Infrared receiving unit

1. An infrared receiver comprising:

a decision logic circuit configured to activate or deactivate a squelch and to determine whether a meaningful signal is present;

a demodulator adapted to demodulate a received intermediate frequency;

a high-pass filter adapted to perform a high-pass filtering of an output of the demodulator; and

a rectifier for rectifying an output signal of the high-pass filter;

wherein the squelch is deactivated when a meaningful signal is determined;

wherein the decision logic circuit is configured to determine whether a signal strength of a received receiver intermediate circuit frequency signal is below a predetermined threshold, and to determine in this case that the signal is not a meaningful signal;

wherein the decision logic circuit is configured to determine whether a variance of a carrier frequency of the received receiver intermediate frequency signal is above a predetermined threshold value, and to determine that this signal is not a meaningful signal in this case;

wherein the decision logic circuit is configured to determine whether a mean value of an audio amplitude is above a predetermined threshold, and to determine that the signal is not a meaningful signal in this case; and

wherein an output signal of the rectifier corresponds to the mean value of the audio amplitude.

2. The infrared receiver as set forth in claim 1 ;

wherein the decision logic circuit is configured to determine whether the variance of the audio amplitude of the receiver intermediate circuit frequency signal is greater than a predetermined threshold, and to determine that this signal is not a meaningful signal in this case.

3. The infrared receiver as set forth in claim 1 ;

wherein the decision logic circuit is configured to store the mean value of the carrier frequency of the received signal in a memory when the variance of the carrier frequency is below a predetermined threshold value.

4. The infrared receiver as set forth in claim 3 ;

wherein the decision logic circuit is configured to determine whether the carrier frequency is sufficiently close to a stored frequency, and to determine that the signal is a meaningful signal in this case.

5. An infrared receiver comprising:

a decision logic circuit which is configured to determine whether a received signal represents a meaningful signal based on an evaluation of a variance of a frequency, a mean value of an audio amplitude, and a signal strength of a receiver intermediate frequency signal;

a demodulator adapted to demodulate a received intermediate frequency;

a high-pass filter adapted to perform a high-pass filtering of an output of the demodulator; and

a rectifier for rectifying an output signal of the high-pass filter;

wherein an output signal of the rectifier corresponds to the mean value of the audio amplitude.

6. A method of activating or deactivating a squelch in an infrared receiver, the method comprising:

deactivating the squelch when the signal is determined as a meaningful signal;

determining whether a signal strength of a received receiver intermediate frequency signal is below a predetermined threshold value, and determining in this case that the signal is not a meaningful signal;

determining whether a variance of a carrier frequency of the received receiver intermediate frequency signal is above a predetermined threshold, and determining in this case that the signal is not a meaningful signal; and

determining whether a mean audio signal amplitude is above a predetermined threshold value, and determining in this case that the signal is not a meaningful signal;

demodulating a received intermediate frequency to obtain a demodulated output;

high-pass filtering the demodulated output to obtain a high-pass-filtered output signal; and

rectifying the high-pass output signal to obtain a rectified output signal;

wherein the rectified output signal corresponds to the mean audio signal amplitude.