Patent US5500871A successfully refreshed from Google Patents.
US5500871A
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Spread spectrum communication transmitter an LSI therefor
Assignee: Mitsui Kinzoku Co Ltd
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Filing: 1994-04-08
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Granted: 1996-03-19
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Expires: 2014-04-08
Abstract
Abstract High-sensitivity transmission can be performed in a wide temperature range, and spread spectrum communication free from jitters and bit errors in high-speed digital signal transmission can be performed. There is provided a spread spectrum communication transmitter for performing FSK modulation for switching the frequency in correspondence with the level of each bit of the serial digital data, performing spread spectrum modulation of a resultant FSK-modulated signal, and transmitting the data, wherein an FSK modulation unit (1) for performing the FSK modulation has a direct digital synthesizer and a synchronization circuit (19) is arranged to synchronize an FSK signal having a frequency corresponding to at least one level of the each bit with a PN code for the spread spectrum modulation.
Inventors
- 👤 Shunji Kato
- 👤 Hiromitsu Miyajima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 04:09
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/69
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
133 words
A spread spectrum communication transmitter comprising: FSK modulation means for performing FSK modulation for switching frequency in correspondence with whether a binary level of each bit of the serial digital data to be transmitted is high or low, and SS modulation means for performing spread spectrum modulation of a resultant FSK-modulated signal and transmitting resultant data, wherein said FSK modulation means comprises a direct digital synthesizer and synchronizes an FSK modulation signal having a frequency corresponding to at least one binary level of said each bit with a PN code for the spread spectrum modulation, said PN code having a period which does not vary based upon a ratio of a number of said high level bits of said serial data to a number of said low level bits of said serial data.
Claim 2
Dependent Claim
133 words
A spread spectrum communication transmitter comprising: FSK modulation means for performing FSK modulation for switching frequency in correspondence with whether a binary level of each bit of the serial digital data to be transmitted is high or low, and SS modulation means for performing spread spectrum modulation of a resultant FSK-modulated signal and transmitting resultant data, wherein said FSK modulation means comprises a direct digital synthesizer and synchronizes an FSK modulation signal having a frequency corresponding to at least one binary level of said each bit with a PN code for the spread spectrum modulation, said PN code having a period which does not vary based upon a ratio of a number of said high level bits of said serial data to a number of said low level bits of said serial data.
Claim 3
Dependent Claim
116 words
A transmitter according to claim 1 further comprising a synchronization means for synchronizing a first clock for said direct digital synthesizer with a second clock for generating the PN code, wherein said FSK modulation means reads out, in a phase of every integer fraction of 2 in response to the first clock, an amplitude value of a sine or cosine wave stored in a sine or cosine wave memory constituting said direct digital synthesizer, said integer being switched in its number in accordance with whether a binary level of each bit of said serial digital data is high or low,-thereby forming sine or cosine wave FSK signals each having a frequency corresponding to said binary level.
Claim 4
Dependent Claim
97 words
An integrated circuit used in a spread spectrum communication transmitter for performing an FSK modulation of digital data, performing spread spectrum modulation of an FSK-modulated signal, and transmitting resultant data, comprising a direct digital synthesizer for forming the FSK-modulated signal in response to a first clock, a PN code generator for generating a PN code for the spread spectrum modulation in response to a second clock, said PN code having a sequence that is independent of serial digital data that is to be transmitted, and a synchronization circuit for synchronizing the first clock with the second clock.
Claim 5
Dependent Claim
97 words
An integrated circuit used in a spread spectrum communication transmitter for performing an FSK modulation of digital data, performing spread spectrum modulation of an FSK-modulated signal, and transmitting resultant data, comprising a direct digital synthesizer for forming the FSK-modulated signal in response to a first clock, a PN code generator for generating a PN code for the spread spectrum modulation in response to a second clock, said PN code having a sequence that is independent of serial digital data that is to be transmitted, and a synchronization circuit for synchronizing the first clock with the second clock.
Claim 6
Dependent Claim
105 words
A spread spectrum communication transmitter comprising: PN generating means for generating a PN code sequence: FSK modulation means for subjecting serial digital data to be transmitted to a frequency shift keying modulation and outputting a resultant FSK-modulated signal; and SS modulation means for subjecting said FSK-modulated signal to a spectrum spread modulation using said PN code, said PN code having a sequence that is independent of said serial digital data that is to be transmitted, wherein said FSK modulation means comprises a direct digital synthesizer and at least one of FSK modulation signals for said frequency shift keying modulation is synchronized with said PN code.
Claim 7
Dependent Claim
105 words
A spread spectrum communication transmitter comprising: PN generating means for generating a PN code sequence: FSK modulation means for subjecting serial digital data to be transmitted to a frequency shift keying modulation and outputting a resultant FSK-modulated signal; and SS modulation means for subjecting said FSK-modulated signal to a spectrum spread modulation using said PN code, said PN code having a sequence that is independent of said serial digital data that is to be transmitted, wherein said FSK modulation means comprises a direct digital synthesizer and at least one of FSK modulation signals for said frequency shift keying modulation is synchronized with said PN code.
Claim 8
Dependent Claim
118 words
A transmitter according to claim 4 additionally comprising a synchronization means for synchronizing a first clock for said direct digital synthesizer with a second clock for generating the PN code, wherein said FSK modulation means reads out, in a phase of every integer fraction of 2π in response to the first clock, an amplitude value of a sine or cosine wave stored in a sine or cosine wave memory constituting said direct digital synthesizer, said integer being switched in its number in accordance with whether a binary level of each bit of said serial digital data is high or low, thereby forming sine or cosine wave FSK modulation signals each having a frequency corresponding to said binary level.
Claim 9
Dependent Claim
25 words
A transmitter according to claim 5, wherein said synchronization means synchronizes a predetermined number of the first clock with one period of said PN code.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-03-19 | 1999-09-18 | 2000-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-03-19 | 2003-09-18 | 2004-03-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-03-19 | 2007-09-18 | 2008-03-19 | $7700.00 | Window Closed / Lapsed |