Forum: GNU Radio implement d8psk on benchmark_tx.py

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Daniel Steven (Guest)
on 2009-02-17 01:52
(Received via mailing list)
Hello, guys!

We are using the file, benchmark_tx.py residing in the directory of
python/digital to do some researches. We found that gmsk, dbpsk and
dqpsk are the supported modulation schemes for that file, but d8psk is
not the supported modulation technique. Is there any reason for the
absence of d8psk? Is that because carrier tracking is very difficult for
d8psk? We wish to sort that problem out and get d8psk to work! Thanks a
lot!

Daniel
George N. (Guest)
on 2009-02-17 02:06
(Received via mailing list)
Hello, Tianning/Bill/Daniel!

The performance of 8PSK matches pretty similarly to 16-QAM.  So, 8PSK is
usually never used in a real system as you get better spectral
efficiency with 16-QAM without taking a huge hit in required SNR.

- Rick Stevens
Daniel Steven (Guest)
on 2009-02-17 03:16
(Received via mailing list)
Great Smart GUY!

So, what is the obstacle for us to implement QAM demodulator? Is that
because of the carrier tracking or symbol synchronization? We really
wish to sort that problem out and get QAM running on USRP!!!

Thanks!!!

Best Regards!

Daniel




________________________________
From: George N. <removed_email_address@domain.invalid>
To: Daniel Steven <removed_email_address@domain.invalid>
Cc: removed_email_address@domain.invalid
Sent: Monday, February 16, 2009 7:05:23 PM
Subject: Re: [Discuss-gnuradio] implement d8psk on benchmark_tx.py

Hello, Tianning/Bill/Daniel!

The performance of 8PSK matches pretty similarly to 16-QAM.  So, 8PSK is
usually never used in a real system as you get better spectral
efficiency with 16-QAM without taking a huge hit in required SNR.

- Rick Stevens
Firas A. (Guest)
on 2009-02-17 06:31
(Received via mailing list)
Hi,

> On Tue, 2/17/09, George N. <removed_email_address@domain.invalid> wrote:

> Hello, Tianning/Bill/Daniel!
>
> The performance of 8PSK matches pretty similarly to 16-QAM.
>  So, 8PSK is usually never used in a real system as you get
> better spectral efficiency with 16-QAM without taking a huge
> hit in required SNR.
>
> - Rick Stevens

8PSK modulation is widely used by VSAT modems for SCPC-SCPC links.


Best Regards,

Firas
David I. Emery (Guest)
on 2009-02-17 06:38
(Received via mailing list)
On Mon, Feb 16, 2009 at 08:30:26PM -0800, Firas A. wrote:
> >
> > - Rick Stevens
>
> 8PSK modulation is widely used by VSAT modems for SCPC-SCPC links.

  And for both DTH (DirecTV and Dish HD) and broadcast/cable
satellite signal distribution... witness the DVB-S2 8PSK modes being
rapidly deployed and the older DSNG-trellis 8PSK.

  It is prefered for the non-linear environment of satellite
transponders with significant HPA compression... 16-QAM takes better
linearity... and many satellite channels are power rather than BW
limited.


--
  Dave Emery N1PRE/AE, removed_email_address@domain.invalid  DIE Consulting, 
Weston,
Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole
- in
celebration of what could have been, but wasn't and is not to be now
either."
Eric B. (Guest)
on 2009-02-17 20:31
(Received via mailing list)
On Mon, Feb 16, 2009 at 08:30:26PM -0800, Firas A. wrote:
> >
> > - Rick Stevens
>
> 8PSK modulation is widely used by VSAT modems for SCPC-SCPC links.
>
> Best Regards,
> Firas

Thanks Firas.  (QAM needs a linear amp.)

Eric
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