Hi Dan, The downconversion was the first idea that we had before Prof Inggs steered us towards the SNAPs. I made a quick costs overview:
If each channel cost $100. Total cost for 48 is $4800. PCIe ADC with 16channels at 1MSPs will come at $500 each. Three of these will be $1500. Add to that the cost of three mainframes which would be around $1500 as well plus the need of a switch(1GbE 24 channels is atleast $2000). This should bring the total cost to $9800. Four SNAPs will come around $14000 at $3500 with much less complexity. There is a $4000 difference and this is one of the reasons I am seeking out the CASPER group in case someone can get us the SNAPs at a reduced price. I may have forgotten to mention that while we are only building a one station pathfinder, the plan is for 20 or so stations which will give us over a 1000 channels. The added advantage of using something like the SNAP is that I get to expose the radio astronomy community to SDR and FPGA development and once the experiment is over the SNAP can be reused for any other experiment. Prof Inngs and I agreed that to build expertise for hosting SKA type telescopes it is essential we get started with what the astronomy community is using. Cheers, Vinand On Sat, May 26, 2018 at 2:44 AM Dan Werthimer <d...@ssl.berkeley.edu> wrote: > > hi michael, > > if you decide you want to have 48 downconverters, and then use a low rate > 48 input ADC board, then > > a) you could implement downconverters with connectorized > (eg:minicircuits) mixers, filters, amplifiers > about $100 per channel > > > b) you could make your own PCB, or perhaps use the downconverter boards we > made for arecibo multibeam receiver: > see section 4: "16-Channel Quadrature Downconverter (IF to IQ > Baseband Converter) of > https://casper.berkeley.edu/galfa/ > > lower parts cost but more work. > > photos of this 16 channel downconverter are at: > https://casper.berkeley.edu/galfa/pictures/pictures.html > > best wishes, > > dan > > > On Fri, May 25, 2018 at 9:04 AM, Michael Inggs <miki...@gmail.com> wrote: > >> Hi Dan >> >> One of the tradeoff studies the guys are doing is the cost of a 48 >> channel analogue downconverter and low sample rate ADC. At present, direct >> demod with a SNAP looks simpler in terms of hardware complexity, but has >> not been costed. >> >> One of the team has actually implemented all the digital backend >> (including RFI excision) on a GPU, so in principle, all we need are time >> stamped packets of samples, and nothing on the FPGA, except demod, >> decimation. >> >> Thanks for the ideas coming in to the team. >> >> Regards >> >> >> On Fri, 25 May 2018 at 18:59, Dan Werthimer <d...@ssl.berkeley.edu> >> wrote: >> >>> >>> >>> if vinand, >>> >>> if you want to digitize 48 signals with 250 KHz bandwidth, you might >>> want to consider >>> purchasing a 48 input PCIe ADC board and doing the signal processing in >>> a computer (in software). >>> (not use FPGA boards). >>> but then you'd have to mix the deuterium line to baseband, so you'd need >>> 48 downconverters. >>> >>> if you want to use snaps, and you don't have much processing to do on >>> the fpga, and you want to save money, you could >>> plug in a ADC16 board into the snap - >>> this is a bit of a cludge, but would give you 28 channels per snap (16 >>> external ADC channels, and 12 on board ADC channels). >>> >>> if you have a roach1 or roach2 lying around, there's a 64 channel adc >>> board you could use that sample at up to 50 Msps; >>> i'm not sure about the analog bandwidth - you might not have to use >>> downconverters... >>> >>> best wishes, >>> >>> dan >>> >>> >>> >>> >>> On Fri, May 25, 2018 at 6:24 AM, Vinand Prayag <vinan...@gmail.com> >>> wrote: >>> >>>> Hi, >>>> >>>> Please find attached the User Requirement. The bandwidth is actually >>>> only 250KHz >>>> >>>> Cheers, >>>> Vinand >>>> >>>> On Fri, May 25, 2018 at 5:20 PM Marcus D. Leech <mle...@ripnet.com> >>>> wrote: >>>> >>>>> On 05/25/2018 07:28 AM, Vinand Prayag wrote: >>>>> >>>>> Hi all, >>>>> >>>>> We are looking at building a telescope in Mauritius which is called >>>>> the Mauritius Deuterium Telescope, MDT for short. As the name suggests it >>>>> is a Deuterium focused experiment. We have planned for a pathfinder >>>>> station >>>>> to be built for the end of this year and had in mind the SNAP boards for >>>>> the digital back-end. We were set to buy four SNAPs by the end of next >>>>> month but a sudden slash in funding has put a dent in our plans. I was >>>>> wondering if anyone has any unused SNAPs that we can get off their hands >>>>> at >>>>> a reduced price. Currently one SNAP is sitting at $3500 from Digicom. >>>>> Anything below $3000 will greatly help us. We will obviously be extremely >>>>> grateful for donations. Hope to have some positive feedback from some of >>>>> you. >>>>> >>>>> >>>>> Kind Regards, >>>>> Vinand Prayag >>>>> >>>>> Do you have a pointer to a project description? >>>>> >>>>> Why such high bandwidth if you're looking at Deuterium? >>>>> >>>>> >>>>> >>>>> -- >>>>> 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 post to this group, send email to casper@lists.berkeley.edu. >>>>> >>>> -- >>>> 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 post to this group, send email to casper@lists.berkeley.edu. >>>> >>> >>> -- >>> 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 post to this group, send email to casper@lists.berkeley.edu. >>> >> >> >> -- >> Michael Inggs >> 10 Devon Street, Simon >> <https://maps.google.com/?q=10+Devon+Street,+Simon+s+Town,+South+Africa&entry=gmail&source=g> >> 's Town, South Africa >> <https://maps.google.com/?q=10+Devon+Street,+Simon+s+Town,+South+Africa&entry=gmail&source=g>. >> Tel: >> +27 21 786 1723 Fax: +27 21 786 1151 Skype: mikings Cell: +27 83 776 7304 >> "Ex Africa semper aliquid novi" >> >> -- >> 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 post to this group, send email to casper@lists.berkeley.edu. >> > > -- > 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 post to this group, send email to casper@lists.berkeley.edu. > -- You received this message because you are subscribed to the Google Groups "casper@lists.berkeley.edu" group. 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