Citation
Abstract
The Block IV Subcarrier Demodulator Assembly (SDA) has been designed with four loop bandwidths. Two of these bandwidths are designed with unity damping, while the other two are achieved by increasing the loop gain. Normal tracking can be done in any one of the four bandwidths, or the “high-gain” bandwidths of the set may be used as an acquisition bandwidth. The transition from acquisition to tracking mode should be accomplished by providing a slow reduction in gain in order to limit the peak phase error during the transition time. Excessive phase errors can lead to loss of lock or a greatly diminished quality of data. Experimental evidence and preliminary analysis have shown that the original phase error transient due to acquisition should be allowed to die out before bandwidth reduction is initiated in order to minimize the peak phase error. This article documents the experiments and analysis that led to the bandwidth reduction procedure used in the Block IV SDA so that acquisition is complete 80 seconds after phase lock for the 3.9- to 0.5-Hz configuration and 1300 seconds after phase lock for the 0.23- to 0.03-Hz configuration.
Details
- Volume
- XIII
- Published
- February 15, 1973
- Pages
- 42–47
- File Size
- 499.2 KB