"Diversity Receive" is used 100% of the time at K0UO

With the Icom 7610 and the new IC7760 using the new True Diversity Tracking Function, just turn on the Tracking from the main menu. Not needed, but I also use a Linrad program, so by attaching separate antennas to the antenna ports in the Tracking receive mode, you have true "Diversity Receive".  It is a fantastic Improvement in reduction of QSB/fading. If one antenna is experiencing a deep fade, it is likely that another has a sufficient signal. Pattern diversity consists of two or more co-located antennas with different radiation patterns. This type of diversity makes use of directional antennas that are physically separated by some distance. Spatial diversity employs multiple antennas, usually with the same characteristics, that are physically separated from one another. Phase Synchronous Diversity Reception uses two widely spaced antennas (500 to 1500+ feet) feeding two identical high performance SDR receivers. Depending upon the expected incidence of the incoming signal, on the order of a many wavelengths. Collectively they are capable of discriminating a large portion of angle space and can provide a higher gain versus a single omni-directional radiator. This is absolutely a major Improvement, with Diversity Receive. My station uses over a mile of wire, listening to signals coming in at different angles. Signal-to-noise ratio (S+N/N ratio, or SNR) is one technical aspect not too many amateurs give a second thought about, however if you can't hear them you can't work them.  This is very apparent on audio reception, Diversity eliminates much of the audio amplitude fading. The RF signal is almost never in a stable phase relationship at both places at the same time. This means the signal will have random phase and amplitude differences. The arrival angle and polarization of incoming signals will change. This generally results in the fading, by having two antennas, the chances are that while one experiences a fade, the other will not. The power is in the diversity and what you can now hear with out QSB fading.

Icom did it right on the IC 7610 and IC 7760.

Two separate DIGI-SEL preselectors, two separate Band Pass Filter networks, feed two separate A/D converters into the FPGA, not just two Receivers. You need 2 ADCs for diversity reception.

The IC7610 has synchronized ADCs using a single clock and customized VCXO used with the Master Clock for phase synchronous streams.

The 7610/7760 has an input for a 10 MHz reference signal for higher precision.

Direct Sampling means incoming RF signals are digitized by the Analog-to-Digital Converter and immediately processed by the FPGA (Field-Programmable Gate Array). This process greatly reduces distortion that naturally occurs in the various mixer stages found in traditional superhetrodyne receivers.

RF Direct Sampling System in the IC-7610 is capable of 110 dB RMDR, and the new IC7760 is even better. This performance gives you the ability to pull weak signals out of the noise of strong adjacent signals.

The DIGI-SEL preselectors are RF filters with sharp, narrow passband characteristics preventing Analog-to-Digital Converter overflow from large out-of-band signals when sampling the RF signals. Additionally the third and higher order IMD components are reduced. This is ideal when strong signals are received in a contest pile-up or from broadcast stations on adjacent frequencies or bands.

The IC-7610/7760 can output I/Q signals to a connected PC. Using the I/Q signals on the HDSDR (freeware), you can listen to received signals, or observe the spectrum scope on the PC to be used in combination with the LinRad software.

A few years ago I was very honored to have been personally invited by Icom's American President Hiro Nakaoka, to meet with him and key staff members, at their WA office to discuss a mutually interesting project. Later several key Icom executives also visited my office in Kansas.

SmartDiversity™ is an improvement on basic antenna phase switching by using a microprocessor controlled algorithm to determine optimum timing for the switching activity. The algorithm analyzes both the incoming RF level and the rate of change in RF level to determine the optimum timing for phase switching, and the optimum antenna phase.

K0UO uses the Linrad program which has routines to correct amplitude and phase for complex input signals These routines operate in the frequency domain and can absorb frequency dependent phase and amplitude errors that are introduced by differences in amplifiers and filters used between the I/Q mixers and the audio board. The only requirement is that amplitude and phase errors are independent of amplitude, time and temperature.

Linrad together with hardware that can bring RF signals into digital form, Linrad forms an SDR receiver (A Software Defined Radio receiver). There is also a transmit part inside Linrad that will form an SDR transmitter together with appropriate hardware. see http://sm5bsz.com/linuxdsp/videos.htm

You can also do Diversity Receiption by using the THETIS software on many SDR radios

BELOW Apache Labs Anan 7000DLE Mk3 Diversity Reception Setup

https://www.youtube.com/watch?v=v0Pwa3mFkKg

BLOW:  Enhanced Signal Clarity (ESC) feature of the KE9NS PowerSDR software, but not true Diversity.

https://youtu.be/bDOl5ou-Ls8

MORE NOTES

The Icoms, Flex, Anan, and supposedly even the K3/K4 have dual diversity processing and tracking not just dual receivers, a big difference.

I have played with the Flex and Anan, if you have a lot of time with software you can probably actually do more, but it can be complicated too.

With any of those radios you can use external computers and processing programs, as I've noted in my blog above.

I use diversity 100% the time, however now I keep it simple. So I let the radio do the work internally, and I listen to the results on one speaker. Once you've proven to yourself that it's working and is a truly valuable Aid, keep it simple.

My goal NOW is not to be constantly looking at the different signal strengths, and fiddling with software.

To prove diversity is going to work for you, you will want to listen and look at the individual receivers to start, which is interesting, and even listening on individual stereo headphones or two speakers. 

Once you've seen/heard it in action, on signals with lots of QSB fading, you'll be satisfied that diversity is available tool.

For very strong signals where fading is not a problem, the diversity may not be a real advantage. However when I'm in a QSO with a strong station, I'm still using diversity. A lot of times a second or third party will join with a much different signal and distance from me. So it's just an automatic thing, in my operating practice now to always use it.

To me, fiddling with software is more of a distraction. Sometimes you may be missing a contact while you're playing with the software and computers.

I feel the most bang for your buck, time, and enjoyment, is to get a standalone radio, built with diversity features. Not just two receivers.

If you really big into software and want to spend a lot of time, then there are many options. And I know other developers are coming up with more software possibilities.

I'm very happy using the IC7610 or 7760, and keep it simple. They track and mix correctly, and are very stable.

Get up some very good antennas. Some people believe that you need a vertical or horizontal antenna and that's satisfies for diversity. The RF signals are coming in at different angles from the F layer at different times and distances. You want to capture all those signals, so the more distance between your antennas and capture area will have a big effect.

You could even to start, just combine your existing antenna with a loop, dipole, end feed, or vertical antenna, and you will see big differences, at different times of the day on different frequencies.

MY SETUP

I always use one of my Rhombic antennas, and I will either use a dipole, a beverage antenna, or one of my LPDA logs beams. On the lower bands the Beverage antennas are always the go-to.

Note

Don't use an antenna that has a lot of noise if you can help it. That's where the end feed and some verticals well hinder your results. True, some people use diversity to get rid of noise in their system, but they're really not getting the reduction in fading benefit, they're just fighting noise.

If you can definitely spread out your antennas, and if you can put up a second good antenna, they do not have to be identical in any way.

Your second receive antenna does not even have low swr.

At least now amateur radio operators have a choice in radios and software. In the past I have been at some sophisticated diversity DOD setups, using monster computers and antenna setups.  Now amateur radios can do it with off The Shield equipment.

Your best bang for your buck would probably be with the 7610 and getting a good second antenna. But the sky is the limit and how much time you want to invest in software.

Using two receivers with two antennas, and the human brain/ears doing the computing, is also a simple way to start. You'll see that it actually works,  the human brain is amazing.

AI noise reduction for radio receivers has emerged as a significant breakthrough in amateur radio technology, offering substantial improvements in signal clarity and reception. Here are the key developments and features of AI-based noise reduction for radio receivers:

RM Noise is a cloud-based AI noise suppression application that has gained popularity among amateur radio operators

• Uses a customized AI model trained on amateur radio phone and CW traffic

• Provides real-time noise reduction by sending audio to a dedicated inference server

• Capable of eliminating RF, appliance, and power line noise

• Can make S1 signals copy-able in S9 noise levels

• Requires only a Windows computer with internet access and audio input from the radio

Hytera has implemented AI-based noise suppression in their H-Series DMR Radios and Push-to-Talk over Cellular devices3:

• Utilizes deep learning technologies to identify human voice and eliminate background noise

• Employs machine learning models trained on 78 different noise environment datasets

• Developed using over 250 test scenarios to evaluate the algorithm's effectiveness

• NVIDIA Broadcast: While not specifically designed for amateur radio, it has shown potential for strong signal noise reduction1

• Various AI-based audio processing apps originally designed for online meetings can be repurposed for radio signal noise reduction

AI noise reduction technology is revolutionizing amateur radio by:

• Improving weak signal reception in high-noise environments

• Enhancing overall audio clarity and intelligibility

• Allowing older radios to benefit from advanced noise reduction capabilities

• Potentially eliminating the need for hardware-based noise reduction solutions

As this technology continues to evolve, it is expected to become more widely adopted and potentially integrated directly into radio hardware, further improving the amateur radio experience

TO SEE the complete Blog list check @  https://www.k0uo.com/k0uo

73 from,

The K0UO " Rhombic Antenna Farm"  miles of wire in the Air & On the AIR daily