Category Archives: Wireless

The Sunset on Lambs Gap

A couple of months ago, I started to notice a few issues when watching YouTube videos at my home.  It seemed that the videos were taking longer to buffer, and a quick check of my Ubiquiti NanoBridge M5 (NMB5-25) revealed my signal had deteriorated from it’s usual -64dBm signal to around -75dBm. The Airmax Quality had also significantly tanked, now reading around 40%. An Airview scan didn’t seem to indicate any new interference:

Airview Before
The Access Point is in use.

Throughput tests to two on-network Mini sites still showed decent rates, but it became obvious that TCP retransmissions were starting to significantly impact surfing the web. Unfortunately, I didn’t think to grab a tcpdump to support that theory.

Before Speedtest
Decent Throughput it would seem

I had been holding off installing the new NanoBeam M5 (NBE-M5-400) since I wanted to ensure they were stable. While I’ve not been burned by the problems with ToughCable or chain burnout problems on the Rocket Titanium M5’s, I’ve heard my fair share of grumbling from people that have. On the Ubiquiti forum people have mostly raved about the new units so I figured I’d see how well it performs.

On the roof of my home, I have a non-penetrating mount atop two anti-fatigue mats purchased from the Home Depot. The mats aren’t UV rated, something I didn’t consider until later. After a yearlong installation, the mats are in surprisingly good shape. I don’t anticipate having to replace them in the next two years based on their current wear.

The Mount.
Carrying 3 of these up a ladder makes you sleepy… that’s why there’s no fourth.

The NanoBridge M5 dish itself was still tightly connected to it’s mast, and the 3 concrete ballasts holding the mount in place seem to prevent any possible shifting.  Initially when my signal deteriorated, I thought a bird may have slammed into the dish or mount and somehow moved it, but I don’t believe this is the case. The more likely culprit is a tree.

Tree Clipping
A view from behind the new NanoBeam — I’m fairly certain I’m clipping the tree on the right.
Hey What's That Picture
Courtesy of – the line to the tower.

I knew when I installed the link that it was very likely clipping the tree on the right. Our tower is slightly to the right of the valley.  Not particularly liking heights and trying to limit visibility from the street, I opted not to move the mount closer to the front of my home.  I may revisit that decision in the future. Before I removed the NanoBridge I did try to correct it’s position but was only able to receive around an average of -70dBm at best.

The NanoBridge M5
This is about where my signal settled.

Losing sunlight, I upgraded the dish to the NanoBeam M5. The only thing about the dish I dislike is that it has one U-bolt instead of two. I’m sure it’s ample but the NanoBridge’s 2 U-bolt configuration really seemed to hold it to the pole so that it couldn’t possibly be knocked out of alignment. My roof is mostly flat with a slight angle, so I wasn’t able to fully straighten the dish.

The Level
Do Not Point the Laser into Someone’s Eyes.

Installing the NanoBeam was quick and easy. The first thing that was obvious was the noise floor had gone from -93dBm to -103dBm. The signal was significantly improved, now running in the -63dBm range, and overall stats were a remarkable improvement over the NanoBridge.

NanoBeam Stats
A bit of a difference


Post Upgrade Speedtests

The week before I performed the upgrade, I finally added the Ubiquiti radio to my home Cacti installation. Forgive the ugly colors of the graphs (I plan of making them more visually appealing one day), but as Adam Savage says “The only difference between screwing around and science is writing it down“.  These graphs display a pretty clean-cut before and after of the upgrade, which took place at about 20:00.

Frequency in Use
I didn’t change frequencies, but here’s a graph.
Mo Memory
The NanoBeam has more memory than the NanoBridge.
Client Connection Quality (not much of a change here)
Signal Graph
The signal is substantially improved.
Data Rates
My data rates improved.

I incorrectly saved the Airmax graph after the upgrade and only noticed the next day (that’s why this graph is hours after the others).

Much better Airmax Quality.

I’m extremely pleased with the upgrade. My initial problems with YouTube buffering have gone away and three days later things are still going strong. In the end I had a chance to see a pretty cool sunset on Lambs Gap.

The Sunset on Lambs Gap

Wireless Iperf Graphing – Part Two

After dusting off the old source for my previous post, I started realizing one of the main limitations to Ubiquiperf — the results aren’t displayed real-time.  If they were, one could easily move radios around and see the impact almost instantly. This got me thinking, and not having worked in Java for a while I knew what to do: Fork JPerf and get to work:

Announcing: UbiquiJPerf
Announcing: UbiquiJPerf

It’s got a long way to go, and comments/suggestions are always welcome. Source (including a pre-compiled .jar) are available at github.

Wireless Iperf Graphing

About a year ago, we were doing some wireless throughput/interference testing at the office  to acclamate ourselves to the wireless world. Most importantly, we were trying to answer the question “Why can’t I just lease a 10 foot section on a tower and  install a zillion radios there?”

Despite having a handful of BCP design documents at hand, as well as input from established and respected members of the wireless community, the question kept seeming to pop up. So how does one present a worthwhile answer?

My solution was to build a small section of a tower leg on our back lot using a non-penetrating roof mount, 2 Ubiquiti Rocket M5 90 5G-20-90 degree sectors (mounted 90 degrees from each other, without shielding), 2 Nanostion M5 CPE’s, 4 laptops, and a couple of inverters and car batteries to power 2 of the laptops (the other 2 were run off extension cables).  The two laptops connected at the Access Point side ran as Iperf servers, each laptop ran as a client.

Plug this in here, that in over there, and this cable.. here.

The thought was to grab Iperf and AirOS datapoints at every couple of seconds  and see “what happens when I do this?” “THIS ” generally entailed doing something BCPs warned against doing.

To gather the Iperf data and AirOS statistics, I put together a quick script i called “Ubiquiperf“. Basically it polls an iperf test every second, pulls the stats off the radio (Capacity, Quality, RSSI, etc) , generates a CSV file of all the data, and finally creates a graph using the jpgraph PHP libraries.

Due to weather conditions our testing was cut short and our initial results had a simple problem: we needed to turn the transmit power down on all the radios.

For a baseline, we performed a quick throughput test one at a time, where each Access Point operating on the same frequency could perform at about 85Mbps:

AP1 Baseline
AP2 Baseline

So what happens if I perform the same throughput test on both units but at the exact same time, over a longer duration?

AP1 concurrent iperf test
AP2 concurrent iperf

Well, it obviously cut off about 20Mbps from the first access point. Of course, the power on the radios really needs to be turned down so this test is unfortunately not worth much. We’ll be doing additional testing in the near future, and hope to have meaningful results that include mounts with and without RF Armor, Titanium model equipment, etc. I’ll publish our results when I can.

In the meantime, feel free to play with it yourself. Full PHP source is available on GitHub.

Back to an old hobby

I’m working more and more with wireless equipment at work these days, and I’ve found that it’s once again sparked my interest in an old hobby – Amatuer Radio.

I worked in commercial radio for eight years, mostly as an on-air entertainer hoping to follow in the footsteps of Johnny Carson and David Letterman. Radio was a perfect outlet for my sense of humor, and the Internet hadn’t yet developed into the “broadcast yourself” state that it is today.

KCMQ Remote Broadcast
Broadcasting Live for KCMQ radio.

In those days my interests were solely in writing and performing, and occasionally when someone asked what I did for a living they would respond, “Oh – I used to be in HAM radio”. The two are completely different beasts. (I left commercial radio in 2004 and doubt that I’ll ever return)

Kenwood TM733a
The Kenwood TM-733A dual-bander

About 3 years ago I purchased my first mobile radio, the Kenwood TM-733a. One of my main motivating factors was the 6-din connector that allows for easy connection to a TNC or computer, and knowing what APRS could do I wanted to explore other forms of packet radio. Like with most hobbies, starting out is a bit expensive. Instead of a proper power supply, I modified an ATX power supply from a computer and purchased a dicone style antenna from Radio Shack and mounted it on my roof.

Radio Shack Dicone Antenna
The perfect antenna when you want to pick up broken elements in your yard.

The antenna elements screw into the main pole of the antenna, and unless glued into place they  come out over time. Overall I would NOT recommend it.

The power supply could never provide enough amperage to power the radio, and the faceplate would dim any time the microphone was keyed. Eventually I lost interest and the radio remained on my shelf unused. Then road construction began outside of work.

Road Construction
Why yes, that is a piece of sewage pipe holding that phone cable out of the way.

In my area of Pennsylvania you thankfully don’t have too many traffic jams. I’ve offset my work hours to miss the morning and evening rush hour traffic, so I’m lucky in most regards. Unfortunately the latest road construction causes me to sit in traffic for 10 minutes while I wait for my turn so that I can make it to the office parking lot.

That’s when I dug out my trusty old BC80-XLT scanner. My intentions were to find what frequency that the traffic flaggers were using, adopt their lingo and occasionally pipe in with a “Uh, yeah… westbound traffic is piling up, let’s let them go.” Instead it led me back to a hobby that I never got to fully enjoy.

Using WXtoIMG and a 2Meter radio, you can download your own satellite images from NOAA satellites (source N3FW)

I’d pulled the dicone antenna off my roof prior to installing my Ubiquiti equipment, and decided a year ago while looking over WXtoImg that if I were to ever build my own antenna it would be a J-pole. Eventually I came across a dual j-pole for sale on Ebay which fit my needs (it supports both bands of my Kenwood – 70cm and 2M).

Dual Jpole
My dual-jpole. As you can see, it needs to be raised a bit higher.

The gang at Freenode #hamradio walked me through a number of options for powering the radio. In the end I settled on a 100 amp hour marine battery from the local Walmart along with a battery box. Going this route I can use my smart battery charger (that otherwise sees no use) and in the future explore solar power options for recharging the battery. I’ve since been informed that a sealed lead battery is much more preferable for indoor use as it doesn’t produce gas when being recharged (and will upgrade to one shortly).

Battery Box
Present: Battery box, powerpoles, Doc Wattson. Missing: Lemon Pledge for dusting.

For monitoring battery consumption I picked up a Doc Wattson meter from PowerWerx. While at it, I also placed an order for Anderson PowerPole connectors – and I’m EXTREMELY impressed with how easy they’ve made connecting and disconnecting power from the radio. For added safety, there is an inline fuse before the battery powerpoles connected to the Doc Wattson.

I’ve made contact with a number of people in the area using various 2M and 70cm repeaters, so my setup is up and functioning. I have mylar capacitors en-route so that I can build an isolated sound-card interface (The Sound Card Buddy) and safely connect my radio to my pc. From there, the gameplan is to find someone in the area interested in communicating via PSK.

FLDigi – the digital modem software.

Why work with PSK? I’m looking for a better understanding of the modulation types used in 802.11n – the so-called “MCS” values.While these modulations are typically automatically agreed upon between access-point and station, are there instances in which a person could say “High fog today, <this modulation type> is actually better than what the AP and station are going to agree upon automatically”?

Each MCS index refers to a specific modulation type, some of which can be generated in FLDigi.

I’d wager that the AP will always negotiate the best scheme, but knowing the properties of each still won’t hurt.

So I’m back to an old hobby, and my timing is good – at the end of this month is a Hamfest in my town. In the future, I anticipate that I’ll be working extensively with fldigi, exploring solar power, and installing a conduit system into my home office. As always, I’ll document my work here at BrainDeadProjects.