Yes. The "magic" is in the DSP (software).
-Tim
---
W4TME
FlexRadio Systems Internet Systems Admin.
Product Verification Team
Tune In Excitement™
On 2/14/2011 9:42 PM, Edwin Marzan wrote:
I get great audio reports on AM with my SDR-1000. Does that mean I will get
results similar to Rob's?
Edwin Marzan AB2VW
Date: Mon, 14 Feb 2011 14:07:28 -0600
From: [email protected]
To: [email protected]
CC: [email protected]
Subject: Re: [FlexEdge] Flex 5000A – PSDR 2.X.X and Amplitude Modulation
Surprise
It is all software.
The DSB suppressed carrier, fully complex signal is made just like any other
DSB signal would be. This is added coherently to the carrier. Since you
are not modulating the envelope of the carrier, but adding two coherent
signals, this allows the supermodulation AM you have discovered. You are
the first I KNOW ABOUT to have expressed all of this so clearly. The
"200%" modulation stuff in your videos is something I have not thought about
since I never dreamed anyone would go that high.
Congrats.
Bob
N4HY
On Mon, Feb 14, 2011 at 1:57 PM, W1AEX - Rob<[email protected]> wrote:
Setup: Flex 5000A, Power SDR 2.0.16, Win XP/SP2
I use my Flex 5000A now and then on AM when I don’t feel the urge to fire
up my big plate modulated rigs. Naturally, I was curious how the Flex looks
on my scope in the AM mode. I was pleasantly surprised at how the Flex could
handle the asymmetry in my voice and produce very healthy looking positive
peaks without nearing the baseline. Performance on the test bench was
equally impressive. The Flex 5000A passes triangle waves cleanly from 10 cps
to over 5000 cps in the AM mode. My plate modulated rigs can’t do that! The
biggest surprise came when I ran a 1000 cps sine wave through the Flex. It
cleanly reaches 125% in the positive direction before it reaches the
baseline. Normally, an AM transmitter will reach 100% positive and 100%
negative simultaneously when fed a sine wave. Broadcast stations use
expensive processing equipment to limit negative peaks to achieve asymmetry
like this. I’m not aware of any Inovonics processing equipment inside my
Flex 5000A, so this has me wondering how the asymmetry was achieved. Note
that the Power SDR compander and EQ were not active during the triangle wave
and sine wave measurements.
1. Is this asymmetry common in all Flex 5000A’s or is mine extra special?
2. Is this a result of hardware or software?
3. Is this a symptom of possible I/Q imbalance?
Don’t get me wrong, I like the concept of asymmetry in the AM mode (as long
as it’s heading in the positive direction) and I don’t view this as a
problem. I’m just curious how it was achieved.
73,
Rob W1AEX
Picture sine wave test:
http://members.cox.net/w1aex.fn31/flexsine.jpg
Picture triangle wave test:
http://members.cox.net/w1aex.fn31/flextri.jpg
Video sine wave test: http://www.youtube.com/watch?v=1gNsWl8BBD0
Video triangle wave test: http://www.youtube.com/watch?v=UpoCipk-U08
--
One thing I'm certain of is that there is too much certainty in the world.
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posting topics related to SDR software development and experimentalist who are
using beta versions of the software.
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[email protected]
http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz
This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is used for
posting topics related to SDR software development and experimentalist who are
using beta versions of the software.
