Orthogonal is the mathematical term applied to two RF sinusoidal signals when their phase relationship is precisely 90 degrees. Alternatively they may be said to be in 'quadrature'.
Industry Leading Performance
The BCM2930 and BCM2940 devices offer significant improvements over existing mobile TV solutions on several fronts. Utilizing an innovative design and aggressive process technology implementation, both the BCM2940 and BCM2930 significantly reduce power consumption by up to 40% and footprint requirements by up to 30% from current handset design budgets. Additionally, the advanced tuner and demodulator design of both chips allows for measurably improved reception indoors and in high-speed environments. With these capabilities, all of which are critical for commercial success and widespread adoption, the BCM2940 and BCM2930 are the ideal choices for portable digital TV applications.
Broadcom''s single-chip mobile TV receivers extend its broad portfolio of mobile and wireless connectivity solutions. Broadcom is a leading supplier of Bluetooth?, FM, Wi-Fi? and GPS solutions that enable next generation features in many popular mobile phones and other handheld devices. In developing the BCM2940 and BCM2930, Broadcom leveraged its RF expertise and IP portfolio to include a high performance RF tuner and television demodulator, which are prevalent in Broadcom''s industry leading and field proven cable set- top box products. Today''s announced mobile TV solutions will enable new service capabilities that provide significant revenue opportunities for wireless network providers.
In DAB the sub-carrier frequency spacing is chosen to be the reciprocal of the active symbol period . Under this condition the DAB modulation results in successive sub-carriers having a quadrature relationship with each other. The frequency spectra components of one modulated sub-carrier will therefore integrate to zero at the corresponding components from both of the adjacent sub-carriers. This has two advantages: (a) the modulated sub-carrier spectra will efficiently occupy the allocated bandwidth with a degree of controlled overlapping and (b) simple I-Q demodulation to zero intermediate frequency (zero-IF) can be used in the receiver without needing the costly hardware overhead of many bandpass filters to extract the sub-carriers