DAB decoder power consumption, the bane of portable radio designers, will drop close to FM levels in the next few years.
“DAB will come within 20 per cent of FM eventually,” Pren Rajalingham, digital audio product manager at Frontier Silicon told EW. “30mW is the target we will be looking to DAB from for the next two to three years.”
While DAB is welcomed in mains-powered radios, consumers have been disappointed with battery life - particularly from pocket radios.
The FM demodulator in traditional all-analogue radios consumed a few milliwatts. “New FM radios consume more than FM radios 10 years ago,” said Rajalingham. “With the chips used today it is around 20mA.”
This is 30 or 60mW depending on the supply voltage - and this what DAB chip makers are aiming at.
First-generation DAB decoders were based on general-purpose DSPs. “In the second [current] generation, a lot of processes are hardware accelerated,” said Rajalingham. “Our Chorus 2 has hardware Reed-Solomon decode and also a lot of on-chip memory so we don’t waste power with external bus transceivers.”
The result is a 70mW 1.2V DAB decoder.
Work continues to cut decode power, but Frontier sees a quicker way to boost battery life.
Radio makers persist in feeding decoders through linear regulators and Frontier is taking steps to persuade cost-obsessed Chinese factories to include DC-DC converters for the core voltage - cutting power consumption from 175mW (3V) or 525mW (9V) to the basic 70mW.
UK radio designer Roberts Radio is already using DC-DC conversion. “We will have a radio on the market this year that will give 180 hours using six D-cells, and a pocket radio with 4 AAs that will give 25 hours,” Robert’s product director Gerry Thorn told EW.
He also sees improvements over the next few years. “The battery life of CD walkman’s was originally awful. Now you get 20 hours from two AA batteries. We have had 30-plus years of analogue radio and only three years of DAB.”