HDM8513 datasheet(63/67 Pages) HYNIX

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A3. Performance with Interference.

In order to evaluate the filter employed within the HDM8513A with respect to attenuating out-of-

band interference, a test was performed utilizing the COSSAP simulator. The desired signal, at

zero frequency, was configured to utilize 16 samples-per-symbol (corresponding to 3.75MHz

symbol rate if a 60MHz clock is employed). An interfering signal was added with the same

characteristics, except that the amplitude was made to be 10dB higher than that of the desired

signal, the data pattern was different and the carrier frequency was offset from that of the desired

signal. Several offset frequencies were evaluated for this case. Figure A4 illustrates the spectrum

of the test condition when the offset frequency is 1.35 times the symbol rate.

Figure A5 illustrates the measured bit error rate for various conditions. The error rate on the I

channel was measured separately from that of the Q channel, and the horizontal axis is scaled in

dB for one component (I or Q of the signal). For example, the point labeled 1dB corresponds to

SNR (noise bandwidth = symbol rate) of 4dB or Eb/N0 of 4dB if rate 1/2 coding is employed.

The theoretical performance for coherent PSK is shown with the solid line. The curve closest to

theoretical is the demodulator performance with no other interferers and corresponds to an

implementation loss of about 0.2dB. When the interferer was placed at a frequency of either 2.0 or

1.35 times the symbol rate away from the desired carrier, there is an additional degradation ranging

from 0dB to 0.1dB. The worst case occurs when the interferer is placed at only 1.28 times the

symbol rate from the carrier of the desired signal. In this case, the performance has degraded with

respect to the no interference case by 0.3 to 0.5dB.

Figure A6 illustrates performance with an interferer which is 20dB higher than the desired signal

and separated in frequency by 2 times the symbol rate. In this case, the performance has

degraded by 0.7 to 0.8dB from the case with no interferer.

HDM8513 Datasheet(PDF) 63 Page - Hynix Semiconductor