I've got an idea to connect a three axis seismometer station to a rotating drum chart recorder (like the one in my avatar) using living streaming over an ordinary video sharing site like YouTube. The ultimate goal is to be able record earthquakes from selected sites throughout the U.S. on a recorder in my home or possibly at a museum.

The seismometer station is at a remote site and already has a FM multiplexer that converts the output of the three seismic amplifiers into a composite audio tone (consisting of 125, 180, and 275 Hz.) for each respective channel. That tone is sent over a phone line to an FM discriminator that converts the audio tones back into DC signals which are amplified to operate the pens on the chart recorder.

Obviously, video sharing sites can easily handle the audio tone, however what devices do I need to continuously upload the audio at the remote site and play it back to the discriminator at the recording station? Seems the input from the multiplexer could be connected to a simple device that can connect to the Internet (like a tablet) and have it continuously upload the audio stream to the video sharing site. The streaming would be done continuously on a 24/7 basis

Once I've got the audio streaming over the video sharing site, I could connect the output of the head phone jack on another tablet to the discriminator and ultimately the amplifier and chart recorder.

Seems pretty simple, but is this idea really workable?

 

Workable maybe, but a bit convoluted IMO. Seems it would be a lot simpler and probably more accurate to catch the signals straight out of the sensor before the tone generator and feed to raspberry pi server. On the other end of the internet log into the Rpi and get the real sensor values without a long string conversions and feed that to your chart recorder.

 

If I log onto Raspberry Pi at the receiving end, then would I need a digital to analog converter (DAC) to "play back" the original signal?

 

If I log onto Raspberry Pi at the receiving end, then would I need a digital to analog converter (DAC) to "play back" the original signal?

Yes, assuming your chart recorder requires an analog interface.

 

Yes, the chart recorder (a pre 90s vintage unit) already has an analog input that receives a signal of +/- 5 volts (a maximum of 10 volts peak to peak) and amplifies it to drive the pens.

Essentially, I need a device that will receive a digitized stream and provide an analog output (like what's used to drive the headphones on a computer or smart phone.

 

http://www.analog.com/en/parametricsearch/11060#/p4910=Precision DAC&p4386=Bipolar