Patent ID: 7483365

Claim:
Process for obtaining notches in the transmission of signals over the electricity network, that includes sending signals by means of orthogonal frequency division multiplexing OFDM, where communication nodes have a transmitter, means for adding a cyclic prefix and means for converting the OFDM symbols from frequency domain to time domain, where each carrier of the OFDM has a main lobe and a plurality of secondary lobes; wherein this includes: adjusting power of one or more OFDM signal carriers by means of a process selected from attenuation, elimination and a combination thereof over the OFDM signal of these carriers, wherein adjusting the power of one or more OFDM signal carriers is by means of gradual attenuation comprising that both the main lobe of the signal transmitted in the carriers within the notch and the secondary lobes of the signals transmitted in the adjacent carriers are lower than the power spectral density, PSD, demanded for the signal transmitted in the notch; applying a inverse discrete Fourier transform IDFT that is used to transform the signal from frequency domain to time domain signal with a number of points of at least 1024 if said IDFT is complex, and of at least 2048 if the IDFT is real; adding a cyclic prefix; and multiplying the OFDM symbols in the time domain by a window; to achieve an effect selected from achieving abrupt notches of over 30 dB in depth and without interfering with other licensed services that use the same frequency bands, achieving compliance with the power spectral density required for transmitting the signal and a combination thereof.