F
Fabian Wondratschek
Dear All!
I have an audio signal where I need to filter out a "control signal"
(532 Hz). I used a NE567 for that, but this chip is too slow. The user
can hear a short "cut-off-sound", which is not acceptible for me. The
good thing is, that the signal won't come mixed with audio signals. I
just need to filter it out when there is no other frequency. The
signal itself has some pause (>100ms and <5sec...various) in it. I
don't mind to filter out the 532hz even from the audio, because the
user won't realize that really.
I searched in the NGs and found too many recommendations, ideas,
chips, etc. and now I'm not able to make a decision for which way to
go.
I guess I have make an audio delay (with a delay of 10-30ms). I don't
want to use the audio-delay-chips, because they seem to be too
expensive. The whole app shouldn't cost me more than 5-10 US$/€ AND
(and I guess this is my biggest problem) it should be driven by a
battery (3V or 9V...with a good power-down-mode this should be
possible...hopefully
)
I could do the audio delay with either a DSP (but not preferred,
because I never used them), or a uC with ADC -> memory -> DAC. I'm
still hoping there is another possibility without using DSP/uC, etc.,
because this extend my production costs too much (loading firmware),
but in case I have to use them, it's also ok, as long as I can get the
532Hz filtered out without hearing the "cut-off-sound"/mute. I want to
make a mass-production of the final device, thus any recommended chips
should be available for 10.000 devices.
Every idea/recommendation are highly appreciated!
Thank you very much!
Cheers,
Fabian
I have an audio signal where I need to filter out a "control signal"
(532 Hz). I used a NE567 for that, but this chip is too slow. The user
can hear a short "cut-off-sound", which is not acceptible for me. The
good thing is, that the signal won't come mixed with audio signals. I
just need to filter it out when there is no other frequency. The
signal itself has some pause (>100ms and <5sec...various) in it. I
don't mind to filter out the 532hz even from the audio, because the
user won't realize that really.
I searched in the NGs and found too many recommendations, ideas,
chips, etc. and now I'm not able to make a decision for which way to
go.
I guess I have make an audio delay (with a delay of 10-30ms). I don't
want to use the audio-delay-chips, because they seem to be too
expensive. The whole app shouldn't cost me more than 5-10 US$/€ AND
(and I guess this is my biggest problem) it should be driven by a
battery (3V or 9V...with a good power-down-mode this should be
possible...hopefully
)I could do the audio delay with either a DSP (but not preferred,
because I never used them), or a uC with ADC -> memory -> DAC. I'm
still hoping there is another possibility without using DSP/uC, etc.,
because this extend my production costs too much (loading firmware),
but in case I have to use them, it's also ok, as long as I can get the
532Hz filtered out without hearing the "cut-off-sound"/mute. I want to
make a mass-production of the final device, thus any recommended chips
should be available for 10.000 devices.
Every idea/recommendation are highly appreciated!
Thank you very much!
Cheers,
Fabian
