Comments on: Need for I-Q modulator and demodulator http://www.dsplog.com/2008/04/05/need-for-i-q-modulator-and-demodulator/ Signal Processing for Communication Fri, 30 Jul 2010 01:36:27 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: anil kumar http://www.dsplog.com/2008/04/05/need-for-i-q-modulator-and-demodulator/#comment-18302 anil kumar Tue, 19 Jan 2010 20:47:49 +0000 http://www.dsplog.com/2008/04/05/need-for-i-q-modulator-and-demodulator/#comment-18302 Hi evry one in this.Nice to c u all here buddy's. Ofcourse I am new to this. I have a small problem with my calculation in OFDM USING QAM AND IQ modulator . I ll just paste the question here. I have done some calculations, but i was unable to judge those.Please help as early as possible. We are required to build a SIMULINK model of a 16-QAM OFDM Digital Communications System (OFDM transmitter and OFDM receiver) operating over an AWGN channel. • The OFDM system has a cyclic prefix of 20% of the (data) symbol duration Ts. • Use an I-Q modulator at the transmitter and I-Q demodulator at the receiver to upconvert and downconvert, respectively, the analogue signal to a central frequency of fc=2 MHz (so, the passband transmitted signal is centered on 2 MHz). • The symbol duration is set to Ts =1 msec. • Chose the number of carriers, N, so as to achieve a bitrate of Rb = 192000 bits / sec (you have to evaluate the correct N). • Test the system performance for Eb/N0=5, 8, 10, 12 and 14 dB, and report the respective BER measurements. • Subsequently, use a channel encoder of your choice and repeat the BER measurements for the same values of Eb/N0. Hi evry one in this.Nice to c u all here buddy’s.
Ofcourse I am new to this. I have a small problem with my calculation in OFDM USING QAM AND IQ modulator .
I ll just paste the question here. I have done some calculations, but i was unable to judge those.Please help as early as possible.

We are required to build a SIMULINK model of a 16-QAM OFDM Digital Communications System (OFDM transmitter and OFDM receiver) operating over an AWGN channel.
• The OFDM system has a cyclic prefix of 20% of the (data) symbol duration Ts.
• Use an I-Q modulator at the transmitter and I-Q demodulator at the receiver to upconvert and downconvert, respectively, the analogue signal to a central frequency of fc=2 MHz (so, the passband transmitted signal is centered on 2 MHz).
• The symbol duration is set to Ts =1 msec.
• Chose the number of carriers, N, so as to achieve a bitrate of Rb = 192000 bits / sec (you have to evaluate the correct N).
• Test the system performance for Eb/N0=5, 8, 10, 12 and 14 dB, and report the respective BER measurements.
• Subsequently, use a channel encoder of your choice and repeat the BER measurements for the same values of Eb/N0.

]]> By: Krishna Sankar http://www.dsplog.com/2008/04/05/need-for-i-q-modulator-and-demodulator/#comment-16636 Krishna Sankar Sun, 06 Dec 2009 11:25:51 +0000 http://www.dsplog.com/2008/04/05/need-for-i-q-modulator-and-demodulator/#comment-16636 @kwame: Well, its not that we were not utilizing the other half of the spectrum. Rather the same information (mirrored in frequency) was present in the other half of the spectrum. In previous case, we were not sending anything on the Q arm. @kwame: Well, its not that we were not utilizing the other half of the spectrum. Rather the same information (mirrored in frequency) was present in the other half of the spectrum. In previous case, we were not sending anything on the Q arm.

]]> By: kwame http://www.dsplog.com/2008/04/05/need-for-i-q-modulator-and-demodulator/#comment-15805 kwame Sat, 21 Nov 2009 09:03:12 +0000 http://www.dsplog.com/2008/04/05/need-for-i-q-modulator-and-demodulator/#comment-15805 Hi krishna, good work on your posts. I have a small question on the IQ modulator, Since we were previously not utilizing the other half of the spectrum in passband transmission and hence introduced the IQ scheme to fully use the bandwidth, does it mean we are actually sending the same data (data symbol) in both I and Q arm? i.e if its a1, then its a1 carried in both arms? Hi krishna,

good work on your posts. I have a small question on the IQ modulator, Since we were previously not utilizing the other half of the spectrum in passband transmission and hence introduced the IQ scheme to fully use the bandwidth, does it mean we are actually sending the same data (data symbol) in both I and Q arm? i.e if its a1, then its a1 carried in both arms?

]]> By: Krishna Sankar http://www.dsplog.com/2008/04/05/need-for-i-q-modulator-and-demodulator/#comment-15177 Krishna Sankar Sun, 08 Nov 2009 03:55:29 +0000 http://www.dsplog.com/2008/04/05/need-for-i-q-modulator-and-demodulator/#comment-15177 @mhamdi: Sorry, I do not have posts on cognitive radio @mhamdi: Sorry, I do not have posts on cognitive radio

]]> By: mhamdi http://www.dsplog.com/2008/04/05/need-for-i-q-modulator-and-demodulator/#comment-14928 mhamdi Thu, 05 Nov 2009 08:39:40 +0000 http://www.dsplog.com/2008/04/05/need-for-i-q-modulator-and-demodulator/#comment-14928 can you give me some programm for cognitive radio can you give me some programm for cognitive radio

]]> By: Krishna Sankar http://www.dsplog.com/2008/04/05/need-for-i-q-modulator-and-demodulator/#comment-10412 Krishna Sankar Mon, 10 Aug 2009 23:45:30 +0000 http://www.dsplog.com/2008/04/05/need-for-i-q-modulator-and-demodulator/#comment-10412 @Umair: Sorry, I do not have experience with Simulink. Anyhow, am planning to write a post on FM transmission/reception in the near future. @Umair: Sorry, I do not have experience with Simulink. Anyhow, am planning to write a post on FM transmission/reception in the near future.

]]> By: Umair http://www.dsplog.com/2008/04/05/need-for-i-q-modulator-and-demodulator/#comment-10296 Umair Sun, 09 Aug 2009 12:04:01 +0000 http://www.dsplog.com/2008/04/05/need-for-i-q-modulator-and-demodulator/#comment-10296 Hi,...can anybody guide me in making an FM transmitter and receiver on Simulink and System Generator and its implementation on Lyrtech SFF SDR DP.... :( i dont kno how to do it for implementation :( kindly do help me Hi,…can anybody guide me in making an FM transmitter and receiver on Simulink and System Generator and its implementation on Lyrtech SFF SDR DP…. :( i dont kno how to do it for implementation :( kindly do help me

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