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Radio Communications of Charleston, Inc.

Radio Communications of Charleston, Inc.
Your Professional Wireless Solutions Provider

Saturday, April 21, 2012

Towers and their associated pluses and minuses !

Oh well, you now have this new tower site.   And, to add insult to injury, you're expecting it to be the save all or fix all of your communications system.........Yeah....Right !

I've written on this subject previously, so this information isn't new from my perspective.   But, it deserves repeating to those that wish to invest in or have already invested in a "new" tower site.

There are basically three physical characteristics of importance when designing or otherwise using a tower site.   In order to get maximum advantage, one must consider location, height and transmitter power, in that order.

Location ~
   This the most basic of all physical attributes and sometimes the most overlooked.   If your tower isn't near your area of need, why even consider it?   Makes sense doesn't it.   Well, you'd be surprised how many people purchase a tower or decide to use one that just isn't near their area of need.  

Height ~
   Ironically, this parameter is more important than high power output of your transmitter.   It also serves a high purpose in developing better receiver sensitivity.   Both of those needs are very important.   But, you just won't get them until you have some height, adequate height.   It's worth considering what type of antennas you plan to install on the new higher tower at the correct location.   Some antennas are 20ft long or more.....so, you should consider that and how many more of them you plan to install on the tower.   Vertical separation is a must, so just do the measurement math and see what you get.   Keep in mind that the lowest antenna on your tower is your new height.....hmmm.

Power ~
   After the above attributes are available, power is an important issue.   But, I must say, if you have a lot of power and neither of the above attributes, you're sunk.
  2-way radio power for a repeater is typically 100 watts.   So if you want it to perform properly, you will need the first two properties plus the appropriate power output....100 watts.

Tower sites nowadays must have a lot of issues solved in order to be constructed properly and legally.   Like it or not, this mechanism is an environmental issue, at least if you consider the opinions of those that want to protect you from the ferns, birds, swamps, and probably yourself.

So plan for this or you'll never make it in the tower business.   You will never even get the permits to carve out the road thru the woods to get to your prospective tower site.   That's a lot of data for another conversation.

Good luck with your new antenna site...

Till next time, happy radio range.

Saturday, April 7, 2012

PTP and Crooks - Don't get caught in their web.

PTP speeds are growing up.   Those speeds are challenging wired circuits in a big way.   We've seen reliable radio speeds and bandwidths upwards of 600mbs......and growing.

Unfortunately, there are unscrupulous vendors out there that promise the moon and provide something that is amost just good enough.   What do I mean by that?

We all know that PTP links work best using LOS (line of sight) from one point to another.   In some instances PTP works in a deteriorated capacity in NLOS (non-line of sight) situations.

We have witnessed some vendors offering 300mbs in NLOS situations knowing well that speed would not be achieved.   Instead, they elected to argue down the system owner that they didn't need that amount of bandwidth and encouraging them to settle for less.   The customer ends up settling for the lesser amount with some sort of compromise on expense as a method of paying less for less.   In some situations the customer can't check it ..... or even know what they are viewing if they did.

This is a bait and switch routine in its finest form.

Don't get caught settling for less.   If your new PTP doesn't do exactly as expected, yank it out.   There are vendors out there that give you what is expected.   You nust need to hold the line on expectations and you'll get it.   And, remember.......sometimes the cheapest isn't always the best deal.

Till next time.....happy computing (radio-ing ?)

MOTOTRBO operation DMR

MOTOTRBO is real cool.   It is an experience into a greater radio experience and cause us to believe that radio has been "re-invented."   2 slot digital radio, (DMR standard) is starting to become standard knowledge in the radio industry.

I wanted to post a comment on the analog operation of a MOTOTRBO radio.

While using the MOTOTRBO radio in the analog mode I noted a substantial increase in performance even while in the analog mode.   After researching and studying that un-expected benefit for a while, I surmised that the performanc increase was coming from the digital processing of the analog signal.

So,, if you want a better analog radio, with digital operation performance, then get a MOTOTRBO (DMR) radio.   You'll be pleasantly surprised at the un-expected performance characteristics.

Public safety and business are experiencing this benefit today.

Good luck with your radio operation.

Lightning Strike ! (Fact or Fiction ?)

Ok....here we go. 
We have had the warmest winter in years.   And, that signals we will most likely experience more summer weather events such as lightning storms, high temperatures and strange weather.  

The radio business must have their tower sites and antenna systems ready to tolerate a lightning strike experience.   These lightning strikes can be devasting.   And, sometimes we can tolerate those events and sometimes we cannot.   Just why is it that we can sometimes tolerate the lightning strikes?

For those in the know, Motorola's R56 grounding standard brings several, if not most, electrical standards under one compiled document.   This doucment provides guidance for grounding tower sites and their associated equipment to allow for lightning strike tolerance.   Wow, what a document!

I have read that the average lightning strike is 26k amps.   So, using basic electrical math, if one has 5 ohms of resistance in their tower ground system, you could experience 130k volts of electrical potential across equpment in your shelter.    That can and probably will be devasting to most solid state equipment.   Conversely, if you have 1 ohm of resistance it would be possible to develop 26k volts across your ground system.   Even though 26k volts is high, it's a lot smaller than 130k volts.   Either can be harmful to your electronic equipment.

Needless to say, grounding and protecting equipment at a tower site is important.   But, the further point I wish to make is, it's more than important.   You need a great ground and great ground system conductivity....and should have much less than 5 ohms of resistance in your ground system.   Your equipment survival depends upon it.

And, as a last safety comment, don't be at a tower site during an electrical storm.   It could cost your life.

Till next time....keep yourself grounded !

Sunday, November 27, 2011

P25 phase two - TDMA, fate or consequence?

Did you know that phase one of P25 is FDMA and that phase two of P25 is TDMA?   Ironic isn't it.
Motorola's MOTOTRBO radio is 2 slot TDMA now....and really cool.
If you haven't seen one and demo'd one, you're missing out.   Don't buy another radio until you do.
Even more cool is the MOTOTRBO radio when operating with a repeater, or a multi-site repeater system.  It just gets better and better.
Happy Radio-ing...........10-4?
Till next time......

Saturday, March 13, 2010

P25, Who needs it? Myths and common sense things you wanted to know.

Well by now everyone is involved somewhat in getting their radio systems "narrow-banded" and quite possibly could be migrating towards the P25 phas I protocol.   I'm going to assume that you are already familiar with the P25 Phase I Protocol and consideration of that technology is underway.
Well, what's next, you might ask?   What may I realistically expect my radio system to do that it doesn't already do?   Basically, I would imagine you may be looking for cost/benefit points.

In this posting I'm going to get beyond the origin of the protocol and will try to bring some of those cost/benefit things to make sense to every day radio users.

P25 is a major change and isn't compatible with any other protocol directly, even though the radio sporting the protocol may be capable of multiple protocols on the same or different channels.   Radio technicians will really perk up their ears when first testing P25 as it requires a completely different mind set and testing ability.   There are lots of changes.   So on to cost/benefit deals.

1) P25 is a digital protocol that responds to a different distance window therefore changing operational range somewhat.   While the same analog radio is fading to noise, the P25 radio is still corresponding at 100% but will avalanche to non-existence similar to what is shown to the right on the graphical representation.   Basically the user will experience a little better range and clarity while within range.

2) The user will get other nice operational benefits by seeing what radio is talking or what radio is having the emergency.   The radio ID can be either a number or an alias such as "chief" or "officer" or whatever name you can squeeze into the window during programming.   Some users are very skeptical or conservative about implementing this feature.  If implemented P25 programming in Full Alias mode, constant reprogramming may be needed or at least every time someone ebbs and flows into the system.   That can be a real maintenance nightmare.   But, overall, if implemented properly, radio ID represents a great benefit to the users.

3)  Historical documentation of calls received and made are available on some P25 radios via scrolling the display.   This cost/benefit function could have it's purpose.   One could only imagine.

4)   No your battery doesn't last longer because of P25.   You may think so but if it does, that may be a function of the radio.   As a matter of fact, it may last less.   So be prepared for this possible benefit or possible extra baggage coming along with the new P25 radio.

5)   Clarity of audio in high noise environments is a definite plus.   Most if not all P25 radios process their audio via DSP (digital signal processing) and the radio computer makes the audio decision on a bit by bit basis.   This spits out generally better, or more intelligible audio.   Sometimes your radio may sound like it is receiving "star war" signals, but those signals will be more intelligible.  

Well, I could go on with cost/benefits but they fade quickly.  Are you involved in narrow-banding now?   Frequency efficiencies are gained by narrow-banding and that modification to bandwidth protocol is mandated by the Feds with a definite date of conversion.   So, I ask.   When will P25 Phase I be mandated?   This author believes it will be mandated before long, maybe with a long window of implementation, but mandated never-the-less.

What about P25 Phase II?   Aha, another kick in the pants for your radios.   Your radios possibly won't be able to even do Phase II.   How about that for obsolescence and radio upgrade planning.   Just think, the radio you hold in your hand may not be able to do P25 Phase I much less Phase II.........!

Oh well, we gotta sell radios somehow.   This kinda reminds you of the computer industry.   Ironic coincidence.....yep your radio is a computer now.

Till next time......happy computing.

Sunday, February 7, 2010

Tower Sites and their associated expenses

Who even thinks of tower sites anyway?  Most people don't.   But, us in the wireless business know what it takes to get radio signals from one place to the other.   And tower sites play a key role in making things like that happen efficiently.

I was in a county council meeting one evening several years ago and was told that everyone wanted to get more cellular phone coverage out in the rural country.   The conversation continued and I moved us to the subject to tower sites.   You would have thought I was rude or something, the way they reacted to that conversation about towers.   But, from their perspective they just wanted cellular coverage and thought somehow coverage just happened and that nothing really big had to be done.   Cellular coverage was just supposed to "happen."   The consensus among the audience seemed to be that we all drive around with telephone connections plugged into our automobile tail pipes and that any additional thoughts about how the radio signal gets there are discounted.   A lot was said about "visual pollution" and "I don't want that thing in my back yard" and other stuff like that.   Well, no one wants towers in their back yard, but everyone wants cellular coverage.   Mobile radio & cellular service engineering, necessitates that something must give in order to achieve everyones needs.
A little later the conversation lead to satellite coverage and why couldn't we just use those ominous things floating around in space for everything wireless.   Boy, that's a whole new conversation there for sure.
To put some wraps on this thought process I once heard from a truck driver that if you eat it, wear it or otherwise use it, a truck brought it.   That makes sense and is believable once you think about it.   Well, to further that thought towards our topic, if you talk on it, look at it or otherwise use it via wireless, a tower brought it to you.   That's right, somewhere in the path a tower probably brought it to you.   That's not to mean that towers are the only things wireless or comprise all the support you have.   But, they are important, very important.
We'll get into more details later when we shall discuss some of the mechanics of vertical real estate......towers
Until later.........

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As a woodworker I'm always looking for interesting and unique wood working projects. Also, I love catching fish and watching the wildlife of the ocean while in the Fish Whisperer off shore.