Application information

TSH512

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Doc ID 8120 Rev 7

4.2

Sub-carrier generator application: voice-operated wireless

camera

Thanks to its operating frequency, the TSH512 offers the possibility of generating usual

audio sub-carriers for video applications (Figure 23). The camera can be voice-activated

using the VOX-MUTE output of the TSH512. The TSH512 also provides bias, amplification,

ALC for the electret microphone.

Figure 23.

Typical block diagram for audio sub-carrier generator

4.3

Multimedia application

4.3.1

Headset side

The TSH512 is used in mono mode to transmit the signal of the electret condenser

microphone of the headset. The circuit is supplied by batteries and the VOX function

switches off the output stages to save energy. The usual working frequency is 1.7 MHz for

infrared mono operation.

TSH512

LNA + ALC

LNA + ALC

MIC. BIAS

MIC. BIAS

TX2

VOX

SBY

buffer1

buffer2

Vcc

6 or 6.5 MHz

filter

Electret Condenser

Microphone

Miniature camera

FM 2.4 GHz

transmitter

6 or 6.5 MHz

Audio sub-carrier

Video

VOX-MUTE

Stand-By

S

Sub-carrier

Stand-By

TX1

TSH512

LNA + ALC

LNA + ALC

MIC. BIAS

MIC. BIAS

TX2

VOX

SBY

buffer1

buffer2

Vcc

6 or 6.5 MHz

filter

Electret Condenser

Microphone

Miniature camera

FM 2.4 GHz

transmitter

6 or 6.5 MHz

Audio sub-carrier

Video

VOX-MUTE

Stand-By

S

Sub-carrier

Stand-By

TX1