Gamma Spectroscopy
See also McMaster
Genera notes:
- Set the microphone input to unamplified (ie not at default "100%") or you may experience significant quality loss
- At 100% the bar was mostly full
- At unamplified ("100 %") it was mostly empty with occasional spikes
- Ubuntu 12.04 vs 14.04
- 14.04 eliminated "profiles" sound settings option
- Did profiles just eliminate some menu options to simplify navigation?
- Use a laptop with a dedicated line in port or consider a (quality) USB adapter
- http://www.thinkpads.com/forum/viewtopic.php?t=100606
Contents
Gamma Spectacular
Mono audio input
Y 3.5 mm adapter: signal on "tip" connection
850V NaI(Tl) probe: roughly 85 mV Cs-137 high peak out to scope
Having issues using a stereo 3.5 mm cable on a
Verification
PC audio
What are typical line/mic specs?
https://en.wikipedia.org/wiki/Line_level
- Line in
- 2V p-p
- 20 Hz to 20 kHz
- Impedance: ~10 k
- Mic
- Expects much weaker signal
- Preamplifier
- No specifics
http://www.tomsguide.com/forum/40768-6-microphone-voltage
- "A line in input might require 1 volt rms (p-p?)...A mic in input is at least 10 times more sensitive - 100 mv."
- "Nominal line level for consumer equipment is −10dBV, which is about "
- 447 mV peak
- 894 mV p-p
- 1.5 V (3.0 V p-p)
Sounds like I should measure/characterize a bit
Impedance?
ALSA notes
Live audio gst-launch-1.0 autoaudiosrc ! audioconvert ! alsasink Live audio + record gst-launch-1.0 autoaudiosrc ! audioconvert ! tee name="source" ! queue ! vorbisenc ! oggmux ! filesink location=file.ogg source. ! queue ! audioconvert ! alsasink
Audio card
For low cost capture solutions like Gamma Spectacular, Thermino, etc
W520
OS: Ubuntu 14.04
Can't get the audio in port to work. Its a shared in/out port and probably related to that. Note the system does detect the jack being plugged in (ex: output tab only displays mode when unplugged), but can't get it to actually use that port as an input
suggested audio adapter (per forum)
USB adapter
manhattan
ID 0d8c:000c C-Media Electronics, Inc. Audio Adapter
Source: fry's?
OS: Ubuntu 14.04
Mono input
Easily becomes choppy. It will work for very basic applications, but really you should get something better
t61p
Aside that the audio in is expected to be generally better over USB adapter, also consider using the Advanced Dock and install a high quality card
Test: worked well after I moved the microphone input from 100% to unamplified. Maybe this is the probelm
- U12.04
- Hardware: Profile: Analog Stereo Duplex
- Tried various inputs (microphone, dock, input) and all sound the same as long as set to unamplified
- LND 723
- 800V barely prevents clipping (30k / 32k)