2013-09-22

IT9500/IT9503/IT9507 DVB-T modulator chipset

First USB DVB-T modulator chipset

There is interesting new device arrived to marked recently, relatively cheap USB DVB-T modulator (modulator = television transmitter). Device is build upon ITE IT9507 chipset, which is world first DVB modulator chipset aimed for mass production devices for home user segment. There has been FPGA based PCI/USB modulators long time, most notably from company called Dektec. These devices are mostly targeted to research and development having price ticket something too much for home users. IT9507 USB dongle manufactured by HiDes costs under  $200 USD currently and price will likely go down in the future.

Chipset family is named as IT9500 and it contains two different chip versions, IT9503 and IT9507. IT9503 offers very limited set of DVB-T transmission parameters (constellation QPSK, code rate 1/2, guard interval 1/4) whilst IT9507 is full featured.

Linux DVB API and driver

Linux DVB API does not have support for DTV modulators yet. Adding new commands to API is not very big task as there is almost everything already, due to large amount of supported digital television receivers and standards. Biggest challenge I see is to study how to feed transport stream (TS, video and audio data) to Kernel and then from Kernel to device. I think proper solution is to generate correct TS, that match desired transmission parameters, on userspace and then feed that data via Kernel driver to the device.

Dave Chapman has got GPL'd Linux driver from device vendor and is now porting that to the mainline. His work is available on GitHub:
https://github.com/linuxstb/it9507

Related links:

http://www.avalpa.com/the-key-values-product/9-avalpa-answers/79-opencaster-bundle-with-usb-modulator-card
http://www.sunnic.com/english/01_product/02_brand_detail.php?AID=69
http://www.edaboard.com/thread251637.html
http://www.hides.com.tw/product_cg74469-cn.html

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