September 2008

VHF Two Way Radio

The VHF radio band for a commercial VHF two way radio is between 130 – 174 MHz. FM radio, two-way radios, and television broadcasts operate in this VHF range.

Both UHF and VHF radios are prone to line of sight factors, but VHF a little more so. The radio waves make it through trees and rugged landscapes, but not as well as UHF frequencies do. However, if a VHF wave and a UHF wave were transmitted over an area without barriers, the VHF wave would travel almost twice as far. This makes VHF easier to broadcast over a long range. Since VHF frequency waves are bigger, a VHF antenna must also be bigger.

If you are working mostly outdoors, a VHF radio is probably the best choice, especially if you are using a base station radio indoors and you add the external antenna. The higher you can place the antenna, the further you can transmit and receive. One exception to using a VHF radio outdoors is if you are using it in a heavily wooded area. Under these conditions a UHF radio may be able to transmit better though the trees.

VHF radios also have a smaller number of available frequencies. Interference with other radios could be more likely to be a problem. However, the FCC recently made this less of a problem when they opened up the MURS frequencies. The 150 MHz frequency is a Citizens Band radio spectrum that is called the MURS service. MURS stands for Multi-Use Radio Service. This service is for use in the United States and Canada. It is a low power, short range service in the VHF 150 MHz Citizens Band radio spectrum. There are 5 channels in the MURS frequencies with 38 privacy codes under each one that enable you to only pick up conversations from radios transmitting your code. The FCC does not require users of products for MURS to be licensed.

With MURS you can add a larger or external antenna to improve range. If you want to put an antenna on top of your building or a tower, you can do it with MURS. Some antenna manufacturers claim an external antenna can increase the effective radiated power of a transmitter by a factor of 4. These MURS intercoms can transmit up to four miles, and perhaps more with an external antenna depending on the terrain.

One benefit of VHF wireless radios is that battery life is almost always better than for similar UHF units. For handheld radios this is a plus.

In summary, if you are planning on using your two-way radios mainly inside buildings, then UHF is likely the best solution for you, but it in lots of applications VHF could still work fine. If you are mainly using your two-way radios for communication outside, then VHF would be a good choice, unless the area you are covering is heavily wooded. Either radio technology can work for you if you don’t really have a long range to cover. There are also repeaters you can install that relay a UHF signal. We’ll talk about those in the Accessories section.

For an excellent, free resource on VHF two way radios, click on this link: two way radio review

There is also an article about UHF Versus VHF by clicking the link in this sentence.

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Use Wireless Callboxes for ADA Compliance

No matter what industry you are in the American Disabilities Act (ADA) likely has some impact on your business. Accessibility by wheelchairs is one of the more common modifications made.

If you have a business that has two public entrances, in most cases, only one must be accessible. When one entrance is not accessible and another entrance is accessible, a sign must provide direction to the accessible entrance. The alternative entrance must be open during store hours.

If the alternative accessible entrance remains locked due to security concerns, you must provide an accessible way for notifying staff to open the door. A wireless callbox provides a good way to alert staff provided it is located on an accessible route and mounted at an accessible height (generally not more than 48 inches above ground). See this article for more detailed info: ADA Intercom Mounting Requirements

To assist businesses with complying with the ADA, Section 44 of the IRS Code allows a tax credit for small businesses and Section 190 of the IRS Code allows a tax deduction for all businesses. The tax credit is available to businesses that have total revenues of $1,000,000 or less in the previous tax year or 30 or fewer full-time employees. This credit can cover 50% of the eligible access expenditures in a year up to $10,250 (maximum credit of $5000). The tax credit can be used to offset the cost of undertaking barrier removal and alterations to improve accessibility; providing accessible formats such as Braille, large print and audio tape; making available a sign language interpreter or a reader for customers or employees, and for purchasing certain adaptive equipment. The tax deduction is available to all businesses with a maximum deduction of $15,000 per year. The tax deduction can be claimed for expenses incurred in barrier removal and alterations.

Purchasing wireless callbox equipment could be tax deductible, but you will want to seek advice from a tax accountant on this.

The MURS Callbox XT Outdoor Intercom is a good choice for this application since it does not require getting an FCC license and it can communicate directly with two way radios or base station intercoms.

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Two Way Radio Frequencies

Understanding Two Way Radio Frequencies

There are two major formats for two-way radios.They are Ultra High Frequency (UHF) radio and Very High Frequency (VHF) radio. Neither frequency band is inherently better than the other.They each have their pluses and minuses. Both formats are effective ways to communicate with another person so deciding on the right radio for you depends on your application.

Two-way radios communicate with each other through use of radio waves. Radio waves have different frequencies, and by tuning a radio receiver to a specific frequency you can pick up a specific signal.

Radio waves are transmitted as a series of cycles, one after the other. You will always see the “Hz” abbreviation used to indicate the frequency of a radio. Hertz is equal to one cycle per second.

Radio waves are measured by kilohertz(kHz), which is equal to 1000 cycles per second, or megahertz (MHz), which is equal to 1,000,000 cycles per second–or 1000 kHz. The relationship between these units is like this: 1,000,000 Hertz = 1000 kilohertz = 1 megahertz.

You may also hear the term “wavelength” when you hear about radio waves. This term is from the early days of radio when frequencies were measured in terms of the distance between the peaks of two consecutive cycles of a radio wave instead of the number of cycles per second. Lower frequencies produce a longer wavelength.

While wavelength measures distance between the peaks of cycles, frequency refers to how long the measured time is between the “crest” and “trough” of a wave arriving at the source. So frequency measures time instead of distance, but they are essentially both saying the same thing.

What is significant about wavelength for two-way radios is that it affects transmission range under certain conditions. A longer wavelength as a general rule lets a radio signal travel a greater distance.

Lower frequencies or wavelengths have greater penetrating power. That’s one of the reasons they are used for communicating with submarines. VLF radio waves (3–30 kHz) can penetrate sea water to a depth of approximately 20 meters. So a submarine at shallow depth can use these frequencies.

So from what you read above you may think VHF is always the better choice for a two-way radio no matter where you are using it. That’s not necessarily true. Even though VHF has better penetrating capabilities, that doesn’t necessarily make it the better choice for buildings. Remember the conversation about wavelength above?Wavelength has a big impact on transmission.

To explain this let’s assume we are communicating from one side of a commercial building to the other. In between these two points is a metal wall with a three foot door in it. Metal is an enemy to radio waves and they typically don’t pass through it.

For our example let’s assume that the UHF wavelength the radio uses is about a foot and a half long and a similar VHF radio is around five feet long. These are in the ballpark of their normal wavelengths.

When the UHF transmits its signal the foot and a half long wave will pass through the door since the door is wider than the wavelength. The VHF signal will be totally reflected since it is wider than the opening to the door.

Your microwave oven is an example of this. The glass front door has a metal mesh with very small holes. Microwaves being a very high frequency have wavelengths that are only several inches long. The mesh keeps the microwaves trapped in the oven but it allows you to see inside because light waves have a microscopic wavelength.

Just imagine walking through the building carrying a five foot wide pole. You will encounter the same challenges a VHF signal encounters. Now imagine walking through the building with a pole that’s only a foot and a half wide like a UHF wave. There are lots fewer doorways you couldn’t get through.

The one difference is that wireless signals will penetrate through drywall, masonry, human bodies, furniture, wall paneling, and other solid objects. All these objects will reduce the signal strength though. The more dense the object, the more it reduces the signal. VHF will penetrate these obstacles better than UHF, but that doesn’t necessarily mean that VHF is better for indoor applications as we will talk about in the UHF section below.

In our example above we assumed you had a metal wall with an opening. If you reverse this and you have a three foot metal object in front of the transmitting radio, then VHF would win. Since the object is three foot wide it will totally block the UHF signal whereas the VHF signal will get around it. Lower frequencies such as VHF diffract around large smooth obstacles more easily, and they also travel more easily through brick and stone.

For most applications, lower radio frequencies are better for longer range. A broadcasting TV station illustrates this. A typical VHF station operates at about 100,000 watts and has a coverage radius range of about 60 miles. A UHF station with a 60-mile coverage radius requires transmitting at 3,000,000 watts.

So there is no clear choice for which is better, VHF or UHF. There is a lot of “black magic” to radio technology so it’s not always easy to tell which will work better for your application. To help you decide on the best technology for you, more detail about each one is included below.

To find out more about two way radio frequencies, go to the following address for the free book called Two-Way Radio Success: How to Choose Two-Way Radios,Commercial Intercoms, and Other Wireless Communication Devices For Your Business.

http://www.wirelessintercomsonline.com/downloads/freebook.htm

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Reduce Employee Cell Phone Usage With Two-Way Radios

When economic conditions get tight and businesses look for ways to cut back on costs, everything gets looked at for opportunities.

One expense cutting measure is to use two-way radios for business campus usage instead of cell phones. The per minute charges on cell phones can add up quickly on long conversations between two people who aren’t even that far apart.

Two-way radios have some other advantages too such as no waiting for connect times, broadcasting messages to groups, reachability in natural disasters even when the cell phone network is jammed,  mil-spec durability, and the emergency call (man down) feature.

Go to the following address for the free book called Two-Way Radio Success: How to Choose Two-Way Radios,Commercial Intercoms, and Other Wireless Communication Devices For Your Business.

http://www.wirelessintercomsonline.com/downloads/freebook.htm

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Best Two Way Radio

Choosing the best two way radio out of all the two way radios available can be a daunting task. Fortunately there is a free resource that will help choose the best two way radio for your application.

The book is called Two-Way Radio Success: How to Choose Two-Way Radios, Commercial Intercoms, and Other Wireless Communication Devices for Your Business.Best two way radio guide

The book covers all aspects of walkie talkie type radios including frequencies used, accessories, applications, batteries, antennas. channels, licensing, features, and everything you need to know to pick the best radio for you.

You can download the best two-way radio book at the following address: http://www.wirelessintercomsonline.com/downloads/freebook.htm

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Employee Safety in Parking Lots

Most businesses do a pretty good job of ensuring the safety of their employees within the walls of their business. But what is often neglected in employee safety in parking lots. Parking lots can be prone to accidents and other incidents.

One way to improve parking lot safety is to install wireless callboxes in parking lots so wireless callboxemployees can call for assistance.

If an employee’s car won’t start they can use the callbox to call for jump starting. If a woman notices a van with tinted or no windows parked next to her car, which is a tool sexual predators use, then she can use the callbox to call for an escort. If an accident occurs employees can call for help.

The MURS Callbox XT Outdoor Intercom works well for this application. It can be battery, solar, or AC powered. With a push of a button an employee can reach your security personnel who are on a two way radio or base station intercom.

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Small “Green House” Nursing Homes Use Intercoms to Talk to Elderly

There is a new type of nursing home that is being called the “Green House” nursing home. These are residences for 6 to 10 elders who require skilled nursing care, but who don’t want to live in a large, traditional nursing home.

A Green House nursing home has private bedrooms and bathrooms, a residential-style kitchen, and communal dining and sitting areas. Just like traditional nursing homes, they are staffed with the same staff that includes physicians, nurses, social workers, dietitians, and therapy personnel.

Research suggests that residents of small nursing homes appear better satisfied and report a better quality of life than do residents of traditional large nursing homes.

Most of the newly developed green house nursing homes are pre-wired with intercoms or call buttons.  However there are times where a wireless intercom system is needed. In houses that have been retrofitted to act as a nursing home, installing a wired system may be cost prohibitive. Also a wired system typically requires a resident to go to where the intercom is located to make a call. With a portable wireless unit, they can put it where they are.

The main deficiency of these wireless intercoms is that there are a limited number of channels available so if multiple units are on the same channel, any message will be broadcast to all units on the same channel. Units like the WireFree Portable 900MHz Wireless Intercom System set up a private conversation between two intercoms when someone responds to a broadcast.

While a wired intercom system may not fit all the needs of a green house nursing home, there are applications where it works very well. Click here

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Office Building Evacuation Plan

A business needs a safety plan and part of that plan is the office building evacuation plan. If a fire, bomb threat, chemical spill, or some natural disaster occurs that requires everyone to get out of the building, then each person should go to an external checkpoint where a safety coordinator can log that person’s safe arrival.

In the chaos that occurs during an evacuation, there needs to be a way for the safety coordinators to let appropriate personnel know if a person is missing.

The MURS Callbox XT Outdoor Intercom is the perfect device for this application. The Callbox enableOffice Building Evacuation Callboxs the coordinators to press a button to instantly notify security personnel who are carrying two-way radios that receive calls from the Callboxes. Unlike using cell phones for this application, there is no delay in dialing, no worry about finding the phone number to call, or no worry about not having a cell phone at all.

You could also install a wireless PA system at each external checkpoint so security personnel can make announcements to each group.

Especially for a large campus environment implementing a system like this is the best way to ensure that everyone gets out of the building safely. But no matter what the size of the company, effective communication during an emergency is key to saving lives.

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Video Intercom Records Full Motion Video

One of the most popular video intercoms on the market not only lets you see who is at the door, it also records a short video clip to an internal memory card.  You can use the Expandable Recording Color Video Intercom System to safely identify visitors even before answering. When someone rings the doorbell, the system sends live audio and video to the indoor 4-inch, full-color monitor. You simply press a button and you can then speak hands free.

This intercom is also the first video intercom in the industry to offer a full motion Video and Audio clip recording on a removable Secure Digital card. Video clips are viewed and archived on any PC or MAC. Chances are if someone breaks in to your home or business, they’ll ring the doorbell to make sure no one is there (and pretend they’re selling something if you are). You’ll have a nice video to show the police!

This system even has a night vision mode to accommodate any lighting environment. A built-in infrared system provides supplemental lighting to enhance night viewing. The door phone camera operates in color during daylight and black & white in low lighting conditions.

For the visitor, this unit in no more difficult to use than a normal doorbell (and the button is still lighted). The unit is not only convenient to use but also designed to provide an additional measure of security. For business/commercial applications where access control is a concern, the system safeguards the entrance while remaining user-friendly to guests.

You can even add an external electric door lock to open the door from the indoor monitor and the door status indicator tells you when the lock is open!

The attractive design of the hands-free intercom system is not only functional, but is also a stylish addition to any décor. Installation is a quick and easy.

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Light-Duty versus Heavy-Duty Wireless Intercom

Heavy duty wireless intercomThere are two styles of MURS wireless intercom base stations you can choose from. The MURS Multi-Mile Intercom is a light-duty, less featured intercom. The MURS Commercial Intercom is a heavy-duty fully featured intercom. There is a big difference in price so you’ll want to make sure you choose the right one for you.

Both units will achieve a similar range and they can both take an external antenna to improve range. They both have all 5 of the MURS channels. For basic communication you could choose either radio.

Light Duty Intercom

The only advantage the MURS Multi-Mile intercom has other than price is the fact that it integrates with a long-range motion sensor (MURS Base and MURS Alert Kit ) and that sensor can activate relay contacts on the back of the intercom. These contacts can be used to activate lights, cameras, or other electronic devices.

The MURS Commercial Intercom has several advantages over the MURS Multi-Mile. For starters the audio quality is better. The speaker has a richer, more full sound. Not that the MURS 4 Mile Range sounds bad, but the MURS Commercial is just a little more hi-fi sounding.

Here are some other advantages of the MURS Commercial Intercom:

  • Ability to wall mount (the MURS Multi-Mile can not)
  • Enclosed in a tough metal housing instead of plastic
  • Audio output and microphone input jacks so you can use external speakers
    and headsets
  • Channel Scanning so you can monitor multiple channels at once
  • NOAA weather radio capability for weather reports or for automatic
    alerts of storms
  • Programmable softkey that can be used for weather radio, gate opening,
    or for activating other devices that use 2-tone decode. Programmable on a
    per channel basis

So if all you need is plain voice communications and the environment you are putting the intercom in isn’t too harsh, then the MUR S Multi-Mile  Intercom would be sufficient. If you need a really tough intercom with some features, then the MURS Commercial Intercom is for you.

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