Posts Tagged ‘n0ssc’

Repeater work on Sandia Crest

I had the opportunity of a lifetime to traverse through the nation’s most RF dense mountaintop towersite, and possibly reduce my chances of having children by a large amount…in any case, today’s work was bucket loads of fun.

Towers lining the crest. [Wikimedia user Skoch3, Photo]

The work at the site was simple — some regular maintenance to the W5MPZ D-STAR repeater and gateway.

So, I got up early and headed off to Ed’s (KA8JMW) place to pick up the caravan to the peak. We packed the truck with some server rack shelves and tools, and headed to pick up Brian (N5ZGT), then Chris (NB5T).

And then, the 10,768 ft (3,255m) summit.

The road was blocked by the Forest Service since the park was closed due to fire danger. Thanks to some prior planning, we had no trouble getting past.

And not two turns in to the curvy mountain road, we meet our first deer, head on. Thanks to Ed’s quick foot on the break (maybe he was practicing for QLF?) the deer zipped across the road, perhaps only with a bruised tail.

We were warned that with the lack of humans, nature tends to take over a bit

The one thing I though of going up the road is, what if you had this road all to yourself (like we did then) with a nice, fast rally car?

I think deer would have a problem with that.

Anyway, we got to the top, and met the first obstacle:


Chris dispatched the lock on the well-signed gate and we were in. At that point, we had entered the danger zone; the steel forest. With at least 26 FM stations, almost half being over 20 kilowatts, 33 TV stations, more than half over 100 kW, and an uncountable number of microwave dishes, log periodics, yagis, verticals, radomes, funny looking phased arrays and dipoles supported on dozens of massive towers, I swear I could hear KOB in my teeth.

After driving through the entire site, we arrived at our final destination: the Sandia Nat’l Lab’s personal radio  playhouse.

The guys began working on equipment, while I snapped photos and gazed in awe of the city of Albuquerque all within my field of view.

Chris, Ed, and Brian “working.”

Brian took the job of tightening the D-STAR antenna, which he did adamantly, without falling, thanks to his fancy harness. It’s funny how dinky that antenna seems, but being over 3,000 ft ( 914m) above the rest of the world, it can see almost 100 radio miles (150km). With my 40w mobile radio, it comes in full signal in Socorro, NM, 75 miles (50km) away.

The team was successful of getting things done, cleaning up the shelves of an obtrusive monitor, keyboard and mouse (by going SSH only) and installing a NetIO internet-controlled AC power killswitch.

Before…
After. Notice the new black box on the top right. That controls power for the whole thing via the web. 

The work was complete right on the dong of noon, and we had ribs for lunch. YUM! After that, Chris’s wife treated us to some homemade ice cream at his place, and we toured his shack, nestled on the edge of a HOA-restricted subdivision. That doesn’t stop him from loving ham radio!

Next on the list is to move this stuff to its permanent home on server racks. Sadly, I won’t be here, with only two weeks left in my VLA internship. I don’t wanna leave! 🙁

I would like to thank Ed James KA8JMW, Chris Aas NB5T and last but not least, Brian Mileshosky N5ZGT for taking me on this mighty heighty outing. Perfect timing for knocking another thing off my New Mexico to-do list.

The only part I forgot on that list was to bring a spectrum analyzer up there. It would have probably blown up in my hands.

Me, Ed, Chris and Brian on the edge of the crest. 

Upcoming SOTA Activation of W5N/BA-005 on 20 July

If you’re coming from sotawatch.org, welcome!

—Details—
Peak: W5N/BA-005 – 7284 [Socorro Peak]
Location: Socorro, NM, DM64mb
Time: 20 July 2013, 1700 UTC
Bands: anything I can manage. Likely 20m and up, and 2m
Mode: SSB preferred, but I want to try to muddle through some CW. I’ve never done CW without a computer (shame on me) so PSE QRS!

On 20 July, I plan to activate a nearby mountain for SOTA. This isn’t any regular mountain – the some parts of the road up to the peak is owned by EMRTC, or, simply speaking, its a bombing range. Therefore access is permit-only and this plan is tentative at the moment [edit — It’s a go!!]. However, at last night’s Socorro ham club meeting, I met a guy willing to be my escort, so I don’t get blown up, and to make sure I don’t steal anything, I suppose.

Map of the area and the Summit. [http://sotamaps.wsstvc.org/]

BA-005 is known as 7284 on the SOTA map, but the peak is commonly referred to as M-Mountain or Socorro Peak. A nearby peak which has a large, limestone M on it isn’t included in the database because it’s too near the taller peak.They only differ in elevation by about 60 feet.

This shorter peak is the home of the famous Elfego Baca Golf Shoot, where participants tee off at about 1500ft above and 2 miles awaythe hole. I think it’s a par 36 😀

Instead of golf, we’re going to shoot for some QSOs.

I’ll be using my new fangled End Fed Half Wave coupler and some conveniently placed towers. If those don’t work, then I’ll revert to some hamsticks. Stay tuned for more on the antenna project, and the summaryof the activation!

W5MPZ Field Day!

I had the honor of joining the Sandia National Labs Amateur Radio Club’s (W5MPZ) Field Day activities. The team consisted of 20 or so people who sought out this ham radio haven of a campground in the north edge of the Zuni Mountains near Gallup, NM. There was a lot of open space, many places to set up tents, and best of all, tall pine trees to hoist antennas. 

Our station was active for almost 24 hours, minus a lull at about 1:10 am Sunday morning. Our backup arrived at around 2 am, which included Brian (N5ZGT, Rocky Mtn Division Director), who just got back from a Turks and Caicos island vacation (or DXPedition, you might say), and Scott (N5SQR) who worked PSK and SSB.

Setup and Operation 

Beam

Before I arrived, the triband TA-33 beam was set up on poles over a center stake pounded in the ground.  It was rotatable by simply spinning the mast. The guy ropes were left slightly loose so that it’s rotatable, and they spool and tighten around the mast when you rotate it. They tighten just enough to cover the northerly half of the horizon without much added tension.
TA-33 with the 80m windom in the background
The beam was top. It was fun but frustrating to hear a section you haven’t worked on the back side of the beam, run out, turn it, and discover the station disappeared completely. 

Dipoles

The 40-50′ tall Ponderosa Pines were more than adequate antenna masts. Our method of pulling lines over the trees was with a spud gun — a PVC contraption with an air tank, electric valve, and 3′ long barrel which shoots a PVC slug with fishing line attached to it.

On my first shot, I got over this tree and the line sat perfectly on the brown number post.

The perfect shot.
After shooting the line over the tree, we’d tie and pull thin twine to it, then pull heavier rope to attach to the antenna. Repeat for the other side, and hoist away.
Old Glory on our 80/40 trap dipole
We had an 80/40 m resonant trap dipole on one tree, and the other was an 80m Carolina Windom. They were both oriented for maximun E-W reception and did a great job.

RPi camera

 A nifty setup was a motion sensitive camera connected to a Raspberry Pi. It snaps photos when it sees movement, and stores them on an SD card and posts them to our LAN. The router was for the LAN for syncing our logs.

Operation

We were 2A, so we had 2 stations on the air, all supported by batteries. We operated SSB, CW and PSK31.

 

Scott, N5SQR working SSB
After setting up the last dipole, we began calling CQ on a clear frequency a few minutes before Field Day start to secure our spot in chaos. Once it began, signals filled the band but we had an interestingly slow time throughout the day. We shifted operators on the top of the hour, usually having a logger and radio op on each station. We made around 150 QSOs on SSB, CW and PSK31 before sunset.

No field day station is without its problems. We were lucky to only have minor issues, like the logs not syncing or the digital station computer interface not working. These were easily and promptly fixed. Everything else (except for the band conditions) was perfect.

Our ops came from all areas of the hobby. Brian, for example, just got back from Turks & Caicos, and worked hordes of stations from VP5-land, while Seth never worked a contest before being a technician.

Brian and Seth teaming up to send Radiograms for bonus points
Seth taking names and gettign mults on the voice station

Seth quickly caught the Field Day bug and worked the 12-1am shift by storm, and eventually took both working and logging on the voice station on solo.

It was very cool to see him warm up to the air and get excited to work stations. It reminds me of my first Field Day, where I was thrown into the action and started racking up QSOs as fast as any other operator after only having a few hours to figure it out.

Seth also worked PSK31 after showing him the macros. He first though it was going to be too difficult, like CW, but was amazed at how simple it is.
The county sheriff got the call from us to visit the site. He visited on his regular patrol and we explained our operations to him. He was certainly impressed.

A visitation by the local sheriff

  Satellites

The Arrow LEO-SAT yagi and other antennas in the background

Sat Station Setup — FT-817 for RX and an 897 for TX

My job at W5MPZ was to bring a satellite QSO to the log for an extra 100 points. Unfortunately, this didn’t happen.

I had several attempts at SO-51 (the only FM satellite), VO-52, FO-29 and the zombie AO-7 (all SSB/CW transponders). I had most luck with the SSB satellites but had problems in being able to hear myself.

To work the SSB satellites (all but SO-51) you need to know where your signal ends up after it gets translated to the other band. For example, FO-29’s uplink band is 145.8-145.9 MHz, while the downlink is 435.9-436.0 MHz. One would think the 100 kHz passband would be linearly related, e.g. I transmit on 145.85, and hear myself on 435.95, but this isn’t the case. The doppler effect causes the frequency to differ by up to 500 kHz on UHF, so you need a way of calculating doppler, or simply finding yourself.

My technique was to spin a carrier through the passband until I heard it on the downlink, and switch to SSB to call CQ and tune into myself. Upon the switch, I lost myself.

I figured out the solution on the last pass of the weekend. The FT-897 has a feature in SSB mode that allows you to send CW at your tone frequency. So if I’m on 145.000 and have a 700 HZ CW pitch, it would send it at 145.000.70 MHz. Therefore, if you were tuned into 145 MHz on another rig, you’d hear that same pitch. All I had to do was zerobeat on the flipped bandpass, and call away. I finally heard myself repeated by the satellite, but didn’t have any replies within the last 5 minutes of the pass.

It was worth the effort (and in hindsight I should have just worked the ISS’s message system via packet)!

Summary

The underlying point of Field Day (aside from preparedness) is to have fun. W5MPZ did exactly that. Our support team of family members kept us well fed, watered, sheltered, and our batteries charged. One could not ask for a better place to set up and operate from, and the weather (despite being cold in the mornings) was amazing – not having wind and the 100°F temperatures to contend with was a huge relief.

I’m not sure of the final QSO count or score, but we only missed a few sections in Canada – NT, MAR, and ONN I believe — like we expected. Field Day isn’t a contest, so the score isn’t important to me or any of the operators aside from personal club goals and whatnot, so that wasn’t a worry. What matters is the coming together of like-minded people to getaway from the daily grind, have a ton of fun, share stories, and work stations.

Fire, Lightning, Wind and Dust: New Mexico Weather

New Mexico is dry. I was floored when it rained three days ago. But for 11 months out of the year, the air is dry, the sun is bright, the clouds are facetious, and everything’s on fire. 

Smoke plume from the 30,000 acre Silver fire
Smoke fills the horizon

 Such is life in NM. The 10% humidity caused me some pain and suffering for a while, but I seemed to got used to it. I used a lot of normal lotion, which wasn’t the best idea for being out in the sun so much.

Currently, a large chunk of the Gila mountain range is on fire, but thankfully few people live in the area. The Silver fire (named because its near Silver City, NM) is currently at 32,000 acres, making it the biggest fire in the US. From atop a VLA dish, you can see the smoke plume and the long trail of smoke being carried by 30-40 mph surface winds. It’s quite dark in Truth or Consequences.

Aside from the fire, the plains of central New Mexico have a variety of weather, typically involving some kind of dust and lots of wind:

Dust carried aloft by 40 mph winds

We even have tornadoes of dust! (Seriously, some of them are big enough to cause damage):

A particularly strong dust devil with a well defined center column

Then, all of a sudden, it storms:

A snowstorm to the north…it’s a rare event to see precip actually get to the ground.

Above, you see it’s snowing. Snowstorms in the southwest isn’t a myth after all! Just last year, a snowstorm dumped 2′ of snow on Socorro, NM.

Typically though, the air is so dry that any precipitation just evaporates before it hits the ground. This phenomena is called virga, and is the sole reason why the clouds are so facetious. What does hit the ground are tendrils of lightning, graupel — basically mini snowballs from the sky — and hail.

A tendril of lightning betwixt two VLA dishes

In 2004, hail fell with a vengeance:

So its dry, its dusty, windy and usually boring (minus the bits of hail, getting caught in a haboob, and waking up to lightning barrages)…but now is the season for rain. And we’re in dire need. NM has been in a 10 year drout, and wells are drying up like int he community of Magdalena, NM, just east of the VLA.

Locals believe that July 4 is the day which marks the start of the monsoon season…don’t take monsoon to seriously though, it’s not like the monsoons of India and Asia. They may dump 2″ of rain, but that gets sucked up so quickly by the dry, absorbent dust and flora of the mountain ranges that it was like it never happened the next day.

We’ll see what the skies bring.

Don’t play Ingress at Radio Observatories

A few weeks ago, the IPG got some curious email from some ABQ-ians asking if they could play Ingress at the VLA to capture some GPS-based portals. If you’ve never heard of Ingress, think of it as geocaching with a Virtual Reality spin. Check out their website here.

Ingress is played on smart devices, which require data connections to operate. These data connections are fine and dandy unless you’re at the world’s greatest radio observatory; here they aren’t so dandy.

RF-EMS

Below is a screencap of our RF-EMS (Radio Frequency-Environmental Monitoring System) which captured two WiFi access points (the darker blotches) from an RV containing a Verizon 4G hotspot and another router for something else.

Your VLA on WIFI

In the last blog I described the 10′ dish for pinpointing RFI. We also have a (usually) 24/7 monitor that uses some pretty nifty antennas and preamps on a 50′ tower, sending it to an HP 70000 Spectrum Analyzer in a RF-shielded room from which we can record and upload plots like the one above, every day for the past 5+ years. 

RF-EMS Tower and Bunker

The biggest downfall is adequate locating of interfering transmitters. Currently, I’m designing a method which will allow the IPG to quickly and accurately pinpoint people with any kind of transmitter, be it a cell phone, hotspot, or vehicle keyfob (if we wanted to locate such things). My idea is based on multilateriation, which uses multiple receivers around the site which compare arrival times to calculate a four dimensional location. Keeping the bill of materials as low as possible, simplicity, ease-of-use and network integration (without causing RFI itself) a prime focus.

It may be overkill, but it gives me something to do in the free time.

Other Doin’s: Testing out and Debugging the 74 MHz System

When I’m not having free time, this is what I’m doing. A new feature of the Expanded-VLA is observations on the 4 meter band. The current system in place uses these simple crossed dipoles hoisted a few meters below the sub-reflector.

Installing the 74 MHz Crossed Dipoles

The cross dipoles connect to our receiver, which hooks up to the rack that magically digitizes the signal and turns it into pulses of light which the correlator feeds upon.

One of the problems we face are things broken that don’t have to do with our antennas and receivers. For example, the first test we do to examine the receivers performance is a band pass plot. Often times, we see something like this:

A bad bandpass plot caused by a faulty relay in the T301.

This is ugly! What we want to see is this:

A beautiful bandpass! You can see 4 band on the left, and P-band in the middle with RFI spikes all over.

First we go digging in the LO-IF and FE racks for a place to stick a spectrum analyzer to…

Eric the BAMF next to the LOIF and FE rack. Our culprit is on the left, in the middle of the top rack of modules

And from that we figure its’ this T301 which does the first IF up-conversion from 0-1GHz to 1-2GHz.

The faulty module in question

We get a new one, stick it in, turn it on and voila, it’s alive!

    What I’m up to at the VLA

    Back last November I was offered this internship to work for up to 8 months at the Very Large Array, as you see pictured behind this post. The VLA is the worlds most prolific radio observatory, having the most citations in of any radio observatory in all of science. I could not turn this offer down/

    The VLA is a well oiled machine of 27 cassegrain feed parabolic reflectors each 25 meters, or 82 feet wide, that send concentrated RF to massive feedhorns at its vertex. One VLA dish covers all frequencies from 1-50 GHz, and has two extra bands at 74 and 350 MHz using extra antennas. Together, they can make a dish that theoretically measures over 20 miles in diameter!

    Apex of a Dish Showing the Cassegrain Subreflector, 350MHz cross-dipole at the center of it, and the new strut-straddling sleeve-dipoles for 74MHz around the edges being installed

    My primary job at the VLA is to learn. Everything RF exists here, so I’m soaking up as much as I can. I’ve learned more about microwave RF design, Radar, synthetic aperture synthesis, correlation, radio astronomy, antenna design, transmission lines, test equipment, RFI, and much more that I have ever (and perhaps will have ever) at college.

    Learning is a sort of meta-job. What I really do is two-fold.

    The first fold is Interference Protection. The IPG specializes in the detection, location, analysis, and mitigation of radio frequency interference that has the potential of ruining and/or corrupting observations of the radio sky. The VLA is located in a lake bed, 20 miles away from any town, 90 miles from Albuquerque, surrounded by 360° of mountains that buffer the observatory from radar, wifi, cellular, aircraft, and other terrestrial sources of RFI. Satellites are also a source of RFI, so they must be documented and their transmissions well understood so that the VLA Correlator  can learn how to discern orbiting transmitters from galactic transmitters.

    On IPG, we’ve done a few RFI Site Surveys at places like the Magdalena Research Observatory on South Baldy and at the Pie Town VLBA site. Unfortunately, a Verizon 4G LTE cell tower exists on a hill only 5 miles from the center of the array. The signal it produces isn’t bad — it’s the amount of visitors who show up with a full signal, assuming it’s okay to use their smartphones to upload photos, videos, sprout WiFi APs, and cause all kinds of problems. That’s when we break out the CELL PHONE DESTROYER 6000.

    THE CELL PHONE DESTROYER 6000 is nothing more than a 1.8-2.4 GHz feedhorn attached to a spectrum analyzer, which is directly integrated into the neural cortex of this RFI Seeking Unit known only as Mert.

     For quieter RFI, like satellites and terrestrial transmitters, we use a big-ugly 10-foot dish with a wideband conical-log spiral feedhorn to determine bearings to RFI: 

    Along with intentional radiators, unintentional  transmitters like microprocessors, screens, TVs, and other electronics produce noise that can be detrimental to the RF environment. Such electronics need to be tested in the Reverberation Chamber, and shielded if necessary.

    The second fold is Front End — Front end of receivers that is. On the FE group, I’ve been tasked of removing old low-band receivers (74 and 350MHz) and installing new consolidated ones along with about 200 feet of heliax and control cables for them. I’ve also been building and improving antenna designs for the LBRs, including the new strut straddling dipoles pictured above. I’ve come across a cool 74MHz widebanded antenna design that may or may not be patentable, so we’ll see from it’s creator if I can get acknowledged in a paper or something 🙂

    The LBRs are located in the apex, also pictured above. It’s fun becoming a grease monkey while getting a view of the VLA few have seen.

    Such a view

    So how did I get this job? Ham radio of course! My boss actually e-mailed me after an unsuccessful run through career fairs and internship searches for this summer. He noted my experience with the Missouri S&T ARC, W0EEE, as a big kicker on my resume. At S&T I’ve done a lot of work mitigating RFI, fixing repeaters, learning about radio, and having fun with it. He himself is a ham, albeit inactive, but still understands the value a license can have at such a job.

    Ham radio gets jobs! (Girls? No.)

    Today Paul Harden (NA5N) and I will be installing a few new LBRs in antennas 18 and 20. The weather looks beautiful for it too! Check out Paul’s personal website, chock full of receiver data, photos, and the history of the area.

    That’s about the gist of it. 73 for now!


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