Yes, I have heard of 'software radios', but what you are describing is
not a 100% 'software radio'. I have checked the vanu site. It still
requires a 'multi-band front end' which the RF to IF mod/demod section I
was referring to.
The key element in such a radio is a DDS (direct digital synthesizer),
and an RF I/Q modulator IC (mixer) See:
http://products.analog.com/products/info.asp?product=AD8346
This product is specifically designed for WCDMA (wideband CDMA).
Analog Devices also provides solutions.
Jithesh Kizhakkekkara wrote:
>
> Have u heard abt software radios....looks like u havent....now
> adays...irrespective of what signals it is we can do sampling of a very wideband
> signal..and do all mod/demod/if stuff in digital level.....for more info u should
> probably take a peek in to http://www.vanu.com.....,
> So here there is no I and Q channels.....it is all done after sampling the
> wideband...I hope u understand......
> Any way....we did figure out couple of boards to start with....the only problem
> is we got write Linux drivers in near future for these boards.....,
>
> thanx again,
> Jithesh....
> Kulwinder Atwal wrote:
>
> > How many channels do you need?
> >
> > I have done sampling of RF at 900 MHz. I sampled I and Q of the
> > signal after it was demodulated from the carrier and sent through a
> > mixer to produce separate I and Q channels.
> >
> > Do you need two channels? One for I and one for Q?
> >
> > Also, since your carrier is 1 GHz and your IF 10 MHz there is a
> > mod/demod stage between your 1 GHz RF and your 10 MHz IF. It is not all
> > done at a 'digital level'. The mod/demod of your IF is all digital.
> >
> > Your answer to the I and Q question will determine the type of ADC you
> > need.
> > - Kal Atwal.
> > > Again ...our application is not the traditional analog ones as u think....we
> > > do digitize the whole band and do the mod/demod at the digital level....
> >
> > > 1. Physical parameter...?? Say a wideband signal centred at 1Gc.....(10Mhz
> > > bandwidth...)...to be more specific let it be a wideband CDMA signal....
> > > 2. If I say 20Msps at 10 bits....I hope u understand...how often...
> > > 3. We have a dsp testbed here with an A/D which takes max 1 to -1V
> > > inputs....at 10 bit resolution this means the no : of significant digits is
> > > 3...that will be fine for us....
> > > Look forward to ur reply......,
> > > thanx,
> > > Jithesh...
> > > Kulwinder Atwal wrote:
> > >
> > > > Obviously, you have not done data acquisition before. It is meaningless
> > > > to talk about sampling rates without stating the desired resolution. It
> > > > is like talking about velocity in terms of direction alone. I have
> > > > worked on research projects requiring real time A/D and none of them
> > > > have used the lowest resolution. Further, there is the SINAD of the
> > > > analog front end to consider when calculating 'true' resolution. Many
> > > > solutions exist to meet your needs. To provide you with an optimal
> > > > solution I need to know the following:
> > > >
> > > > What is the physical parameter being measured?
> > > >
> > > > How often does it need to be measured?
> > > >
> > > > How many significant digits are required?
> > > >
> > > > - Kal Atwal.
> > > >
> > > > Jithesh Kizhakkekkara wrote:
> > > > >
> > > > > Hi,
> > > > > Iam working on a research project which requires real time data
> > > > > acquisition of the order of 20Mega samples /sec.... To be more specific
> > > > > I would like to know whether there are any LINUX drivers written to date
> > > > > for PCI based A/D cards of speeds above 20Msps... I will be extremely
> > > > > grateful if any body could give pointers to some product which is
> > > > > existing or some work happening in this domain...
> > > > > The max speed of the A/D for which a linux driver exists, I could
> > > > > spot out was around 2 Msps...
> > > > >
> > > > > thanx in advance,
> > > > > Jithesh....
> > > > >
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