Sony Computer Entertainment is bringing mobile digital TV to its second-generation PlayStation Portable, it said Tuesday.

The company, which last week disclosed plans to launch the new PSP model in the US and Europe, this week said it will go on sale in Japan on Sept. 20. A week before it debuts the company will also start selling a plug-in digital TV tuner for Japan's "OneSeg" format mobile digital TV broadcasts.

OneSeg broadcasts are already available in much of Japan and are becoming a popular feature on cell phones. The broadcasts send a QVGA resolution (320-x-240 pixel) resolution video signal that can be easily processed by portable gadgets such as the PSP.

As the new PSP features a video-out connector it will also be possible to hook-up the device to a TV to watch programs although as the same channels are available on conventional TV at higher quality there would be little to gain.

The PSP-2000 will cost ¥19,800 (£79) and the TV tuner will cost ¥6,980 (£28). OneSeg-format broadcasting is only done in Japan so the tuner isn't compatible with the formats used in other countries.

The new PSP will be available in six colours in Japan: black, white, silver, pink. purple and blue. It will go on sale on Sept. 20, the first day of the Tokyo Game Show.

Additionally Sony and game-maker Square Enix plan to launch a version of the new PSP with a custom design to mark the 10th anniversary of Final Fantasy VII. The silver PSPs will be "limited" to 77,777 customers and will cost ¥25,890 (£103) when they hit store shelves, from Sep 13.

The new PSP is being launched to help push up poor sales of the handheld console. The device hasn't lived up to Sony's expectations and the company has revised down sales estimates. It sold 8.4 million PSPs in the fiscal year from April 2006 to March 2007, which was down from 14.1 million in the prior 12-month period. This year it hopes to sell 9 million of the devices.