An Inexpensive High Speed Modem for the Universal SerialBus (USB)
Thomas Sailer, HB9JNX/AE4WA,and
Johannes Kneip, DG3RBU
August 3, 1999
Abstract
This article describes a simple and inexpensive modem intended to link end users at 76.8kBit/s tothe high speed backbone network. The modem can be connected to standard PC’s using the UniversalSerial Bus (USB).
1 Introduction
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3 DESIGN CONSIDERAT/ONS
2 Design Goals
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3 Design Consi
3.1 Microcontroller selection
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3 DESIGN CONSIDERATIONS
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3.2 Power Supply Considerations
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3.3 Firm ware Download
3.3 Firmware Download
3.4 The FSK Mode
3 DESIGN CONSIDERATIONS
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3.5 The AFSK Mode
3.6 Modification of the analog circuitry for AFSK demodulation
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3.6 Modification of the analog circuitry for AFSK demodulation
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3 DESIGN CONSIDERATIONS
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3.7 The Demodulator
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3.7 The Demodulator
5 STATE OF THE PROJECT
3.8 The Modulator
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3.9 Microcontroller Interface
4 The Analog IO mode
5 State of the Project
6 Conclusion
7 Outlook
112
REFERENCES
References
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[ll] Nimpalenxp, Iv3NWy YetA?wtkr9k6ilBmkrnhttp://j~iter.~host~g,cam/-Ilicopal/~/
[12] Janus C chndy, an&Gabor C Tm, C%erxznpZing~~for~dL)/A Ccwtversion, IEEE?Circuits and System society, 1992, ISBNO-87942-285-8
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