WCDMA相邻信道功率比(ACPR)和交替信道功率比(AltCPR)以及噪音的测量Application Note 99 May 2005 LT5528 WCDMA ACPR, AltCPR and Noise Measurements Doug Stuetzle INTRODUCTION ACPR (adjacent channel power ratio), AltCPR (alternate channel power ratio), and noise are important performance metrics for digital communication systems that use, for example, WCDMA (wideband code division multiple access) modulation. ACPR and AltCPR are both measures of spectral regrowth. The power in the WCDMA carrier is measured using a 5MHz measurement bandwidth; see Figure 1. In the case of ACPR, the total power in a 3.84MHz bandwidth centered at 5MHz (the carrier spacing) away from the center of the outermost carrier is measured and compared to the carrier power. The result is expressed in dBc. For AltCPR, the procedure is the same, except we center the measurement 10MHz away fr……