Tower Climber Harnesses

Recently there has been a thread on WISP-Talk about the best tower harness. Rather than going down the road of the best brand I figured I would take a different approach.  I sat down with Lee and Nick from TowerOne Inc. at WISPAPALOOZA 2017 in Las Vegas.

I asked them what they look for in a good harness and here were their top features.

Both said weight was very important.  This makes sense because you will be spending long amounts of time with the harness attached to you. Another feature was the ability to customize the fit.  Belts with synch type adjustments tend to be more comfortable than belt buckles with holes every 1 inch.

Attachment and gear hooks came in next as a must-have feature. Breathability of the material was another one.  After a hot day on the tower, the ability to whisk away as much sweat as possible is vital to be as comfortable as you can.

TowerOne usually brings several different types of harnesses with them to their training events.  This way folks can try things on.  One that has been discovered is people tend to make how the harness is put on an important decision when buying a harness. Some like to put their harness on like a vest.  Others like stepping into the harness and then pulling it up.

So no matter what harness you go with, look into what feature are important to you and how it feels.

Antenna Interference issues

Recently, we had a client question why we didn’t mount antennas higher up on a tower with an FM repeater on it. The top of the tower has an FM repeater on it so we mounted the equipment about 25 feet below that.

When you are talking about antennas and transmitters the basic thing to remember is it’s all radiation.   Good antennas have predictable drop off patterns and, when paired with a good transmitter, have crisp frequency drop offs.  However, there is still radiation emitting from feedline and the antenna on the tower. Many FM repeaters use a dipole design.  Some are folded, others are different types.  Below is an antenna pattern from a Dipole antenna.

As you can see there are a few patterns radiating from the antenna.  These patterns should be taken into consideration when mounting your equipment near FM, UHF, or VHF systems. Radiation may interfere with things such as your cat-5, or your PIM.  In an earlier article, I talk about low-pim cables and what affects PIM.  This is very important when you are deploying LTE gear.  RF radiation from high power transmitters can cause PIM issues if the wavelength happens to coincide with the wavelength of the other transmitter.  This does not mean they are on the same frequency.  Remember, in RF you have full wave, 3/4,1/2, and 1/4 wavelengths to deal with.

Other things to consider are near and far field patterns.  If you want some heavy reading you can read about it on Wikipedia.

Our next issue and the most common issue is the radiation getting into our Ethernet cables as well as our radios on the tower.  Below illustrates the propagation of signals coming out of an antenna on the top of the tower.  If you notice, some of the radiation is directed underneath of the antenna. Any equipment mounted too close underneath will be bombarded with radiation.

Too much radiation can cause link negotiation issues,  signal degradation,  and other issues.  By moving our antennas out of the patterns of other antennas we can make for a more reliable system.  This is one case where higher on the tower is not always better. Just because another antenna is not mounted in front of another it does not mean they are in each other’s radiated patterns.

DOL-OSHA and FCC release Communications tower best practices

The Occupational Safety and Health Administration and the Federal Communications Commission are concerned about the risks faced by employees in the communication tower industry. Employees climb communication towers to perform construction and maintenance activities and face numerous hazards, including fall hazards, hazards associated with structural collapses and improper rigging and hoisting practices, and “struck-by” hazards.

You can read the safety document here.

 

The Importance of cable support in LTE deployments

As the number of WISP LTE deployments increase, there are many things WISPs will need to be mindful of.  One such item is properly supporting antenna cables. LTE systems are more sensitive to cable issues.  In a previous blog post, I talked about pim and low-pim cables.   One of the things that can cause low pim is improperly mated cables.  If cables are not supported they can become loose over time.  Vibration from equipment or even the wind can loosen connections.

How do we support cables?
We can take a cue from the cellular industry. The following are some examples of proper cable support.  Thanks to Joshua Powell for these pics.

Where can you get these?
A good place to start are sites like sitepro1 or Tessco has a selection.

So the next time you are planning your LTE deployment think about cable support.

WISPS growing up in the tower industry Part 1

As more and more Wireless ISPs (WISPS) get into licensed microwaves, bigger antennas, and fiber up the tower (FUTT) they are getting into an arena typically reserved just for the Cellular and broadcast folks.  This can result in an overwhelming amount of things to deal with.

If you are renting space on a commercial tower managed by a regional or national company such as American Tower (ATC) you will run into things like application fees, engineering studies, and closeout documents to just name a few. Once you have your notice to proceed (NTP), the real work begins.

During your negotiation phase, and in your contract, you should have a center line on the tower.  This states the center line on the tower where your equipment is mounted.  An example is if your centerline states 200, on most contracts that means you have something like 5 feet above that and 5 feet below that.  Think of it as a window.  You have a window of 195-205′ on the tower for your equipment to fit in.

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Centerline example. Photo courtesy of Michael Pelsor

The equipment you put on the tower was specified in the engineering phase of the paperwork.  Model numbers of mounts, antenna models, and all that are decided before the first piece of equipment is ever put on the tower. This is very important to adhere to because many tower companies will require a closeout procedure.  This normally includes pictures of your equipment and how it’s mounted, pictures of what is called a tape drop, and other things.

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Tape Drop Pic courtesy of Michael Pelsor

The sheer amount of things to think about on a commercial tower with multiple tenants could extend this blog post on for a long time. But, one of the biggest things to consider is when you are installing how your cable runs, antennas, etc. are in relationship to other equipment.  Are your cables somewhere they might be stepped on by someone passing your equipment to get to theirs? Does your equipment cross mounts which may be removed later or modified?

In the second part of this series we will talk about some of the higher-end tools which may save you tons of time, thus paying for themselves rather quickly.

Towers and pricing

One of the more common questions is what does a tower cost me to put up? As many of you know this can vary quite a bit.  We are going to approach this from a single vendor perspective.  What this means is I am going to take what it would cost to buy a commercially available tower from Texas Towers and put it in the air.

Disclaimers
1.I am not endorsing Texas Towers nor am I affiliated with them. They are one of the few tower manufacturers who publish prices.
2.Consumable costs will vary depending on where you are, time of year, state regulations, and maybe even the cycle of the moon.
3.This is geared toward small deployments.
4.Pricing is based upon the information I had available at time of this writing.

  • Texas towers makes a self supporting 100 foot tower (Model HD8-100).  This tower is rated to support 7.4 square feet of load in 110MPH winds. Cost $4,409.
  • The base which goes in the ground costs $225
  • Freight costs vary
  • Concrete. The base for this tower requires 6 cubic yards of concrete. Pricing near me is $95 per yard plus a $30 delivery fee with a 3 yard minimum.
  • If you are doing the 100 foot tower a small 80-100 foot crane can put this up.  The tower weighs around 500 pounds so a small crane is sufficient.  In my area a crane this size would be around $400 for a half day.  Since it’s not a huge crane it doesn’t require special permits in indiana
  • Engineering Fees for the base run around $1000.

So total cost for the tower: $5734 plus freight.

There are some other factors to consider. Permitting, labor to assemble tower, standoffs, etc. But this gives you a good ballpark estimate.