The Chinese GB20600-2006 terrestrial DTV standard, also known as DTMB (Digital Television Multimedia Broadcast) includes both single carrier (like ATSC) and multiple carrier (like DVB-T) modes. Micronas is now shipping prototypes of a new family of demodulator chips ranging from units supporting individual modes to a chip that handles both modes.
The Micronas DRX 398yZ DTMB demodulator supports automatic detection of single-carrier and multi-carrier modes. In the single-carrier mode, an integrated time-domain equalizer implementing an adaptive decision-feedback algorithm is used to improve reception performance. In the multi-carrier mode, a frequency domain equalizer is used along with an advanced channel estimator.
“DTMB is one of the most complex broadcast transmission standards,” said Zhenning Zhang, Micronas marketing manager. “Our experience in developing advanced demodulator systems for ATSC and DVB allowed us to develop a device that exceeds all DTMB requirements and enables robust and reliable reception performance.”
The device requires only a single 8 MHz SAW filter and provides PWM RF-AGC and IF-AGC outputs. Micronas said the device offers robust synchronization in the presence of phase and frequency offsets up to 500 kHz and robust timing recovery up to 100 ppm of sampling. Detection and operation of the different modes is handled by an on-chip microprocessor.
Micronas sees applications for its demodulators in USB-TV sticks and PC-TV cards, as well as in conventional set-top boxes and TV. It seems to me that the ability of the Micronas DRX 398yZ to detect and demodulate all the DTMB modes is an indication that if a market exists, it’s not unreasonable to expect to see a single “universal” demodulator chip product. This would be able to decode DVB-T, DVB-H, ATSC, and eventually, ATSC M/H standards. Such a chip would allow travelers to view TV without regard to the country they were in and the standard being broadcast.
