Hello all, I was reading the general specifications of Pactor and I note a curious feature.
The first mode of Pactor 3, with 2 carriers (in BPSK) specifies a crest factor of 1.9 dB (ratio of 1.55). Pactor 2 specifies a crest factor of 1.45 (in ratio)...1.6 dB Meanwhile, Pactor 2 applies a root raised cosine window which gives for a one carrier only, a crest factor of about 1.4 /1.45. Now in Pactor 2, with two carriers sent in the same time, mecanically the crest carrier must be increased to 1.6+3=4.6 dB if no overloading is accepted (and it would be curious to apply a cosine window to afterwards overload the signal...). One more information: in Pactor 3, it is written about "crest factor": "without signal clipping or limiting". Even if I don't see the difference between "clipping" and "limiting", it seems clear that they can send two carriers in the same time (and certainly moduled with independant information), without the 3 dB of penalty, which is quite interesting! Has someone information about the way used by SCS (Pactor company) to avoid or to limit this penalty? 73 Patrick
