Thursday, January 30, 2014

How'd He Do That?

A number of folks have asked about the rendering I did of the proposed antenna farm at the new SEOC.  I'm not an artist, I can't draw worth a darn.  The images were produced using constructive solid geometry - that is, the images are the result of a bunch of equations.

The way this works is simple, at least in principle.  You write a bunch of expressions describing a bunch of objects, and the computer figures out what it will look like.  Skilled artists can make breathtaking images, but for a tecchie like me, it can be very helpful to try to visualize something.

The first time I realized this was back in the 90's, and it really hit home when Chip Cohen, (then NI1R) began talking about his patented fractal quad yagi (FQY) antenna.  His claims were fantastic, but people just couldn't understand it.  Try as he might to explain it,  he kept getting accused of trying to hide what he was actually doing.

I made a tracing for myself to try to understand it, and sent some images to Chip, which he used in an article in Monitoring Times.  That led the magazine to commission me to do their cover artwork, which remains my only published artwork.  These images are all created with POV-Ray, a rather old, open-source program, but one capable of amazing results.

While creating a scene like this was can be tedious, it really isn't all that hard.  In the antenna case, I began by modeling an aluminum tube, 1 inch in diameter and 12 inches long, by writing

 cylinder { <0,0,0>,<0,1,0>,1/24 texture {Aluminum} }.

(I used units of feet, so a 1" diameter tube has a radius of 1/24 of a foot).

I then arranged four of these in a square

One foot of tower

and put quarter inch tubes diagonally across each edge.

This gave me one foot of tower.  OK, perhaps it will be a triangular tower, it probably will be a little different size, in fact, we haven't specified the tower as it has to comply with FEMA standards.  It probably won't be your typical ham tower.

5 feet

I had towers of 20, 30, 35 and 125 feet, so I combined the one-foot sections into five-foot sections, which I could then combine into the appropriate heights.

The sky is a standard "texture", and while I probably could have used a more aesthetic sky, the first one I tried looked OK so I just stuck with it.

  sky_sphere { S_Cloud1 }

The General Office Building (GOB) is in the background and mostly obscured, so I simply modeled that as boxes.

  #declare GOB1 = object { box { <-95,0,0>,<95,35,2*95>  texture { Brick } } }
  #declare GOB2 = object { box { <-34.34,0,0><34.34,50,148> texture { Brick } } }
  object { GOB1 translate <-39,0,333> }
  object { GOB2 translate <-39-34.34,0,422> }


I had intended to get fancy with the "Brick" texture, but I ended up with simply a light brick colored pigment, and for the GOB, probably quite a bit different than reality.

One wall
For the SEOC itself, since many of the walls are at odd angles, each wall was modeled as a box, and rotated into position.  Since the measurements were taken off a relatively small drawing, the odds are they aren't very accurate, but they can at least give a feel.  I again used the "Brick" texture because I have no idea what sort of texture will be used on the new building.

Finally, oversized cylinders were used for the wires.  Modeling drooping wires is possible, but a pain in the neck, and copper colored wires of a realistic size would be invisible, especially in the movie, so I used 1.2" diameter black cylinders.

Adding a few trees (from an example macro that produces pretty ugly trees), a little fog to make some things appear a little less prominent, and we have something that can give us a feel for the antenna farm.  I have to admit to being terminally lazy, and even though someone else did the hard work of figuring out how to model a tree, I wasn't about to write a line for every tree.  So, I wrote a C program to generate code for 800 trees in four rows, two on each side, of randomly varying heights and distances.

For the movie, 99 frames were made of the same scene, moving the camera between each frame.  The individual frames were combined with ImageMagick.


Wednesday, January 29, 2014

Hams in Important Places

A few months ago, K8RDN, KA8DDQ and I sat down with the architects for the new SEOC to talk about antennas.  For VHF/UHF antennas it is pretty simple; put up as tall a tower as we can manage and stick the antennas on that.

For HF it's a little messier.  We currently run CW and SSB stations simultaneously, and want to add a Pactor station.  Since we are interested in in-state, beams and huge height aren't useful -- we want wire antennas fairly close to the ground.

We decided on a loop (which has worked well for us) and two G5RVs.  Add to that the inverted Vee for MARS and you have quite a pile of towers.  We were sure to specify power and weatherproof boxes at the bases of the towers to support remote antenna tuners.
Antenna Image
WB8RCR rendering

What we (I) didn't consider is that running the feedline from a tower at the end to the center of the G5 could get a little messy.  I thought of that later, but figured we could cobble something together.

When the drawings arrived from the architects, there was a 6 foot riser with a weatherhead specified at the center of each G5.  Obviously at least one of the architects was a ham.

Tuesday, January 28, 2014

Monitoring Emergency Frequencies

The recent spates of bad weather have served to remind us of the importance of monitoring our emergency frequencies any time we suspect there may be an issue.  If someone really needs us, they are in deep trouble.  They need a place to go to get help and our frequencies are that place.

It would be nice if it were as simple as a single frequency.  But propagation isn't always a kind mistress, so we need to be prepared to operate on different bands depending on the mood of the sun, and different modes as different modes are affected differently by propagation.  Plus, someone with only simple equipment or little power available may need to operate CW, and only a relative handful of us can do that.  But if someone can afford a large power budget and has capable equipment, then modes that are easier for the untrained are possible.

Here in Michigan, we primarily use 3 bands; 80 is our default, 40 is for times of high flux, and 160 for low flux.  In practice, 40 is daytime, 80 is nighttime, but at the sunspot peak in the summer "daytime" might extend 24 hours, and at night in the winter during the sunspot minimum the flux may be low enough to demand 160.

Our frequencies are as follows:

            CW      NBEMS     SSB
   160     1.812    1.803    1.932
    80     3.563    3.583    3.932
    40     7.068    7.043    7.232

Note that we check CW at the top of the hour, NBEMS at quarter past, and SSB at the bottom of the hour. 

IMPORTANT NOTE: You should have these frequencies available on paper at your EOC station.  You may remember them, but you might not be the operator at your EOC when they are needed.

In addition to HF, monitoring should include your local repeater, 146.58 and 146.52.

We should use the 160 meter frequencies whenever the F2 critical frequency is below 4 MHz, and the 40 meter frequencies if the critical frequency is above 8 MHz.  If you have Internet available, you can check the Near-Real-Time F2-Layer Critical Frequency Map. If you really need to call out on these frequencies chances are you don't have the Internet.  So you should always be aware of where we are in the sunspot cycle.  Basically, 80 is the default, go up in frequency in the daytime, down at night, up near the solar maximum, down near the minimum.

You can also tell by listening.  If you can hear close in stations then you aren't too high in frequency.  If the noise is so high you can't hear anything, then you are probably too low in frequency.

For monitoring purposes, we use Olivia 8/500 for NBEMS.  MT-63 1K long works well too, as long as there aren't thunderstorms in the area, but for calling and monitoring, Olivia 8/500 is the ticket.  

For CW, call at a relatively low speed.   The Michigan CW nets operate at 20WPM or higher, but the station in trouble might not have that skill.  Call at 15WPM or less.

When monitoring, it is useful to announce your presence.  This shouldn't be some long dissertation, QRV de WB8RCR is adequate.  Even if you can't hear the station in trouble, them hearing you gives them some confidence that someone is listening and they should keep trying.

And also keep your station status up to date in MI-CIMS if at all possible whenever an incident is available.  The SEC watches this closely and has a number of communications paths to MSP.  If someone is in trouble it can be a huge help to know a station is on the air in a particular area.  If you don't have access to MI-CIMS, ask your county emergency management coordinator if access can be arranged.

So when there is any reason to suspect a problem, please monitor.  Even if you simply leave the radio on in the background on the appropriate frequency, it could be a real benefit to someone in trouble.

Friday, January 17, 2014

Good Morning Michigan

This is an attempt to sort out whether this can be a useful vehicle for communicating with the Section, and more importantly, can I keep it up?

I occasionally send out, sometimes long, emails to the DECs and ECs, and once in a while I also post those to the MIARPSC Yahoo group. But there are plenty of ARES members who may be interested in some of the ramblings but don't get a chance to see them.

I'm not real happy with the cosmetics of this thing, and over time perhaps I'll work on that.  But for now I'll try to make it a point to get useful content here so that those folks around the Section interested in emcomm can be included in some of the news.

The coming months

So, my schedule for the next few weeks does have a few significant items on the docket:
  • Feb 1 - MCSAR Training
  • Feb 6 - Midland Amateur Radio Club
  • Feb  8 - District 2 EC meeting - Detroit
  • Feb 11-13 - Interop conference - Traverse City
  • Feb 20 - MCSAR General Meeting
  • Feb 24 - D3 AuxComm Meeting - Standish
  • Mar 1 - MCSAR Training
  • Mar 4-6 - IEMC Training - Lansing
  • Mar 6 - Midland Amateur Radio Club
  • Mar 8 - Section Staff - Lansing
  • Mar 20 - MCSAR General Meeting
  • Mar 21-23 - Docs FAD - Raleigh, NC
  • Apr 1 - E. Fermi II Drill #1 - Lansing
I'm sure other stuff will pop up.