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Re: [TenTec] Looking for NB for Triton 544

To: geraldj@weather.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] Looking for NB for Triton 544
From: Ken Brown <ken.d.brown@hawaiiantel.net>
Reply-to: ken.d.brown@hawaiiantel.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Tue, 27 Jul 2010 22:24:54 -1000
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
You may be right about the pulses needing to be narrow and strong in 
order for most noise blankers to work on them. I do not think you are 
correct about them needing to have a regular repetition rate. For 
example the noise blanker in the Omni VI has a detector to trigger the 
generation of a blanking pulse, and a switch in the IF signal path 
controlled by the blanking pulse, which performs the blanking. There is 
nothing in the Omni VI noise blanker that requires repetitive noise 
pulses in order to work. It can blank a single noise pulse as long as 
the pulse is strong enough to trigger the blanking pulse.

There are noise blanker circuits that are designed to work on repetitive 
pulse type noise, particularly 60 and 120 Hz repetition rate noise 
pulses produced by AC power lines (or 50 and 100 Hz in the other 
hemisphere) These circuits are typically synced to the the AC power 
source using a sample directly from the mains rather than from the 
receiver IF, and can blank the receiver even when the noise pulse would 
not be strong enough to trigger a blanking circuit such as in the Omni VI.

There are other types of noise blankers which use a whole separate 
receiver, working at a different frequency from the one the main 
receiver is tuned to, to sense noise pulses and trigger the blanking of 
the main receiver. These also do not require repetitive noise pulses to 
> characteristics its made for are ignition noise and line noise that have 
> a regular repetition rate but are made of isolated narrow but VERY 
> STRONG pulses. Unless you have a thunderstorm close by, you don't get 
> similar pulses from the static crashes and the noise blanker doesn't see 
> big enough or narrow enough pulses to work to cut them out.
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