AN ALTERNATE PROPOSAL FOR ARTM CPM

• Main Author: Perrins, Erik
• Other Authors: Rice, Michael
• Language: en_US
• Published: International Foundation for Telemetering 2004
• Online Access: http://hdl.handle.net/10150/605802; http://arizona.openrepository.com/arizona/handle/10150/605802

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California === Since the Advanced Range Telemetry (ARTM) program first proposed the use of multi-h continuous phase modulation (ARTM CPM), there has been much work done to characterize the performance of this waveform. The ideal performance of ARTM CPM is well understood and has been shown to be close to that of PCM/FM and the Tier I modulations (FQPSK-B and SOQPSK). In practice, however, ARTM CPM is very sensitive to phase noise at the receiver and also requires very long synchronization times. These difficulties can be addressed with additional link margin. In this paper we propose an alternate set of modulation indexes which are approximately 2 dB superior in performance with respect to the original set (we use minimum distance concepts to characterize the performance of each set). Brief consideration is also given to frequency pulses other than the existing raised cosine (RC) pulse. We also characterize the effect these new parameters have on the signal spectrum. This 2 dB gain gives ARTM CPM some of the system flexibility currently enjoyed by PCM/FM and the Tier I modulations. One such option is to realize this 2 dB gain using low-complexity coherent detection schemes, which we demonstrate; we also show a noncoherent detection scheme that performs within 2 dB of optimum (or in other words, it has the same performance as the existing coherent detector for ARTM CPM). This is significant since noncoherent detection avoids some of the synchronization burdens that have plagued ARTM CPM thus far.