[TenTec] notch filter for Eagle?

rick@dj0ip.de Rick at DJ0IP.de
Thu Jul 20 11:05:30 EDT 2017

Gary, you are covering your "assets", aren't you.
Once you say "to me", END of discussion - hi.

The notch filter outside of the AGC loop can be very affective as long as the disturbing carrier is weaker than the wanted signal.  That happens as often as not, but  Murphy tries to prevent that when you are trying to work that rare one.

Once the disturbance is stronger that the desired signal, game over.

I would not say Icom is the leader;  I would say it's the winner.
It found the winning combination of good enough new technology, while listening to what the majority of the users want (i.e. KNOBS).  FLEX's stubbornness in that respect will possibly lead to the downfall of the company.

Currently I would say ANAN is the technology leader but as you say, who wants a radio without knobs.  That's like having a good bottle of wine but no cork screw!

I'm no expert on SDR technology but they achieve the notch through a combination of phasing and time slices.  All I can say is that it certainly works!

For me the little SKY-SDR is finally a replacement for my Argonaut 509 radio.


-----Original Message-----
From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Dukes HiFi
Sent: Thursday, July 20, 2017 4:21 PM
To: Discussion of Ten-Tec Equipment
Cc: Greg S
Subject: Re: [TenTec] notch filter for Eagle?


Since your SDR has notch inside the AGC loop, it must not be all that difficult to accomplish. Of course, I do not have sufficient knowledge of SDR designs to know how they manage AGC or notch functions.

Too bad no one is writing software for the Orion anymore. It would be nice if that change could be done. I might even buy one then...

I should have added the caveat in my remark regarding the relative uselessness of a notch filter outside the AGC line by saying “useless to ME”. Others are certainly free to believe that an external notch filter (that is, external to the AGC loop)  is equally effective (manual or otherwise).

This topic was beaten to death maybe 30 to 40 years or so ago when relatively decent external filters, such as the Autek and later on when DSP devices were introduced. They were pitched as offering Collins or Drake-like performance in otherwise mediocre receivers. They didn’t, but they did make operation less annoying to some degree. They also worked pretty well if you turned off the AGC and used the RF gain pot to compensate for variations in signal strength.


PS: Icom is the leader here in direct SDR, FOR ME. The performance is not there yet but I have zero interest in needing to have my PC on to run my radio. The 7300 does not need a PC to work, the others do. They are headed in the right direction. If Ten Sec ever introduces a new radio, likely it will head in that direction too.

> On Jul 20, 2017, at 7:08 AM, rick at dj0ip.de <Rick at DJ0IP.de> wrote:
> notch

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