Monday, October 05, 2015

The Art of Electronics


I read in a newsletter today that the Third Edition of the classic Art of Electronics is out. This is a "must have" reference for anyone serious about electronics in general. While it does not cover many RF topics if you had only this book and a copy of the ARRL Handbook you would have a pretty awesome reference library at your fingertips.

73,

Tim N9PUZ

Hellschreibner Digital

Last night was a first for me. Even after all these years in Amateur Radio.

Last week my Friend Mitch K9ZXO gave a presentation on the digital mode Hellschreibner at the Sangamon Valley Radio Club. I'd heard of Hellschreibner or "Hell" as it's affectionately known, but had never given it a try. Well this weekend I made sure my copy of the FLDIGI software was up to date and Sunday evening Mitch and I had a Hell QSO on 20 Meters. Woot!


Unlike other digital modes a decoded Hellschreibner signal is displayed as a picture on your screen as is shown in this Wikipedia image. This gives Hell a unique flavor that is really intriguing and takes advantage of that awesome Digital Signal Processor that sits between your ears under weak or noisy signal conditions.

73,

Tim N9PUZ

Wednesday, June 17, 2015

Thoughts on Backups

The last few weeks seem to have brought a lot of, sometimes confusing, information about backing up your computer. I don't think it should be as complicated as so many authors make it seem. Here's my take on things...

We live in a digital world. Most things that are important to our family either came to us digitally or we've scanned into digital format. Much of our lives and memories live on an inexpensive, cheaply made hard drive spinning at 7200 rpm.

Scenario #1: Computers or one of their components will periodically break. That means you need to have a second copy of anything stored there that's important to you.

Scenario #2: Crooks can break into your home or office and steal your stuff. Hurricanes, tornadoes, floods, fire, etc. are all possibilities you should consider. If you do have a copy of your important data it should be somewhere other than where your computer is located so it doesn't get stolen or destroyed by the same disaster that got the computer.

In Scenario #1 it is more likely that the disk drive will break than other failures. In this case it is nice to have an image backup so you can put in a new disk, restore the image, and be back where you left off without having to reinstall your operating system, application programs, data, etc. If it is NOT the disk drive that fails and you'll have to buy a new computer or motherboard the image won't do you much good since it's specific to the configuration of your old computer. You have a lot of reinstalling ahead of you but you should not have lost any information.

In Scenario #2 you or your insurance carrier will be buying a new computer. All of your important data was stored elsewhere so although it may be inconvenient, you haven't lost anything and you can restore it.

Please note: In any situation where you will have to reinstall application programs you need to have made copies of the originals along with the product keys, serial numbers, etc. If you copy those installation files, scanned copies of your invoice, license keys, etc. and store them in a folder on your hard drive they will be backed up along with all of your other important stuff. The one thing you do need to have separately (and off-site) is your operating system installation disks and information. This mainly applies to those of you who build your own computers. Most off the shelf computers come with the OS pre-installed if you have to buy a new one.

My recomendations?

I use an external USB hard drive and use a program such as Macrium Reflect or Acronis True Image to make a fresh image backup once a month. I also subscribe to a service called Crashplan which backs up data on an ongoing basis. It makes copies to the external USB hard disk, another computer on my home network, and off-site to Crashplan's cloud storage. You don't have to do anything specific, it just works all on it's own.

There are other products that do similar things to what Macrium and Crashplan offer. I'm sure that many are good products. These were what I used first and they have never let me down so I haven't explored others.

I know a lot of people will think this is a lot of trouble or that none of this can ever happen to them. Well, I'm sorry, you're wrong. It happens to people all over the world every single day.


Friday, February 20, 2015

What's the Difference Between Resistance and Impedance?

I was reading a Facebook discussion today and there was a lot of confusion between resistance and impedance. Someone was trying to measure a speaker with an ohmmeter and didn't understand why his "8 Ohm Speaker" measured less than 8 Ohms. One reply posted this link which I thought was pretty good...

Difference Between Resistance and Impedance

Wednesday, February 18, 2015

W9DUA D-STAR Repeater Update

A few days ago some Sangamon Valley Radio Club members and other friends from the central Illinois area got the gateway computer for W9DUA/R up and running again. The repeater is permanently linked to REF051 so it's tied together with D-STAR repeaters in Decatur and Bloomington. If you have D-STAR capability please tune up the machine nearest you and say hello to central Illinois hams!

5 Million Raspberry Pi Computers

I read earlier today that the Raspberry Pi Foundation reported than over 5 Million Raspberry Pi computers have now been sold. This number supposedly includes only true sales and does not include the number that have been given away for educational and philanthropic reasons.

Tuesday, February 17, 2015

Raspberry Pi and Arduino Tech Night

On Thursday, March 5, 2015 the Sangamon Valley Radio Club is hosting a "Show and Tell" evening that will focus on uses of the Arduino and Raspberry Pi single board computers that you've seen mentioned in Amateur Radio and Maker publications. The meeting will be held at 7:00 p.m. The location is:

American Red Cross Building
1045 Outer Park Dr.
Springfield, Illinois 62704-4408

An specific agenda is not yet finalized. There will be a presentation on considerations for applying devices such as these to an application and several SVRC members will be describing and demonstrating experiments they have been working with on their own. If anyone has an Arduino or Raspberry Pi project of your own you are welcome to bring it and share your story as well.

The SVRC will be supplying some light refreshments at the event. As such, if you are not an SVRC member, we ask that you please let us know that you will be coming just so we can get a rough head count.

There is no charge to attend.

If you plan to attend, please send an email to Roger K9LJB at:
president@svrc.org so we can plan for the refreshments.

Monday, February 02, 2015

Web Site Update

I've made a few edits to the EMCOMM Email Via Radio In Sangamon County, Illinois page on the main web site. In recent times the Byonics TT4 Tracker/KISS Mode TNC has become one of the dominant TNC types in the Amateur world. Just trying to keep people pointed in an appropriate direction.

Find out more or buy a TT4 at the Byonics web page