|
|
|
|
|
|
||
| إعلانات منتديات ألم الإمارات |
|
|
|||||||
 |
|
|
LinkBack | أدوات الموضوع | تقييم الموضوع | طرق العرض |
12-03-2005, 05:36 PM
|
#1 | |||
 
|
I need the answers of these questions (help)
I need the answers of these questions pls
The idea of the Quadrature Amplitude Modulation? The advantages of QAM over the other type of digital modulation techniques? Draw the block diagram of the QAM modulator circuit? Sketch the constellation diagram of 64-QAM?
|
|||
|
|
12-20-2005, 11:06 PM
|
#2 | |||
|
This site my help you
Quadrature amplitude modulation, or QAM, is a big name for a relatively simply technique. It is simply a combination of amplitude modulation and phase shift keying www.physics.udel.edu/wwwusers/watson/ student_projects/scen167/thosguys/qam.html - 4k -
|
|||
|
|
|
12-20-2005, 11:09 PM
|
#3 | |||
|
Quadrature Amplitude Modulation
Quadrature amplitude modulation (QAM) is a modulation scheme in which two sinusoidal carriers, one exactly 90 degrees out of phase with respect to the other, are used to transmit data over a given physical channel. Because the orthogonal carriers occupy the same frequency band and differ by a 90 degree phase shift, each can be modulated independently, transmitted over the same frequency band, and separated by demodulation at the receiver. For a given available bandwidth, QAM enables data transmission at twice the rate of standard pulse amplitude modulation (PAM) without any degradation in the bit error rate (BER). QAM and its derivatives are used in both mobile radio and satellite communication systems. You can use the numerically controlled oscillator (NCO) Compiler to design a dual-output oscillator that accurately generates the in-phase and quadrature carriers used by a QAM modulator. The carrier frequency of each sinusoid can be set to any precision by defining the phase increment input to the NCO. A block diagram of the QAM modulator is shown Figure 1. A raised cosine finite impulse response (FIR) filter is used to filter the data streams before modulation onto the quadrature carriers. When passed through a band-limited channel, rectangular pulses suffer from the effects of time dispersion and tend to smear into one another. This pulse shaping filter eliminates inter-symbol interference by ensuring that at a given sampling instance, the contribution to the response from all other symbols is zero you can find some pictures and diagram in this site too www.altera.com/products/ip/altera/t-alt-qam.html - 25k
|
|||
|
|
|
| العلامات المرجعية |
| عدد الأعضاء الحاليين الذين يشاهدون محتوى هذا الموضوع : 1 (0 عضو و 1 ضيف) | |
| أدوات الموضوع | |
| طرق العرض | تقييم هذا الموضوع |
|
|
أقسام الموقع
العرض العادي
