Well, this is all very good info and suggests that the Orion
sub-receiver is not really all that useful as a GC SW or BC receiver, if
you really want to listen.
I've made the case to a few folk in the south that an Orion III, or an
Orion "Contest" that had two identical amateur band only receivers, like
the current primary receiver, and no sub (par) receiver would make for
an even better and more popular radio. After all, their competition all
have identical receivers these days. Besides, they could sell a lot more
filters!
I suppose if enuf folk joined me in telling them, they might do it. I
would think they would sell a lot of them!
73, Joel, W1ZR.
Sinisa Hristov wrote:
>AM demodulation is a nonlinear process and AM BW
>testing using noise input is meaningless.
>The filter bandwidth cannot be reliably estimated
>from the resulting audio spectrum measurements
>because of the unknown spectral components generated
>by the nonlinear demodulation process.
>
>The testing can be done reliably in two ways:
>
> a) using a carrier swept around to determine bandpass edges, or
>
> b) using an amplitude modulated signal with the carrier centered
> in the bandpass, and modulation frequency swept to determine
> edges.
>
>Just to be sure, I've retested V1.373b5 and V2.056,
>using both of the above methods (BW set at 6 kHz):
>
> a) V1.373b5 bandwidth is 12 kHz (center +/- 6 kHz)
> V2.056 bandwidth is 6 kHz (center +/- 3 kHz)
>
> b) V1.373b5 is capable of reproducing up to 6 kHz modulation
> V2.056 is capable of reproducing up to 3 kHz modulation
>
>Therefore, the entire audio spectrum of AM broadcasts
>can not be received using V2.056 (and probably Orion II).
>
>Furthermore, attempting to amplitude-demodulate only the carrier
>and a single sideband generates nonlinear distortion, caused by
>the fact that the resulting RF envelope no longer represents
>the audio signal faithfully.
>
>A single sideband of an AM signal can be demodulated without
>distortion by a linear process, i.e. a product detector supplied
>with a carrier of the proper frequency and phase. But this is not
>possible with Orion.
>
>
>73,
>
>Sinisa YT1NT, VE3EA
>
>
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>
>
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