On 8/23/2010 5:31 PM, David Gilbert wrote:
> Creeping senility is such an ugly thing ....
>
> While working outside on a project I realized I had referred to K9YC as
> Gary, when everyone (including me) knows his name is Jim. My sincere
> apologies ...
Tis qute alright Sam!.
73
Roger (K8RI)
> 73,
> Dave AB7E
>
>
>
> On 8/23/2010 1:12 PM, David Gilbert wrote:
>> Thanks for the feedback, Rick ... good comments. I wasn't really trying
>> to simulate what happens in a receiver, though, because there is no way
>> I can account for all the various receiver characteristics of AGC
>> threshold and non-linearity. I own an Elecraft K3 that has a very wide
>> range of possible settings, and I know from personal experience that it
>> is possible to make multiple weak signals virtually unintelligible if I
>> try hard enough.
>>
>> Based upon your comments and those from Gary, K9YC, though, I think I
>> will go back to the original .wav files and remix them, then feed them
>> into my backup rig (756Pro) with it transmitting into a dummy load. I
>> can then record the result as received by my Elecraft K3 to see if the
>> results are significantly different than what I already have. I'll
>> give it a try with and without mixed background noise and see how it works.
>>
>> Thanks es 73,
>> Dave AB7E
>>
>>
>>
>> On 8/23/2010 11:43 AM, Rick Karlquist wrote:
>>> The intent of these tests is good. It is always good
>>> to get confirmation that a 2 dB difference in S/N
>>> is significant. That's why I run 150W in low power
>>> contests instead of 100W, if the rules permit.
>>>
>>> There is some question as to the validity of your
>>> experiments. It sounds like you added perfect audio
>>> tones to receiver background noise. This isn't
>>> necessarily equivalent to actually receiving signals
>>> through the receiver. The receiver could have some
>>> nonlinearity and the receive filter could have some
>>> ringing.
>>>
>>> Rick N6RK
>>>
>>>
>>> David Gilbert wrote:
>>>> I've added a page to my web site covering some investigations into how
>>>> much difference in signal strength might be noticeable in weak signal
>>>> and/or contest conditions, with several audio files included as
>>>> illustration. Please don't consider any of it to be authoritative since
>>>> I am not an audio professional, but maybe some of it will be useful to
>>>> someone. If anyone has suggestions for different comparisons, please
>>>> let me know.
>>>>
>>>> http://www.ab7e.com/weak_signal/mdd.html
>>>>
>>>> 73,
>>>> Dave AB7E
>>>>
>>>>
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