RTL2832 查看數據表（PDF） - Realtek Semiconductor
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RTL2832 Datasheet PDF : 2 Pages
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Realtek RTL2832U
The mystery chip at the heart of RTL-SDR.
VERSION 1 2015
Corrections are welcome.
1. INTRODUCTION
The Realtek RTL2832U is a 6 mm square chip (QFN) with 12 pins per side. It uses 3.3 Volts
and a 28.8 MHz crystal. The chip's datasheet comes with a non-disclosure agreement. The IC is a
DVB-T COFDM Demodulator. DVB-T stands for Digital Video Broadcasting: Terrestrial and COFDM
stands for Coded Orthogonal Frequency-Division Multiplexing. The “U” in the name stands for the
USB (2.0) interface. USB uses 4 pins: +Voltage, D-, D+, and ground. A USB extension cord is
recommended with RTL-SDR to keep the radio away from computer generated noise. The
RTL2832U contains eight general purpose input/output ports and an infrared remote control port.
2. TUNERS
The RTL2832U supports tuners at IF, low-IF, and zero-IF (direct conversion). The most
common tuner is the Rafael Micro R820T. This chip has an advantage over the Elonics E4000 in
that it only uses two of the RTL2832U's four I/Q pins. The unused pins, if not grounded, can be
used as clean inputs for direct sampling purposes. The unused pins are the Q+ and Q- branches.
3. RTL_TEST
In Linux, using the terminal, “rtl_test” can be used to test the RTL2832U (Ctrl-Z exits).
Program switches include: -s sample rate (the default is 2,048,000 Hz), -d device index, -t Elonics
E4000 tuner, -p ppm error measurement, -b output block size, and -S force synchronous output.
4. DATA THROUGHPUT
A high-end sound card will push 32-bits at 192-kHz, a data throughput of 6.144 Mbps. The
RTL2832U has only an 8-bit ADC but can run at 3.2 MS/s (million samples per second, 3200-kHz).
This calculates out to a throughput of 25.600 Mbps or four times that of a good sound card. The
RTL2832U was made to handle compressed MGEG2 and MPEG4 (H.264) transport streams;
including video, audio, and data. Modulation schemes include: 4QAM (QPSK), 16QAM, or 64QAM. In
2k mode (1705 carriers), the carrier spacing is 4464 Hz. In 8k mode (6817 carriers), the carrier
spacing is 2232 Hz. Under both modes the sampling rate is 18.284544 MHz and the final LO
frequency is a fourth of that or 4.571136 Mhz (low-IF). Common bandwidths are 6, 7, or 8 MHz.
5. IMPORTANT PINOUTS
The important RTL2832U pinouts are as follows: pins 1/2 In-phase Input pos/neg, pins 4/5
Quadrature Input pos/neg, pins 11/12 28.800 MHz Crystal Oscillator, pin 13 Tuner AGC, pins 16/17
SCL/SDA Tuner Serial clock/data, pins 18/19 SCL/SDA 2k (256 byte) EEPROM Serial clock/data
S24CS0, pins 25/26 LDO 3.3V AMS1117, pin 38 Infrared Port, and pins 40/41 USB Data pos/neg.
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