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?
>>>>
>>>>
>>>>
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