[Elecraft] dynamic range question was [FT817] ELECRAFT

[Fred Jensen]

On 12/30/2011 1:03 PM, Jim Brown wrote:
> On 12/30/2011 4:51 AM, goldtr8 at charter.net wrote:
>> Ok I admit I do not clearly understand this 30dB better dynamic range.
>
> In very simple terms, it means that when a very strong signal is very
> close in frequency to another much weaker signal that you want to listen
> to, the KX3 can reject a signal that is 30dB stronger than the 817 can
> reject.  Putting it another way, on the 817, the stronger signal would
> take over, and you wouldn't hear the weaker one, but the KX3 would pull
> it through.

OK ... yet another thing I've apparently forgotten or confused since 
college oh so many years ago.  I thought [and thought I've always thought]:

Dynamic Range:  For a device, the difference between the peak level of 
*undistorted* output it will produce and the RMS value of the inherent 
noise within the device [i.e. zero input].  For an audio *signal* [like 
music in a concert hall], the difference between the lowest level and 
the highest peak level of the signal.  Symphonic music has a very high 
dynamic range ... very quiet parts, very loud parts [think "1812 
Festival Overture"].  Rap ... not so much.  DR="one signal"

Dynamic Blocking Range [sometimes Blocking Dynamic Range]:  For some 
specified separation between a desired signal and an interfering signal, 
it's the difference between the level of the interfering signal and the 
level of the desired signal at the point where the interfering signal 
has produced some specified effect on the desired signal.  DBR="two signals"

If this is wrong, I'd sure like to get it right because I'd like to 
understand, "The KX3 will have about 30 dB better dynamic range than the 
IC-7000, even without the roofing filter."

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2012 Cal QSO Party 6-7 Oct 2012
- www.cqp.org