WO1998008299A1 - Transmitter controller - Google Patents

Transmitter controller Download PDF

Info

Publication number
WO1998008299A1
WO1998008299A1 PCT/GB1997/002187 GB9702187W WO9808299A1 WO 1998008299 A1 WO1998008299 A1 WO 1998008299A1 GB 9702187 W GB9702187 W GB 9702187W WO 9808299 A1 WO9808299 A1 WO 9808299A1
Authority
WO
WIPO (PCT)
Prior art keywords
frequency
signal
data
crystal
synthesiser
Prior art date
Application number
PCT/GB1997/002187
Other languages
French (fr)
Inventor
Robert Edmund Todd
Original Assignee
Cedardell Limited
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Cedardell Limited filed Critical Cedardell Limited
Priority to AU39487/97A priority Critical patent/AU3948797A/en
Publication of WO1998008299A1 publication Critical patent/WO1998008299A1/en

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C3/00—Angle modulation
    • H03C3/02—Details
    • H03C3/09—Modifications of modulator for regulating the mean frequency
    • H03C3/0908—Modifications of modulator for regulating the mean frequency using a phase locked loop
    • H03C3/0916—Modifications of modulator for regulating the mean frequency using a phase locked loop with frequency divider or counter in the loop
    • H03C3/0933—Modifications of modulator for regulating the mean frequency using a phase locked loop with frequency divider or counter in the loop using fractional frequency division in the feedback loop of the phase locked loop
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C3/00—Angle modulation
    • H03C3/02—Details
    • H03C3/09—Modifications of modulator for regulating the mean frequency
    • H03C3/0908—Modifications of modulator for regulating the mean frequency using a phase locked loop
    • H03C3/0916—Modifications of modulator for regulating the mean frequency using a phase locked loop with frequency divider or counter in the loop
    • H03C3/0925—Modifications of modulator for regulating the mean frequency using a phase locked loop with frequency divider or counter in the loop applying frequency modulation at the divider in the feedback loop

Definitions

  • This invention relates to a transmitter controller, and particularly, but not exclusively, to a controller for controlling a transmitter for transmitting and receiving digital signals.
  • a varactor diode is used to pull the frequency of a received signal to a predetermined desirable frequency.
  • a varactor diode is a diode, the voltage output of which varies with its capacity, in other words it is an electrically variable capacitor and is used to convert analogue signals received by a transmitter into digital signals for transmission .
  • VCO voltage controlled oscillator
  • a disadvantage of the known means for controlling the output of a transmitter results from the fact that a varactor is an analogue device in that its voltage output varies continuously, but non-linearly with its capacitance. This means that the signals transmitted by the transmitter are only approximately digital and therefore there is a wide variation in the frequency at which either a data zero or a data one may be located.
  • a disadvantage of such a system is that a wide band channel is required for transmission of the signals because the frequency of the data zero signals, and the data one signals may vary significantly. A wide band is required to ensure separation of the data one signals and the data zero signals.
  • the above described method of controlling a transmitter output are used for both digital and analogue received signals.
  • a transmitter controller comprising: a synthesiser; a voltage controlled oscillator, the synthesiser and voltage controlled oscillator being connected to one another in a feedback loop, means for producing a signal at a predetermined frequency which signal comprises a reference signal; input means for inputting the reference signal into the synthesiser, and output means for outputting a digital signal having a frequency falling with the radio frequency (rf) waveband.
  • the transmitter controller according to the present invention thus obviates the need to use a varactor diode.
  • a varactor diode is an analogue device, and by obviating the need to use such a device, true digital signals may be produced for transmission.
  • the means for producing a signal at a predetermined frequency comprises a crystal .
  • the crystals may be any suitable crystals such as quartz.
  • the controller further comprises a variable capacitor for initially tuning the frequency of the signal produced by the crystal to a predetermined frequency.
  • the frequency of the signal produced by the crystal will remain constant .
  • the frequency of either a data zero or a data one signal will therefore be substantially constant and will vary by a small amount only. Consequently, in order to ensure separation between data one signals and data zero signals, it is not necessary to use such a wide band.
  • the data one signals and the data zero signals may be allocated frequencies which are closer together to one another than had previously been possible. This is particularly advantageous as the airwaves are becoming more and more crowded, and by having narrower band requirements, more users may be accommodated.
  • the controller further comprises a processor for processing incoming digital data.
  • the processor comprises a "divide by" register.
  • Figure 1 is a schematic representation of a known transmitter controller
  • Figure 2 is a schematic representation of a transmitter controller according to the present invention.
  • Figure 3 is a schematic representation of the processor of the controller of Figure 2.
  • a known transmitter controller is designated generally by the reference numeral 10.
  • the controller comprises a synthesiser 12, a voltage controlled oscillator 14, a radio frequency (rf) antenna 16, a crystal 18 and a varactor 20.
  • rf radio frequency
  • the synthesiser 12 and the voltage controlled oscillator 14 are connected together to form a feedback loop.
  • Scale data enters the synthesiser at input 22.
  • Data to be transmitted, for example, in the form of speech enters the controller via the crystal 20 at input 24.
  • the data entering at 24 will be serial data in the forms of zeros and ones.
  • the crystal oscillates at a frequency of say lOmHz.
  • the signal from the crystal serves as a reference signal.
  • the serial data entering at input 24 will either be high (data one) or low (data zero) .
  • the signal transmitted at 16 must correspond to the data coming in at 24. In other words " when a data one is input at 24 , a high signal must be transmitted at 16, and when a data zero is input at 24 a low signal must be output at 16.
  • a transmitter controller according to the present invention is designated generally by the reference numeral 50.
  • the controller comprises a synthesiser 52, a voltage controlled oscillator 54, a signal processor 56, a crystal 58 and a variable capacitor 60.
  • Data to be transmitted enters the system at 62.
  • the data is serial data in the form of a series of ones and zeros.
  • the frequency at which the crystal 58 oscillates remains constant throughout transmission.
  • the variable capacitor 60 is used to tune the crystal initially and thereafter is not used.
  • the synthesiser comprises a first "divide by" 64 and a second "divide by" 66.
  • the first "divide by" 64 is used to process scale data and the second "divide by" 66 is used to process the reference data from the crystal.
  • the synthesiser is shown in more detail in Figure 3.
  • the synthesiser 52 comprises the first "divide by" 64, a second "divide by” 66 and a phase' locked loop 70.
  • the frequency of signals output at antenna 72 is say, 430MHz for a low signal and 430.01MHz for a high signal .
  • the crystal 58 oscillates at a frequency of 1MHz . Crystals which oscillate at a frequency of about 1MHz are commonly available and are therefore relatively cheap to purchase.
  • the reference signal with a frequency of 1MHz enters the signal processor so where it is divided by 100 by "divide by" 66. This means that the reference frequency (f ref) product is 10kHz.
  • the output signal is divided by 43,000 by "divide by" 64 which means that the frequency of the output signal product (f out) is also 10kHz.
  • the f ref product and the f out product are arranged to remain constant throughout transmission.
  • the scale data is varied in response to incoming data.
  • the reference signal remains constant.
  • the frequency of the reference signal remains 1MHz and is divided by 100 to produce an f ref product of 10kHz.
  • the frequency of the output signal is divided by 43,001. This means that the f out product stays at 10kHz and the frequency of the output signal at the antenna is 430.01mHz.

Abstract

A transmitter controller (50) comprises a synthesiser (52), a voltage controlled oscillator (54), a signal processor (56), a crystal (58) and a variable capacitor (60). Data to be transmitted enters the system at 62. The data is scale data in the form of a series of 1's and 0's. The frequency at which the crystal (58) oscillates remains constant throughout transmission. The variable capacitor (60) is used to initially tune the crystal. The synthesiser comprises a first 'divide by' (64) and second 'divide by' (66). The first divide by (64) is used to process scale data and the second divide by (66) is used to process the reference data from the crystal.

Description

TRANSMITTER CONTROLLER
This invention relates to a transmitter controller, and particularly, but not exclusively, to a controller for controlling a transmitter for transmitting and receiving digital signals.
It is known to control the output of a transmitter using a varactor diode. A varactor diode is used to pull the frequency of a received signal to a predetermined desirable frequency.
A varactor diode is a diode, the voltage output of which varies with its capacity, in other words it is an electrically variable capacitor and is used to convert analogue signals received by a transmitter into digital signals for transmission .
It is known to use a varactor in combination with a synthesised radio and a voltage controlled oscillator (VCO) which together form a feedback loop. Such a circuit will produce approximately digital signals which may be transmitted within the radio frequency by a transmitter.
A disadvantage of the known means for controlling the output of a transmitter results from the fact that a varactor is an analogue device in that its voltage output varies continuously, but non-linearly with its capacitance. This means that the signals transmitted by the transmitter are only approximately digital and therefore there is a wide variation in the frequency at which either a data zero or a data one may be located.
A disadvantage of such a system is that a wide band channel is required for transmission of the signals because the frequency of the data zero signals, and the data one signals may vary significantly. A wide band is required to ensure separation of the data one signals and the data zero signals. The above described method of controlling a transmitter output are used for both digital and analogue received signals.
According to the present invention there is provided a transmitter controller the controller comprising: a synthesiser; a voltage controlled oscillator, the synthesiser and voltage controlled oscillator being connected to one another in a feedback loop, means for producing a signal at a predetermined frequency which signal comprises a reference signal; input means for inputting the reference signal into the synthesiser, and output means for outputting a digital signal having a frequency falling with the radio frequency (rf) waveband.
The transmitter controller according to the present invention thus obviates the need to use a varactor diode. As mentioned hereinabove a varactor diode is an analogue device, and by obviating the need to use such a device, true digital signals may be produced for transmission.
Advantageously, the means for producing a signal at a predetermined frequency comprises a crystal .
The crystals may be any suitable crystals such as quartz.
Preferably, the controller further comprises a variable capacitor for initially tuning the frequency of the signal produced by the crystal to a predetermined frequency.
Once the initial tuning has been effected, the frequency of the signal produced by the crystal will remain constant .
The frequency of either a data zero or a data one signal will therefore be substantially constant and will vary by a small amount only. Consequently, in order to ensure separation between data one signals and data zero signals, it is not necessary to use such a wide band. In other words the data one signals and the data zero signals may be allocated frequencies which are closer together to one another than had previously been possible. This is particularly advantageous as the airwaves are becoming more and more crowded, and by having narrower band requirements, more users may be accommodated.
Preferably the controller further comprises a processor for processing incoming digital data.
Preferably the processor comprises a "divide by" register.
The invention will now be further described by way of example only with reference to the accompanying drawings in which:
Figure 1 is a schematic representation of a known transmitter controller;
Figure 2 is a schematic representation of a transmitter controller according to the present invention;
Figure 3 is a schematic representation of the processor of the controller of Figure 2.
Referring to Figure 1, a known transmitter controller is designated generally by the reference numeral 10. The controller comprises a synthesiser 12, a voltage controlled oscillator 14, a radio frequency (rf) antenna 16, a crystal 18 and a varactor 20.
The synthesiser 12 and the voltage controlled oscillator 14 are connected together to form a feedback loop.
Scale data enters the synthesiser at input 22. Data to be transmitted, for example, in the form of speech enters the controller via the crystal 20 at input 24. The data entering at 24 will be serial data in the forms of zeros and ones.
The crystal oscillates at a frequency of say lOmHz. The signal from the crystal serves as a reference signal. The serial data entering at input 24 will either be high (data one) or low (data zero) .
The signal transmitted at 16 must correspond to the data coming in at 24. In other words" when a data one is input at 24 , a high signal must be transmitted at 16, and when a data zero is input at 24 a low signal must be output at 16.
In order to achieve this result, in the prior art system the frequency at which the crystal 18 oscillates is pulled by a varactor diode 20 appropriately. The scale data entering at 22 remains constant throughout the transmission. A disadvantage with this known system is that the use of the varactor diode introduces an analogue component into the system which introduces inaccuracies in the output frequency. In other words, there is a wide variation in the frequency of signals transmitted at 16 corresponding to a "data high" signal. Similarly there is a wide variation in the frequency of signals transmitted at 16 corresponding to a "data low" signal. This means that a wide band is necessary to ensure that the high and low signals output at 16 are separated from one another.
Referring to Figure 2, a transmitter controller according to the present invention is designated generally by the reference numeral 50. The controller comprises a synthesiser 52, a voltage controlled oscillator 54, a signal processor 56, a crystal 58 and a variable capacitor 60.
Data to be transmitted enters the system at 62. The data is serial data in the form of a series of ones and zeros.
The frequency at which the crystal 58 oscillates remains constant throughout transmission. The variable capacitor 60 is used to tune the crystal initially and thereafter is not used. The synthesiser comprises a first "divide by" 64 and a second "divide by" 66. The first "divide by" 64 is used to process scale data and the second "divide by" 66 is used to process the reference data from the crystal.
The synthesiser is shown in more detail in Figure 3. The synthesiser 52 comprises the first "divide by" 64, a second "divide by" 66 and a phase' locked loop 70.
In the illustrated example, the frequency of signals output at antenna 72 is say, 430MHz for a low signal and 430.01MHz for a high signal .
The crystal 58 oscillates at a frequency of 1MHz . Crystals which oscillate at a frequency of about 1MHz are commonly available and are therefore relatively cheap to purchase. The reference signal with a frequency of 1MHz enters the signal processor so where it is divided by 100 by "divide by" 66. This means that the reference frequency (f ref) product is 10kHz.
The output signal is divided by 43,000 by "divide by" 64 which means that the frequency of the output signal product (f out) is also 10kHz.
According to the present invention the f ref product and the f out product are arranged to remain constant throughout transmission. In order to maintain these products constant, the scale data is varied in response to incoming data. The reference signal remains constant.
This means that if a high signal is to be transmitted, the frequency of the reference signal remains 1MHz and is divided by 100 to produce an f ref product of 10kHz. The frequency of the output signal is divided by 43,001. This means that the f out product stays at 10kHz and the frequency of the output signal at the antenna is 430.01mHz.
By maintaining the reference signal constant, it is not necessary to use a varactor diode which means that the system is truly digital . This means that the frequency of the high and low signals transmitted by the antenna are more accurately placed and therefore a narrower band width may be allocated for the transmission.

Claims

CLAIMS :
1. A transmitter controller comprising: a synthesiser; a voltage controlled oscillator, the synthesiser and voltage controlled oscillator being connected to one another in a feedback loop, means for producing a signal at a predetermined frequency which signal comprises a reference signal; input means for inputting the reference signal into the synthesiser, and output means for outputting a digital signal having frequency falling within the radio frequency (RF) waveband .
2. A transmitter controller according to claim 1, wherein the means for producing a signal at a predetermined frequency comprises a crystal .
3. A transmitter controller according to claim 1 or claim 2, further comprising a variable capacitor for initially tuning the frequency of the signal produced by the crystal to a predetermined frequency.
4. A controller according to any one of the preceding claims, further comprising a process for processing incoming digital data.
5. A transmitter controller according to claim 4, wherein the processor comprises a "divide by" register.
PCT/GB1997/002187 1996-08-17 1997-08-14 Transmitter controller WO1998008299A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU39487/97A AU3948797A (en) 1996-08-17 1997-08-14 Transmitter controller

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9617313.3A GB9617313D0 (en) 1996-08-17 1996-08-17 Transmitter controller
GB9617313.3 1996-08-17

Publications (1)

Publication Number Publication Date
WO1998008299A1 true WO1998008299A1 (en) 1998-02-26

Family

ID=10798631

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1997/002187 WO1998008299A1 (en) 1996-08-17 1997-08-14 Transmitter controller

Country Status (3)

Country Link
AU (1) AU3948797A (en)
GB (1) GB9617313D0 (en)
WO (1) WO1998008299A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999049565A1 (en) * 1998-03-24 1999-09-30 Microchip Technology Incorporated Adjustable frequency stabilizing internal chip capacitor system

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2069788A (en) * 1980-02-13 1981-08-26 Inst Tele I Radiotech Improvements in or relating to tuneable quartz overtone oscillators
US4492936A (en) * 1981-08-17 1985-01-08 Thomson-Csf Fractional-division frequency synthesizer for digital angle-modulation
EP0522425A1 (en) * 1991-07-02 1993-01-13 Canon Kabushiki Kaisha Signal generating device
EP0550249A2 (en) * 1991-12-31 1993-07-07 Nokia Mobile Phones Ltd. Modulation method and circuit arrangement
GB2270218A (en) * 1992-07-15 1994-03-02 Futaba Denshi Kogyo Kk Radio control device
US5467373A (en) * 1992-01-15 1995-11-14 Robert Bosch Gmbh Digital frequency and phase modulator for radio transmission

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2069788A (en) * 1980-02-13 1981-08-26 Inst Tele I Radiotech Improvements in or relating to tuneable quartz overtone oscillators
US4492936A (en) * 1981-08-17 1985-01-08 Thomson-Csf Fractional-division frequency synthesizer for digital angle-modulation
EP0522425A1 (en) * 1991-07-02 1993-01-13 Canon Kabushiki Kaisha Signal generating device
EP0550249A2 (en) * 1991-12-31 1993-07-07 Nokia Mobile Phones Ltd. Modulation method and circuit arrangement
US5467373A (en) * 1992-01-15 1995-11-14 Robert Bosch Gmbh Digital frequency and phase modulator for radio transmission
GB2270218A (en) * 1992-07-15 1994-03-02 Futaba Denshi Kogyo Kk Radio control device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999049565A1 (en) * 1998-03-24 1999-09-30 Microchip Technology Incorporated Adjustable frequency stabilizing internal chip capacitor system
US6058294A (en) * 1998-03-24 2000-05-02 Microchip Technology Incorporated Adjustable frequency stabilizing internal chip capacitor system

Also Published As

Publication number Publication date
GB9617313D0 (en) 1996-09-25
AU3948797A (en) 1998-03-06

Similar Documents

Publication Publication Date Title
US5430890A (en) Radio receiver for mobile reception with sampling rate oscillator frequency being an integer-number multiple of reference oscillation frequency
US5973570A (en) Band centering frequency multiplier
JPS62272629A (en) Method and apparatus for controlling operating frequency andat least one other variable operating parameter of wireless communication apparatus
CA2104182A1 (en) Double Conversion Digital Tuning System
NO165270B (en) PROCEDURE FOR TUNING THE CIRCUIT CIRCUITS IN AN INFORMATION RECEIVER.
WO1999000902A1 (en) Communication device a frequency compensating synthesizer and method of providing same
EP2247959A1 (en) Integrated frequency calibration architecture
EP0495514A2 (en) Auto-tuned apparatus for band-pass filter
US6535719B1 (en) FM transmitter
US5243356A (en) Antenna circuit and wrist radio instrument
GB2292867A (en) Radio system with means to reduce interference due to radiation of clock signal
EP0565362B1 (en) Frequency tuning with synthesizer
US6509802B2 (en) PLL-tuning system having a phase detector with a sampling frequency equal to a reference frequency
WO1998008299A1 (en) Transmitter controller
US4320357A (en) VHF-FM Frequency synthesizer
US4097816A (en) Tuning system
US6091943A (en) Combining oscillator with a phase-indexed control circuit for a radio receiver
NO164330C (en) PROCEDURE FOR AUTOMATIC TRIMMING OF TELECOMMUNICATION RECEIVER DEVICES.
US4095190A (en) Tuning system
US4816782A (en) Modulation sensitivity correction circuit for voltage-controlled oscillator
KR19990080891A (en) Phase lock frequency synthesizer with multiple bands
EP1271788B1 (en) Circuits for use in radio communications
EP1689083B1 (en) Am/fm radio receiver and local oscillator circuit used therein
EP0182549A1 (en) Radio frequency synthesis
US4095183A (en) Tuning circuit

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AU CA JP US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FI FR GB GR IE IT LU MC NL PT SE

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase

Ref country code: JP

Ref document number: 1998510490

Format of ref document f/p: F

122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: CA