Or do they use a 3000 Hz BW for testing purposes and compare modes that way?
Yes to compare. For example, I want to compare modes at S/N=-10 dB:
I send a a signal of 1 mWatt and 10 mW of noise in 3KHz (so 3.33 mW per KHz).
Now among this noise you can send your 1 mWatt signal in the way
] On
Behalf Of Jose A. Amador
Sent: Friday, October 26, 2007 2:26 PM
To: digitalradio@yahoogroups.com
Subject: Re: [digitalradio] Re: QEX Article on HF Digital Propagation
Yes, a 3 kHz voice channel...not the inmediate environment of the
digital signal, but much, much farther away. And as noise
Rud Merriam wrote:
Jose,
Just as you were posting this message I was stumbling on a web site that
agreed with your comment.
With further searching I think I have the relationship. The QEX article has
the statement that to go from the 3kHz bandwidth used you subtract 34 dB
and add 10 log
] Re: QEX Article on HF Digital Propagation
How wide is 45 baud RTTY ?
At 07:52 PM 10/26/2007, Rick, KV9U wrote in part:
How do you make a wider bandwidth for a given mode? Isn't the bandwidth
based on the baud rate to begin with?
The part that I don't fully understand is the bandwidth calculation.
When I use PSK31, isn't the bandwidth pretty much set by the baud rate
and width of the signal? Often it is expressed as around double the baud
rate or ~ 60 Hz.
Now if I have my rig wide open with the 3.6 kHz bandwidth and
http://TheHamNetwork.net
-Original Message-
From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] On
Behalf Of Rud Merriam
Sent: Saturday, October 27, 2007 1:47 AM
To: digitalradio@yahoogroups.com
Subject: RE: [digitalradio] Re: QEX Article on HF Digital Propagation
Jose,
Just
Sorry but I may have missed something.
Your point is ? ? ?
At 07:11 PM 10/27/2007, you wrote:
I took the dB results from the authors web page and calculated the bandwidth
adjusted dB and the Shannon-Hartley channel capacity:
Report
SNRBWBW Adj
?
No it is indifferent.
73
Patrick
- Original Message -
From: Rick
To: digitalradio@yahoogroups.com
Sent: Sunday, October 28, 2007 1:20 AM
Subject: Re: [digitalradio] Re: QEX Article on HF Digital Propagation
The part that I don't fully understand is the bandwidth calculation
AEC Montgomery County, TX
http://TheHamNetwork.net
-Original Message-
From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] On
Behalf Of John Becker, WØJAB
Sent: Saturday, October 27, 2007 7:16 PM
To: digitalradio@yahoogroups.com
Subject: RE: [digitalradio] Re: QEX Article on HF
--- In digitalradio@yahoogroups.com, Walt DuBose [EMAIL PROTECTED] wrote:
Rud Merriam wrote:
After a comment off list from Demeter I checked the Pactor
specifications.
It uses DBPSK or DQPSK.
Why do the reports about Pactor indicate it is more robust than
the QEX
article would
PSK31 failed, bad copy even under good SNR, with 3 ms multipath and
10 Hz
Doppler. It did not do well with 2 ms multipath and 1 Hz Doppler.
Since Pactor uses PSK I wondered if it would similarly fail as shown
by the
PSK31 results. I suspect that it handles Doppler better through
frequency
Something that has long been unclear to me is how can we have all these
modes that work far below zero db S/N and yet the Eb/No (energy per bit
relative to noise) can theoretically not go much lower than between 1
and 2 dB below zero dB according to the Shannon Limit?
Then you need to take the
as defined above).
73
Patrick
- Original Message -
From: Rick
To: digitalradio@yahoogroups.com
Sent: Friday, October 26, 2007 8:39 PM
Subject: Re: [digitalradio] Re: QEX Article on HF Digital Propagation
Something that has long been unclear to me is how can we have all
://TheHamNetwork.net
-Original Message-
From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] On
Behalf Of Rick
Sent: Friday, October 26, 2007 1:39 PM
To: digitalradio@yahoogroups.com
Subject: Re: [digitalradio] Re: QEX Article on HF Digital Propagation
Something that has long been unclear
My understanding is that the Eb/No is more of what you would find at the
antenna terminals, without the bandwidth of the receiver?
Using your data on your web site, how does this relate to say, PSK31
modulation? Would the SNR also be at zero with the 31 bps baud rate with
the B/C (Bandwidth in
How wide is 45 baud RTTY ?
At 07:52 PM 10/26/2007, Rick, KV9U wrote in part:
How do you make a wider bandwidth for a given mode? Isn't the bandwidth
based on the baud rate to begin with?
: [digitalradio] Re: QEX Article on HF Digital Propagation
My understanding is that the Eb/No is more of what you would find at the
antenna terminals, without the bandwidth of the receiver?
Using your data on your web site, how does this relate to say, PSK31
modulation? Would the SNR also be at zero
Rick wrote:
Something that has long been unclear to me is how can we have all these
modes that work far below zero db S/N and yet the Eb/No (energy per bit
relative to noise) can theoretically not go much lower than between 1
and 2 dB below zero dB according to the Shannon Limit?
That's
I thought about the same. On pactor, the doppler perturbation is 31/100
of the signalling rate, thus, results less affected, even without taking
into account the FEC and QRQ strenghts that Pactor also packs along.
73,
Jose, CO2JA
Vojtech Bubnik wrote:
PSK31 failed, bad copy even under good
After a comment off list from Demeter I checked the Pactor specifications.
It uses DBPSK or DQPSK.
Why do the reports about Pactor indicate it is more robust than the QEX
article would indicate?
Rud Merriam K5RUD
ARES AEC Montgomery County, TX
http://TheHamNetwork.net
-Original
Rud Merriam wrote:
After a comment off list from Demeter I checked the Pactor specifications.
It uses DBPSK or DQPSK.
Why do the reports about Pactor indicate it is more robust than the QEX
article would indicate?
Rud Merriam K5RUD
ARES AEC Montgomery County, TX
One other comment.
I have said before on this list that I have seen and used to have data produced
by SouthWest Research Institute here in San Antonio that shows the maximim
probable data capability of a single PSK signal.
This study was done for the U.S. Government in research to find the
://TheHamNetwork.net
-Original Message-
From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] On
Behalf Of Walt DuBose
Sent: Thursday, October 25, 2007 9:38 PM
To: digitalradio@yahoogroups.com
Subject: Re: [digitalradio] RE: QEX Article on HF Digital Propagation
Rud Merriam wrote
PROTECTED] On
Behalf Of Walt DuBose
Sent: Thursday, October 25, 2007 9:51 PM
To: digitalradio@yahoogroups.com
Subject: Re: [digitalradio] RE: QEX Article on HF Digital Propagation
One other comment.
I have said before on this list that I have seen and used to have data
produced
by SouthWest
Rud,
How did DominoEx rate?
73,
Steve N6VL
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