GB2039441A - Frequency synthesizer - Google Patents
Frequency synthesizer Download PDFInfo
- Publication number
- GB2039441A GB2039441A GB7943489A GB7943489A GB2039441A GB 2039441 A GB2039441 A GB 2039441A GB 7943489 A GB7943489 A GB 7943489A GB 7943489 A GB7943489 A GB 7943489A GB 2039441 A GB2039441 A GB 2039441A
- Authority
- GB
- United Kingdom
- Prior art keywords
- signal
- khz
- synthesizer
- frequency
- output
- 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
- 230000002194 synthesizing effect Effects 0.000 claims abstract description 11
- 238000000034 method Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 230000001131 transforming effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B21/00—Generation of oscillations by combining unmodulated signals of different frequencies
- H03B21/01—Generation of oscillations by combining unmodulated signals of different frequencies by beating unmodulated signals of different frequencies
- H03B21/02—Generation of oscillations by combining unmodulated signals of different frequencies by beating unmodulated signals of different frequencies by plural beating, i.e. for frequency synthesis ; Beating in combination with multiplication or division of frequency
- H03B21/025—Generation of oscillations by combining unmodulated signals of different frequencies by beating unmodulated signals of different frequencies by plural beating, i.e. for frequency synthesis ; Beating in combination with multiplication or division of frequency by repeated mixing in combination with division of frequency only
Landscapes
- Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
- Transmitters (AREA)
- Superheterodyne Receivers (AREA)
- Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
- Radio Relay Systems (AREA)
Abstract
A frequency synthesizer has at least one signal synthesizer II, III, IV driven by a basic signal 1 composed of an 8 kHz signal and of its odd harmonic frequencies for producing pilot frequency signals 36,38,40 (of 84,08 kHz, 84,14 kHz and 104,08 kHz) and corresponding carrier frequency signals at 37,39,41 which are each 12.08 kHz less than the associated pilot frequency signal, an auxiliary synthesizer I deriving the difference frequency at 42 (12.08 kHz) from the basic signal, this being used (at 12, 17,29) to derive the pilot signal from the carrier. In the signal synthesizer II, a filter circuit such as 14, 16 is used to produce the carrier frequency signal, and a synthesizing circuit comprising a modulator 12, in which the basic signal and the carrier frequency signal are combined, a band pass filter 13 and an amplifier 15, is used to obtain the required pilot frequency signal. <IMAGE>
Description
SPECIFICATION
Frequency synthesizer for generating pilot frequency and carrier frequency signals.
The present invention relates to a frequency synthesizer for generating pilot frequency and carrier frequency signals, which comprises an auxiliary synthesizer for providing on its output an auxiliary frequency signal, and at least one signal synthesizer for generating the pilot frequency signal on its first output and for generating the carrier frequency on its second output, the carrier frequency signal having a frequency which is 12.08 kHz less than the pilot frequency, both the signal and auxiliary synthesizers having band-pass filter means, amplifier means, modulator means and, preferably, frequency divider means and having respective first inputs connected to each other for receiving a basic signal, the signal synthesizer comprising a second input connected to the output of the auxiliary synthesizer.
The synthesizer according to the invention generates pilot frequency and carrier frequency signals used in telecommunication systems so that the parameters of these signals meet the CCITT requirements.
In telecommunication systems undisturbed operation is generally ensured by means of various pilot and carrier frequency signals. These signals are commonly generated by two methods. The first method is based on the application of different oscillators for generating signals of different frequencies. In this case frequent frequency control is required. According to the second method the required frequencies are synthesized from a common basic frequency signal. In the synthesizing process complicated electric circuits are required, though the only frequency control needed is for the basic frequency. In these circuits frequency dividers, multipliers and modulators, further band-pass filters as well as amplifiers are generally used.
A frequency synthesizing device is described in the German Patent No. 1 260 546. In this device the signals of required frequencies (having values of 40, 48,60,72, 100, 114,300,420 and 496kHz) are synthesized in different groups from a basic signal of 12kHz. The pilot and carrier frequency signals are generated on the basis of these signals. This device is characterized by a sophisticated circuit structure, and comprises a very sophisticated unit for generating the basic frequency signal.
The object of the present invention is to provide a frequency synthesizer which can generate the required values (84.08kHz, 84.14kHz and 104.08 kHz) of the frequency of the pilot and carrier signals using subsantially fewer means and units than the prior art.
The invention is based on the recognition, that the structural design of a frequency synthesizer can be simplified by using a basic signal composed of an 8 kHz signal and of its odd harmonic frequencies in combination with an auxiliary signal of 12.08kHz generated by the premodulation of the basic signal, and by generating the required pilot and carrier frequency signals by suitably transforming the au xiliaryfrequency signal and the basic signal. The structural design of the device can furthermore be simplified when each pilot frequency signal is gener- ated in respective separate units together with the suitable carrier frequency signal associated therewith. If the ratio of the input and output frequencies of the frequency dividers is always an even number, the structure of the band-pass filters can be simplified.It is also advantageous to use intermediate frequencies so that the modulation products thereof should lie far from the frequencies used.
According to the invention there is provided a frequency synthesizer for generating pilot frequency and carrier frequency signals, comprising an auxiliary synthesizer for providing on its output an auxiliary frequency signal of 12.08 Hz and at least one signal synthesizer for generating said pilot frequency signal on its first output and for generating said carrierfrequency signal on its second output, said carrier frequency signal having a frequency which is 12.08 kHz less than the pilot frequency, wherein the auxiliary and signal synthesizers have respective first inputs for receiving a basic signal composed of an 8 kHz signal and its odd harmonic frequencies, and said signal synthesizer comprises a second input connected to the output of said auxiliary synthesizer, and wherein the auxiliary synthesizer the input thereof is connected to a common input terminal of a pair of band pass filters for selecting signals of 104 kHz and 168 kHz, respectively, from the basic signal and the output terminals of the band - pass filters are connected to a circuit for generating the auxiliary frequency signal of 12.08 kHz in response to the output signals of the said band - pass filters and wherein the or each signal synthesizer comprises a filter circuit for generating the said carrier frequency signals and a synthesizing circuit for generating a pilot frequency signal of 84.08 kHz or 84.14 kHz or 104.08 kHz, the filter circuit comprising a band - pass filter and having an input coupled to the first input of the signal synthesizer and providing at its output the said carrier frequency signal generated from the basic signal, the input of the said synthesizing circuit being coupled to the said second input of the signal synthesizer, the said synthesizing circuit comprising a modulator having an input coupled to the said second input for receiving the said auxiliary signal and another input coupled to the output of said filter circuit, the said synthesizing circuit comprising band-pass filter means connected between the output of said modulator and said first output of the signal synthesizer.
In an advantageous embodiment of the invention the band-pass filter of the signal synthesizer is tuned either to 72 kHz, 168 kHz or 184 kHz in order to generate a corresponding pilot frequency signal of 84.08 kHz, 84.14 kHz or 104.08 kHz frequency.
In an advantageous embodiment of the invention both the signal and auxiliary synthesizer units comprise frequency divider means in which the ratio of the input and output frequencies is always an even number.
The device according to the invention can be constructed using substantially fewer circuit units than the prior art. The device according to the invention can be modular in structure, which facili tates both the production and the use of the device, since each signal synthesizer can be replaced or switched out without disturbing the operation of the other signal synthesizer(s).
An embodiment of the invention is shown in the accompanying drawing which is a block diagram.
The illustrated embodiment comprises a harmonic generator 1 coupled to an input 43 of an auxiliary synthesizer I and to inputs 44,45,46 of respective signal synthesizers ll, III and IV. The harmonic generator 1 generates a basic signal composed of an 8 kHz signal and its odd harmonic frequencies. An output 42 of the auxiliary synthesizer I is connected to inputs 47,48 and 49 of the respective signal synthesizers II, lli and IV. The signal synthesizers ll, lil and IV are driven through the inputs 44,45 and 46 respectively by the basic signal and through the inputs 47, 48 and 49 respectively by an auxiliary signal of 12.08 kHzfrequency generated on the output 42 by the auxiliary synthesizer I.The signal synthesizer II comprises an output 36 for delivering the pilot frequency signal of 84.08 kHz and an output 37 for providing the carrier frequency signal of 72.00 kHz. The signal synthesizer III comprises an output 38 for delivering the pilot frequency signal of 84.14 kHz and an output 39 for providing the carrier frequency signal of 72.06 kHz. The signal synthesizer
IV comprises an output 40 for delivering the pilot frequency signal of 104.08 kHz and an output 41 for providing the carrier frequency signal of 92.00 kHz.
The input 43 of the auxiliary synthesizer I is connected to a common terminal of a pair of band-pass filters 9 and 2 used for the selective passage of signals having respective frequencies of 104 kHz and 168 kHz. The output terminals of the band-pass filters 2 and 9 are connected to the input of a respective signal processing series chain. The first chain comprises the band-pass filter 2 tuned to 168 kHz, a frequency divider 3 with a dividing ratio of 1!1 0, a band-pass filter 4 turned to 16.8 kHz and coupled to an input of a modulator 5, a band-pass filfter 6 tuned to 120.8 kHz, a frequency divider 7 with a dividing ratio of 1'10, a band-pass filter 8 tuned to 12.08 kHz and an amplifier 10. The output of the chain is coupled to the output 42 of the auxiliary synthesizer I.The second chain consists only of two units i.e. the input band-pass filter 9 tuned to 104 kHz and an amplifier 11. The output of the amplifier 11 is
connected to another input of the modulator 5.
The input band - pass filters 2 and 9 are driven by the basic signal of the harmonic generator 1, which basic signal comprises only an 8 kHz signal and its odd harmonic frequencies. Therefore the input band-pass filters can have a simple design. The dividing ratio of the frequency divider 3 is an even number, therefore the markispace ratio of the output signal of the divider is equal to 1 : 1. From this follows that the even multiples of the 16.8 kHz frequency will be virtually absent from the output signal of the divider and this fact simplifies the structural design of the band-pass filter 4.With the given frequency values the two signals fed to the modulator 5 cannot produce high modulation components near to the operational frequency of the modulator 5 of 120.8 kHz, and therefore the bandpass filter 6 can be made from comparatively few elements. The selected even number for the dividing ratio of the frequency divider 7 simplifies the structural design of the band-pass filter 8. The band-pass filter 8 transforms the rectangular output signal of the frequency divider 7 to a sine wave, and this wave is amplified by the amplifier 10 which couples the auxiliary signal of 12.08 kHz thus obtained to the output 42 of the auxiliary synthesizer 1.
The signal synthesizer II is fed in the aforesaid way i.e. by the auxiliary signal through the input 47 connected to an input of a modulator 12, as well as by the basic signal through the input 44 connected to an input band-pass filter 14 tuned to 72 kHz. The output of the band-pass filter 14 is coupled to an amplifier 16. The amplified signal, being the carrier frequency signal of 72.00 kHz, is supplied to a second input of the modulator 12, as well as to the output of the signal synthesizer II. The output signal of the modulator 12 is selected in a band-pass filter 13 tuned to 84.08 kHz and fed to the output 36 of the signal synthesizer II as the pilot frequency of 84.08 kHz after having been amplified in an amplifier 15.
The frequency values used in the units 12, 13 and 15 are very preferable, because in that case the disturbing components will be far away from the utilized frequency of 84.08 kHz, whereby the band-pass filter 13 can be designed with a small number of elements.
The signal synthesizer Ill comprises three signal generating series chains. The input 48 of the signal synthesizer III is connected to a common input terminal of the first and of the second chain and this common input terminal is fed by the auxiliary signal of 12.08 kHz. The third series chain is connected to the input 45 of the signal synthesizer Ill and it is driven by the basic signal. The first chain comprises a modulator 17 an input of which is coupled to the common terminal, a band-pass filter 18 tuned to 84.14 kHz and an amplifier 19.The output of the first chain is connected to the output 38 of the signal synthesizer III, which output provides the pilot frequency signal of 84.14kHz. The second chain comprises a frequency divider 20 with a dividing ratio of 1/4, a band-pass filter 21 tuned to 9.06 kHz, a moudlator 22 and a band-pass filter 23 tuned to 72.06 kHz. The output signal of this chain, which forms the carrier frequency signal of 72.06 kHz, is supplied to the output 39 of the signal synthesizer III, as well as to another input of the moudlator 17. The third signal generating chain produces intermediate carrier frequency signal of 63 kHz for the modulator 22 of the second chain. The third chain comprises an input band-pass filter 22 tuned to 168 kHz, a frequency divider 26 with a dividing ratio of 1/8, a band-pass filter 27 tuned to 63 kHz and an amplifier 28.
The frequency of the auxiliary signal is divided in a ratio of 1/4 by the frequency divider 20. The output of the frequency divider 20 provides a rectangular signal of 3,02 kHz frequency, from which the third harmonic frequency i.e. the signal of 9,06 kHz frequency is selected by the band - pass filter 21. The output signal of the frequency divider 20 does not comprise even harmonic frequencies at all, and therefore the band-pass filter 21 can have a relatively simple design. Among the disturbing signals produced by the modulator 22 only the signal of81.12 kHz frequency falls near to the signal of the required 72.06 kHz frequency, so that the band-pass filter 23 can also have a comparatively simple structure.In the first chain the required frequency of 84.14 kHz is generated by the band-pass filter 18 having a comparatively simple design, because this filter must reject only the signals of 72,06 kHz and 59.98 kHz. The input band-pass filter 25 of the third chain selects a signal of 168 kHz frequency, and this frequency is divided by the frequency divider 26 in a ratio of 1/8. The band-pass filter 27 selects the third harmonic frequency i.e. the frequency of 63 kHz from the output rectangular signal of the frequency divider 26. The output signal of the band-pass filter 27, being an intermediate carrier frequency signal, is coupled after having been amplified in the amplifier 28 to the modulator 22.
The signal synthesizer IV consists of two signal generating series chains. The first chain comprises a modulator 29, a band-pass filter 30 tuned to 104.08 kHz and an amplifier 31, and it generates the pilot frequency signal of 104.08 kHz. The input of this chain receives a driving signal, which is the aforesaid auxiliary signal, through the input 49 of the signal synthesizer IV, and the output of the chain provides the above mentioned pilot frequency and is common with the output 40 of the signal synthesizer
IV. The second signal generating chain is fed by the basic signal through the input 46 of the signal synthesizer IV and its output signal, being the carrier frequency signal of 92,00 kHz, is coupled to the modulator 29 of the first chain, as well as to the output 41 of the signal synthesizer IV.This chain comprises an input band-pass filter 32 tuned to 184 kHz, a frequency divider 33 with a dividing ratio of 1/2, a band-pass filter tuned to 92,00 kHz and an amplifier 35.
The input band-pass filter 32 selects a signal of 184 kHz from the basic signal and the selected signal is divided by the frequency divider 33 providing a signal of 92.00 kHz. The rectangular signal thus obtained, having a mark/space ratio of 1:1 is coupled from the output of the frequency divider 33 to the band - pass filter 34. Because of the rectangularity of its input signal the band - pass filter 34 can have a relatively simple design. The output of the band-pass filter 34 provides a sine wave of 92.00 kHz which comprises only the fundamental (first) harmonicfrequency. This signal, being a carrier frequency signal of 92.00 kHz, is coupled to the output 41 of the signal synthesizer IV, as well as to the input of the modulator 29 of the first chain.The band - pass filter 30 is connected to the output of the modulator 29 and must have a high attenuation at the carrier frequency of 92.00 kHz and at an intermediate frequency of 79.92 kHz. The other modulator and
harmonic frequency products fall far from the useful
range so that the required damping factor can be achieved by a relatively simple filter structure.
The frequency synthesizer according to the invention can be constructed with fewer circuit units than conventional synthesizers. For example, owing to the fact that the dividing ratios of the frequency dividers are even numbers, their output signals will be rectangular, and these signals therefore comprise only the odd harmonic frequencies of the basic signal. The band - pass filters can therefore have a relatively simple structure. For example, each of the band-pass filters used for the selection of the first (fundamental) harmonic frequency can simply be a single resonance circuit. The values of the intermediate modulation and auxiliary frequencies used, as can be seen from the above examples, can be selected so that the disturbing modulation products fall far away from the useful frequency values. This fact simplifies the design of the filters. A harmonic generator can be used as a source of the basic signal, and therefore the accuracy and the stability of all output frequency values will be determined by the accuracy and stability of the basic signal. A further advantage of this structural design lies in the fact that the channel carrier frequencies of the telecommunication system in which the present device is used are not used for the synthesis of the output signals, and therefore when the channel carrierfrequencysignals are missing, the pilot frequency signal will not break off. This increases the reliability of the system.
The modular structural construction which can be used for the device according to the invention facilitates both its production and application, since each signal synthesizer can be replaced or switched out without disturbing any other synthesizer in the device.
Claims (4)
1. A frequency synthesizer for generating pilot frequency and carrier frequency signals, comprising an auxiliary synthesizer for providing on its output an auxiliary frequency signal of 12.08 Hz and at least one signal synthesizer for generating said pilot frequency signal on its first output and for generating said carrier frequency signal on its second output, said carrier frequency signal having a frequency which is 12.08 kHz less than the pilot frequency, wherein the auxiliary and signal synthesizers have respective first inputs for receiving a basic signal composed of an 8 kHz signal and its odd harmonic frequencies, and said signal synthesizer comprises a second input connected to the output of said auxiliary synthesizer, and wherein the auxiliary synthesizer the input thereof is connected to a common input terminal of a pair of band pass filters for selecting signals of 104 kHz and 168 kHz, respectively, from the basic signal and the output terminals of the band - pass filters are connected to a circuit for generating the auxiliary frequency signal of 12.08 kHz in response to the output signals of the said band - pass filters and wherein the or each signal synthesizer comprises a filter circuit for generating the said carrier frequency signals and a synthesizing circuit for generating a pilot frequency signal of 84.08 kHz or 84.14 kHz or 104.08 kHz, the filter circuit comprising a band - pass filter and having an input coupled to the first input of the signal synthesizer and providing at its output the said carrier frequency signal generated from the basic signal, the input of the said synthesizing circuit being coupled to the said second input of the signal synthesizer, the said synthesizing circuit comprising a modulator having an input coupled to the said second input for receiving the said auziliary signal and another input coupled to the output of said filter circuit, the said synthesizing circuit comprising band - pass filter means connected between the output of said modulator and said first output of the signal synthesizer.
2. A frequency synthesizer according to claim 1, in which the said band-pass filter of the or each said signal synthesizer is tuned either to 72 kHz, 168 kHz or 184 kHz in order to generate a corresponding pilot frequency signal of 84.08 kHz, 84.14kHz or on 104.08 kHz.
3. A frequency synthesizer according to claim 1 or 2, wherein the auxiliary synthesizer and signal synthesizers comprise frequency divider means in which the ratio of the input and output frequencies is always an even number.
4. A frequency synthesizer substantially as herein described with reference to the accompanying drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| HUTE000919 HU177519B (en) | 1978-12-22 | 1978-12-22 | Frequency synthetiser for generating pilot signals and subcarriers |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2039441A true GB2039441A (en) | 1980-08-06 |
| GB2039441B GB2039441B (en) | 1983-03-23 |
Family
ID=11002089
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7943489A Expired GB2039441B (en) | 1978-12-22 | 1979-12-18 | Frequency synthesizer |
Country Status (8)
| Country | Link |
|---|---|
| BG (1) | BG39300A3 (en) |
| DD (1) | DD148131A5 (en) |
| DE (1) | DE2945987C2 (en) |
| FR (1) | FR2445063A1 (en) |
| GB (1) | GB2039441B (en) |
| HU (1) | HU177519B (en) |
| PL (1) | PL125237B1 (en) |
| RO (1) | RO76970A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2336493A (en) * | 1998-03-18 | 1999-10-20 | Bosch Gmbh Robert | Circuit arrangement for producing frequency signals |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| HU191731B (en) * | 1984-12-19 | 1987-04-28 | Telefongyar | Circuit arrangement for generating system carrier, line pilot and channel carrier-control frequencies of multichannel open cable telephon equipments |
| ES2064746T3 (en) * | 1989-07-20 | 1995-02-01 | Scientific Atlanta | SUB-CARRIER MULTIPLICATION METHOD THAT PRESERVES THE AM INFORMATION IN THE FM SYSTEMS. |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DD68253A (en) * | ||||
| GB780152A (en) * | 1955-11-28 | 1957-07-31 | Standard Telephones Cables Ltd | Improvements in or relating to carrier wave generators |
| GB961028A (en) * | 1960-01-14 | 1964-06-17 | Plessey Co Ltd | Improvements in frequency synthesis apparatus |
| DE1260546B (en) * | 1964-08-26 | 1968-02-08 | Siemens Ag | Arrangement for generating the pilot frequencies in carrier frequency systems |
| DE1762627B2 (en) * | 1968-07-23 | 1971-02-18 | METHOD OF DERIVING THE CHANNEL CARRIER FREQUENCY FROM 112 TO 156 KHZ FOR A PRE-MODULATION CARRIER FREQUENCY SYSTEM | |
| GB1337166A (en) * | 1971-10-28 | 1973-11-14 | Marconi Co Ltd | Frequency generators |
-
1978
- 1978-12-22 HU HUTE000919 patent/HU177519B/en not_active IP Right Cessation
-
1979
- 1979-11-09 BG BG045446A patent/BG39300A3/en unknown
- 1979-11-14 DE DE19792945987 patent/DE2945987C2/en not_active Expired
- 1979-12-11 PL PL22032279A patent/PL125237B1/en unknown
- 1979-12-18 GB GB7943489A patent/GB2039441B/en not_active Expired
- 1979-12-19 RO RO7999610A patent/RO76970A/en unknown
- 1979-12-20 DD DD21794379A patent/DD148131A5/en unknown
- 1979-12-20 FR FR7931284A patent/FR2445063A1/en active Granted
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2336493A (en) * | 1998-03-18 | 1999-10-20 | Bosch Gmbh Robert | Circuit arrangement for producing frequency signals |
| GB2336493B (en) * | 1998-03-18 | 2000-09-27 | Bosch Gmbh Robert | Circuit arrangement for producing frequency signals |
Also Published As
| Publication number | Publication date |
|---|---|
| DD148131A5 (en) | 1981-05-06 |
| FR2445063B1 (en) | 1983-04-22 |
| GB2039441B (en) | 1983-03-23 |
| FR2445063A1 (en) | 1980-07-18 |
| DE2945987A1 (en) | 1980-06-26 |
| DE2945987C2 (en) | 1985-01-17 |
| PL220322A1 (en) | 1980-09-22 |
| RO76970A (en) | 1981-06-22 |
| PL125237B1 (en) | 1983-04-30 |
| BG39300A3 (en) | 1986-05-15 |
| HU177519B (en) | 1981-10-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |