[TenTec] Receiver Specs

[James Duffer]

Here is one dummy version.  Receiver dynamic range was a periodic check that 
was made to a FAA long range radar receiver (part of ARSR-1D).  The check 
was made in the following manner.  A signal generator was set to the 
receiver frequency.   The generator was set up for pulsed output it was 
synced with the radar trigger.  The timing was delayed so that the pulse was 
displayed on an oscilliscope looking at the receiver's detector output. It 
was usually displayed beyond the sentisitivity time control (STC) or STC 
turned off at the receiver.  STC is similar to AGC except it is variable 
with time....greatest at range zero and decreased with range until no longer 
controlling the gain at long range.

Now this what was termed dynamic range:  While observing the pulse at a low 
level, the generator output was slowly increased and the pulse also 
increased.  At some point in increasing the generator the observed pulse 
would reach a level at which further increase in the generator would not 
increase the pulse or what we called the "limit" value.  This poing would be 
noted and then the output of the generator would be decreased until the 
pulse would be reduced so that it could barely be discerned from the 
surrounding noise (called grass) this level was recorded.  The difference of 
the two readings was the dynamic range of the receiver.  There were two 
receivers that were checked, one called "normal" the other called "MTI" 
(Moving Target Indicator)  The MTI used a phase detector producing bi-polar 
video output, while the Normal receiver used a simple amplitude detector.

So Scott, I guess dynamic range could be called, "the range of signal level 
that there is a useful output from the receiver"  I am sure there are other 
non-dummie explanations that could "provoke more thought"

73, Jim, wd4air






>From: CHRSAM195@aol.com
>To: tentec@contesting.com
>Subject: [TenTec] Receiver Specs
>Date: Tue, 7 Jan 2003 17:27:25 EST
>
>Where can I find a " Dummies" version or explanation of the " Dynamic 
>ranges"
>and other associated terms regarding receiver specs. Thanks and 73's Scott
>WB2NYM
>
>
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