We examined the LG Insignia NS-DXA1 converter box, a unit offered at Best Buy that is similar, if not identical, to the Zenith (an LG subsidiary) DTT900, which is sold at several other retailers. Currently, each box sells for $60, so those who get their coupons and paperwork straight end up paying about $20 out of pocket.
The Insignia box is relatively simple, consisting of a main board and a power board wrapped in a painted two-piece stamped-metal enclosure with a plastic front face. The front panel has just a few buttons, two for channel up/down select and a third for powering on and off. An infrared receiver for use with the included remote control also hides behind the front plastic fascia, along with an LED indicating the box's active status. The back of the enclosure has two coaxial cable connectors, one for the DTV antenna input and the other for analog RF output. These connectors are joined by three RCA jacks, two for left/right stereo audio and the third for line video.
The functional concept of the converter box is straightforward. RF-modulated DTV broadcast input (by way of "rabbit ears" or other antenna) comes in, and RF-modulated analog TV signals go out, feeding the non-DTV-compatible set. Don't confuse DTV with high-definition (HD) broadcasts. Although HD might be supported, DTV signals can be of similar resolution to conventional analog signals. (Of course, any HD programming will be lost on a standard- definition analog TV using the box output, but that's unavoidable.)
Inside, just a few components serve the primary task of going back to analog; all signal processing takes place on the main board, a two-metal-layer FR4 PCB whose simplicity helps keep costs down. A can tuner module from Sanyo, mounted to the main board, lies at the signal headwaters. The can assembly contains a TI SN761668 digital TV tuner for demodulation of the incoming RF DTV signal and a Toshiba TA1372FNG modulator that takes the analog signal back to the RF spectrum for television interface.
Between these two components (which are supported in-can by a number of discrete coils, filters and other parts) lies the MPEG decoder system on chip (SoC) (LGDT1111D) supplied by LG. The SoC is tied to 32 MB of DDR SDRAM memory (HY5DU561622FTP) from Hynix and 2-MB NOR flash memory (MX29LV160C) from Macronix. In addition, a 32-Kb x 8 serial EEPROM (24LC256) is supplied by Microchip for boot-up memory. A Cirrus Logic CS4344 stereo D/A converter is used to create line audio out to accompany line video from the rear panel.
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