Mcmaster: Created page with "See also McMaster Genera notes: * Set the microphone input to unamplified (ie not at default "100%") or you may experience significant quality loss *..."

2019-03-09T06:34:38Z

Created page with "See also McMaster Genera notes: * Set the microphone input to unamplified (ie not at default "100%") or you may experience significant quality loss *..."

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See also [[mcmaster_gamma_spec|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
** https://siliconpr0n.org/media/gamma_spec/t61p_gain_high_bad.wav
* At unamplified ("100 %") it was mostly empty with occasional spikes
** https://siliconpr0n.org/media/gamma_spec/t61p_gain_none_good.wav
* 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

= 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."

http://electronics.stackexchange.com/questions/76010/what-is-the-typical-max-voltage-for-sound-card-line-in
* "Nominal line level for consumer equipment is −10dBV, which is about "
* 447 mV peak
* 894 mV p-p

http://electronics.stackexchange.com/questions/37926/what-is-the-typical-max-voltage-out-of-a-pc-speaker-jack
* 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)
* https://www.amazon.com/gp/product/B002SK66OY/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=1535523722&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B000SR201W&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0Q7R70RMQJK2J8XKJET7

== 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)

Gamma Spectroscopy - Revision history

Mcmaster: Created page with "See also McMaster Genera notes: * Set the microphone input to unamplified (ie not at default "100%") or you may experience significant quality loss *..."