Mr. Vacuum Tube

Butterfly Network Inc.

2012-02-02T20:56:00.003-05:00

For anyone who is interested in what i am doing these days, my startup company now has a website.

We are having lots of fun and moving extremely fast.

We are seeking to find one or two talented individuals to join our team, if you are that person or know someone then please drop us a note.

Learn to sail then travel to amazing places

2012-01-31T08:45:00.000-05:00

I do not post about my vacations but this one was absolutely amazing because it shows the value of learning how to do something old school, in this case sailing, then using it to facilitate an incredible life experience.

My friend Brian has more details on where we went this past January with a google map itinerary and additional photos here: http://pletchtrip.blogspot.com/2012/01/british-virgin-islands-sailing-trip.html

In summary; learn to sail, have fun, and travel to amazing places.

2013 IEEE International Symposium on Phased Array Systems & Technology

2012-01-27T20:51:00.000-05:00

Call for papers is out for the 2013 IEEE International Symposium on Phased Array Systems and Technology.

Please join us for a fascinating week learning about and discussing the latest breakthroughs.

Join the conversation, consider submitting your latest work, please see the call for papers.

To sign up for the conference stay tuned to our website.

DIY Phased Array Radar Demo for MIT IAP 2012

2012-01-24T20:06:00.000-05:00

A demo using the DIY Phased Array Radar system made from pegboard and wi-fi antennas.

The purpose of this system is to show students how phased array systems work by actually building one.

DIY Phased Array Radar using pegboard and wi-fi antennas

2012-01-23T18:57:00.000-05:00

I am very excited to report that I am one of the lecturers for this very unique MIT IAP short course in radar, where teams of 3 build a digital phased array radar system using $950 in parts using pegboard, wi-fi antennas, and a handful of other parts.

The abstract for this course can be found here (scroll half-way down).

The creators of this class include:
Dr. Bradley Perry, Dr. Jonathan Paul Kitchens, Dr. Patrick Bell, Dr. Jeffrey Herd, Dr. Gregory L. Charvat. Brad Perry is the lead and has done an amazing job putting everything together!

This phased array radar system is a switched antenna array based on my previous work on thru-wall imaging here.

The radar back end is in fact one of the coffee can radar systems, where you can build your own here.

Complete documentation and lectures from this phased array radar course will be posted on the MIT OCW site soon so that you too can build your own phased array radar using pegboard and wi-fi antennas.

If that is not enough, anyone can sign up for this course offered by the MIT professional education program: http://web.mit.edu/professional/short-programs/courses/phased_array_radar_sensor.html

News Flash: MIT Students measure the doppler signature of a shopping cart, with someone in it

2012-01-22T22:59:00.002-05:00

Vinay Ramasesh, Kevin Fischer, and Emily Davis measure the doppler signature of a shopping cart traveling down a concrete slope. To be discussed tomorrow at the MIT IAP '12 radar course.

Doppler Radar Explanation and Demo using the coffee can radar

2012-01-15T13:26:00.000-05:00

A doppler radar demonstration and explanation using the MIT coffee can radar.

http://ocw.mit.edu/resources/res-ll-003-build-a-small-radar-system-capable-of-sensing-range-doppler-and-synthetic-aperture-radar-imaging-january-iap-2011/index.htm

re-winding an RF coil in a Colin B. Kennedy model 20B

2012-01-13T09:25:00.000-05:00

Even after re-stuffing the decoupling caps my CBK 20B was still not working properly.

It turns out that one of the primary windings was broken in one of the 3 high-Q RF resonator transformers.

Removing the transformer was difficult (see photos above). I had to remove a bottom panel then bend-out small metal tabs, and break-free the glue that glued the top of the transformer to its shield (very unusual construction techniques are used in this radio compared to most old radios that i've worked on).

I un-wound this coil and found the break about half-way in, probably due to the bad decoupling capacitors.

After re-winding it the radio still did not work well. It turns out that the wiring in the schematic did not match the factory wiring in my radio. No surprise, as my AF output tube is different (class A as opposed to push-pull) and a few other things.

I touched the grid cap on the first RF amplifier and the radio came to life. I then traced the circuit from the primary of the first RF transformer to a potentiometer on the front panel. It turns out that the RF input of this radio goes directly through a potentiometer which is ganged with the control grid potentiometer which controls the volume. This was not a bad repair job, it was factory wiring cable laced in, etc etc.

I removed this wiring and tied the primary to the antenna input and radio came to life. Very sensitive as expected, but a new problem was noticed.

The control grid rheostat is not working well. I think there are open windings or the bushing is not making electrical contact with the wiper.

Stay tuned for more....

Colin B. Kennedy Model 20B radio repairs

2012-01-06T09:14:00.003-05:00

Recently had some new problems occur with my CBK 20B:

http://www.glcharvat.com/Dr._Gregory_L._Charvat_Projects/Restoration_of_a_Kennedy_Model_20B_Console_Radio.html

The RF decoupling capacitors on each stage of the TRF circuit were going bad. At least one or more were shorting out. I neglected to replace these initially because they were in nice metal enclosures, but after watching some of bandersontv's videos on re-stuffing caps i decided to re-stuff these.

The caps look great, but the radio still did not work properly. Stay tuned for more...

Coffee Can Radar used for senior design project at MSU

2011-12-17T08:16:00.000-05:00

A senior design team at Michigan State University has built a coffee can radar as part of their senior design project. For more info check out their site:

http://www.egr.msu.edu/classes/ece480/capstone/fall11/group07/file/Home.html

To see the final presentation watch this video (see design team 7):

http://designday.egr.msu.edu/video

Briefing on my ARRL Homebrew Challenge 3 Radio posted

2011-12-15T06:57:00.000-05:00

I presented a talk on my entry into the ARRL Homebrew 3 challenge at the MIT Haystack Observatory a few weeks ago.

Here is a link to this talk:
G. L. Charvat. “N8ZRY's ARRL 'homebrew' (develop a 6 & 10m SSB/CW transceiver) challenge 3 radio,” MIT Haystack Observatory, November 2, 2011.

Time Harmonic Electromagnetic Wave Propagation Demo

2011-12-13T19:53:00.000-05:00

DEFCON 19: Build your own Synthetic Aperture Radar

2011-12-11T11:13:00.000-05:00

At the Defcon 19 (2011) conference Michael Scarito demonstrated how to construct your own radar system. The project is based on a design by Dr. Greg Charvat from MIT and uses synthetic aperture techniques to generate a two- or three-dimensional image. (You can read Dr. Charvat’s research paper here.)
The hardware operates in the 2.4 GHz ISM band (shared with WiFi.)

For a further detailed explanation of this technology, see the dissertation of Manh Hung V. Le, Dimitris Saragas and Nathan Webb from the Worcester Polytechnic Institute here.

A free MIT course on this topic is available through their Opencourseware presentation“Build a Small Radar System Capable of Sensing Range, Doppler, and Synthetic Aperture Radar Imaging.”

This entry was posted in DIY, RF, talks and tagged Defcon 19, MIT, opencourseware,radar.

ARRL Homebrew Challenge 3 Radio Schematics posted, photos from my visit to ARRL HQ

2011-12-08T07:00:00.000-05:00

Photos from my visit to ARRL HQ on 10/31 to drop of the homebrew challenge 3 radio:

Welcome sign at the ARRL HQ

Bob Allison testing the TX spurs in the ARRL Lab

Plugged into the 10m broadcast beam at W1AW, made several DX contacts that day.

Schematics for my ARRL Homebrew Challenge 3 radio, a 6 & 10m SSB/CW 60w radio, have been posted to the web.

Scroll down to the bottom to download the drawing package):
http://www.glcharvat.com/Dr._Gregory_L._Charvat_Projects/6_%26_10m_SSB_CW_Transceiver.html

If you build something cool from these, or a more improved radio, i would enjoy seeing your work.

Part-time Passions: Breathing New Life Into Old Things - The Institute

2011-12-06T17:54:00.000-05:00

Part-time Passions: Breathing New Life Into Old Things - The Institute

Enrollment now open for IAP '12: Build a Small Phased Array Radar System Capable of Imaging Moving Targets

2011-12-01T08:31:00.000-05:00

Build a Small Phased Array Radar System Capable of Imaging Moving Targets
Dr. Bradley Perry, Dr. Jonathan Paul Kitchens, Dr. Patrick Bell, Dr. Jeffrey Herd
Tue Jan 17, Fri Jan 20, Mon Jan 23, Tue Jan 24, 01-03:00pm, 4-153
Fri Jan 27, 01-03:00pm, 4-149
Enrollment limited: advance sign up required (see contact below)
Signup by: 11-Jan-2012
Limited to 24 participants.
Participants requested to attend all sessions (non-series)
Prereq: Participants supply their own laptops with MATLAB installed

Are you interested in building and testing your own phased array radar system? MIT Lincoln Laboratory is offering a unique course in the design, fabrication, and test of a laptop-based phased array radar sensor capable of imaging moving targets in real-time, like a ‘radar video camera’. You do not have to be a radar engineer but it helps if you are interested in any of the following; electronics, amateur radio, physics, electromagnetics, or phased array systems.

It is recommended that you have some familiarity with MATLAB.

Teams of three will make a phased array radar system and attend a total of 5 sessions spanning topics from the fundamentals of radar to digital beamforming. You will bring your radar kit into the field and perform experiments including, imaging moving targets from around campus. Imaging unusual targets is encouraged; a final radar video competition will determine who acquired the most creative real-time radar imagery.
Contact: Dr. Bradley Perry, (781) 981-0861, radar.course@ll.mit.edu

http://student.mit.edu/iap/nsll.html

Enrollment now open for IAP '12: Build a Small Radar System Capable of Sensing Range, Doppler, and Synthetic Aperture Radar Imaging

2011-11-29T08:29:00.001-05:00

Enrollment now open for IAP '12:

Build a Small Radar System Capable of Sensing Range, Doppler, and Synthetic Aperture Radar Imaging
Dr. Bradley Perry, Dr. Melissa Meyer, Dr. Stephen M. Kogon, Dr. Alan Fenn
Tue Jan 17, Fri Jan 20, Mon Jan 23, Tue Jan 24, 10am-12:00pm, 4-153
Fri Jan 27, 10am-12:00pm, 4-149
Enrollment limited: advance sign up required (see contact below)
Signup by: 11-Jan-2012
Limited to 24 participants.
Participants requested to attend all sessions (non-series)
Prereq: Participants supply their own laptop with MATLAB installed

Are you interested in building and testing your own imaging radar system? MIT Lincoln Laboratory is offering a course in the design, fabrication, and test of a laptop-based radar sensor capable of measuring Doppler, range, and forming synthetic aperture radar (SAR) images. You do not have to be a radar engineer but it helps if you are interested in any of the following; electronics, amateur radio, physics, or electromagnetics. It is recommended that you have some familiarity with MATLAB. Teams of three will receive a radar kit and will attend a total of 5 sessions spanning topics from the fundamentals of radar to SAR imaging. Experiments will be performed each week as the radar kit is implemented. You will bring your radar kit into the field and perform additional experiments such as measuring the speed of passing cars or plotting the range of moving targets. A final SAR imaging contest will test your ability to form a SAR image of a target scene of your choice from around campus, the most detailed and most creative image wins.
Contact: Dr. Bradley Perry, (781) 981-0861, radar.course@ll.mit.edu

http://student.mit.edu/iap/nsll.html

N8ZRY's ARRL Homebrew Challenge 3 radio Demo

2011-11-22T18:19:00.000-05:00

Demo of my ARRL 'Homebrew' Challenge 3 radio, to design and build a SSB/CW amateur radio transceiver in less than 12 months for the 6 & 10m bands.

New Website Announcement!

2011-11-20T11:49:00.001-05:00

I recently joined a startup company and I am not sure how long i will have my mit.edu website. For this reason i purchased a URL and uploaded an updated website to it:

www.glcharvat.com

Please be sure to drop by and check out all of the improvements, including embedded youtube demos of various proejcts, and a new page on my ARRL Homebrew Challenge 3 radio entry.

what we're trying to do about this: 'Why Science Majors Change Their Minds (It’s Just So Darn Hard)'

2011-11-05T09:33:00.002-04:00

Why Science Majors Change Their Minds (It’s Just So Darn Hard)

By CHRISTOPHER DREW

Published: November 4, 2011

http://www.nytimes.com/2011/11/06/education/edlife/why-science-majors-change-their-mind-its-just-so-darn-hard.html?pagewanted=1&_r=1

Here is what we are trying to do in our own way with applied electromagnetics (see link to lecture about this course on the right side of the page):
http://www.ll.mit.edu/news/iapradarcourse.html

Dropping off my ARRL Homebrew Challenge 3 radio at the ARRL Headquarters today

2011-10-31T09:02:00.000-04:00

Hitting the road to drop of my entry into the ARRL Homebrew Challenge 3 (challenge to build a complete amateur radio from scratch). This is for the 10m and 6m class.

TX power is about 70-75 watts on both 10 and 6. It uses the NXP BLF647 LDMOS for the PA, an Si570 for the VFO, AD8009a current feedback op-amps for the pre-driver and first IF amplifier. It also uses lots of old school parts for the chassis and front panel controls (each of which has an easy-to-find modern equivalent).

I will post two youtube videos soon. One on the construction of this radio and the 2nd on how to use this radio with an on-air demo.

73, Greg N8ZRY

MSU alumnus can see through walls

2011-10-25T14:17:00.000-04:00

Check out this article and video in the State News. The video is hilarious!

'if i could see through walls i would....'

MSU alumnus can see through walls

I miss Michigan State. Can't wait to go back again soon to visit everyone. Thank you Kelsie for your article, Go Green!

MIT: Real X-Ray Vision?

2011-10-19T11:09:00.000-04:00

Interview on Fox 25 Boston this morning on our through-wall radar sensor:

MIT: Real X-Ray Vision?

Seeing through walls - MIT's Lincoln Laboratory

2011-10-18T22:41:00.000-04:00

Seeing through walls - MIT News Office

2011-10-18T07:08:00.000-04:00

Seeing through walls - MIT News Office

The through wall radar has made it into MIT news this morning!

Surprisingly enough it is on the front page of mit.edu on 10/18/11:

www.mit.edu

2011-10-16T20:35:00.002-04:00

Just married, to someone who appreciates vacuum tubes, old clocks, and likes to dance:

http://www.nytimes.com/2011/10/16/fashion/weddings/kathryn-phillips-gregory-charvat-weddings.html

http://video.nytimes.com/video/2011/10/14/fashion/100000001113420/kathryn-and-gregory.html

bandersontv's Radio 101 youtube series: how to restore an antique radio, a step by step process

2011-10-12T07:52:00.000-04:00

This is the best reference i have found online for learning how to restore antique radio equipment. Here, youtuber bandersontv takes his viewers every step through while he restores an antique radio:

http://www.youtube.com/user/bandersentv#p/search/0/WylSXLou9y0

http://www.youtube.com/user/bandersentv#p/search/0/2Hke0L_Jsa4

http://www.youtube.com/user/bandersentv#p/search/0/p2wKjiwD5wA

http://www.youtube.com/user/bandersentv#p/search/0/vUHoMC-0dEA

http://www.youtube.com/user/bandersentv#p/search/0/rhlY0v3cBGY

http://www.youtube.com/user/bandersentv#p/search/0/n05AjEKhgIY

http://www.youtube.com/user/bandersentv#p/search/0/sa3o_rB3WZk

http://www.youtube.com/user/bandersentv#p/search/0/7fkRlNtLJeM

http://www.youtube.com/user/bandersentv#p/search/0/hW4IKUJK8o4

homebrew amateur radio equipment inspiration: K5AM's homebrew contest station

2011-10-10T08:19:00.000-04:00

This is a truly amazing radio station! All of the equipment was developed and built by K5AM. I like the appearance of this gear, it is how a radio should look.

For more info: K5AM - NCJ Article

Senior Member of the IEEE

2011-10-08T08:02:00.000-04:00

Was recently elevated to Senior Member of the IEEE. Hopefully this will help me to contribute more to the engineering community as a whole and further some of the more crazy ideas (such as learning by making something), or help to grow some of our popular conferences such as the 2010 Symposium on Phased Array Systems and Technology.

homebrew amateur radio equipment inspiration: N6QW

2011-10-06T07:25:00.000-04:00

A mmic based 20M transceiver. This makes implementation of complicated radio systems less complicated allowing the developer to focus on system level issues such as tuning, transmit signal chain stability, well-built chassis, etc.

homebrew amateur radio equipment inspiration: Wa7MLH

2011-10-04T08:12:00.000-04:00

The WA7MLH home brew radio equipment is very intersting, extensive re-use of old chassis and parts.

Many unique designs all of which appear to be lowest cost possible.

Impressive work and worth looking at:

http://www.neoanderthal.com/wa7mlh.html

ARRL Homebrew Challenge 3 Radio is Complete!!

2011-10-02T06:30:00.000-04:00

My ARRL Homebrew 3 Challenge radio is now complete! This radio is dual band, 10m & 6m, SSB and CW. It provides over 100 watts of transmit power at 10m and 70 watts at 6m.

It features new technology such as the NXP Semiconductor BLF647 LDMOS power RF mosfet, AD8009a current feedback op-amps for the IF and pre-drivers. Signal meter shows RF voltage at the antenna terminals. It uses an old Motorola police microphone, military connectors for power and microphone, and has 1 Hz tuning resolution with a digital display.

Next step: use it on the air. I'm sure i will run into further issues using it on the air, but this is part of the process.

Stay tuned.....

ARRL Homebrew 3 Challenge update: TR sequencing circuit

2011-09-30T06:09:00.000-04:00

As soon as i installed my fast acting VSWR protection circuit i started tripping it when i was feeding my LPF & TR assembly. There were moments where, the TR relay was not engaged but the PA was already biased and transmitting. This would cause an instantaneous VSWR fault detected by the VSWR protection circuit, which would shut down the PA bias.

For this reason i had to add a delay which would turn on the bias to the PA after a short duration and which would keep the TR relay on for a while after the PA bias was shut off (see green board located below the PA itself).

It is certainly a challenge, TR switching a 100 watt + PA.

ARRL Homebrew 3 Challenge Update: VSWR protection circuit

2011-09-28T06:04:00.000-04:00

Had to install a VSWR protection circuit to protect the 100 watt output transistor from greater than 10:1 reflection.

The comparator measures VSWR, trips an S/R flip-flop which then biases an NMOS that shorts out the bias supply varactor diode regulator circuit, thereby turning off the PA. A buzzer sounds to indicate VSWR fault.

To reset, the power must be cycled on the radio.

Best Paper Award, Tri-Services Radar Symposium 2010

2011-09-26T07:42:00.000-04:00

I was surprised to find out this summer that we won best paper at the 2010 Tri-Services Radar Symposium for our work on the real-time through-wall radar imaging system.

We hope that others will consider this work as a potential solution to the thru-wall problem given the results we have achieved thus far.

Here is a press release.

Link to information on the thru-wall radar system.

Link to some thru-wall 'radar videos.'

ARRL Homebrew III Challenge Update: Cleaning up transmit spurs

2011-09-23T07:26:00.003-04:00

TX spurious emissions test

front panel of 10m/6m SSB/CW ARRL homebrew challenge 3 challenge entry

I've spent the past two weeks working on mitigating spurious emissions from the transmitter at 6m. The specification for 6m is to have the spurs at least 60 dB below carrier. This radio may be unusual compared to other homebrew challenge 3 radio entries in that it has a 100 watt transmitter rather than the specified 25 watts. For this reason there are multiple driver stages, some of which are driven into compression, amplifying and multiplying transmit mixer spurs. Great care was taken in the strategic placement of filters to eliminate these to meet spec.

Now that the transmitter is clean i hope to have this radio on the air soon. Stay tuned.....

Radar Short Course at MIT

2011-09-20T21:32:00.000-04:00

More feedback on our 1-week radar course, where you learn about radar while making one.

We are preparing for next summer's courses, where we will run an improved version of this course and offer a new phased array course, where everyone learns by making their own small phased array radar system.

Heathkit is back!

2011-09-17T07:31:00.000-04:00

I first read about this in IEEE spectrum,

good news: Heathkit will be making kits again soon...

"Thank you for your overwhelming response to our announcement that Heathkit is back into the Do-it-Yourself kits business. We received many great suggestions for kits you would like to build.

We will be releasing Garage Parking Assistant kit (GPA-100) in late September and soon after the Wireless Swimming Pool Monitor kit will be available.

Based on your input, we are looking at developing amateur radio kits. Our goal is to have kits available by the end of year.

Please keep your suggestions coming so that we can continue to bring you interesting, unique Heathkit products."

Build a Small Radar System Capable of Sensing Range, Doppler, and Synthetic Aperture Radar Imaging, OCW Site update

2011-09-15T07:25:00.000-04:00

Matlab files and example data have been posted here (scroll to bottom and download the .zips).

Now you can run and process sample data sets and see what your coffee can radar data should look like.

Education Society and IEEE Women in Engineering: The MIT IAP 2011 Radar Course: Build a Small Radar System Capable of Sensing Range, Doppler, and Synthetic Aperture Radar (SAR) Imaging

2011-09-12T20:08:00.000-04:00

Tomorrow at Tufts i will be presenting a talk on the coffee can radar course:

This will be a fun talk with a spirited discussion on both how to make a radar out of coffee cans and also how to use it to teach the basics of radar and applied electromagnetics.

Education Society and IEEE Women in Engineering

3:00 PM

Tuesday, 13 September

The MIT IAP 2011 Radar Course: Build a Small Radar System Capable of Sensing Range, Doppler, and Synthetic Aperture Radar (SAR) Imaging

Dr. Gregory L. Charvat, MIT Lincoln Laboratory

Recently, MIT Lincoln Laboratory sponsored a radar short course at MIT main campus during the January 2011 Independent Activities Period (IAP). The objective of this course was to generate student interest in applied electromagnetics, antennas, RF electronics, analog circuits, digital signal processing, and other engineering topics by building a short-range radar sensor and using it in a series of field tests. Lectures on the basics of radar, modular RF design, antennas, pulse compression and SAR imaging were presented. Teams of three students received a radar kit. This kit was developed by the authors and uses a frequency modulated continuous wave (FMCW) architecture. To save costs, empty metal coffee cans are used for antennas, parts are mounted on a wood block, it uses only 6 coaxial microwave parts, analog circuitry on a solderless breadboard, and runs on 8 AA batteries. Data is acquired by the audio input on a laptop computer sampling the video output (right channel) and transmit synchronization pulses (left channel). The total cost of each kit was $360. Of the nine student groups, all succeeded in building their radar, acquiring doppler vs. time and range vs. time plots, seven succeeded in acquiring at least one SAR image, and some groups improved the radar system itself. Great interest in these topics was generated by this course. By presenting these difficult topics at a high level while at the same time making a radar kit and performing field experiments, students became self motivated to explore these topics. In the long term, courses using this continuous engagement philosophy could help fill the gap as the current generation of radar engineers continues to retire.

Gregory L. Charvat grew up in the metro Detroit area, where the hands-on approach to engineering within the automotive culture was a great influence on his life. He earned his PhD in electrical engineering in 2007, his MSEE in 2003, and BSEE in 2002 from Michigan State University where he worked as a graduate research assistant for the Electromagnetics Research Group. He is currently a technical staff member at MIT Lincoln Laboratory since September of 2007 and teaches short radar courses at the Massachusetts Institute of Technology.

This meeting of the Boston chapter of Education Society and the IEEE Women in Engineering Boston Affinity Group is scheduled for 3 PM, Tuesday September 13th at Tufts University, Halligan Hall, Room 111 Department of Electrical and Computer Engineering, 161 College Avenue, Medford, MA 02155. It is free and open to the public. For more information, contact IEEE Boston Section Chair and Chair, Education Society, Dr. Karen Panetta, (Karen@ieee.org)

Directions to the Tufts University are available at http://www.eecs.tufts.edu.

Halligan Hall is located across the street from the Cousen’s parking lot, and is adjacent to the Tufts Cousen’s Gymnasium.

Radar Short Course at MIT

2011-09-10T15:40:00.000-04:00

Reviews are in from our radar course: we were the top ranked MIT Professional Education short course this year!

ARRL Homebrew 3 Challenge update: system level trouble shooting

2011-09-03T06:26:00.000-04:00

Everything worked well on the bread board, why does it not work when installed into the chassis?

This is why system level trouble shooting must be performed after system integration. In this case i have measured significant loss in sensitivity, what could be the cause?

Only a few more hours and another cup of coffee will tell.

Stay tuned.....

ARRL Homebrew 3 Challenge update: wiring it together

2011-09-01T06:21:00.000-04:00

I'm now wiring up all of the modules. This is a very tedious process but must be done carefully.

From the top photo; front panel with the main power light and the LCD lights; bottom of the radio showing the RF/IF/Prod/audio/agc mostly wired; the VFO board being modified to access I/O pins and the 'function' button.

Next step: complete wiring then trouble shooting of the system, starting with power amplifiers and working way down to the RF/IF.

ARRL Homebrew 3 Challenge update: all modules mounted inside chassis

2011-08-30T07:11:00.000-04:00

Have mounted all of the RF modules into the chassis. From the top; photo of the driver, PA, and low pass filter; photo of the front panel with digital display mounted; photo of the bottom with the front-end, IF, product detector, audio/AGC board.

Next step: wire it together then trouble-shoot system level problems.

ARRL Homebrew 3 Challenge update: front panel of the chassis is complete!

2011-08-28T07:43:00.000-04:00

The front panel of my ARRL Homebrew III challenge radio is complete. This radio is designed for both 10m and 6m operation SSB and CW modes.

It features 100 watts transmit power (or more), a digital display, and provides 1 Hz tuning resolution (digital display to be mounted in black box on upper right of front panel).

Looking forward to putting this rig on the air soon!

IEEE AP-S Boston Chapter: August 26, 6pm Marta Martinez-Vazquez from IMST Gm...

2011-08-23T07:34:00.000-04:00

Everyone is welcome to the

IEEE AP-S Boston Chapter: August 26, 6pm Marta Martinez-Vazquez from IMST Gm...: We are pleased to announce that Marta Martinez-Vazquez is flying out from Germany to speak to a joint meeting of AP-S, WIE, AES, and GRSS so...

Be sure to register (registration is free) by following the directions. Hope to see you there!

ARRL Homebrew 3 Challenge update: chassis machining completed

2011-08-21T06:08:00.000-04:00

I've completed the front panel machining on the chassis for my homebrew 3 challenge radio. Shown above is the completed chassis, below is the chassis before machining.

I am recycling an old Nemes Clarke receiver chassis for this project because it is a good size allowing room to work. It is also 'green' to re-use old chassis like this rather than throwing them away. Chassis like this one, of approximately the same size, are readily available at almost any hamfest.

MIT Opencourseware Site is now up: Build a Small Radar System Capable of Sensing Range, Doppler, and Synthetic Aperture Radar Imaging

2011-08-19T07:31:00.000-04:00

Now you too can teach yourself how to

Build a Small Radar System Capable of Sensing Range, Doppler, and Synthetic Aperture Radar Imaging

Goto the MIT Opencourseware site for this class to view all lecture slides, read the how-to instructions on the coffee can radar kit, and see results from the doppler, ranging, and SAR imaging experiments.

Stay tuned to OCW because periodic updates to this site will include samples of data acquired from a coffee can radar and additional resources.

Very happy to report that i am now a Senior Member of the IEEE

2011-08-16T21:46:00.003-04:00

I found out today that i've been elevated to Senior Member of the IEEE. I am very excited about this news and thankful for those who wrote recommendation letters on my behalf.

Looking forward to serving on the IEEE Boston Section Executive Committee in 2012 as a Member at Large and working on lining up more awesome speakers at the Boston Chapter of the Antennas and Propagation Society.

The IEEE is an excellent organization and i encourage anyone who is passionate about engineering to join. Hang out with like-minded individuals, work together to setup talks, conferences, write, communicate, and have a great time while doing it.

Why Your Dad’s 30-Year-Old Stereo System Sounds Better than Your new One

2011-08-15T07:22:00.000-04:00

http://gizmodo.com/5825359/why-your-dads-30+year+old-stereo-system-sounds-better-than-your-new-one

"If you fashion yourself as an audiophile and just threw down a decent wad of cash on a new A/V receiver, you probably won't like hearing that the receivers of yesteryearproduce comparable sound. Why is that? Technological advancement, ironically."

from the ARRL: A Simple Regen Radio for Beginners

2011-08-13T07:15:00.000-04:00

I found this simple single-transistor regenerative receiver design while reading through the QRZ.com forums.

1 transistor and 1 LM386 audio amplifier lets you listen to short wave and amateur stations.

This is a great little radio for those who want to start learning about receivers! I am posting it here because i was in fact thinking about designing such a radio, fortunately it already exists.

Here is the article on how to make your own.

ARRL Homebrew Challenge 3 radio update: front panel layout on re-used chassis

2011-08-11T07:09:00.000-04:00

One of the most important parts of building anything in your basement laboratory is a good front-panel layout.

Re-using old parts and equipment is tricky. As can be seen above, there are many 'extra' holes in this chassis that i must either use or cover up. At the same time, i want the layout of knobs, toggles, buttons, displays, etc to look nice and be ergonomic for the end user.

To do this i un-bolted the front rack mount panel and placed the necessary controls and connectors on the front panel in various configurations until i found one that i really liked (shown above).

Now i am looking forward to machining out the front panel, it should have that 1950's cold war vintage look that i try to give all of my projects.

ARRL Homebrew Challenge 3 radio update: re-use of an old radio chassis

2011-08-09T06:56:00.000-04:00

I picked up this old Nemes Clarke receiver at a local hamfest. It is a VHF FM tube receiver.

I then salvaged the chassis of this receiver, removing all internal components and saving those for a later date for re-use in other projects.

Some of these salvaged components included a nice power supply transformer for tube gear, two chokes, and a pair of 10 uF oil capacitors. A number of tubes were pulled out including a few 12AU7's, a full-wave rectifier, and a voltage regulator. Sounds like the beginnings of another vacuum tube audio power amplifier to me....

I plan to use this rack-mount chassis for my homebrew challenge 3 radio. Chassis like these are readily available at local hamfests at very low cost, therefore i believe that it is a valid part to use. Furthermore i believe that we homebrew radio enthusiasts should recycle this legacy equipment instead of throwing it in the trash, sending it over seas to be recycled, or letting it sit on the shelf for decades without use.

update on the MIT Prof Ed 1-week radar course: SAR image of Kresge auditorium

2011-08-06T08:11:00.002-04:00

Student results from the final day of the MIT Professional Education 1-week radar course, where everyone learns about radar, then makes one, then uses it in a series of field tests.

Shown here is a SAR image using the student-built radar kit of the outside of Kresge auditorium. The railing around the underground garage entrance shows up really well, as does the edge of Kresge itself.

An excellent image for a radar built out of coffee cans.

update on the MIT Prof Ed 1-week radar course: RTI plot of Longfellow Bridge

2011-08-04T21:55:00.003-04:00

Student results from day 3/5 of the MIT Professional Ed. 1-week radar course.

Range time intensity plot of vehicles crossing the Longfellow bridge from Cambridge to Boston. This plot shows both the remarkable range of the coffee cantenna radar kit and this student's ability to make a small radar and use it to acquire real measurements.

update on the MIT Prof Ed 1-week radar course: DTI plot of an exercise bike

2011-08-03T07:27:00.003-04:00

Student results from Day 2/5 of the MIT Professional Ed. radar course:

A first in the history of Radar engineering and measurement: a doppler time intensity (DIT) plot of an exercise bike!

MIT prof ed 1-week radar short course update: 35 cantenna radar kits

2011-08-01T21:06:00.002-04:00

Here they are, 35 cantenna radar kits prior to distribution as part of the 1-week MIT professional education radar course. Shown on the top figure are the 70 cantennas. Second photo shows the bags of parts for each kit.

Each kit contains 6 uwave modules, solderless breadboards, a piece of plywood, 50 ft tape measurer, a handfull of analog parts, and 8 AA batteries, plus other stuff.

Welcome to our 1-week radar short course, where we learn about radar systems by actually making one and using it in the field

2011-08-01T07:03:00.002-04:00

I want to welcome our students to this week's radar short course at MIT!

This week we will learn about radar systems by everyone actually making their own and using it in the field.

This will be a fun and challenging week for us all. Thank you for signing up to our course and we hope that you have a wonderful time this week.

This course is completely full with 30 students attending and one or more on a waiting list.

I will post updates to the blog as things progress.

BUILD A SMALL RADAR SYSTEM CAPABLE OF RANGE, DOPPLER, AND SAR IMAGING [PI.80s]

Date: August 1-5, 2011 | Tuition: $3,400 | Continuing Education Units (CEUs): 3.0
Application Deadline »

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COURSE SUMMARY

Are you interested in learning about radar by building and testing your own imaging radar system?

MIT Professional Education is offering a course in the design, fabrication, and test of a laptop-based radar sensor capable of measuring Doppler and range and forming synthetic aperture radar (SAR) imagery. Lectures will be presented on the topics of applied electromagnetics, antennas, RF design, analog circuits, and digital signal processing while at the same time you build your own radar system and perform field experiments. Each student will receive a radar kit, designed by MIT Lincoln Laboratory staff, and a course pack.

This course will appeal to those who want to learn radar systems engineering or SAR imaging, use radar technology in a product or experiment, or make components or sub-systems.

You do not have to be a radar engineer but it helps if you have at least a bachelor’s degree in electrical engineering or physics and are interested in any of the following: electronics, electromagnetics, signal processing, physics, or amateur radio. It is recommended that you have some familiarity with MATLAB. Each student is required to bring a laptop (with a stereo audio input) with MATLAB because this will be used for data acquisition and signal processing.

During the course you will bring your radar kit into the field and perform experiments such as measuring the speed of passing cars or plotting the range of moving targets. A SAR imaging competition will test your ability to form a SAR image of a target scene of your choice from around campus.

An Afternoon with W1FPZ - Part 1 of 3

2011-07-31T14:59:00.000-04:00

It's good to have goals in life. I've made a new goal today, to be like this guy when i am his age.

What amazing work he has done here!

DSP/Software Radios - You Only Live Nine Times

2011-07-30T08:42:00.000-04:00

This is a great tutorial on how software defined receivers work and how to make your own.

You first must get past the funny 'plot line' (if you're making a youtube video why not have fun while doing it? :)

It's worth it because Jeri does a great job explaining signal processing concepts behind software defined radios without getting into too much detail.

Making things as a kid, taking apart old TVs and radios and hooking things up to model railroad power transformers

2011-07-28T08:08:00.002-04:00

My mother is an electrical engineer, i think because of this as a kid i enjoyed nothing more than to take apart an old TV set, radio, or appliance to learn how it worked. Eventually i started to learn how to hook things up to old model railroad power supply transformers such as car radios, lights, motors, and other cool things. After i while i started to use relays and was able to backwards engineer the power connections to almost anything. Things became interesting at approximately age 10 when my uncle described to me how to use transistors and i acquired my first oscilloscope. This lead to more interesting projects, including making power supplies, repairing more complicated appliances, and eventually the amateur radio license at age 13 thanks to encouragement by my mother who thought that i should try a more advanced hobby.

We're lucky to live in an age with so much stuff to take apart and learn from.

ARRL Homebrew Challenge 3 radio update: Power Amplifier complete

2011-07-26T06:00:00.000-04:00

The power amplifier is complete. with -10 dBm in from the front-end mixer my driver will provide 10 watts out. My final power amplifier will provide 110 watts out with the 10 watts of drive power using a push-pull LDMOS transistor.

This is very exciting. Hopefully 100 watts will be sufficient to make some 10m and 6m contacts later this fall when the radio is complete :)

Repairing a Yaesu YP-150 watt meter

2011-07-24T06:54:00.000-04:00

Picked up this Yaesu YP-150 watt meter. Unfortunately it had a cold solder joint on one end of the 50 ohm load resistor that fell out causing the load to not be connected. This was obvious when an input of 20 dBm would cause a full scale meter reading.

To fix this i applied lots of flux and using a large iron i flowed solder back into the broken half of the load resistor.

I then checked the VSWR from HF to 150 MHz and it was good. Next i tried testing a 100 watt transmitter to verify that it was operating soundly and would not suddenly have a problem.

Good to go, i need this watt meter to test my driver and PA boards for my ARRL homebrew challenge 3 radio.

Submitted to Trans. on AP-S: A Through-Dielectric Ultrawideband (UWB) Switched-Antenna-Array Radar Imaging System

2011-07-22T05:21:00.000-04:00

A through-dielectric switched-antenna-array radar imaging system is shown that produces near real-time imagery of targets on the opposite side of a lossy dielectric slab. This system operates at S-band, provides a frame rate of 0.5 Hz, and operates at a stand-off range of 6 m or greater. The antenna array synthesizes 44 effective phase centers providing $\lambda/2$ element-to-element spacing by time division multiplexing the radar's transmit and receive ports between 8 receive elements and 13 transmit elements. Laboratory measurements agree with simulations, the air-slab interface is range gated out of the image, and target scenes consisting of cylinders and soda cans are imaged through the slab. A 2D model of a slab, a cylinder, and phase centers shows that blurring due to the slab and bistatic phase centers on the array is negligible when the radar sensor is located at stand-off ranges of 6 m or greater.

(Hopefully the editors and reviewers will find this project interesting.)

Link to this project.

ARRL Homebrew Challenge 3 radio update: AGC and signal meter circuitry complete

2011-07-20T06:51:00.000-04:00

I've completed the AGC and signal meter circuit. My signal meter displays absolute signal level in volts at 50 ohms. The AGC circuit uses 4 op-amps and is audio derived. I've had good luck with audio derived AGC circuits in the past so i plan to use one again this time.

ARRL Homebrew Challenge 3 radio update: RX/TX audio board and circuitry complete

2011-07-18T06:40:00.000-04:00

Creating the audio circuitry for a SSB transceiver is not a trivial task. Shown on the right is a green prototype board with the completed RX and TX audio and PTT circuitry.

Briefings and notes on using LDMOS RF power mosfets

2011-07-16T07:29:00.000-04:00

I am thinking about using an LDMOS RF Power mosefet push/pull pair for the homebrew challenge 3 radio.

I have prototyped an amplifier and am currently working through design issues. A colleague of mine came across these briefings on using LDMOS RF power mosfets.

Colin B. Kennedy Model 20B Console Radio, ca. 1929

2011-07-13T19:34:00.000-04:00

A demo of my Colin B. Kennedy Model 20B console radio. Built in 1929 this radio still sounds great, especially when listening to vintage jazz music.

a Through-Wall radar imaging system

2011-07-11T18:46:00.005-04:00

Recently we have posted some of the results and info on a very exciting project that i and a number of collaborators have been working on; a through-wall radar system.

It is a real-time through-wall imaging radar, providing a frame-rate of 10.8 Hz (nearly video frame rate), capable of imaging through 4", 8" solid concrete, and cinder block walls.

For a short article on this work and to see the results click here.

For a collection of info with links to previous work click here.

Restoration of a Silvertone model 4686 console radio, ca 1937

2011-07-05T21:24:00.001-04:00

I restored this beautiful old console radio for two dance friends that we know who just got married. This was a fun project, hope that you enjoy!

Un transceiver 20M SSB fait maison...

2011-07-01T07:43:00.004-04:00

Recently an article on the 20m homebrew SSB transceiver was posted on radioamateur.org , which is a French site dedicated to amateur radio. The author, F8BXI, describes the radio and provides the youtube video demo.

Thank you F8BXI for your write-up and kind words. Your article will help encourage others to create their own radio equipment.

73,

Greg N8ZRY

Education Resources on radar, RF design, antique radios, clocks, and vacuum tube audio

2011-06-24T07:22:00.000-04:00

I've added a new page listing useful education resources for making and understanding radar systems, radios, restoring radios, tube audio equipment, and repairing clocks.

These include online video lecture series, sources for data, lists of useful books, and sources of sample data.

Click here for more info:

Education Resources

how to read 'dog bone' resistors from the 1930's

2011-06-15T07:24:00.000-04:00

I'm running into some very old resistors while restoring the '37 Silvertone. Here is how you read these 'dog bone' resistors, apparently the Philco color scheme is the same as Sears Silvertone:

http://www.philcoradio.com/tech/resistor.htm

Also note that in the schematics for this radio the unit M means kilo ohm. Meg means Mega Ohm, and ohmega means simply ohms.

The best YouTube Channel: BandersenTV, antique radio and television restorations

2011-06-12T07:39:00.000-04:00

If you like the TV show 'This Old House' and you like to restore antique radios or televisions then you will love this youtube channel: http://www.youtube.com/user/bandersentv

It is the television and radio restoration equivalent of 'This Old House.' I am a huge fan and have watched almost every video (there are a few hundred so far). New videos are posted a few times a week.

If you are interested in learning how to restore antique radios and televisions then you can learn much by watching these videos, in fact i think there is a mini-series in here on the basics of radio restoration.

Thank you Bob for your excellent work, we look forward to your next video post.

Completed: Sears Silvertone 4686

2011-06-08T08:06:00.000-04:00

I've completed restoration of the Silvertone Model 4686.

I used restore-a-finish on the wood, feedn' wax to buff it out.

Radio also looks great at night with the illuminated tuning dial.

It sounds great and has a nice booming AM sound. Both shortwave bands work and i've listened to many unusual shortwave broadcasts with it. I have also added an ipod input so i can play my vintage music playlist.

Silvertone 4686 console radio, second IF transformer

2011-06-06T08:00:00.000-04:00

I had to make repairs to the second IF transformer.

It was not easy extracting this from its case. The top nut was stuck and i damaged the wires feeding both coils while extracting it.

Shown here are photos of each side of the transformer for reference in case you have to repair one in your Silvertone radio.

update: ARRL Homebrew Challenge 3 radio, pre-driver and driver complete

2011-06-04T22:36:00.002-04:00

This is the pre-driver and driver board.

5 watts out with -10 dBm drive from the front-end mixer, perfect for driving a good sized PA.

Model 4686 Silvertone 1937 Console radio restoration

2011-05-27T07:30:00.000-04:00

Re-wired the line voltage and power switch circuitry, adding a grounded power cord, fuse, new safety caps, and cable clamp.

Re-caped all electrolytics.

Re-caped about 1/3 of the paper capacitors.

Oiled the tuning mechanism, which is a unique 'dial a tune' thing that functions much like a rotary telephone, where you dial in the station you want to hear.

More later...

NTIA Seminar Series on Spectrum Measurement Theory and Techniques

2011-05-26T20:44:00.000-04:00

Check out this video series online on how to measure radio transmitters, mostly for radar. Not an easy thing to do for sure.

ITS Educational and Training Videos

Video Home

SP-09-460: NTIA Seminar Series on Spectrum Measurement Theory and Techniques

Have you ever wondered how a spectrum analyzer works, how to properly adjust all of the analyzer's parameters, or why a stair-step pattern initially appears on a spectrum analyzer screen when you turn it on? Do you know how to precisely calculate the analyzer's sensitivity in your head, merely by glancing at the screen display without any signal present? Are you uncertain about how much gain, and how low a noise figure, you ought to specify when you are ordering a low–noise amplifier (LNA) for a radio receiver? Do you want to know the difference between noise figure and noise factor? Do you wonder how to diagnose and solve radio interference problems?

If you have questions about how to make good radio spectrum measurements or how to diagnose interference problems, you will find the answers in the NTIA Seminar Series on Spectrum Measurement Theory and Techniques. In this series of talks, an NTIA engineer at the Institute for Telecommunication Sciences (ITS) laboratory in Boulder, CO, discusses the fundamentals of radio spectrum measurements. The speaker, Frank Sanders, who has nearly thirty years of experience in this field, recognizes that even for many engineers who routinely use spectrum analyzers, the fundamentals of how they work and how to use them may be a bit murky; even in university lab classes the instructors do not always understand these machines very well themselves.

Most of the talks, which are 80–100 minutes long, are divided into two parts. In the first portion of each video, Sanders explores a particular aspect of radio spectrum measurement technique or theory with a whiteboard lecture. In the second part, the lessons of the whiteboard discussion are implemented with actual measurement hardware and radio signals. A few of the talks, which for example involve large numbers of photographs of radar systems, are videos of his Microsoft Powerpoint presentations.

In this series, Sanders explains spectrum analyzer functionality in terms of convolution bandwidth and shows how, when convolution is understood along with the mechanics of analyzer design, spectrum analyzer operations and outputs become easy to understand and use. Other topics include (1) what you need to know to use spectrum analyzers to examine all types of radio signals, including mobile radios, radars, and digital data links; (2) the use of low noise amplifiers and how to specify the right gain and noise figure for your receiver and measurement applications; (3) how radar systems work, and how to understand and interpret the signals that you see coming from radars; (4) the ways that radio interference can occur; (5) a methodical approach for diagnosing and solving radio interference problems; (6) the math needed to convert spectrum analyzer measurements into field strengths of radio signals; and (7) the proper conversions for radiation hazard calculations.

5/24 @ 4pm: The MIT IAP 2011 Radar Course: Build a Small Radar System Capable of Sensing Range, Doppler, and Synthetic Aperture Radar (SAR) Imaging

2011-05-23T07:34:00.001-04:00

For those of you who are interested in the build a radar course I am presenting a talk on this at the IEEE Life Affinity Members, AP-S, AES, and GRSS joint meeting at 4pm on May 24 at Lincoln Laboratory.

All are welcome but you must pre-register by following the directions at the bottom of the talk summary here:

http://www.ieeeboston.org/org/subgroups/life_members.html

Summary of talk:

Recently MIT Lincoln Laboratory sponsored a short radar course at MIT main campus during the January 2011 Independent Activities Period (IAP). The objective of this course was to generate student interest in applied electromagnetics, antennas, RF, analog, signal processing, and other engineering topics by building a capable short-range radar sensor and using it in a series of field tests. The underlying philosophy being that students have a vested interest in making their own radar work properly, causing them to dig deeper into these subjects on their own volition thereby providing a self-motivated learning experience. A series of lectures on the basics of radar, modular RF design, antennas, pulse compression and SAR imaging were presented. Teams of three students received a radar kit. Nine teams participated in the course.

The radar kit was an S-band coherent frequency modulated continuous wave (FMCW) radar centered at 2.4 GHz with less than 20 mW of transmit power developed by the authors. To reduce cost, the antennas (transmit and receive) were made from coffee cans in an open-ended circular waveguide configuration. To clearly show the RF and analog signal chain, all components were mounted on a block of wood similar to an early 1920’s radio set. The microwave signal chain was made from six Mini-Circuits coaxial components. The analog signal chain was implemented on a solderless breadboard for quick fabrication and easy modification. The video output and transmit synchronization pulses were fed into the right and left audio inputs of any laptop computer. To make the kit portable it runs on eight AA batteries. The total cost of each kit was $360.

The radar operates in three modes; doppler vs. time, range vs. time, and Synthetic Aperture Radar (SAR) imaging. To record data a student uses the .wav recorder program in the laptop. MATLAB scripts read the .wav data and form the appropriate plots.

Of the nine student groups all succeeded in building their radar, acquiring doppler vs. time and range vs. time plots. Seven of the nine groups succeeded in acquiring at least one SAR image. Some groups improved their radar sets by improving the signal processing algorithms, developing real-time radar graphics user interfaces (GUI’s), and by making a more robust chassis.

Most students were from MIT but a small contingent were from Northeastern University and one student built this radar as an independent study at Michigan State University. Great enthusiasm was generated after each field test. Students were engaged throughout the course and they continue to ask questions about how to improve the performance of their radar sets and how to make more sophisticated systems. Many students discussed scattering theory at length when trying to interpret their SAR imagery.

In summary, it is difficult to introduce the current generation of students to the field of applied electromagnetics, RF, analog, and signal processing because of the numerous challenging prerequisites needed before the rewards can be realized. By presenting these difficult topics at a high level while at the same time making a radar kit and performing field experiments, students became self motivated to explore these topics. In the long term, courses using this continuous engagement philosophy could help fill the gap as the current generation of radar engineers continues to retire.

More info about this course can be found:

MIT Lincoln Laboratory: MIT Lincoln Laboratory researchers introduce students to radar engineering

A Modern Approach to Radar | CSAIL

Links to student results and blog entries here.

Model 4686 Silvertone 1937 Console radio restoration

2011-05-18T08:05:00.000-04:00

Starting the restoration of my Silvertone model 4686 console radio. This radio was built in 1937. It works on the standard broadcast AM band and 3 short wave bands.

This radio features a magic eye tuning indicator and a really big speaker with a massive baffle.

The chassis is in excellent condition.

To my surprise, the seller actual plugged it in and it works. Although, it needs alot of work. I found some of the repairs inside to be sub-standard and quite dangerous.

More later as restoration proceeds.

Free Video Courses in Radar Systems Engineering, by Dr. Robert M. O'Donnell

2011-05-13T07:29:00.000-04:00

Sponsored by IEEE Aerospace and Electronic Systems Society and the IEEE New Hampshire Section, for all lectures please goto: http://aess.cs.unh.edu/radar%20se.html

From the intro slide:

This Free Radar Systems Engineering Course (video, audio and screen captured ppt slides) and separate pdf slides) has been developed as a first course in Radar Systems for first year graduate students, advanced senior undergraduates, or professionals new to radar (In the first 17 lectures there are over 1150 slides!)

The video course will contain the screen captured audio and video along with the screen capture of each viewgraph. The textbook for the course will be "Introduction to Radar Systems" 3rd Edition McGraw Hill 2001. Homework problems are taken mostly from that textbook. s Although Skolnik's text is the "text book" over fifty textbooks, (including the recently published text, "Principles of Modern Radar" by M. Richards et al ) and scores of journal articles were read to develop the material in this course. In addition, each lecture has a significant number of references at its end. Each lecture will vary in length from 30 minutes to up to 2 hours. Most will be somewhat over an hour. The video stream of each topic will be broken up into "easily digestible" pieces of approximately 20 to 30 minutes."

phased array radar imaging a 12 oz soda can moving in free-space in near...

2011-05-11T07:27:00.000-04:00

Nearly a real-time image of a moving soda can from a near-field phased array radar that i built in my garage as part of my dissertation.

Other videos show this radar imaging the same moving soda can through a 4" concrete slab.

my ARRL Homebrew Challenge 3 entry, RX/TX audio, keying circuits, and microphone installed

2011-05-08T20:36:00.005-04:00

Update on the HB3 radio for 10m/6m SSB/CW, in the breadboard stage.

Added a plate for all of the front panel controls.

RX audio signal chain works. TX audio signal chain works. Microphone installed. Microphone keying circuit works, radio will transmit -10 dBm PEP.

Next step:

Moving on to the side tone oscillator and CW keying circuit.

After that:

Will make the pre-driver board to get up to 1 watt or so TX.

Stay tuned for the latest updates.....

my entry in to the ARRL Homebrew challenge 3, 10m/6m SSB and CW transceiver

2011-05-04T08:00:00.000-04:00

Shown here is my entry into the ARRL Homebrew Challenge 3. This is a 10m and 6m SSB transceiver, currently in the breadboard prototype stage.

Receiver works well so far and I have already tuned in some DX on 10m.

Next step will be to consider filtering the first LO further and to order the proper BFO crystal for USB.

Once these steps are complete i will move on to the audio and keying board, which will first be implemented using a solderless prototyping board.

phased array radar imaging a cylinder moving in free-space in near real-...

2011-05-01T08:19:00.000-04:00

Posted more results from my dissertation to youtube.

Here we are imaging a cylinder moving in free-space (outdoors) in near-real time.

schematics, block diagram, BOM for MIT IAP '11 radar course, cantenna radar kit

2011-04-27T08:00:00.000-04:00

Per your request and as the documents have been approved i have uploaded the schematics, block diagram, and bill of material for the MIT IAP '11 cantenna radar kit, which is capable of SAR imaging, ranging, and doppler sensing.

I've also uploaded more photos of student radar kits and other info here.

The opencourseware site is in the works, we expect this to be completed in late spring, so stay tuned! With the OCW site you will have access to all of the associated lectures so that you can both learn and make a radar system.

Completed: restoration of the Elgin 12s pocket watch

2011-04-25T07:54:00.000-04:00

Completed restoration. This watch is running strong and keeping great time. Its slim design allows it to fit in your pocket without noticing its presence. And i do like to hear it ticking all day.

The back case has a broken hinge but snaps on anyway. Not much i can do about repairing the case hinge.

For more details of the tear down and restoration i have photographed each step of the way here, hopefully this will help other watch repair enthusiasts who are trying to re-assemble an elgin:

http://www.mit.edu/~gr20603/Dr.%20Gregory%20L.%20Charvat%20Projects/Elgin%201922.html

Radar imaging a cylinder through a 4" solid concrete wall

2011-04-24T19:43:00.000-04:00

Posted some more results from the near real-time phased array array built in my garage a few years back, shown here:

http://www.mit.edu/~gr20603/Dr.%20Gregory%20L.%20Charvat%20Projects/S-Band%20MIMO%20Phased%20Array%20Radar.html

This video is a cylinder through a concrete wall as seen on the radar screen.

pocket watch restoration: Elgin 12s, open-face

2011-04-15T07:49:00.000-04:00

This is my second pocket watch restoration, an Elgin size 12, open-faced grade 303. This watch is very slim and would be great for work because I can leave it out on the podium while I make presentations to keep track of time.

Shown here is the front and back of the movement prior to cleaning and oiling. Also shown are all of the parts after cleaning.

When a pocket watch is disassembled it looks extremely complicated but if you take numerous photographs as you take it apart then re-assembly is possible.

Results are in for the ARRL Sweeps 2010

2011-04-13T07:07:00.003-04:00

6 months of work resulted in developing my first homebrew SSB transceiver. Immediately after completion i entered the ARRL 2010 sweeps to thoroughly test this radio on the air.

The results are in, my station is listed in the results for Eastern Massachusetts! (EMA)

N8ZRY 2,940 49 30 A

http://www.arrl.org/files/file/ContestResults/2010/2010-SS-PH-Results-V4.pdf

I'm 8th from the bottom of 25 stations participating from EMA, but i'm not at the bottom :) Also important to note that i could only work 20M and had a TX power of about 40 watts.

Hoping to have a couple more bands of homebrew radio to use in the ARRL sweeps this fall.

Article and step-by-step how-to instructions on the MIT IAP radar course

2011-04-07T07:22:00.003-04:00

The IAP radar course has made the MIT Lincoln Laboratory News Feed.

"During MIT's Independent Activity Period (IAP) between the fall 2010 and spring 2011 semesters, twenty-six students worked in teams to design, fabricate, and test a laptop-based radar sensor that was capable of measuring Doppler and range, and of forming synthetic aperture radar images. In a course designed and taught by MIT Lincoln Laboratory technical staff members, the teams received class instruction on the fundamentals of radar and SAR imaging, and kits from which to develop their systems. To their surprise, the kits contained coffee cans to be used as transmit and receive antennas."

This article and a slide deck with step-by-step instructions, schematics, and radar block diagram are located here.

Lectures on Adaptive Antennas and Phased Arrays, view online

2011-04-05T08:00:00.000-04:00

For those who are interested in adaptive antennas and phased arrays:

The entire MIT Lincoln Laboratory workshop on Adaptive Antennas and Phased Arrays instructed by Dr. Alan Fenn is available online here.

This is a very interesting course and we are fortunate that Lincoln has decided to share these lectures with the general public.

Completed: New York Standard pocket watch restoration

2011-04-03T07:44:00.000-04:00

Completed restoration of the NY Standard pocket watch.

This watch runs strong and keeps accurate time, no adjusting necessary. The inside really cleaned up well as shown above. This was a successful first pocket watch restoration.

For more info about each step of the tear-down and cleaning:

http://www.mit.edu/~gr20603/Dr.%20Gregory%20L.%20Charvat%20Projects/NY%20Standard%20PW.html

Restoration of a New York Standard pocket watch

2011-04-02T07:37:00.000-04:00

This is my first pocket watch restoration. It's a New York Standard pocket watch, size 16 with a hunter's case, built in around 1914. This is a mid-grade watch, not as high end as a Waltham, but it's a really nice watch and inexpensive start to the hobby of repairing pocket watches.

Similar to the clocks, this watch must be completely taken apart, cleaned in an ultrasonic cleaner, reassembled, and lubricated.

Shown here is the watch before, and during disassembly, and then after it has been cleaned in many pieces.

PHYS 101/102 #1: Electromagnetic Waves

2011-03-29T23:26:00.000-04:00

Restoring a Franz Hermle Westminster chime movement

2011-03-29T07:28:00.000-04:00

I'm restoring an Hermle clock movement that has Westminster chimes. This is the most complicated clock movement i've attempted yet. It has 3 gear trains, 3 barrel springs, 5 hammers, and it's own xylophone!

Was able to get everything back together and the clock ticks and chimes. Still working on the chiming part of it however.

From the photos you can see how complicated this one is to put back together, especially for an amateur clock repair enthusiast.

Radar imaging a 12 oz soda can through a 4" solid concrete wall

2011-03-27T11:25:00.000-04:00

I've posted some of the near-real-time radar imagery from my dissertation on youtube from the phased array portion of the dissertation.

Shown here is a 12 oz soda can moving from left to right through a 4" thick solid concrete wall. Image is in range vs. range. Can is about 30' from front of radar, radar front is at bottom of image. Image rate of about 0.5 Hz.

Had alot of fun with this project and I continue to work on a more sophisticated variant of it.

Introduction to Radar Systems at MIT Lincoln Laboratory online Videos

2011-03-25T08:00:00.000-04:00

For those who are interested in learning about radar systems:

MIT Lincoln Laboratory has posted videos of all lectures of the Introduction to Radar Systems Workshop instructed by Dr. Robert M. O'Donnell.

To watch these lectures and learn about radar systems please start here.

New Haven Clock Company Tambour No. 16 movement

2011-03-18T22:27:00.000-04:00

Video of New Haven clock movement in action, it was awesome to see this one start to go.