1 / 14

FM Modulated IR Audio Transmission

FM Modulated IR Audio Transmission. By John Barton. The Chip. The chips I used were TSH512 and TSH511 from STMicroelectronics They modulate and demodulate, respectively, between analogue audio signals to FM signals. TSH512. Low Noise Amplifier (LNA). The front end of the circuit

seanna
Download Presentation

FM Modulated IR Audio Transmission

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. FM Modulated IR Audio Transmission By John Barton

  2. The Chip • The chips I used were TSH512 and TSH511 from STMicroelectronics • They modulate and demodulate, respectively, between analogue audio signals to FM signals

  3. TSH512

  4. Low Noise Amplifier (LNA) • The front end of the circuit • Gain of 0-40dB • Gain given by GLNA (dB) = 20.Log(1+RLNA2/RLNA1)

  5. Automatic Level Control (ALC) • Prevents over modulation • Reduces distortion and keeps reduced transmit spectrum • 20dB gain at 700mVp-p

  6. Voice Operated Transmit (VOX) • Mutes output when no audio signal is present • Can be bypassed if needed

  7. Voltage Controlled Oscillator (VCO) • Controls the internal oscillator • Has high power supply rejection ratio (PSRR)

  8. TSH511

  9. LNA • Another LNA amplifies the input from the IR receivers, this time with a gain of about 22dB

  10. AMP and LIM • Amplifier and limiter, with gains of 20dB and 60dB respectively amplify the signal and provide a constant amplitude to the FM Demodulator

  11. FM Demodulator • Demodulates the FM signal back into audio signals • Uses a tank circuit and a multiplier to help do this

  12. Squelch section • Prevents FM noise from getting to the speakers when no audio signal is present • Uses RC filter to isolate FM noise, then integrated with a capacitor to connected to MUTE-INT pin. Provides DC level based on noise • Mutes both outputs if noise is only signal present

More Related