IEEE Paper Review: Implementation of a modem based on Quadrature Amplitude Modulation using TMS320C6201 DSP
Authors: N Dahnoun and D R Clewer
Publisher: IEEE
Published in: IEE Colloquium on DSP Chips in Real-Time Instrumentation and Display Systems
Location: Leicester, UK,
Date of Conference: 24 September 1997
Summary:
Modems have traditionally been used to enable data communications via PSTN. This is severely band limited channel, requiring use of highly bandwidth efficient modulation schemes such as Quadrature Amplitude Modulation (QAM) combined with forward error correction and data compression in order to achieve bit rates up to 56 Kbps. The advances in DSP technology have recently enabled these bits rate to be achieved in commercial equipment at a reasonable cost. TMS320C6201 device boasts a maximum of 1600 MIPS at a clock speed of 200 MHz which is said to be more than a magnitude faster than any other fixed-point DSP. Cable modems allowing 36 Mbps transmission rates could be implemented using the same. Each module in transmitter as well as receiver was tested individually by writing a test program to read data in from a file, run the module and write the results on an output file. The data output were compared with expected output to judge failure and success of the DSP processor. To conclude, it was found that programming large functions in C on the DSP processor is both quick and easier than programming in assembler.
Link: http://ieeexplore.ieee.org/document/659698/
Patent Review: Method for generating modern transmission signals with quadrature amplitude modulation.
Application Number: 06/136733
Application Date: 04/27/1982
Filling Date: 04/02/1980
Inventors: Gockler, Heinz and Hofmeister, Hagen
Summary:
Link: http://www.freepatentsonline.com/4327439.html
Authors: N Dahnoun and D R Clewer
Publisher: IEEE
Published in: IEE Colloquium on DSP Chips in Real-Time Instrumentation and Display Systems
Location: Leicester, UK,
Date of Conference: 24 September 1997
Summary:
Modems have traditionally been used to enable data communications via PSTN. This is severely band limited channel, requiring use of highly bandwidth efficient modulation schemes such as Quadrature Amplitude Modulation (QAM) combined with forward error correction and data compression in order to achieve bit rates up to 56 Kbps. The advances in DSP technology have recently enabled these bits rate to be achieved in commercial equipment at a reasonable cost. TMS320C6201 device boasts a maximum of 1600 MIPS at a clock speed of 200 MHz which is said to be more than a magnitude faster than any other fixed-point DSP. Cable modems allowing 36 Mbps transmission rates could be implemented using the same. Each module in transmitter as well as receiver was tested individually by writing a test program to read data in from a file, run the module and write the results on an output file. The data output were compared with expected output to judge failure and success of the DSP processor. To conclude, it was found that programming large functions in C on the DSP processor is both quick and easier than programming in assembler.
Link: http://ieeexplore.ieee.org/document/659698/
Patent Review: Method for generating modern transmission signals with quadrature amplitude modulation.
Application Number: 06/136733
Application Date: 04/27/1982
Filling Date: 04/02/1980
Inventors: Gockler, Heinz and Hofmeister, Hagen
Summary:
The present invention relates to a method for generating modem
transmission signals with quadrature amplitude modulation (QAM) in which
scanned values of elementary bandpass signals are formed in digitally
coded form, the elementary bandpass signals are weighted with
coefficients depending on the information to be transmitted and the
modem transmission signals are formed by superposition of the thus
weighted elementary bandpass signals. It is therefore the object of the present invention to provide a method
for generating modem transmission signals which operates with less
calculating operations and thus enables the circuit to operate at a
greater speed and with greater accuracy. The above object is accomplished according to one embodiment of the
invention in that in a method for generating modem transmission signals
with quadrature amplitude modulation (QAM). Another advantage of the invention is that in the case of m-ASK where m=2, 3, 4, . . . the elementary bandpass signals are additionally
weighted with factors corresponding to the amplitude stages
characteristic for the information to be transmitted.
Link: http://www.freepatentsonline.com/4327439.html
Nice written.Data rate at 1600MIPS is very high than any other processor.
ReplyDeleteYes. That's the advantage of DSP processor
DeleteHowever only disadvantage of AM is it occupy wide band of 2fm
ReplyDeleteYes, right. It occupies a fighter bandwidth and both the side bands carries the same data
DeleteIt can be used to generate AM signal for any desired audio inpu
ReplyDeleteYes
DeleteInteresting application
ReplyDeleteNice. This concept is similar to the software defined radio.
ReplyDeleteIf a signal depends on only one variable then we call it one dimensional, and if a signal depends on two variable we call it a two dimensional signal.
ReplyDeleteBut when we represent an one dimensional signal, we use two axes(amplitude vs.time).
Yes exactly. An example of two dimension signal is image
DeleteGood! Interesting to implement.
ReplyDeleteThanks
DeleteThe above conditions and bit rate can only be implemented with the help of QAM instead of AM and DSP processor Helps us to achieve the required bit rate
ReplyDeleteYes. The bandwidth of AM is 2fm and it contains two side bands which carry the same information
DeleteNice application
ReplyDeleteThanks
Delete