Microwave Engineering Project Dayton 2009 SDR Forum

What is MEP?

How is it to be used?

Why should the average ham operator care?

Mission   To produce a high-speed digital microwave

communications system for amateur radio.

Design Balance

Cost

Schedule

Quality

Like Any Project

  We have to balance cost, schedule, and quality.

  Unlike many other engineering projects, we are not a corporate or commercial project. We’re an open source volunteer engineering project. How many people have heard of, worked on, finished an open source project?

  Due to the nature of the mission, this requires that the work be done by teams of people working together.

Exploratory Results

  The system should transmit and receive high-speed digital data over a full-duplex microwave link.

  The frequencies of operation are 5.6GHz and 3.4GHz.

  The bandwidth should be at least 10MHz.

  The system should cost less than $1000 to purchase.

  The system should transmit high-definition video signals.

Exploratory Results

  The system should be capable of point-to-point communication between any two stations in range of each other.

  The system should be capable of multiple access communications between stations.

  The system should allow stations to discover each other and advertise their current and potential configurations and services.

  The system operates as a fully functional IP network.

Exploratory Results

  The system is intended to be useful, with modifications, in the amateur satellite service as a digital ground station.

  The system should be able to simulate a satellite environment.

  The system should be partitioned in a way that reduces requirements for custom hardware.

  The system should be able to handle an Ethernet 10/100 link as either a control link and/or as a data link.

  The system should be able to handle a wide variety of types of data without modification.

Requirements Requirements are necessary attributes that are defined for an item or system prior to the design effort. Requirements are derived from the mission and are the foundation of the implementation.

Requirements Analysis Requirements Analysis is an organized method for identifying the appropriate set of resources and requirements that satisfies the mission statement of the project.

So, • Requirements Analysis helps turn this, a

software development station, into

This, • Which can be distributed, debated,

implemented, or ignored, to create

This • A repeatable and verifiable development

environment for cooperative work,

Which • Impresses all your family and friends.

High Definition Video

  Transmission of high-definition video is a project requirement because it’s compelling and hasn’t been widely pursued in amateur radio.

  H.264 and Ogg Theora have been proposed as supported video standards. MEP, through the engineering partnership Optimized Tomfoolery, is an MPEGLA licensee.

  High-definition webcams were designated as the best signal source for high-definition video because they provide digital data out in a useful format.

Modern Radios Massively integrated digital systems that take large teams (ugh, management), advanced techniques (oh no NOT book learnin’!), and large amounts of money (Gah!) to bring to completion.

Is modern radio design out of reach of ham radio?

Things worth doing…

  What’s important to appreciate in modern radio projects, similar to the one pictured above?

  Advanced or complex techniques

  Expensive or specialized components

  Commercial projects employ Division of Labor – “is the specialization of cooperative labour in specific, circumscribed tasks and roles, intended to increase the productivity of labour. Historically the growth of a more and more complex division of labour is closely associated with the growth of total output…” -shortcutopedia (wikipedia Division of Labor entry as of 5 May 2009)

…are rarely easy

  Modern radio design is within the grasp of ham radio. It requires people to work together in large teams and “divide” the labor, however, and doing that in the absence of large sums of cash is key.

  What do you expect? People to work for free? No, we expect people to work on what they’re interested in. This is distribution and not division of labor and is a hallmark aspect of open source projects.

  Open source experience and motivation is essentially altruism that acknowledges ambition. Status can be obtained through many paths. Respect the ego. Give credit where credit is due.

No, It Is Not Out Of Reach

  The modern communications experience requires a re-evaluation of what constitutes amateur communications (consumer perspective).

  Ham radio enthusiasts are interested in different things than they were in the past (ham perspective).

  The next step in ham radio design incorporates microprocessors and software as a matter of course, not as a centerpiece, and not as a pinnacle of victory, but as a tool or enabling technology, in the course of completing a design.

Common Conception All amateur radio projects will eventually be implemented entirely in software.

HF SDR Archetype

 Leverages commodity components.

 Low-cost software runs on general purpose processors.

 Provides value to the HF experience.

 Not as easy to duplicate in the microwave bands.

Transverter vs. SDR   Transverters are a well-understood and rational technique for getting

baseband to RF. Transverters of every size and shape and level of performance have been pressed into service for wireless communications for the past 45 years. We don’t hate transverters. However, our goal is to implement MEP using SDR. Why?

  From the MUD 2000 article Future Designs of Microwave Transverters by Steve Kostro N2CEI “With the increasing use of the general publics communication systems such as Cellular, PCS, WLAN, Blue Tooth, and the future use of the ISM bands, amateur band microwave transverters that were designed 5 years ago will soon, if not already, become inadequate. Caused by the increased RF density surrounding and sharing our amateur bands, transverter designs that provided weak signal sensitivity without strong signal immunity or selectivity will soon be of little use to the Microwave enthusiast.”

Transverter SDR

Bandwidth

Flexibility

Simplicity

Cost

Cost   Comparing the cost between a transverter and an SDR is not

necessarily straightforward. How much of the radio should or can be converted to an SDR? Baseband? Baseband + IF? The entire chain? How about the transmit chain as an SDR and the receive side done with a transverter? Transverters range from relatively cheap ($100 SBMS board) to relatively expensive ($450 for DB6NT or DEMI boards). An SDR requires a processor ($50 in 1000 quantity Atom 330, $30 in quantity TI OMAP) and we believe we’ll require an FPGA to do the heavy lifting of the signal processing. Why? Microprocessors are not fast enough. FPGAs have superior performance. FPGAs range in price all over the map. For small quanitites, a transverter might actually be cheaper. However, if the cost of processors and FPGAs drops faster than the cost of the components of a typical transverter, then there is a technical obligation to develop them for amateur radio use.

Transverters

Hardware

Processor

Software

SDR

Less Hardware?

Processor

Software

FPGA

Simplicity

  Unlike a typical HF SDR, MEP’s SDR implementation may (initially) require more types of components, not fewer. What you get in exchange for increased complexity is flexibility and performance, as well as a working amateur design that others can use and learn from.

Flexibility

  How much flexibility is truly required in amateur radio? Are we allowed to use all these fancy modulations schemes?

  Being able to experiment with different modulations, encodings, and protocols is easier with an SDR. Reconfiguring the radio is possible with an SDR. Experimenting with interesting techniques such as genetic algorithms for so-called Cognitive Radio is possible with an SDR.

Bandwidth

  Bandwidth vs. processor speed is the primary trade-off for an SDR. 10MHz bandwidth means a required sampling rate of at the very (impossible) least 20MHz. Since we are going to be using actual real filters, a sampling rate of 40MHz is more likely required (at IF).

  Real filters at RF will be even wider, so higher sampling rates may be required if we sample at microwave frequencies.

Repercussions of Reconfigurability

  Reconfigurability requires that we pay attention to the behavior of the entire system rather than just focusing on the chips and circuits that perform the physical-layer processing.

  There are static and dynamic reconfigurability strategies. Commercial cellular contrasts with government radio in terms of which strategy is employed.

Cellular vs. Military

  Commercial cellular systems handle heavy traffic volume in a defined frequency range.

  Commercial cellular supports one or two air-interface modes.

  Military radio involves a wide range of frequencies, many modulations, software, and rapidly changing interference challenges.

  Cellular = static, military = dynamic

Enter uWSDR

  If we’re not going to be using transverters, then what are we going to be using? New SDRs using direct conversion from microwaves to baseband.

  Coordinated by Grant Hodgson, the Microwave SDR group aims to deliver… (under construction!)

Grant says…

  “Detailed system simulations show that the receiver architecture planned for the uWSDR receivers should give levels IMD rejection that are far greater than those from any currently available amateur microwave transverter+ IF rig combination.”

  “The 2.3GHz uWSDR receiver design has got as far as schematic capture, which is now done. As soon as the GeMMA Tx is sorted work can start on the rest of the layout for the full transceiver.” Schedule for this is indeterminate.

Grant says…

  “The uWSDR project is aimed (at least initially) at producing equipment for narrowband use. However, the key components (PLL, Tx modulator, Rx demodulator) are suitable for very wide IF bandwidths indeed (hundreds of MHz), and therefore the RF hardware should require just a minimal amount of changes in order to be able to carry the bandwidths required for MEP. I don't see these changes as a major problem.”

Development Stations

  Intel ATOM 330 processor “Atom Smash” represents the top-down approach. Intel will reign supreme!

  TI OMAP processor “Dog Pack” represents the bottom-up approach. Intel must be stopped!

Opportunities

  Discovery software application

  Outdoor RF enclosure

  Custom dual-band feed

  Duplicating the development environment allows anyone to program, test, or follow along.

Opportunities

  Signal processing

  Air interface definition

  Encoding, modulation

  Media access control protocols

Microwave Engineering Project contributors, supporters, and participants

Kerry Banke N6IZW, Art Botterell KD6O, Kent Britain WA5VJB, Phil Karn KA9Q, Grayg Ralphsnyder KC8SVT, James W8ISS, Michelle Thompson W5NYV, Roger Thompson AD5T, Paul Wade W1GHZ, Paul Williamson KB5MU, Eric Fort AF6EP, Timothy Salo AB0DO

Thank you – your involvement makes it happen.