Sound sensor question

[mrscorbindallas]

Hi, I am desperate and seeking aid.

As a favor, I am trying to do some research/fact finding for a project my husband and classmates are working on.

Here is the scenario: They are using the nxt brick, sensors, and more to basically make a spycam-type unit. But consider it more in the sense of a baby monitor. Their ultimate goal is that basically they will transmit audio and video to the pc to be viewed in real time.

Here is the question:

The sound sensor. I know it is able to record sound, but can it be used as a basic wireless microphone? Can the sound sensor as it stands transmit live audio to a pc?

I am sorry if this is an extremely noobish question, but I'm not finding out much either way, and I would greatly appreciate any help. Thanks!

[jojoguy14]

Hello,

I'm sorry to say that the NXT's sound sensor can only sense volume (in dB and dBA). But, maybe you can have it sense if the "baby" is crying or not. Have the program go something like this: IF sound sensor is >50: YES>Do something to tell the "parent" that the "baby" is crying. NO>loop back to beginning.

Hope this helps!

jojoguy10

[mrscorbindallas]

Awesome! And great idea about trying to form it into more of an alert system. Thanks!

[mrscorbindallas]

Follow up question.

Has anyone had any luck using a wireless mic with their nxt brick? If so, does anyone have any mic recommendations or even just suggestions of where I should I go to look? Thanks for any help you can offer.

[pbenco]

dear mrscorbindallas

The NXT is not able to handle video data through I2C, as I2C has a very narrow bandwidth, so you should better use wireless spycam, (generally embedding a mic too), to feed a PC program.
The LEGO NXT sound sensor is able to detect the level of noise around the sensor, and not the sound waves reaching your ears, as a mic do. The data from the sound sensor can't be used to retrieve the audio signal.
http://www2.hawaii.edu/~yucheng/projects/nxt-sound/ or http://www.convict.lu/htm/rob/NXT_sound_sensor.htm
The NXT is able to play sound, previously saved into the brick, in a special format.
So if you want to be able to transmit wirelessly a video+audio flux, get a spycam, as philo did and explained here:http://philohome.com/nxtrover/rover.htm
You can use the NXT kit to build a rover to roam into the house, or to build a sleep aid, or something different, who knows...
You can perhaps design a homebrewed sensor, with a mic and fast analog digitizer, but it's not an easy thing, as the fast digitizer is not directly available in standard programming environnement http://www.tau.ac.il/~stoledo/lego/i2c-8591-mpx4250/. You will have to program the "driver" to your device.

[gloomyandy]

Hi,
While the transfer speed of the i2c bus is indeed not fast enough for video, it can be used to create slowscan images and these can be captured from the mindsensors camera. Take a look at:
http://www.youtube.com/user/gloomyandy# ... ppNCzDb7lU
With the latest leJOS firmware and modified NXTCam firmware I can grab and transmit a 352x288 pixel colour image over Bluetooth in about 20 seconds. Not exactly streaming HD but it can be fun to play around with. It can be kind of fun simulating something like a planetary rover (with the associated limited video bandwidth). Choosing when to use low res images (fast to send, but poor quality), or to have the extra cost of grabbing a high res image.

But if you do want real video (and audio), then a wireless cam is probably the way to go...

Andy