Wireless recording device

[Dannyx]

Re: Wireless recording device

for that you could just stream the audio over tcp to vlc on the pc.

I thought that might be a solution. With a little luck, I could probably listen to it on mobile too, which is actually where I'd like to be able to do most of this spy stuff, since I can be in the bathroom or somewhere

[Dannyx]

Re: Wireless recording device

I decided i'd take a step back for now and only focus on recording, since live listening isn't all that relevant if I can just access the recordings anyway at a later point.

[mariushm]

Re: Wireless recording device

Even cheap microcontrollers have 10 bit ADCs so in theory you can have 8 bit audio without any problems. So you could record mono 8 bit 22050 Hz audio for example onto a SD card.

Some microcontrollers like PIC32 even have DMA which would allow you to just send a command and have a memory buffer transferred to a SD card without microcontroller having to monitor everything.

There may be a problem with the ADC being to slow to take so many samples per second but in that case you could easily buy a separate ADC with higher resolution, like for example 14bit or 16 bit or even higher.

You can store the audio as raw pcm, one or two bytes per channel, so 2-4 bytes per sample, anything between 8000 and 48000 samples per second. You can easily import raw pcm files into a software like Audigy and export to WAV or FLAC or whatever, just have to know the channels and sample rate and sample depth.

As for wireless... in theory you could have one of those under 5-10$ microcontrollers with wireless esp something and configure that as a barebones http 1.0 server (after it gets the ip address automatically through dhcp or something) ... this micro could connect to your other micro through spi or i2c and request the data from the micro like "give me a list of files from sd card" or " give me 1 KB of data from offset 123456 in file xyz.pcm" and you transfer the data between micros and send it over the wireless
- the micro with wireless most likely doesn't have enough power to do the actual reading from adc and storing to sd card , or has too small program memory, unless you go for a more expensive version.

[Dannyx]

Re: Wireless recording device

Yeah, I thought I'd go down the more complicated route and build everything from scratch, until STJ came up with the idea of using junk android devices, which is perfect and they have everything built right in. My Viper that I found occasionally has some sudden shutdown issues , but I suspect that's down to a blown battery, which wouldn't be too much of a problem, since I'll power it constantly from a DC supply or something, or even replace the battery for reliable operation. I discovered it even has a FPT server built right in, so I can share files and access them.

Stealth is key, so rather than connecting it to the local network where it'd be discoverable, I was thinking of making it like a hotspot and have my phone connect to IT directly when I want to grab the file it's recorded...that should put people off in case they stumble upon it by accident.

[Dannyx]

Re: Wireless recording device

Just looked through the play store....AirDoid perhaps ? :| Close enough if it does what it says on the tin. All I need is to get in there and hit "record" on the sound recorder and then access the "recording" folder at a later time...

[stj]

Re: Wireless recording device

look here:
https://f-droid.org/