Portable RF Multimedia Transmitter

Michael Bieniek, Mikhail Zakharov,

Vast majority of consumer media content is stored digitally on computers.

Consumers would like to see their media content on a TV.

Background

Technology Pros ConsWire Cheap Not always feasible

Wi-Fi based • Exiting infrastructure• ‘Smart’ TVs

• QoS• Cost• Setup

Custom Transmitter & Receiver

• QoS • Cost• Setup

Common existing methods

Every TV has a wireless tuner to receive broadcast TV

Not all channels occupied by stations

FCC regulation allows for licence-free low power broadcast within the UHF band

Background

Investigate feasibility of building a low-power portable transmitter, operating within the UHF band.

Living room equivalent of FM transmitters for listening to music in the car

Purpose

Minimize hardware costs Scalability: point to multipoint Utilize existing infrastructure Ease of setup

Advantage

Wirelessly broadcast audio and video.

Receive on a TV.

Tune to a UHF channel.

Design Objectives

Criteria Digital (ATSC) Analog (NTSC + BTSC)

High Definition Yes NoQoS Better AverageExisting infrastructure Average BetterImplementation complexity

High Medium

Cost High Low

Broadcast method

Support commonly used digital media storage formats (H.264, MPEG 2, MPEG 4, etc…).

USB for power and PC interfacing. Portable form-factor ready.

Design Objectives

Reference: Dell Unveiled USB Digital TV Tuner [online], Available: http://www.mr-gizmo.com/tag/digital-tv-tuner/

Design

Design: User PC

Prototype User Interface

GStreamer: Video Pipeline

Design: Digital Media Processor

Digital Media Processor Prototype Platform: Beagleboard

Ref: Beagleboard.org

Design: RF Transmission

Input: NTSC video and BTSC audio. Output: UHF modulated signal. Freescale MC44BS373CA.

◦ Capable of modulating on channels 14-69 (471.25 MHz – 801.25 MHz).

RF Modulator

Input: 2-channel analog audio. Output: Stereo encoded audio. Freescale MC44C402.

BTSC Stereo Encoder

Filter

Filter Response Implementation

Two stage amplifier boosts the power level of the RF modulated signal.

Total simulated gain of 44 dB◦ High IP3 points and unconditionally stable.

Amplifiers

Mini-Circuits RF Amplifier

Prototype PCB

Prototype Implementation

Testing and Results

Testing and Results

Spectrum Analyzer Output Parameters

Power (dBm)

Actual -11Simulated 10Maximum (FCC)

17

Use digital modulation techniques (ATSC). Improve output power. Minimize size. $38/unit.

Commercialization Proposal

Reference: Dell Unveiled USB Digital TV Tuner [online], Available: http://www.mr-gizmo.com/tag/digital-tv-tuner/

Questions?