Hi All,
Thanks everyone for all the excellent advice!
I think we are going to try the 14-bit Red Pitatya for this, and just work
to the highest frequencies that we can achieve with the ADCs in the Nyquist
limit (namely 62 MHz).
I might eventually have a go at interleaving the two ADC channels to d
Hi,
Thank you for your reply!
I would consider LimeSDR or maybe XTRX, it have a GPS onboard and PCI-ex
interface.
Best regards,
Tavi
În mar., 11 feb. 2020 la 08:05, Mugundhan vijayaraghavan <
v.vaishnav151...@gmail.com> a scris:
> Hello Tavi,
>
> There are implementations of red pitaya as a
Hello Tavi,
There are implementations of red pitaya as a SDR by Pavel Demin, but the
max. bandwidth (that he has implemented) is about 2.5 MHz and also is
limited in tuning range.
Yes, using SDRs is another option. LimeSDR is a possible candidate which
gives tunability and max. instantaneous band
erlap of the input and output bands
>>>>> means simple conversion methods with normal mixers don't work.
>>>>>
>>>>> Ross
>>>>>
>>>>>
>>>>> On Mon, Feb 10, 2020, 1:09 AM Mugundhan vijayaraghavan <
>&g
:09 AM Mugundhan vijayaraghavan <
>>>> v.vaishnav151...@gmail.com> wrote:
>>>>
>>>>> Hi jishnu,
>>>>>
>>>>> With red pitaya, you have to down convert 20-80 to 0-60 baseband to
>>>>> use the band fully. As such, it has a
to
>>>> use the band fully. As such, it has a cutoff at 65MHz.
>>>>
>>>> Thanks,
>>>> Mugundhan
>>>>
>>>> On Mon, 10 Feb 2020, 13:30 Jishnu Nambissan T,
>>>> wrote:
>>>>
>>>>> Hi Mugundhan,
>>>
ing is a more cost-effective way to
implement this, provided red pitaya supports that mode.
Jishnu
From: "Hariharan Krishnan"
To: "casper"
Sent: Monday, February 10, 2020 4:33:32 PM
Subject: Re: [casper] Solar Spectrometer Channeliser
Hi Jishnu,
Down-conversion i
13:30 Jishnu Nambissan T,
>>>> wrote:
>>>>
>>>>> Hi Mugundhan,
>>>>>
>>>>> With red pitaya, can you sample 20-80 MHz without downconversion ? And
>>>>> if analog down conversion is required, wouldn't tha
you sample 20-80 MHz without downconversion ? And
>>>> if analog down conversion is required, wouldn't that restrict the usable
>>>> dynamic range (unless a high level mixer is used) ?
>>>>
>>>> Jishnu
>>>>
>>>> -
th red pitaya, can you sample 20-80 MHz without downconversion ? And
>>> if analog down conversion is required, wouldn't that restrict the usable
>>> dynamic range (unless a high level mixer is used) ?
>>>
>>> Jishnu
>>>
>>> ---
usable
>> dynamic range (unless a high level mixer is used) ?
>>
>> Jishnu
>>
>> --
>> *From: *"Mugundhan vijayaraghavan"
>> *To: *"casper"
>> *Sent: *Thursday, February 6, 2020 1:06:09 AM
>> *Subject: *Re: [casper] Solar Spectrometer Cha
ghavan"
> *To: *"casper"
> *Sent: *Thursday, February 6, 2020 1:06:09 AM
> *Subject: *Re: [casper] Solar Spectrometer Channeliser
>
> Hi Dan,
>
> We have done integration times from 20ms upto a second. There are bursts
> that last for hours, minutes and a few m
gt;
>> --
>> *From: *"Mugundhan vijayaraghavan"
>> *To: *"casper"
>> *Sent: *Thursday, February 6, 2020 1:06:09 AM
>> *Subject: *Re: [casper] Solar Spectrometer Channeliser
>>
>> Hi Dan,
>>
>> We
*Sent: *Thursday, February 6, 2020 1:06:09 AM
> *Subject: *Re: [casper] Solar Spectrometer Channeliser
>
> Hi Dan,
>
> We have done integration times from 20ms upto a second. There are bursts
> that last for hours, minutes and a few ms to seconds as well.
>
> We have not tri
er"
Sent: Thursday, February 6, 2020 1:06:09 AM
Subject: Re: [casper] Solar Spectrometer Channeliser
Hi Dan,
We have done integration times from 20ms upto a second. There are bursts that
last for hours, minutes and a few ms to seconds as well.
We have not tried AGC on these bursts since we
Hi Dan,
We have done integration times from 20ms upto a second. There are bursts
that last for hours, minutes and a few ms to seconds as well.
We have not tried AGC on these bursts since we were aiming to study them
only. In the 8 bit design, we had 3 bits for background and remaining 5 to
accomm
hi mugundhan,
what's the time scale for these bursts?
rise and fall times?
can you use a AGC circuit (automatic gain control),
eg: computer controlled attenuator
to turn down the power going into the ADC during the bursts,
so you could keep the levels going into the ADC relatively constant?
if the
Hi Dan,
Usually quiet sun doesn't show such abrupt changes, but bursts do (easily
40-50dB or more) for bright bursts. We have built 8 bit spectrometers in
40-80Mhz, but have found then when the burst is pretty strong, saturation
effects starts kicking in.
Thanks,
Mugundhan
On Wed, 5 Feb 2020,
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 fac
Dear Colm,
I think you may find the bandwidth is the issue in this case. The Red
Pitaya (10 bit and 14 bit) seems to only have an input 50MHz (3dB)
bandwidth, so you would only get 10-50MHz bandwidth (total bandwidth of
40MHz). There is also a 16 bit version, but I suspect it has a similar
bandwid
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