Controlled Audio Diversity System
There are three basic schemes for a Diversity Reception System (DRS). It can be accomplished with
1. Diversity Phase Controlled Antenna System (DPC).
Spaced antennas fed to a variable phasing network, then combined to a single signal feed to reduce the effects of phase-related fading (QSB).
2. Synchronous AM Detection (SAM) [see DSB and ISB, and my sync demodulator].
An internally generated carrier that is inserted into the receiver chain to supplement selective fading's lost carrier (QSB) and the propagation loss of the carrier.
3. Multiple Reception Audio Summing (MAS).
The controlled mixing (summing) of recovered (detected) audio from different mode sources.
a. Analog and digital broadcasts. (See the ADM-1 below and on the previous page)
b. Upper and lower sidebands (ISB/DSB) (See the ADC-1 Below)
Here are the two controller
panels together. Combined, they
facilitate both modes of the
Audio Diversity scheme.
The ADC-1 mixes either
LSB/USB detection for diversity
recovery or provides additional
control for the ADM-1
Note that the two channels are
marked for typical stereo (AMS)
control or D/A control.
The ADM-1 controls the
summing of analog and digital
recovered audio. This system
allows for the correction of
analog fading vs. digital dropout.
At this time, the tuner of choice
for the A/D mode is the Sangean
HDT-1X. (See previous page
and youtube video)
For DSB/ISB control, I'm
currently using a pair of
The final system configuration of
this system will be housed in a
3U rack cabinet containing both
these controllers and the
In the short time that I have
been developing these systems,
I have realized the amazing
potential for high quality audio
recovery of AM broadcast
signals, and the reduction of
fading distortion for both
commercial AM and International
It seems that the resolution of one problem always opens the door to subsequent unsolved problems. Since this system can only control the summing
of A/D or LSB/USB at any given time, I questioned the validity of a 4-channel device that could do the mixing for all four of those modes.
Unfortunately, the pragmatic wisdom of that premise proved to be correct! So, the results of my next project, scheduled for mid-2012, will be able to
simultaneously control SAM, LSB, USB, and digital modes, all in one controller.
Yes, this is really taking things to the "sublime and passionate end," but immediately two thoughts come to mind; (A) there really is no "end" in
technology, and (B) if it's there, why not go for it. Without getting into the analogies of mountain climbing, land-speed records, bowling scores, the
Preakness Stakes and the Palm Springs Country Club, suffice it to say that quality is seldom the child of anything other than obsession and passion,
attended by long hours and significant cash ... usually.
Famous quote: "Frustration motivates; satisfaction lets you sleep." (my grandfather)
More as it happens in January 2012.
Thanks for looking.