EP0595013A2
Expired / Lapsed
EP
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Digital frequency synthesizer
Assignee: Nokia Spain SA
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Filing: 1993-09-18
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Granted: —
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Expires: 2013-09-18
Abstract
Abstract The synthesizer uses a numerically controlled oscillator (1) to which a reference signal (f ref ) and a programming signal (PROG) are applied in such a way that, from the reference signal an output signal (f out ) is generated with a frequency that depends on the value of the programming signal. It is characterized in that it comprises a control unit (6) whose output is connected to the programming input (PROG) of the numerically controlled oscillator (1), and to which are applied: an external signal (f ext ), both directly and through a counter (5) that counts the pulses in the external signal, and the output signal from the numerically controlled oscillator (1), through a counter (4) that counts the pulses in the output signal; the purpose of the foregoing being to apply a variable signal to the programming input of the numerically controlled oscillator (1) that compensates for the variations in the reference signal frequency and to obtain an output signal with a frequency as accurate and stable as that of the external signal.
Inventors
- 👤 Diego Enrique Perez Calpena
- 👤 Monica Ramos Font
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 02:09
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/08; H03L7/085; H03L7/099; H03L7/0991; H03L7/0994; H03L7/16; H03L7/18; H03L7/181
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
261 words
DIGITAL FREQUENCY SYNTHESIZER , that uses a numerically controlled oscillator (1) to which a reference signal (f ref ) and a programming signal (PROG) are applied in such a way that, from the reference signal (f ref ), an output signal (f out ) is generated with a frequency that depends on the value of the programming signal (PROG), characterized: - in that it comprises a first counter (5) that counts the pulses corresponding to an external signal (f ext ) with a highly accurate and stable frequency, and whose output is applied to a control unit (6); - in that it comprises a second counter (4) that counts the pulses corresponding to the output signal (f out ) generated by the numerically controlled oscillator (1), and whose output is also connected to the control unit (6); - in that the control unit (6) also receives directly the external signal (f ext ) with a highly accurate and stable frequency and provides, at its output, a programming signal (PROG) whose value, at any given moment, and after an initialization, depends on a defined correction criterion that takes into account the result of the calculation of the frequency shift in the output signal (f out ) obtained by the control unit (6) from an analysis of the content of the counters (4, 5), with the object of compensating the variations in the reference signal frequency (f ref ) and producing an output signal (f out ) with a frequency as accurate and stable as that of the external signal (f ext ).
Claim 2
Dependent Claim
298 words
DIGITAL FREQUENCY SYNTHESIZER according to claim 1, characterized: - in that the control unit (6) comprises an interruption generator (7) that receives the external signal (f ext ), whose frequency is highly accurate and stable, and which is connected to a microprocessor (8) from which it receives the programmable value of the period with which it has to interrupt the microprocessor itself, and to which it transmits the interrupt signal (IRQ); - in that the control unit (6) also has a first cyclic storage register (10) for the content of the first pulse counter (5) of the external signal (f ext ), which also receives the external signal (f ext ) that controls said storage, and that is connected to the microprocessor (8); - in that the control unit (6) also has a second cyclic storage register (11) for the content of the second pulse counter (4) of the output signal (f out ), which also receives the external signal (f ext ) that controls said storage, and that is connected to the microprocessor (8); - in that the microprocessor (8) and its associated memory (9) are also connected to a storage register (15) with the value of the programming signal (PROG), and in that, when it is interrupted by the signal (IRQ) coming from the interruption generator (7), has access to the cyclic storage registers (10, 11) in order to read their contents and calculate the shift in the reference frequency and set the new value of the programming signal (PROG) in accordance with the correction criterion; - in that the microprocessor (8) writes the new value of the programming signal (PROG) into the storage register (15), when it is necessary to modify it, its output being connected to the input of the numerically controlled oscillator (1).
Claim 3
Dependent Claim
90 words
DIGITAL FREQUENCY SYNTHESIZER according to claim 2, characterized in that the interruption generator (7) consist of: - a programmable register (12) in which the microprocessor (8) programs the period with which the interruption signal (IRQ) is generated; - a pulse counter (14) for the external signal (f ext ) that is received directly; and - a comparator (13) that compares the contents of the programmable register (12) and the counter (14) and that, when both contents are the same, generates the interruption signal (IRQ) to apply to the microprocessor (8).
Claim 4
Dependent Claim
128 words
DIGITAL FREQUENCY SYNTHESIZER according to claim 1, characterized in that the preferred correction criterion for the programming signal (PROG) as a function of the frequency shift (D) in the reference signal (f ref ) is: - if D = 0, the programming signal (PROG) is unchanged; - if D = -1, PROG = PROG_previous + 1; - if D = + 1, PROG = PROG_previous - 1; and - if |D|> 1, PROG = PROG_0.(f out .CONT_f ext )/f ext .CONT_f out ) where: PROG_0 = initial value of the programming signal f out = value of the desired output signal frequency f ext = value of the highly accurate and stable external frequency CONT_f ext = value in register (10), CONT_f out = value in register (11).
Claim 5
Dependent Claim
47 words
DIGITAL FREQUENCY SYNTHESIZER according to claim 1, characterized in that in a preferred implementation the external signal (f ext ), with a frequency that is highly accurate and stable, consists of a signal at one pulse per second obtained from a Global Positioning System (GPS) satellite receiver.
References Cited (Backward Citations)
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