Re: Topband: Demo of the value of one dB and the cost of sending too fast
I spent part of my engineering career designing satellite command FSK demodulators - including the deep space Pioneer Venus orbiter. To test the performance of them, we would mix the test signal with white noise. When you look at the FSK Bit-Error-Rate (BER) curve (bit errors versus signal to noise ratio in a bandwidth equal to the bit rate), you can see the BER improves by a factor of 10 to 1 for every dB in S/N ratio. In other words, for every dB improvement, you get one tenth the errors. 73 de Bob N6RW On 2/25/2016 9:40 AM, donov...@starpower.net wrote: The weak signal CW recordings on AB7E's website are well worth a few minutes to listen to. His recordings clearly demonstrate -- much more convincingly than any other demo I've ever heard-- the significance of one dB of improved signal strength and the cost of sending too fast under weak signal conditions http://www.ab7e.com/weak_signal/mdd.html My takeaways from his recordings: - its well worth the effort to improve your signal by as little as one dB - when signals are very weak, sending faster (especially at speeds faster then than 30 WPM) costs the equivalent of many dB of reduced signal strength. If you haven't already clicked on AB7E's webpage, these are direct links to several of his recordings. A weak CW signal buried in noise with the signal strength decremented in one dB steps, http://www.ab7e.com/weak_signal/6_5_4_3_2_1_0_db.mp3 Two weak CW signals buried in noise -- slightly offset in frequency -- with one signal one dB stronger than the other: http://www.ab7e.com/weak_signal/A_vs_B_1db_v1.mp3 http://www.ab7e.com/weak_signal/A_vs_B_1db_v2.mp3 Two weak CW signals buried in noise -- slightly offset in frequency -- with one signal two dB stronger than the other: http://www.ab7e.com/weak_signal/A_vs_B_2db_v1.mp3 http://www.ab7e.com/weak_signal/A_vs_B_2db_v2.mp3 CW signals sent at 20, 25, 30 and 35 WPM when buried in noise. http://www.ab7e.com/weak_signal/A_vs_B_2db_v2.mp3 73 Frank W3LPL _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Demo of the value of one dB
On Fri,2/26/2016 9:49 AM, Doug Grant wrote: Many years ago K1JX casually commented that contest scores improve 6% per dB. I filed that away for future reference. A couple of years ago I did a quick analysis and discovered he was right! There's clearly a difference, but the magnitude of the difference probably depends on the contest. Quite a few years ago, N6ZFO, whose job in pharama development included lots of statistics, did an analysis for NCCC saying that 1 dB was good for 2.6% in ARRL Sweepstakes. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Demo of the value of one dB and the cost of sending too fast
> > ... Maybe most of those hams who preach otherwise have less interest in > weak signals. .. > I fully agree. It's when the S-meter isn't moving that a dB or two really matters! If we're 10 over 9 and in the clear, that's different. 73, Mike www.w0btu.com _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Demo of the value of one dB
Many years ago K1JX casually commented that contest scores improve 6% per dB. I filed that away for future reference. A couple of years ago I did a quick analysis and discovered he was right! The control case was N1UR, who operated the CQWW contest many years in the low power category, then turned on an amplifier and raised his score about 75%, or about 6% per dB! Same op, same QTH, same antennas, just 12dB more signal. Every dB counts! 73, Doug K1DG _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Fwd: Demo of the value of one dB and the cost of sending too fast
I am with Bob 100%. Particularly on Top Band, I want to hear that 1db better. A lot of what we pursue on receive is to squeeze a little bit better copy, a separate receive antenna to hear above the noise level and using APF on CW for instance. I will be trying the Logikit SCAF-1 audio filter on CW audio. I am using an Elecraft K3 and has great RF DSP but hopefully I can gain a another slight edge with the SCAF-1, I hear great reports about using it. Count me in to the wants 1DB better receive camp. 73, Bob K6UJ On 2/26/16 5:44 AM, Chortek, Robert L. wrote: I agree - I am far more limited by what I can "not" hear than I am by those who can't hear me (though that could use considerable improvement too). So, while I would like to be 1 db louder and hear 1 db better if I had to pick only one, it would be to hear 1 db better No contest!!! 73, Bob AA6VB Sent from my iPhone From: Topband on behalf of Bill Cromwell Sent: Friday, February 26, 2016 5:58 AM To: topband@contesting.com Subject: Re: Topband: Demo of the value of one dB and the cost of sending too fast Hi, Doubling the power output translates to less than one "S-unit" at a distant receiver. Maybe most of those hams who preach otherwise ahve less interest in weak signals. That is a matter of personal interest and personal taste. Don't forget that all of this applies on receive, too. There is not much chance for me to work DX with antennas that will fit the space I have available and the power levels I use. I'm happy to work in the region where I live. But I can hear those DX stations. A peeve of mine is the 'alligator' station - all mouth and no ears. Mine is the opposite. We aren't going to work them if we can't hear them regardless of fill legal power output (or more) and huge antenna arrays. 73, Bill KU8H On 02/26/2016 07:35 AM, Mike Waters wrote: - its well worth the effort to improve your signal by as little as one dB It certainly is! This is quite interesting. How many hams have we heard over the years preaching otherwise? "But it's ONLY a fraction of an S-unit!". 73, Mike www.w0btu.com _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Fwd: Demo of the value of one dB and the cost of sending too fast
> I agree - I am far more limited by what I can "not" hear than I am by those > who can't hear me (though that could use considerable improvement too). > So, while I would like to be 1 db louder and hear 1 db better if I had to > pick only one, it would be to hear 1 db better No contest!!! > > 73, > > Bob AA6VB > > Sent from my iPhone >>> From: Topband on behalf of Bill Cromwell >>> >>> Sent: Friday, February 26, 2016 5:58 AM >>> To: topband@contesting.com >>> Subject: Re: Topband: Demo of the value of one dB and the cost of sending >>> too fast >>> >>> Hi, >>> >>> Doubling the power output translates to less than one "S-unit" at a >>> distant receiver. Maybe most of those hams who preach otherwise ahve >>> less interest in weak signals. That is a matter of personal interest and >>> personal taste. Don't forget that all of this applies on receive, too. >>> >>> There is not much chance for me to work DX with antennas that will fit >>> the space I have available and the power levels I use. I'm happy to work >>> in the region where I live. But I can hear those DX stations. A peeve of >>> mine is the 'alligator' station - all mouth and no ears. Mine is the >>> opposite. We aren't going to work them if we can't hear them regardless >>> of fill legal power output (or more) and huge antenna arrays. >>> >>> 73, >>> >>> Bill KU8H >>> >>> >>> On 02/26/2016 07:35 AM, Mike Waters wrote: > - its well worth the effort to improve your signal by as little as one dB It certainly is! This is quite interesting. How many hams have we heard over the years preaching otherwise? "But it's ONLY a fraction of an S-unit!". 73, Mike www.w0btu.com _ Topband Reflector Archives - http://www.contesting.com/_topband >>> >>> _ >>> Topband Reflector Archives - http://www.contesting.com/_topband >>> _ >>> Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Demo of the value of one dB and the cost of sending too fast
Bill - I am uncertain, based on your reply below, whether you are a proponent of worrying about 1 db or not...so, from a 100% QRP op's perspective, saving 1 db, i.e., delivering 1 more db to the antenna, IS important that 1 db can be the difference 'tween being heard above the noise, or not. 72/71.5 de Jim R. K9JWV From: Topband on behalf of Bill Cromwell Sent: Friday, February 26, 2016 5:58 AM To: topband@contesting.com Subject: Re: Topband: Demo of the value of one dB and the cost of sending too fast Hi, Doubling the power output translates to less than one "S-unit" at a distant receiver. Maybe most of those hams who preach otherwise ahve less interest in weak signals. That is a matter of personal interest and personal taste. Don't forget that all of this applies on receive, too. There is not much chance for me to work DX with antennas that will fit the space I have available and the power levels I use. I'm happy to work in the region where I live. But I can hear those DX stations. A peeve of mine is the 'alligator' station - all mouth and no ears. Mine is the opposite. We aren't going to work them if we can't hear them regardless of fill legal power output (or more) and huge antenna arrays. 73, Bill KU8H On 02/26/2016 07:35 AM, Mike Waters wrote: >> - its well worth the effort to improve your signal by as little as one dB >> > It certainly is! This is quite interesting. > > How many hams have we heard over the years preaching otherwise? "But it's > ONLY a fraction of an S-unit!". > > 73, Mike > www.w0btu.com > _ > Topband Reflector Archives - http://www.contesting.com/_topband > _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Demo of the value of one dB and the cost of sending too fast
Hi, Doubling the power output translates to less than one "S-unit" at a distant receiver. Maybe most of those hams who preach otherwise ahve less interest in weak signals. That is a matter of personal interest and personal taste. Don't forget that all of this applies on receive, too. There is not much chance for me to work DX with antennas that will fit the space I have available and the power levels I use. I'm happy to work in the region where I live. But I can hear those DX stations. A peeve of mine is the 'alligator' station - all mouth and no ears. Mine is the opposite. We aren't going to work them if we can't hear them regardless of fill legal power output (or more) and huge antenna arrays. 73, Bill KU8H On 02/26/2016 07:35 AM, Mike Waters wrote: - its well worth the effort to improve your signal by as little as one dB It certainly is! This is quite interesting. How many hams have we heard over the years preaching otherwise? "But it's ONLY a fraction of an S-unit!". 73, Mike www.w0btu.com _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Demo of the value of one dB and the cost of sending too fast
> > - its well worth the effort to improve your signal by as little as one dB > It certainly is! This is quite interesting. How many hams have we heard over the years preaching otherwise? "But it's ONLY a fraction of an S-unit!". 73, Mike www.w0btu.com _ Topband Reflector Archives - http://www.contesting.com/_topband
