On Aug 5, 6:44�pm, Eric Jacobsen <eric.jacob...@ieee.org> wrote:> On 8/5/2009 8:06 AM,amcneillywrote: > > > > > > > On Aug 5, 12:49 pm, Jerry Avins<j...@ieee.org> �wrote: > >> amcneillywrote: > >>> On Aug 4, 5:55 pm, Vladimir Vassilevsky<nos...@nowhere.com> �wrote: > >>>> amcneillywrote: > >>>>> On Aug 4, 4:12 pm, Vladimir Vassilevsky<nos...@nowhere.com> �wrote: > >>>>>> amcneillywrote: > >>>>>>> Whats a good tone detection method if the duration of my tone is 11 > >>>>>>> samples @ 44100 sample rate or 2.494331065760e-04 Seconds > >>>>>> As usual: do-it-yourself method or hire-somebody-else method. > >>>>> They reaction time is not critical. i can do an event based on the > >>>>> tone detection a few seconds after the event.THe problem is i need a > >>>>> good method to detect a very short 20khz signal 2.494331065760e-04 > >>>> Let's see what can be done. This is going to be the business; my contact > >>>> at the web site; please be particular in the description of the problem. > >>>> Vladimir Vassilevsky > >>>> DSP and Mixed Signal Design Consultanthttp://www.abvolt.com > >>> The goal is to send a very short signal from a transmitter device and > >>> then calculate the time it takes for the signal to be reflected back > >>> at the transmitter. My thinking around the signal being very short is > >>> that i am expecting the signal to be reflected in< �40 m.s. > >>> My plan is to detect the source signal and then wait for the reflected > >>> signal then calculate the distance between signals. > >> You chose a poor method for your needs, so you've been asking the wrong > >> questions. You should have started with "What is a good way to do sonic > >> ranging?" Hint: bats use clicks. > > >> Jerry > >> -- > >> Engineering is the art of making what you want from things you can get. > >> ����������������������������������������������������������������������� > > > use a click wazveform over a tone? > > This is an old, old problem that is heavily treated since the days of > early radar and sonar. > > The most ideal waveform for computing time delay is an ideal impulse, > since the time resolution is optimal. �The problem is that it's not > possible to put any appreciable power in a practical "impulse" since the > duration is short. > > For high power, for detectability, a continuous tone is good, but then > you lose the time resolution. > > Bats, dolphins, etc., figured this out eons ago and it turns out that > the real way to get "resolution" is use a waveform with a lot of > bandwidth and enough duration to get adequate power in it. � There are > lots of different waveforms that work. > > It could be that your time/space resolution requirements are very low, > and/or your range requirement is low, so that you could, in fact, use > short bursts of tones. �Some system analysis should reveal whether or > not that's the case. > > -- > Eric Jacobsen > Minister of Algorithms > Abineau Communicationshttp://www.abineau.comWhat methods would you suggest for detecting the echoed sound
detect tone
Started by ●July 28, 2009
Reply by ●August 6, 20092009-08-06
Reply by ●August 6, 20092009-08-06
amcneilly wrote: ...> What methods would you suggest for detecting the echoed soundNow we are properly back to the beginning, with a new possibility of heading off in a fruitful direction. I'm sorry that I can't offer anything that Jacobson hasn't already: As wide a bandwidth as practical, taking into account the hardware and possible dispersion. As short a duration as you can manage while maintaining good SNR. Polaroid used to make ultrasonic transducers for rangefinders for its cameras. They sold them on development boards for other used. If the frequency range is accessible to you, you might consider ultrasound. shorter wavelengths discriminate better. I used one of those boards maybe 20 years ago. It measured distances from 1 to 20 feet with an accuracy of about 1/4 inch per foot. jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●August 6, 20092009-08-06
Jerry Avins wrote:> Polaroid used to make ultrasonic transducers for rangefinders for its > cameras. They sold them on development boards for other used. If the > frequency range is accessible to you, you might consider ultrasound. > shorter wavelengths discriminate better. I used one of those boards > maybe 20 years ago. It measured distances from 1 to 20 feet with an > accuracy of about 1/4 inch per foot.I tried that stuff also. They used just an envelope detector with a threshold; as simple as that. The pulse BW was about several kHz; limited by the response of the transducer. All electronics was implemented in one specialized IC. Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
Reply by ●August 6, 20092009-08-06
Vladimir Vassilevsky wrote:> > > Jerry Avins wrote: > >> Polaroid used to make ultrasonic transducers for rangefinders for its >> cameras. They sold them on development boards for other used. If the >> frequency range is accessible to you, you might consider ultrasound. >> shorter wavelengths discriminate better. I used one of those boards >> maybe 20 years ago. It measured distances from 1 to 20 feet with an >> accuracy of about 1/4 inch per foot. > > I tried that stuff also. They used just an envelope detector with a > threshold; as simple as that. The pulse BW was about several kHz; > limited by the response of the transducer. All electronics was > implemented in one specialized IC.The gain of the receiver increased as time progressed, allowing for the fainter response from more distant reflectors. That was probably the most sophisticated part of the design. It couldn't be built nowadays. It would be too difficult to simulate with Matlab. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●August 6, 20092009-08-06
On 8/6/2009 9:36 AM, Jerry Avins wrote:>> It couldn't be built nowadays. It would be too difficult to simulate with Matlab. > > Jerrylol ... That does seem to be a common thread these days. ;) -- Eric Jacobsen Minister of Algorithms Abineau Communications http://www.abineau.com
Reply by ●August 11, 20092009-08-11
Reply by ●August 11, 20092009-08-11
amcneilly wrote:> What would be the be a good high resolution dsp highpass/bandpass > filter?How about this one: http://www.frequencydevices.com/dm/fdiasc50.html VLV
