Andrew, Norm has a good point. I know you are using the Diamond DMM-32 A/D board. What I'm wondering is if your system is embedded (which I have assumed it is because otherwise why use PC104 form factor) you really need to worry about the type of power supply you run your CPU and PC104 stack from. Switching power supplies are ugly. Linear power supplies are bigger but much better noise wise. I would suggest testing your system with the power supply you are planning on using. We are about to do that and filter out what we can. But, we are in a noisy environment and don' t have such a strict requirement. Plus, Tomek points out that 5 / 2^16 = 76 uVolts. That is a pretty small voltage. Typically we might select a 16 bit A/D to get 12 bits (i.e., you throw away the 4 LSB's). Janet Estabridis Electrical Engineer NAWC Code 473E00D Building 31440 Room 1017 China Lake, CA 93555 [EMAIL PROTECTED] (760) 939-2896 FAX (760) 939 -3075 > -----Original Message----- > From: Dresner, Norman A. [SMTP:[EMAIL PROTECTED]] > Sent: Friday, October 08, 1999 5:31 AM > To: 'RTLinux' > Subject: FW: [OFF TOPIC] [rtl] how to amplify the signal from the > detector ? > > At that sensitivity, power-supply noise becomes significant. While a > really > good quality lab supply can meet the requirements, you can do a lot worse > than to use a pair of 9v batteries. There's NO noise except what your > wiring picks up from the environment. > > Norm > > > -----Original Message----- > > From: Tomasz Motylewski [SMTP:[EMAIL PROTECTED]] > > Sent: Thursday, October 07, 1999 5:26 PM > > To: ahgu > > Cc: RtLinuX (rtl) > > Subject: Re: [OFF TOPIC] [rtl] how to amplify the signal from the > > detector? > > > > On Thu, 7 Oct 1999, ahgu wrote: > > > > > Wonder if anyone encountered the signal amplification problem. My > > detector > > > give out slow-varying DC signal in couple mV range. My A/D board reads > > 0-5V > > > and I need all the 16bit resolution. Where would I get a DC amplifier > to > > > > Look at the list at http://www.xs4all.nl/~ganswijk/chipdir/f/amp.htm > > and choose some high precision low noise stable instrumentation > amplifier. > > > > I have been using OP07, but there are probably better ones. > > See http://www.analog.com/pdf/op07.pdf > > > > Be aware that 16 bits at 5 mV means 76 nV precision. So your amplifier > > should > > be attached directly to the detector, everything well shielded, stable > > (good > > resistors, possibly temperature stabilised, some RC filter to reduce the > > higher frequency noise). If signal changes slowly, avaraging lots of > > samples > > will reduce noise significantly. In my experience, getting noise below > 0.1 > > mV > > might be very tricky. > > > > Best regards, > > -- > > Tomek > > > > --- [rtl] --- > > To unsubscribe: > > echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR > > echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED] > > ---- > > For more information on Real-Time Linux see: > > http://www.rtlinux.org/~rtlinux/ > --- [rtl] --- > To unsubscribe: > echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR > echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED] > ---- > For more information on Real-Time Linux see: > http://www.rtlinux.org/~rtlinux/ --- [rtl] --- To unsubscribe: echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED] ---- For more information on Real-Time Linux see: http://www.rtlinux.org/~rtlinux/
