QAM Example Programs?

On Aug 2, 12:49 am, "Vladimir Vassilevsky"
<antispam_bo...@hotmail.com> wrote:
> "Steve Underwood" <ste...@dis.org> wrote in message
>
> news:f8r824$4kg$1@nnews.pacific.net.hk...
>
>
>
> > Actually, demodulating the QAM is the easy part of the receiever. Symbol
> > sync, carrier sync, and equalisation is the interesting stuff. The
> > complexity of the modulation only affects that a little bit.
>
> Exactly. In the textbooks, they prefer to take that stuff for granted
> whereas it is the very important and probably the most difficult part to
> implement. An interaction between symbol sync, carrier sync and equalizer is
> rather subtle subject. Do you know of any book which has a good treatment on
> that? Is there an efficient algorithm for the joint estimation of symbol and
> carrier sync and the adaptation of the equalizer?
>
> Vladimir Vassilevsky
> DSP and Mixed Signal Consultantwww.abvolt.com

Check out this paper:

N.K. Jablon, "Joint Blind Equalization, Carrier Recovery, and Timing
Recovery for High-Order QAM Signal Constellations," IEEE Transactions
on Signal Processing, vol. 40, no. 6, Jun 1992.

Jason

cincydsp@gmail.com wrote:
> On Aug 2, 12:49 am, "Vladimir Vassilevsky"
> <antispam_bo...@hotmail.com> wrote:
>> "Steve Underwood" <ste...@dis.org> wrote in message
>>
>> news:f8r824$4kg$1@nnews.pacific.net.hk...
>>
>>
>>
>>> Actually, demodulating the QAM is the easy part of the receiever. Symbol
>>> sync, carrier sync, and equalisation is the interesting stuff. The
>>> complexity of the modulation only affects that a little bit.
>> Exactly. In the textbooks, they prefer to take that stuff for granted
>> whereas it is the very important and probably the most difficult part to
>> implement. An interaction between symbol sync, carrier sync and equalizer is
>> rather subtle subject. Do you know of any book which has a good treatment on
>> that? Is there an efficient algorithm for the joint estimation of symbol and
>> carrier sync and the adaptation of the equalizer?
>>
>> Vladimir Vassilevsky
>> DSP and Mixed Signal Consultantwww.abvolt.com
> 
> Check out this paper:
> 
> N.K. Jablon, "Joint Blind Equalization, Carrier Recovery, and Timing
> Recovery for High-Order QAM Signal Constellations," IEEE Transactions
> on Signal Processing, vol. 40, no. 6, Jun 1992.
> 
> Jason
> 
There is no problem finding interesting papers on these subjects. 
However, we normally hope to consult a good textbook to get a broad 
picture of the state of the art in a field. I don't know any textbooks 
which do that for these real world areas of building digital 
communications receivers.

Steve

Steve Underwood wrote:

(snip regarding baseband signaling)

> The contents of an Ethernet packet typically has large DC, but what it 
> on the wire cannot contain DC. Its a wacky definition of baseband that 
> says what is on the wire in the baseband of the signal.

For coaxial ethernet, the signal on the wire does have a DC offset,
which is used for collision detection.  Transformers are used at each
end of the transceiver cable, along with a DC-DC converter so that
there is no DC coupling between the host power supply and the cable.
(To avoid ground loops.)

For UTP ethernet it it transformer coupled on both ends.
10baseT uses manchester coding which averages to zero for
each bit. The fundamental frequency is equal to the
bit rate, twice that needed by Nyquist.

100baseTX uses a more complex coding with extra
logic to keep the average zero.

http://en.wikipedia.org/wiki/MLT-3

MTL-3 has a fundamental at one fourth the bit rate,
trading a little S/N for reduced spectrum and
reduced EMI in UTP cable.  The cable bit rate is
125MHz, so the cable fundamental is at 31.25MHz.

Broadband ethernet (originally 10broad36, and now more
complicated coding used for cable modems) modulates the
signal such that more than one can fit on a single coaxial
cable at once.  (For cable modems, they are designed to fit
within a 6MHz television channel bandwidth.)

-- glen

glen herrmannsfeldt wrote:
> Steve Underwood wrote:
> 
> (snip regarding baseband signaling)
> 
>> The contents of an Ethernet packet typically has large DC, but what it 
>> on the wire cannot contain DC. Its a wacky definition of baseband that 
>> says what is on the wire in the baseband of the signal.
> 
> For coaxial ethernet, the signal on the wire does have a DC offset,
> which is used for collision detection.  Transformers are used at each

That DC isn't part of the content of the packet, though. It is a 
separate media access indicator. Its presence is yet another reason 
Ethernet cannot operate at baseband.

What I said holds. Ethernet packet data is nudged away from its true 
baseband.

Steve

Steve Underwood wrote:
> cincydsp@gmail.com wrote:
>> On Aug 2, 12:49 am, "Vladimir Vassilevsky"
>> <antispam_bo...@hotmail.com> wrote:
[...]
>>
>> Check out this paper:
>>
>> N.K. Jablon, "Joint Blind Equalization, Carrier Recovery, and Timing
>> Recovery for High-Order QAM Signal Constellations," IEEE Transactions
>> on Signal Processing, vol. 40, no. 6, Jun 1992.
>>
>> Jason
>>
> There is no problem finding interesting papers on these subjects.
> However, we normally hope to consult a good textbook to get a broad
> picture of the state of the art in a field. I don't know any textbooks
> which do that for these real world areas of building digital
> communications receivers.

Doing a search on Amazon.com about this topic I found 3 books:

 Synchronization Techniques for Digital Receivers

   by Umberto Mengali, 1997

http://www.amazon.com/Synchronization-Techniques-Receivers-Applications-Communications/dp/0306457253/ref=pd_bbs_sr_1/002-1200865-9895219?ie=UTF8&s=books&qid=1186407160&sr=8-1


 Digital Communication Receivers, Vol. 2: Synchronization, Channel
 Estimation, and Signal Processing

   by Heinrich Meyr, Marc Moeneclaey, Stefan A. Fechtel, 1997

http://www.amazon.com/Digital-Communication-Receivers-Vol-Synchronization/dp/0471502758/ref=pd_bbs_sr_2/002-1200865-9895219?ie=UTF8&s=books&qid=1186407160&sr=8-2


  Advanced Techniques for Digital Receivers
    by Phillip E. Pace, 2000

http://www.amazon.com/Advanced-Techniques-Digital-Receivers-Library/dp/1580530532/ref=sr_1_7/002-1200865-9895219?ie=UTF8&s=books&qid=1186407160&sr=8-7

Does somebody know any of these books and how good they are for self
study in that area?

Cheers,

Guenter