The audio signals presented here were recorded from various FM receivers and processed according to the patented noise reduction method. The method reduces any kind of interference of stereo signals or any combination thereof.
All WAV files contain the disturbed signal and the processed signal twice in alternating sequence.
Please download and convert the WAV files to mono if you need a mono version for comparison.
ACI (adjacent channel interference)
ACI + random RF noise
EMI (electromagnetic interference)
EMI 03 is a recording of an outdoor radio play. FM reception is disturbed by a blowdryer. The interference from the blowdryer mixes with the sound of croaking frogs.
As you can hear in the processed version, the frog sounds are clearly reproduced with full spatial information. In the background you can hear water splashing.
Both car radios and smartphones with built-in FM receivers reduce the stereo channel separation when the reception becomes poor to keep the audio SNR at a bearable level. An audio example with current car radios or smartphones can therefore unfortunately not demonstrate that the stereo channel separation can be maintained while at the same time improving the audio SNR.
Instead, the audio examples „mobile fast“ and „mobile slow“ were recorded with an FM receiver that does not reduce the stereo separation and does not change the audio signal when FM reception becomes poor.
In preparation: audio examples „mobile“
MP_01.WAV and MP_02.WAV each show disturbed and processed signals twice in alternating sequence. For comparison the undisturbed source WAV files are given.
The disturbed audio sections were created by means of a software tool ‚multipath simulator‘ by Brian Beezley (email@example.com).
In both cases a replica with a delay of 41 us was added to the undisturbed FM signal. The replica was attenuated by 6 dB.
For details to the software tool ‚multipath simulator‘ please go to Brian’s website http://ham-radio.com/k6sti/ssb.htm.
Please note that a simulation of multipath is not real multipath. Nevertheless, you can get an idea of what the noise reduction does. If you have stereo recordings with multipath interference and unrestricted stereo separation you are welcomed to send it to me per email. I will process it and make it available here.