hi colm, regarding dynamic range --------------------------------- for your solar spectrometer, do you need 14 bits of ADC dynamic range? it's very unusual in radio astronomy to need that much instantaneous dynamic range on the input. does the sun vary on short time scales in the radio band by factor of 1000 in voltage (1,000,000 in power) ? or do you have very strong bursting RFI that is 1000 times the average noise voltage (1M in power) in the whole band?
as you probably know, you'll have lots more dynamic range in the output power spectrum than the dynamic range of the ADC: if you are building a 1024 channel spectrometer with 1 ms integration, you'll get about 8 bits more bits of dynamic range above your ADC dynamic range in frequency domain voltage, which is 16 bits more of dynamic range above your ADC dynamic range in power spectra. so you'll have about 20 bits of spectral dynamic range if you use an 8 bit ADC, (power spectrum dynamic range of about 1 million in 1 ms with an 8 bit ADC, setting noise at 3 bit RMS). and 24 bits of spectrral dynamic range for a 10 bit ADC, 28 bits for 12 bit ADC, and 32 bits for for 14 bit ADC). regarding boards for your spectrometer --------------------------------------------------- 1) as adam pointed out, the red pitaya is cheap, but sample rate and bandwidth don't quite get the specs you need. 2) another possibility is to use a snap board, which costs more, but can sample 3 inputs at 950 Msps, or 6 inputs at 500 Msps, or 12 inputs at 250 Msps with 8 bit ADC's. most people populate the snap board with 8 bit ADCs, but a few people have populated it with 12 bit ADC's, although the sample rate goes down by 8/12. 3) another possibility is to use a xilinx RFSOC board. the first gen has a bank of 12 bit ADC's (8 inputs at 4 Gsps, or 16 inputs at 2 Gsps), but i think the new generation has 14 bit ADC's ? the RFSOC boards cost more than snaps, but RFSOC was designed in dublin, so you can probably get one from xilinx dublin.... the ZCU111 board has not been fully casperized yet though. best wishes, dan Dan Werthimer Marilyn and Watson Alberts Chair Astronomy Dept and Space Sciences Lab University of California, Berkeley On Wed, Feb 5, 2020 at 5:06 AM Colm Bracken <colmbrac...@gmail.com> wrote: > Hello CASPER people, > > We are looking to build a spectrometer with not too demanding requirements. > Based on the specs below, would the Red Pitaya be up to the job do you > think? > Or, is there another, better suited (but similarly affordable) solution? > > Chanel widths: ~< 100 kHz > Time sampling: ~< millisecond > Polarisation: 2 channels > Antenna freq range: 10-85 MHz (total bandwidth of 75 MHz) > Digitisation: 14 bit > > Any advice on this would be great! > > Thanks in advance, > Colm > -- > > *Dr Colm Bracken* > Lecturer > Maynooth University Experimental Physics > > > Maynooth University, Maynooth, Co. Kildare, Ireland. > > T: +353 1 708 3641 > E: colm.brac...@mu.ie W: www.maynoothuniversity.ie > > Follow my work on https://nuim.academia.edu/ColmBracken > > > > And > > > Research Associate > > Astronomy & Astrophysics Section > School of Cosmic Physics > Dublin Institute for Advanced Studies > 31 Fitzwilliam Place > Dublin 2, D02 XF86 > > > > T: +353 1 440 6656 ext 352 > E: cbrac...@cp.dias.ie W: www.dias.ie/2017/06/22/dr-colm-bracken > > Follow my work on https://nuim.academia.edu/ColmBracken > > -- > You received this message because you are subscribed to the Google Groups " > casper@lists.berkeley.edu" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to casper+unsubscr...@lists.berkeley.edu. > To view this discussion on the web visit > https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CAEx9wh8jNxeUnPGaSvwwuAtPCRsnNoCbOFnhbpU9EDb%2BPKh-Bg%40mail.gmail.com > <https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CAEx9wh8jNxeUnPGaSvwwuAtPCRsnNoCbOFnhbpU9EDb%2BPKh-Bg%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "casper@lists.berkeley.edu" group. To unsubscribe from this group and stop receiving emails from it, send an email to casper+unsubscr...@lists.berkeley.edu. To view this discussion on the web visit https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CAGHS_vH-6MvNUAxsZVs8KOW%2BUhOB5tUAZQdmu3_%3D9A24RL1Fqw%40mail.gmail.com.
