It depends on what you want. A digital scope equivalent to a cheap old Hameg 20MHz Dual Channel scope needs a real 12 to 14 bits and 200MHz sampling at least!
My Tektronix 10MHz scope was useful to 150MHz! I had a USB based 100MHz scope: 1) X - Y mode was rubbish 2) though claiming 8bits, it was 6 to 7 bit. You need a genuine 10 bits after conversion. 3) Useless above 5MHz. Divide sample MHz by 2 * Number of channels. Assume Analogue Anti- aliasing filters are not "brick wall response" so divide by 2 again. A 100MHz sampling 2 channel digital scope is thus 15MHz at best. An Analogue 15MHz scope will work up to much higher MHz.. Really either spend KKKK Euro on a 14bit 500MHz Digital scope, or get a second hand analog one (Try www.helmutsinger.de ) or make one by using an SDR and a Laptop + software. Soundcard is good to 20KHz or 40KHz depending on Model (some 192KHz cards / USB are filtered at 20KHz, some at 40kHz, I don't know of any that really are flat to 96kHz). Or buy a nice Analog Devices ADC and add to USB PIC. You can buy 16bit 200MHz parts :) (not cheap!) The 1Msps digital scope will be good to maybe 200kHz or less. The Maximum input bandwitdh MUST be less than 1/2 the sample rate. With reasonable priced analogue anti-aliasing filter, often close to 1/4. This is reason that Audio (20KHz CDs or 22kHz MP3) uses 44.1KHz and 48KHz sampling originally and now uses 192kHz to make the analogue filters cheaper. In fact Stereo uses 384Ksps of 16bits. The actual audio bandwidth is still about 20KHz. Again 24 bits is used to allow 16bit accuracy with cheaper parts... You can't actually get true 16bit accuracy of playback with a cheap 16bit DAC. -- You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/jallib?hl=en.
