| 摘要 |
RF spectrum and FM characteristics of an SSC clock signal is measured with a high speed single-bit test channel that can be present in the Agilent 93000 SOC System. Such a channel can be configured to measure, at up to 2.5 Gbps, the logical value of an input signal applied thereto. The SSC clock of interest is applied to one of the high-speed single-bit test channels. A conventional FFT (Fast Fourier Transform) is performed on the captured data to discover the aggregate nature of the distributed spectral components, which can then be compared with associated specifications. The captured data is applied to another algorithm to find the FM modulation profile. That algorithm involves operating on captured digital data to perform a frequency translation operation (equivalent to heterodyning), a first filtering operation, a discrete differentiation operation that includes raw phase extraction, followed by a second filtering operation. The algorithm for finding the SSC modulation profile does not require the high-speed digital channel to meet Nyquist sampling requirements.
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