Re: KX2/3 DSP AM Demodulation
Posted by
Don Wilhelm on
Sep 10, 2017; 3:13am
URL: http://elecraft.85.s1.nabble.com/KX2-3-DSP-AM-Demodulation-tp7634311p7634316.html
Scott,
The KX2/3 does not convert directly to audio.
It converts the RF to "baseband" which is a zero frequency IF (in the
KX3). The KX2 has the "8kHz shift" built in at all times, so the IF is
8kHz rather than baseband.
The KX3 can shift to the 8kHz IF if there is breakthrough of AM
broadcast stations.
Again, these are not Direct Conversion receivers.
73,
Don W3FPR
On 9/9/2017 10:46 PM, K9MA wrote:
> On 9/9/2017 21:35, Fred Jensen wrote:
>> A DC receiver converts the signal once to audio. Regardless of the
>> mechanics [which these days can get very complex], that's really all
>> there is.
>
> Ah, but the only way direct conversion can convert AM to audio, without
> some kind of fancy DSP stuff, is to phase lock the conversion oscillator
> to the carrier. My KX2 doesn't sound like it's doing that when I tune
> across a signal; it sounds more like a conventional superhet AM
> receiver. I'm trying to figure out how you take the I and Q mixer
> baseband ("audio") outputs of an AM signal and convert them to audio,
> and in a way that works when the carrier is not exactly zero beat.
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