has not expired, the next bit position is obtained in a step 116 and it is outputted, following which the routine is exited in a step 118 .
- the modulation bits supplied to resistor 50 are fed to a line 130 after having been reduced in potential by the voltage divider, including resistor 50 and a resistor 132 , connected thereto.
- a capacitor 140 connected to ground, comprises a stabilizing filter capacitor and is connected to a series inductor 142 which blocks radiation of stray harmonics of the radio frequency in the range of 300 to 400 MHz.
- the modulated signal is then fed to a base 144 of an NPN transistor 146 , also having a collector 148 and an emitter 150 .
- the emitter 150 is connected through an inductor 152 for harmonics suppression and through a parallel resistor 154 and capacitor 156 .
- the resistor 154 and capacitor 156 which are connected to ground.
- the resistor 154 supplies control over the DC bias and the capacitor 156 controls the radio frequency gain of the oscillator of transistor 146 .
- the emitter 148 of the transistor is connected via a line 160 to a grounded capacitor 162 , having an antenna coil connected thereto.
- a second grounded capacitor 164 is connected to the line 81 as well as to the antenna coil 20 .
- the coded transmission is transmitted by the antenna 20 to a garage door operator or other device to be operated as appropriate.
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Transmitters (AREA)
- Mobile Radio Communication Systems (AREA)
- Selective Calling Equipment (AREA)
Abstract
A hand-held radio frequency transmitter for use in generating a coded radio frequency transmission has a switched mode power supply energizable by a battery. A radio frequency oscillator is driven by the switched mode supply. A modulator controls operation of the oscillator which produces a coded radio frequency signal.
Description
- The invention relates in general to radio frequency transmitters and, in particular, to a switched mode power supply for a radio frequency transmitter.
- Garage door operators commonly may be controlled from wired switches as well as radio frequency transmitting switches such as hand-held radio transmitters. Hand-held radio transmitters are energized by a battery and it is desirable to maintain as long a battery life as possible. However, it is also important for hand-held radio transmitters to be inexpensive, while still conforming with requirements of the Federal Communications Commission for center frequencies, bandwidth limitations, power limitations and the like. In the past hand-held radio transmitters, particularly of the type disclosed in U.S. Pat. No. 4,806,930 to Wojciak, Jr., were directed to battery operated systems wherein a radio transmitter might include a code generator as well as an oscillator having an output modulated in some fashion by a code generator for producing a modulated radio frequency output. The transmitter was energized by a battery E.
- Such a transmitter, however, was relatively bulky, in part because relatively large batteries, such as 9-volt and 12-volt batteries were used to energize the transmitters. Today, however, people have come to enjoy keyfob-type transmitters which have very small volumes and, accordingly, in many cases are now using 3-volt lithium batteries. Unfortunately, 3-volt lithium batteries do suffer from voltage drop-off with battery life and the initial voltage of the batteries as received from the supplier varies to some extent. As a result, the transmitter radio frequency generating section will not always receive the same energizing voltage and this may lead to the transmitter drifting in frequency and possibly having its electrical characteristics affected greatly by the change in the battery voltage that it will be unable to oscillate at all and, hence, will be unable to generate a radio frequency signal.
- What is needed, then, is a hand-held radio frequency transmitter including a voltage stabilized power supply which is compact and has a relatively small number of components.
- A hand-held radio frequency transmitter includes a switch mode power supply for delivering a pre-selected potential to a radio-frequency oscillator. The switched mode supply is controlled by a microprocessor or other digital logic device, such as an application-specific integrated circuit or a custom integrated circuit and includes a switch controlled by the microprocessor, which switch enables or disables current from flowing through an inductor coupled to a storage capacitor. A feedback loop is coupled to the storage capacitor for signalling the microcontroller when the storage capacitor has reached a preselected voltage. A radio frequency oscillator is connected to be energized from the storage capacitor and includes an input for receiving a modulating code. The modulating code causes the oscillator to be switched on and off, thereby producing a pulsed carrier wave which may be supplied to a garage door operator or other device to be operated.
- It is a principal aspect of the present invention to provide a hand-held radio frequency transmitter including a switch mode power supply driven from a battery for supplying uniform potential electrical energy to a radio frequency oscillator.
- Other advantages of the present invention will become apparent to one of ordinary skill in the art, upon a perusal of the following specification and claims in light of the accompanying drawings.
- FIG. 1 is a schematic diagram of a hand-held radio frequency transmitter embodying the present invention; and
- FIG. 2 is a flow chart showing operation of a microcontroller of the radio frequency transmitter shown in FIG. 1.
- Referring now the drawings and especially to FIG. 1, a hand-held radio frequency transmitter embodying the present invention is generally shown therein and is identified by
numeral 10. Thetransmitter 10 includes a switchmode power supply 12 coupled to aradio frequency oscillator 14. Amicrocontroller 16 produces a modulating code on anoutput line 18 which is supplied to theoscillator 14 for causing theoscillator 14 to generate radio frequency energy which is emitted by anantenna 20 and which may be received by a garage door operator or other device to be operated. - A plurality of switches, respectively numbered30, 32 and 34, are connected in parallel to a
ground 36 and to threeinputs microcontroller 16. Closure ofswitches microcontroller 16 on theline 18. For instance, each of the switches may be dedicated to a particular garage door so that three garage doors could be operated separately from the three switches. In the alternative, one of the switches might be dedicated to sending the code, which would cause a light to be illuminated within the garage even when a garage door is not being operated. In response to closure of one of the threeswitches line 18 to aresistor 50 which ultimately feeds to theoscillator 14. Theoscillator 14, however, must be energized in order to provide an output. It should be appreciated that abattery 52 is coupled to VCC pin of themicrocontroller 16 to energize it at all times. Themicrocontroller 16 may, for instance, be a CMOS 8-bit microcontroller such as a Zilog Z86C03. One of the pins of themicrocontroller 16 provides a pulsed output atpin 54 which is fed through a 470-ohm resistor 56 to anNPN transistor 58 which receives the pulses at itsbase 60,transistor emitter 62 is connected to ground and itscollector 64. Current from thebattery 52 may be supplied to a onemillihenry inductor 70 coupled to thebattery 52 and to thecollector 64. A pulse on theline 54 switches thetransistor 58 off uncoupling theinductor 70 from ground and causing current to flow through adiode 80 to a 10 microfaradelectrolytic capacitor 82 and charging the 10 microfaradelectrolytic capacitor 82 until the point that it reaches a voltage which is equal to the breakdown voltage of a Zenerdiode 84 connected to thecapacitor 82. A 100kilohm resistor 86 is connected between the Zenerdiode 84 and ground and afeedback line 88 couples the junction of the Zenerdiode 84 andresistor 86 to a feedback input terminal on the microcontroller. Thus, when the Zener diode goes into avalanche, driving theline 88 high, the microcontroller drives thepulsed output 54 high, biasing thetransistor 58 on and interrupting current flow to thecapacitor 82. Thecapacitor 82, however, has received sufficient potential to energize theoscillator 14 as will be seen hereinafter. - Referring now to FIG. 2, operation of the
microcontroller 16 is shown therein. In astep 100 an interrupt occurs every 50 milliseconds. In astep 102, a test is made to determine whether the pulsed output pin connected to theline 54 is high. If it is high, the switched mode output on theline 54 is set low in astep 104. If the test ofstep 102 is negative, a test is made in astep 106 to determine whether the feedback input online 88 is high. If it is, control is transferred to thestep 104, causing the pin connected toline 54 to switch low. If it is not, control is transferred to astep 110, causing the switch mode output line connected toline 54 to switch high, turning ontransistor 58. In astep 112, a test is made to determine whether the period for the modulation bit timing for the modulation generated online 18 has expired. If the period for modulation bit timing has expired, the routine is exited in astep 114. If it has not expired, the next bit position is obtained in astep 116 and it is outputted, following which the routine is exited in astep 118. - The modulation bits supplied to
resistor 50 are fed to aline 130 after having been reduced in potential by the voltage divider, includingresistor 50 and aresistor 132, connected thereto. Acapacitor 140, connected to ground, comprises a stabilizing filter capacitor and is connected to aseries inductor 142 which blocks radiation of stray harmonics of the radio frequency in the range of 300 to 400 MHz. The modulated signal is then fed to abase 144 of anNPN transistor 146, also having acollector 148 and anemitter 150. Theemitter 150 is connected through aninductor 152 for harmonics suppression and through aparallel resistor 154 andcapacitor 156. Theresistor 154 andcapacitor 156 which are connected to ground. Theresistor 154 supplies control over the DC bias and thecapacitor 156 controls the radio frequency gain of the oscillator oftransistor 146. Theemitter 148 of the transistor is connected via aline 160 to a grounded capacitor 162, having an antenna coil connected thereto. A second groundedcapacitor 164 is connected to theline 81 as well as to theantenna coil 20. The coded transmission is transmitted by theantenna 20 to a garage door operator or other device to be operated as appropriate. - While there have been illustrated and described particular embodiments of the present invention, it will be appreciated that numerous changes and modifications will occur to those skilled in the art, and it is intended in the appended claims to cover all those changes and modifications which fall within the true spirit and scope of the present invention.
Claims (1)
1. A hand-held radio frequency transmitter for use in generating a coded radio frequency transmission, comprising:
a switched mode power supply;
an oscillator coupled to be driven by the switch mode power supply; and
a modulator for controlling operation of the oscillator to cause the oscillator to be modulated by coded signals.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/970,574 US20020070878A1 (en) | 1995-06-05 | 2001-10-04 | Radio frequency transmitter having switched mode power supply |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US46359095A | 1995-06-05 | 1995-06-05 | |
US08/953,696 US5831548A (en) | 1995-06-05 | 1997-10-17 | Radio frequency transmitter having switched mode power supply |
US11615698A | 1998-07-16 | 1998-07-16 | |
US09/970,574 US20020070878A1 (en) | 1995-06-05 | 2001-10-04 | Radio frequency transmitter having switched mode power supply |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11615698A Continuation | 1995-06-05 | 1998-07-16 |
Publications (1)
Publication Number | Publication Date |
---|---|
US20020070878A1 true US20020070878A1 (en) | 2002-06-13 |
Family
ID=23840626
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/953,696 Expired - Lifetime US5831548A (en) | 1995-06-05 | 1997-10-17 | Radio frequency transmitter having switched mode power supply |
US09/970,574 Abandoned US20020070878A1 (en) | 1995-06-05 | 2001-10-04 | Radio frequency transmitter having switched mode power supply |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/953,696 Expired - Lifetime US5831548A (en) | 1995-06-05 | 1997-10-17 | Radio frequency transmitter having switched mode power supply |
Country Status (6)
Country | Link |
---|---|
US (2) | US5831548A (en) |
EP (1) | EP0775428A4 (en) |
AU (1) | AU6026196A (en) |
BR (1) | BR9606493A (en) |
CA (1) | CA2194383A1 (en) |
WO (1) | WO1996039780A1 (en) |
Families Citing this family (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6005508A (en) * | 1994-07-05 | 1999-12-21 | Tsui; Philip Y. W. | Remote transmitter-receiver controller system |
KR100288196B1 (en) | 1999-03-04 | 2001-04-16 | 박종섭 | Transmission control device for preventing transmitting radio frequency from oscillating in wideband wireless local loop terminal |
US7545833B2 (en) * | 1999-11-17 | 2009-06-09 | Ms Sedco | RF door activation system |
US8325008B2 (en) * | 2001-04-25 | 2012-12-04 | The Chamberlain Group, Inc. | Simplified method and apparatus for programming a universal transmitter |
US7167076B2 (en) * | 2001-12-19 | 2007-01-23 | Lear Corporation | Universal garage door operating system and method |
JP3956725B2 (en) * | 2002-03-05 | 2007-08-08 | 古河電気工業株式会社 | Data communication system |
US7012508B1 (en) | 2003-04-10 | 2006-03-14 | Briggs & Stratton Corporation | System and method for controlling a door |
US7084781B2 (en) * | 2003-07-30 | 2006-08-01 | Lear Corporation | Programmable vehicle-based appliance remote control |
US7161466B2 (en) | 2003-07-30 | 2007-01-09 | Lear Corporation | Remote control automatic appliance activation |
US7068181B2 (en) | 2003-07-30 | 2006-06-27 | Lear Corporation | Programmable appliance remote control |
US7183941B2 (en) | 2003-07-30 | 2007-02-27 | Lear Corporation | Bus-based appliance remote control |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4761644A (en) * | 1985-06-03 | 1988-08-02 | Aisin Seiki Kabushikikaisha | Data transmission system |
JPH0683085B2 (en) * | 1986-03-26 | 1994-10-19 | ソニー株式会社 | Transmitter |
JPS62186537U (en) * | 1986-05-16 | 1987-11-27 | ||
US4814770A (en) * | 1986-12-29 | 1989-03-21 | International Marine Instruments, Inc. | Power supply apparatus for a radar system |
US4890108A (en) * | 1988-09-09 | 1989-12-26 | Clifford Electronics, Inc. | Multi-channel remote control transmitter |
US5383044B1 (en) * | 1992-09-18 | 1998-09-01 | Recoton Corp | Systems methods and apparatus for transmitting radio frequency remote control signals |
BE1006603A6 (en) * | 1992-12-30 | 1994-10-25 | Antwerp Distribution And Produ | Device for supplying energy |
JPH06252820A (en) * | 1993-02-26 | 1994-09-09 | Sony Corp | Power supply circuit and radio communications equipment using thereof |
US5420536A (en) * | 1993-03-16 | 1995-05-30 | Victoria University Of Technology | Linearized power amplifier |
FI94685C (en) * | 1993-11-22 | 1995-10-10 | Nokia Mobile Phones Ltd | Key switched power source for time-multiplexed radio telephone systems |
-
1996
- 1996-05-30 BR BR9606493A patent/BR9606493A/en not_active IP Right Cessation
- 1996-05-30 WO PCT/US1996/007980 patent/WO1996039780A1/en not_active Application Discontinuation
- 1996-05-30 AU AU60261/96A patent/AU6026196A/en not_active Abandoned
- 1996-05-30 CA CA002194383A patent/CA2194383A1/en not_active Abandoned
- 1996-05-30 EP EP96917859A patent/EP0775428A4/en not_active Withdrawn
-
1997
- 1997-10-17 US US08/953,696 patent/US5831548A/en not_active Expired - Lifetime
-
2001
- 2001-10-04 US US09/970,574 patent/US20020070878A1/en not_active Abandoned
Also Published As
Publication number | Publication date |
---|---|
WO1996039780A1 (en) | 1996-12-12 |
BR9606493A (en) | 1998-07-14 |
AU6026196A (en) | 1996-12-24 |
EP0775428A4 (en) | 2003-03-05 |
EP0775428A1 (en) | 1997-05-28 |
US5831548A (en) | 1998-11-03 |
CA2194383A1 (en) | 1996-12-12 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |