Steve's comments are very good. I'd suggest adding an in-line stepped
attenuator to have better control over just where the threshold of detection
will exist. Also, some type of analog meter on the audio output to
accurately see where the signal level reached the 3 dB mark or whatever
value one wishes to determine. Ears just won't do it at this petite level.
In the FM world of communications we call the measurement SINAD. (Signal in
Noise and Distortion)
73
Bob, K4TAX
----- Original Message -----
From: "Steve Ellington" <N4LQ@igLou.com>
To: <tentec@contesting.com>
Sent: Saturday, May 15, 2004 7:06 PM
Subject: Re: [TenTec] Practicing with the Orion
> A good place to experiment with weak signals and high noise is around
> 7.040mhz during daytime hours. Those QRP signals provide a real
opportunity
> check the effectiveness of your noise reduction features, agc settings and
> filter bandwidth. I've found the filter bandwidth has a huge effect on the
> ability to copy cw in noise. I've been doing a lot of A/B test between the
> Orion and PRO2. About the time I think I know which one does best, along
> comes a signal that changes my opinion. It's madding! Specifications have
> nothing to do with it either. BDR and MDS are out the window. There are no
> strong local signals to give problems and the noise level is far above the
> MDS. Sometimes I'll peak up a weak signal on one rig but I can't decipher
> the code, tune it in with the other rig and although it sounds noisier, I
> can copy it. What would you call this measurement? Throughput? What we
need
> is a generator that generates random atmospheric type noise and modulates
it
> with cw then a computer program that analyzes the throughput and produces
an
> error percentage much like is done in the data transmission business.
> Steve
> N4LQ
>
> ----- Original Message -----
> From: "Don" <kd6hq@sonic.net>
> To: <tentec@contesting.com>
> Sent: Saturday, May 15, 2004 10:56 PM
> Subject: [TenTec] Practicing with the Orion
>
>
> After reading through the manual today and paying particular attention to
> "Weak Signal DX Reception, Contest Operation and the Orion" section it
> occurred to me that I don't know what a 3db above the noise signal
threshold
> sounds like. I know what I consider to be a weak signal but if you want
to
> sit down and just practice using the filter settings it would be nice to
> have a reliable signal to use. So my question is does anyone know of a
> (relatively) inexpensive signal generator (schematic) so that I could
> purchase/build one? OR perhaps someone knows of another way to do this?
>
>
>
> Thanks
>
> Don kd6hq
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>
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