In direct sequence spread spectrum, which is the basis of CDMA systems, the baseband signal is multiplied with a pseudo noise (PN) sequence which has a high chip rate, thus the resulting modulated signal will have high rate and thus larger bandwidth. But the power of the original baseband signal and the power of spreaded signal resulting from the multiplication process is the same. Then, why this spreading process provides jamming resistance property?
Viewed in time domain, they have the same power. Does the jammer depend on the power value to detect the signal or not? I read in a reference that the spreaded signal appears as noise for the unintended receiver. But this only when viewed in frequency domain. Does the jammer depends on frequency domain measurements for detecting the signal, not on time domain power measurements?