I need to simulate symbol recovery of a 16QAM or a higher constellation
QAM. I am looking for an algorithm which I can simulate using c code. I am
using the baseband signal modulated using 16QAM. I have goe through few
papers like Interpolation in digital Modem Part I/II. It doesnt seem to
work well with QAM. 
I would also like to tell that I plan to use this recovery mechanism for
DVB environment i.e. satellite environment in Ku/Ka band and terminals are
stationary. So any suggestions on what modulation should be used and
suitable references for the same are more then welcome. I am not
intesrested in carrier recovery because for simulation I am using the
baseband so I am not carrier modulating the signal to be transmitted.
Kindly suggest some good references as well if possible
TIA
Regards
Rajenish 


		
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"Rajenish_jain" <r...@gmail.com> wrote in message 
news:a...@giganews.com...
>I need to simulate symbol recovery of a 16QAM or a higher constellation
> QAM. I am looking for an algorithm which I can simulate using c code. I am
> using the baseband signal modulated using 16QAM. I have goe through few
> papers like Interpolation in digital Modem Part I/II. It doesnt seem to
> work well with QAM.
> I would also like to tell that I plan to use this recovery mechanism for
> DVB environment i.e. satellite environment in Ku/Ka band and terminals are
> stationary. So any suggestions on what modulation should be used and
> suitable references for the same are more then welcome. I am not
> intesrested in carrier recovery because for simulation I am using the
> baseband so I am not carrier modulating the signal to be transmitted.
> Kindly suggest some good references as well if possible
> TIA
> Regards
> Rajenish
>
>
>
> This message was sent using the Comp.DSP web interface on
> www.DSPRelated.com
Hi Rajenish, if you want 4 bits per symbol before FEC and are using it for 
DVB over satellite you might want to look at the DVB-S2 standard for 
16APSK - you can get it from the ETSI web site.  Otherwise I guess you could 
use Gray Mapped 16QAM as your basic modulation format if your amplifiers 
aren't clipping just above your average power level.

Best of Luck - Mike

On Wed, 10 Aug 2005 06:48:57 -0500, "Rajenish_jain"
<r...@gmail.com> wrote:

>I need to simulate symbol recovery of a 16QAM or a higher constellation
>QAM. I am looking for an algorithm which I can simulate using c code. I am
>using the baseband signal modulated using 16QAM. I have goe through few
>papers like Interpolation in digital Modem Part I/II. It doesnt seem to
>work well with QAM. 
>I would also like to tell that I plan to use this recovery mechanism for
>DVB environment i.e. satellite environment in Ku/Ka band and terminals are
>stationary. So any suggestions on what modulation should be used and
>suitable references for the same are more then welcome. I am not
>intesrested in carrier recovery because for simulation I am using the
>baseband so I am not carrier modulating the signal to be transmitted.
>Kindly suggest some good references as well if possible
>TIA
>Regards
>Rajenish 

16QAM is used pretty commonly in satellite applications, so that's
reasonable.

I'm not quite sure what you're asking for, though.   A second-order
PLL with an appropriate phase detector is typically all that's needed
to recover the symbol clock with 16QAM.


Eric Jacobsen
Minister of Algorithms, Intel Corp.
My opinions may not be Intel's opinions.
http://www.ericjacobsen.org

>On Wed, 10 Aug 2005 06:48:57 -0500, "Rajenish_jain"
><r...@gmail.com> wrote:
>
>>I need to simulate symbol recovery of a 16QAM or a higher constellation
>>QAM. I am looking for an algorithm which I can simulate using c code. I
am
>>using the baseband signal modulated using 16QAM. I have goe through few
>>papers like Interpolation in digital Modem Part I/II. It doesnt seem to
>>work well with QAM. 
>>I would also like to tell that I plan to use this recovery mechanism
for
>>DVB environment i.e. satellite environment in Ku/Ka band and terminals
are
>>stationary. So any suggestions on what modulation should be used and
>>suitable references for the same are more then welcome. I am not
>>intesrested in carrier recovery because for simulation I am using the
>>baseband so I am not carrier modulating the signal to be transmitted.
>>Kindly suggest some good references as well if possible
>>TIA
>>Regards
>>Rajenish 
>
>16QAM is used pretty commonly in satellite applications, so that's
>reasonable.
>
>I'm not quite sure what you're asking for, though.   A second-order
>PLL with an appropriate phase detector is typically all that's needed
>to recover the symbol clock with 16QAM.
>
>
>Eric Jacobsen
>Minister of Algorithms, Intel Corp.
>My opinions may not be Intel's opinions.
>http://www.ericjacobsen.org
>

Hi,
 Thanks Eric and Mike for your inputs. I agree 16QAM could also be used
for modulation. What I am interested is in simulating a blind  (Non-Data
aided), feedforward or/and feedabck SYMBOL RECOVERY algorithm. I could not
find any easy to understand algorithm which can be implemented for blind
symbol recovery. So it would be very helpful if you can name soe algorithm
along with their reference which I can simulate. 
At the end of excersice I tend to design a burst to achieve good enough
spectral efficiency for  satellite network in Ku/Ka band. Any Idea till
what level of modulation can be achieved in satellite channel for Ka band
say 256 QAM etc.
waiting for the respose,
Thanks
Best Regards
Rajenish

		
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"Rajenish_jain" <r...@gmail.com> wrote in message 
news:c...@giganews.com...
> >On Wed, 10 Aug 2005 06:48:57 -0500, "Rajenish_jain"
>><r...@gmail.com> wrote:
>>
<snip>
>
> Hi,
> Thanks Eric and Mike for your inputs. I agree 16QAM could also be used
> for modulation. What I am interested is in simulating a blind  (Non-Data
> aided), feedforward or/and feedabck SYMBOL RECOVERY algorithm. I could not
> find any easy to understand algorithm which can be implemented for blind
> symbol recovery. So it would be very helpful if you can name soe algorithm
> along with their reference which I can simulate.
> At the end of excersice I tend to design a burst to achieve good enough
> spectral efficiency for  satellite network in Ku/Ka band. Any Idea till
> what level of modulation can be achieved in satellite channel for Ka band
> say 256 QAM etc.
> waiting for the respose,
> Thanks
> Best Regards
> Rajenish
>

O.K. Rajenish - in inverse order:

As you intend to operate over satellite I would find out whether you wish to 
operate in a Single Carrier Per Channel mode -  there is a large difference 
between operating one channel only through a (possible linearised) satellite 
TWTA near saturation direct to small receive antennas or operating multiple 
carriers through a nearly linear transponder for contribution quality 
between large hubs.  If you have very large hubs with extremely good phase 
noise characteristics then find out what the phase noise characteristic of 
the satellite is as this will probably be the limiting factor for your 
multicarrier system. If you have a SCPC direct broadcast system then it is 
likely that the cheap LNB used in the small subscriber terminals will 
contribute significant implementation loss AND that you will need to use 
something like QPSK or 16APSK at most, to ensure that you get adequate EIRP 
from the satellite.

The only standard that I know of at present that uses 16APSK is the DVB-S2 
standard - if you are not interested in building a full DVB-S2 receiver with 
adaptive coding and modulation ( giving the possibility to transmit a higher 
bit rate when  your link is not so badly faded but essentially no use if you 
have designed to provide receive only terminals with a fixed data rate for 
95% of locations for at least 99.5% of the average year say) then you will 
probably find that a QPSK system is adequate UNLESS your boss is demanding 4 
bits per Hz .  You will see that I have assumed that you are talking about 
the forward link of a DVB system OR about a trunking system and NOT the 
return link from a small satellite interactive terminal : if this is not the 
case please give more details as things will rapidly get complicated.

 The only web references for 16APSK symbol recovery that I can find are 
written by Dietmar Rudolph and are in german - the diagrams are very clear 
however so you may wish to download them- google will find them.  With most 
blind recovery techniques you will find that it is expected that you know 
the symbol period reasonably well ( so that you don't have a significant 
difference in the number of symbols in a few hundred symbol periods ). You 
might want to check to find out whether your symbol period is related to the 
carrier frequency and whether you have a reliable reference from the carrier 
recovery section.

Best of Luck - Mike