Specifications

This Equipment Under Test (EUT) is a ATSC Set Top Box, it used to
receive the digital TV signal (ATSC) and demodulate to Audio / Video signal out
put via the RF tuner. This EUT is powered by 120V/AC. Besides , it can also
modulated the ATSC signal to TV receiver via RF output terminal which is
designed to convert the Audio / Video signal to standard NTSC CH3 or CH4 RF
signal. There are two different channels available, Channel 3 and Channel 4, it
can be selected by the switch on the back panel. A coaxial cable (75 ohm, 0.8m)
is provided with this device. Power and channel-select buttons are located on the
front panel, most of the input or output terminals are located at the back panel
including a smart antenna terminal that can be connected to a terrestrial antenna,
the EUT can control the terrestrial antenna gain and direction automatically to
optimize the receiving signal via the smart antenna terminal.
When the EUT is switched on, the software stored in the flash U8 (2
M-byte) and the memory U2 (16 x 16M DDR) is active, controls the MCU U1
(ZR39741) to search the ATSC TV signal via RF tuner, the RF tuner
demodulates the RF signal to IF signal and transmit to the MCU U1, the MCU U1
demodulates the IF signal to audio / video signal and outputs via the A / V output
terminal after the IC2 (CE2752, audio decoder) and U7 (4558, audio filter and
amplifier), and U6 (FMS6143, video filter and amplifier). Also, the MCU U1
transmits the audio / video signal to the RF tuner, the RF tuner modulates the A /
V signal to NTSC RF signal and output via the RF output terminal.
IC Function：
U1 (ZR39741) MCU, Program search, demodulation and decode
U2 （Memory） Software store
U8 （FLASH） Software store
IC1 （AF1071）Reset IC
IC2 (CE2752) Audio Decode IC
U6（FMS6143）CVBS active filter and amplifier
U7（4558）Audio active filter and amplifier
U13（AP1530）DC converter, convert 5V to 1.8V
U15(AP1513) DC converter, convert 5V to 3.3V
U10(TNY277) MCU of the built-in SMPS
D14, transformer, transfer 3.3V to 2.6V
The RF Tuner specification is attached as the following pages.