Hi,
I'm a retired EE, having worked most of my career in software development (Mainframe Operating System - Unisys) but the last 10 years before I retired in hardware - circuit design and microprocessors -? mainly in medical devices.?
Originally licensed in 1964 at age 14 but had a 20 year gap before returning in 1995.? I've been working with PIC microprocessors and making PIC-controlled VFO kits for others to build and use since about 2000 (see May, 2006 QEX) .? For the last 10 years or so I've switched to using the Si570 programmable PLL in the kits. A 2011 QEX article described this project. All of my PIC programming for these projects is in Assembler - just because like to to it that way at home. I've used "C" in work projects.
Now I'm out of the kit business and just building what I want to build.? As such, I'm now designing / testing an all-homebrew transceiver with 3 PIC processors in it.? Features 5 boards that plug into a base board which contains the interconnections. Signal Generator (Si570), Receiver, Transmitter, Transmit / Receive switch, and Filter boards.? It's coming along nicely.??
In the coming days I'm very interested in exploring the use of a STM32F4 microprocessor in an SDR rig with DSP and few analog components.? Looking forward to diving in.?
73,
-Craig, AA0ZZ

I've had an interest in electricity and electronics since about age 4, when I stuck a bobby pin into my grandparent’s outlet to see if I could get some juice out. That cost my grandfather a trip to the hardware store for a new fuse. I thought the sparks were pretty cool, but not the paddling I got as a result.

After a few attempts at getting a college education in partying with a side in electrical engineering, I found myself in Columbus OH actually knuckling down, and completed my BS in 2-1/2 years. My commutes were from Columbus OH to New Providence NJ (525mi) only took 6 hours in my Porsche powered VW, but that's another story...

So after getting my BS, along came work, marriage, kids, house, more kids, moving, more kids, moving again,

I first got exposed to ham radio by K2RHR SK in about 1963 when I was in 6th grade, and thought it was pretty cool so I rushed out and got my ticket 44 years later in 2007 as KC2RPJ, and became AC2GL in 2009 because the code requirement was dropped, and I could only send an SOS on CW, I just didn't get around to studying CW, but I can still send SOS.

I never imagined when I created the group that I'd get so many responses. It shows that the traditional ARRL DIY attitude still lives. I'm particularly pleased by the variety of people.

I just wish I could figure out how to stop "new subscriber" messages.

Thanks and have fun!
Reg

I was originally licensed in 1968 while in college as WN0SMV and WA0SMV.? Yes, dual licenses during that peculiar period when you could hold the novice and technician licenses at the same time.? I retired from AT&T a few short years ago and am now wanting to get back into working on a few technical projects.? QTH is in rural central Georgia.

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This is Dave Daniel, KC0WJN.

I am a subscriber to QEX and have been involved in radio one way or another since I was in high school.

I am a retired embedded systems engineer with about forty years of experience with various design jobs, working for Storage Technology/Sun/Oracle for most of that time. Most of my experience is with digital hardware and embedded code, about 2:1 hardware to code with a lot of Verilog thrown in. For the first eleven years of my time with StorageTek, my manager asked me to solve various problems for which he had no other engineers to assign, so I have worked on everything from large motor-generators to raster image processors. I've designed things for IBM-compatible printers, disk drives, tape drives, tape automation and finally virtual tape systems until I was laid off along with a bunch of other engineers by Oracle in 2017.

I've since moved back to central Florida and have almost finished setting up my home lab, which consists of a lot of vintage Heath gear as well as a lot of vintage HP and Tektronix instruments. I also have a significant engineering, math and physics library.

I have some schooling in EE and physics (I was a double major and attended classes while I was working) but had to drop out of college after I was transferred out to Colorado by StorageTek in 1991, got married and was assigned to work on a high-pressure product development effort,so I have no degrees.

I have limited experience with RF and am working to correct that deficiency in my retirement years, hence my subscription to QEX and to this list, as well as other lists.

Reg,
I am probably stating the obvious and oversimplifying but WSPR is a great starting point to really see low power propagation.? I am in Northern Illinois, USA and have been running a RPi Zero W (previously used a 3) with the TAPR WSPR shield outputting 100mw into a wire antenna inside one of my out buildings in a fairly low noise area.? The antipode of my QTH is somewhere in the Indian ocean but when propagation is good I am routinely received by VK and ZL stations.? On my rx side I mostly use a ?BITX with an EFHW antenna and can rx VK and ZL when propagation cooperates.? I could probably do better with better antennas.
Doug
AC9RZ

Hello Reg

I was first licensed in 1964 at age 15.? Ham radio was the source of my career.? Graduated as a EE in 1970 and have worked in radio related jobs for much of the last 50 years.? I'm still working but at a much more reduced schedule.? The current project is a 100 MHz to 20 GHz synthesizer.? I am teamed up with another consultant.? He is doing the RF portion and I did the digital design and software.? The MCU is a STM32F407 and the code is written in C.? Some hams are more interested in operating and some, like me, more interested in designing and building.? My current ham project is a single band (40m) Mag Loop antenna.? The antenna structure is done and working but is manually tuned.? I am working on the remote control portion that uses a wireless link and a stepper motor.

For my next project I am interested in building a general coverage radio that uses DSP to do most of the work.? Back in the early 90's I was the engineering director of a small defense company that built DF systems.? Our best product had a receiver that covered 2-2000 MHz and used a then state-of-the-art DSP to do fine tuning and demodulation.? The input to the DSP was at a 2 MHz IF so lots of superhet style conversions before the DSP.? I'd like to update that approach to only have a single mixer in front of the DSP.

I'm looking forward to some interesting technical topics being discussed in this group.

Fred

An additional comment that came up in a PM reply:

Send a packet multiple times until the sender gets an ACK in the form of a correct CRC. Once the packet is decoded place the entire recorded signal in the A matrix, the decoded signal in the y vector and solve Ax=y for the deconvolution operator that best transforms the signal into the corrected packet. Use that operator to deconvolve the next packet. Do that with each packet so that the propagation inverse operator is constantly updated. Effectively it should be diversity reception from a single antenna.

Not sure how well that would work at HF, but it's a minor variation of standard practice in seismic processing to eliminate water column reverberation.

Have Fun!
Reg

The idea is to make it easy to learn a bit more about someone before you reply to them. There is a very wide range of education and experience in the list. It is my hope this will help improve the quality of discourse so experts get the expert version and novices get the novice version.

Reg

Hello all, not an Amateur but retired EE and consulted for many years in Broadcast industry, with many Ham friends.

QEX was always a fascinating resource.

Now happily retired, still messing with electronics....lot of test gear.

-73-

Jon

Hi to all,
Bob de K2KI in VT here.
I have been a ham since 1984 and I originally held the call KA2UZC. While I have always been into Boatanchors and hybrid radios (Mainly Kenwood), I have always wanted to try my hand at QRP levels.

I started off with an FT-817 which I had made made many contacts with that radio I had to sell after an accident which left me disabled. I do miss the radio! I started my pilgrimage to the land of QRP with Tony Park's Softrocks. I collected 160, 80 & a 40/30M units which I packaged all in one box and control with an Arduino. While I made some progress with this setup and a few contacts, more work with the Arduino was needed. I never finished it but hope to do so soon!

I then collected starting Rockmite's starting with a 40M Original Dave Benson release. I put it in a "Mity Box" and have a Pico Keyer and Nescaf filter which is not installed. I did make a few local contacts but nothing past 300 Miles. I then received a 30M RM (Also original) which someone else built. It works well and has nice output although I have yet to make a contact yet. I have another Rockmite 40 in an altoids tine (also someone else assembled). I cannot get any output so that goes on the checklist of fun and exciting things for Bob to-do. I plan to have one for each band (with the QRP Gods blessing of course!) :-) I created a daily hour-long dance to attract their attention. But, only attracted the neighbors attention! (What? They never heard of Nekkid hour dancing to the QRP Gods???) :-) Maybe I should do it inside from now on! :-P

I also picked up a very nice Midway ME-80+ that works wonderful. I have made a few contacts with one as far away as Ohio.

Another two kits are Chinese kits. One is a "51 RM" for 40 with enclosure. The toroid's and the lumpy-Bumpy type red ones. KC9RON s has replacements plus rocks to bring it up from 7.023, I have to order these. And finally, a built Chinese 49'er that is in a plastic Tupperware style container. No contacts made on this yet.

I recently received a DC40B kit which I am salivating over and can't wait to create some Solder Fumes. and have a great enclosure to put it in.

I have two NC-40 bare board that will one day be working radios. Chuck K0QO seems to have taken down the videos he had for their build.

My antennae's are: an 88' Doublet, G5RV and a TH6-DXX which is presently down because all the plastic parts I replaced back in 2015 disintegrated. I ordered new ones from Hy-Gain/MFJ but they are on backorder. For how long, nobody knows including MFJ. I have some Un-Un's coming and want to try an EFHW and a Long Wire.

So, that us my present QRP me. Will keep my QRP bio updated when I can.

--

I expect it would have to be mulithop for that distance. However, there was a WSPR report of UK to Australia by Jenny List of Hackaday using a single frequency at 100 mW IIRC. So clearly possible. I have in mind using multiple bands and changing frequency as the propagation changes. However, I am merely stating a goal, not an expectation. I'd be happy with reliable radio mail over shorter distances. A variant of UUCP/packet radio might be needed to meet the "reliable" requirement over antipodal distances.

The underlying concept is that the time-bandwidth-power product controls the SNR at the receiving station. I propose to trade time for power.

A general outline is as follows:

Based on station locations, historical data and atmospheric modeling, the transmission times and frequencies would be chosen for best propagation. During the transmission as the propagation changes the stations would shift frequency. If there is propagation on more than one band both might be used. A major issue with DX on HF is multipath propagation, however, I suspect that could be measured accurately enough to phase shift multiple arrivals at the same antenna and sum them coherently. Seismic processing is full of such shenanigans sometimes to attenuate noise and other times to boost the signal. A Raspberry Pi 4 can perform a mind boggling number of FLOPS.

For efficiency messages would need to be packetized and the sender would repeat the same packet until it received an ACK from the receiver in the form of a correct CRC.

An operator to sum multiple arrivals in phase is easy to implement once you know the statistics of the arrival delays. So once a packet is correctly received the actual signal can be analyzed to model the multipath and correct for it. That filter can then be used to speed up acquisition of the next packet and update the operator.

As an example, suppose the sender and recipient each had a pseudorandom sequence generated from their respective call signs. A low data rate signal a la QRSS is spread out over a wider BW by the PRN of the intended recipient. The sender is also listening for transmissions using its PRN so it can receive the packet ACK. Yet another version of the Aloha protocol from which ethernet and packet radio grew.

By *design* the GPS signal at the receiver is 56 dB (IIRC) below the noise floor of the receiver. 64 dB of processing gain makes it work. That is a *lot* of gain. There is a detailed discussion of the design in one of my spread spectrum books, but I don't recall which one and they are pretty thick.

This would need to be developed at the 2-3 W level over shorter distances before lowering the power. I'm in central Arkansas in the USA, so I've got 1500 miles (2500 km) E-W to the coasts.

However, I am still a long way from starting to build such a system. First I need to master basic RF amplifier and oscillator design. I mentioned the project to make clear that the group is intended to discuss anything from very exotic DSP techniques to basic small signal RF amplifier design.

Have Fun!
Reg

Hi, thanks for the add. I've been a ham since 1973, but I am rarely found on the air, my main interest is in designing and trying electronics stuff, particularly RF stages and analog electronics. Some of my jobs included TV, communications and CATV industries, and my experiences there and some new I have dumped them in my page ?(in Spanish). I aim to designs that can be easily reproduced with components that are commonly used for entertainment electronics, or salvaged from scavenged TVs or computers. My country is having a hard time with economics, imports are severely restricted, it's not a matter or ordering a fancy part from ebay or aliexpress, so, use what you have!
Daniel Perez LW1ECP

Nice to see the group getting going.

I'm currently a general class ham (KI5CBG), and I'm an enthusiastic RF hobbyist. My primary interest is microwave/mm wave and radar, so my lab is starting to be geared more towards those things, in terms of my selection of test equipment (by and large from Hewlett-Packard). I am also a hopeless collector of Tektronix scopes and associated equipment. Case in point, I brought home a 577D1 curve tracer and a 519 nuclear bomb scope this weekend.

My educational background is BSc in computer science and BSc in mathematics, with MSc in CS (but the focus was really more EE than CS). I work in cybersecurity professionally. I strive to do more EE stuff for fun.

Sean

While my intent is for this to be a forum for discussing QEX articles, I hope that more will come of it. So I thought I'd make a post about my personal major interest.

An almost 40 year obsession of mine dating from when I started work in the oil industry and first learned DSP is the idea of creating a reliable communication system capable of achieving antipodal range at mW ERP.

FT8 provides similar real time capability, but requires higher power levels to keep the QSO time tractable. My goal is reliable asynchronous transmission of ~ 2 kB text in 24 hours to another station at <100 mW ERP. Email by ham radio. There are a slew of ways to implement the concept.

At the moment I am trying to master basic RF amplifier and oscillator design, so it will be a while before I get back into familiar territory doing DSP. My present goal is to be able to take a small signal transistor and based on either the data sheet or if needed measurements consistently design a circuit that does precisely what I want it to do.

I *think* I've finally deciphered Chris Boswick's and Thomas Lee's books and know how but have not yet built an amplifier to test my calculations against a VNA.

I should note that I am severely ADD and am prone to wander off and do something completely different such as play jazz guitar for weeks or months or do precision metal work. No matter what I do, I feel guilty about all the things I'm not doing. A few too many interests.

Have Fun!
Reg

Peter Bunge.
I design and build things and make things work. I repair HP test equipment.
History: Canadian Airforce Radar Tech, Atomic Energy of Canada research tech working on Neutron dosimetry, Accelerators, and the Superconducting Cyclotron RF system. Retired.
An ongoing project is an underwater ROV on a 300ft tether with camera, lights, etc. Working but constantly being improved. I can send details to anyone interested.
Present projects are a robotic arm and scanning sonar for the ROV.

I've been a ham since about 1967, mostly interested in designing and building.? While my formal education was in physics, including experimental elementary particles, my heart has generally been in electronics, software and music, mostly saxophone, but now piano.? I worked for HP / Agilent for 25 years in R&D (spectrum analyzers, high-speed fiber optic modulators and detectors) and metrology (NIST-traceable calibration of RF power sensors and fiber optic detectors using laser heterodyne techniques), with some work on network analyzer calibration.? Antennas have always been my weak link...? The nanoVNAs are an amazing new tool!
David? WA8YWQ

I am a retired oil industry reflection seismologist. My BA is in English lit, my MS is in igneous petrology (behavior of light to the Nth degree) and I'm an ABD in geophysics. I have no formal training in electronics, but a life long interest, a very large technical library and a set of mid 90's lab gear which had an MSRP of around $500K. Thank you ebay!

My strong suite is DSP and numerical simulations of the elastic wave equation. I've been humiliated by RF enough to have a very healthy respect for the complexities it creates. My goal between now and when I disappear into the black hole that awaits us all is to reach the same level of skill in RF as I possess in reflection seismology.

Have Fun!
Reg