October 2008

Security Gate Control Wireless Intercom

If you have a motorized security gate that you want to control wirelessly from a remote location, a wireless intercom with a gate control relay is one way to do it. Not only can you control the security gate, you can also talk to the people at the gate before you let them in.Security gate control

You can get a heavy duty outdoor wireless intercom or Callbox that you install at the gate. When people press its button it sounds a tone on a handheld two-way radio or wireless base station intercom. You can then press a button that activates a relay, which opens the gate or performs some other action. These Callboxes can work up to a mile or more away.

This Callbox has a switch output that can be used to open or close a gate, turn on a light, sound an alarm, or any application where remote control of an On/Off switch is required. The switch can be programmed to operate in several ways:

  • On/Off Code: The switch will close when a preprogrammed code is received, and open when it is received again. The switch will also open by itself when the Callbox’s preprogrammed Automatic Turn Off feature is activated.
  • Switch On When Called: The switch closes when the callbox first receives the call and it remains on until its Talk button is pressed, or a programmable timer expires (1-255 seconds).
  • Switch On When Callbox In Use: The switch will close when the Callbox first sends or receives a call and remains closed until a preprogrammed timer expires.
  • Switch On When Active Includes Turn-Off Code: Switch closes when the Callbox sends or receives a call with the added ability to open the switch when the Callbox receives a preprogrammed code.
  • Momentary Close: Switch will close for 1-255 seconds when a preprogrammed code is received.
  • Alternate Open and Close: Switch will toggle between open and closed when it receives a preprogrammed code. The Callbox transmits a single beep when open and a double beep when closed.

The MURS Callbox with Gate Relay also has a Sensor Input that allows it to also operate as a motion, gate entry, tamper or vehicle detection device. It will send a tone alert when optional switch/sensor status changes. The Callbox will send a warning tone when a change in the Sensor Input is detected. The Sensor Input will respond to an OPEN or CLOSED switch.

You can get these wireless outdoor intercoms that work in FCC licensed UHF or VHF frequencies or on the unlicensed MURS frequencies. See the free book called Two-Way Radio Success: How to Choose Two-Way Radios, Commercial Intercoms, and Other Wireless Communication Devices for Your Business for more information about MURS and these security gate control wireless intercoms.

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Commercial Intercom System

A commercial intercom system could be either wired or wireless. They are usually a little more industrial in appearance and built a little tougher for the harsher environments commercial intercoms find themselves in.

Wired Intercom SystemA wired commercial intercom system is usually used for a specific application like monitoring an outside entrance door. The days where an intercom is put on every desk are long gone. These intercoms have been replaced by telephone systems for this application.

The majority of commercial intercom applications are wireless. The labor cost of running wires is often too high, plus the mobility offered by wireless is often a plus.Wireless intercom

The benefit of a wireless commercial intercom or door phone system is that the installation is greatly simplified for existing buildings. Fishing wire through existing walls and ceilings can be a challenging proposition, and is not something most businesses want to spend their money on. Most commercial wireless systems are plug and play…meaning you can use them almost immediately after taking them out of the box.

The downside of the ease of installation for wireless systems is possible interference from other wireless devices. Before adding wireless intercom systems to an installation you must consider what other wireless devices are being used in the area such as radio data networks, other two way radios, and other wireless devices. Usually you can find a wireless intercom that will work for you.

Some commercial intercom systems use two way radio technology. In fact, you can get base station intercoms that communicate directly with handheld two way radios. These units are available in UHF and VHF frequencies that generally require an FCC license to operate. However, there are intercom units in the newly created MURS frequencies that are unlicensed. These MURS Radios let you communicate over long range of up to a mile or more.

If you need an outdoor commercial intercom you’ll find that these are called “call boxes.” These wireless call boxes are essentially two way radios placed in a waterproof housing. To use them you simply press a button on the front and you are able to speak to someone on a handheld two way radio or wireless intercom. Some of these wireless callboxes have a gate opening relay so you can remotely unlock a gate.

So if you have a business application with communication needs that a traditional telephone system can’t handle, that’s when you need to look for a commercial intercom system.

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Wireless Callbox With Voice Recording Playback

A wireless call box can be used for any application where you need an an outdoor communication device that people can use to contact you on your wireless intercom or two way radio. These callboxes have a range that’s measured in miles, not feet so they can be a long distance away from you.wireless callbox

One version of these callboxes can sound and send recorded voice messages. These pre-recorded voice messages notify other intercoms and two-way radios when specific events occur. These voice messages are recorded and stored on the callbox, and automatically played back when the associated event occurs.

There can be a total of 5 event messages as follows:

  • Greeting Message: This message plays when a user presses the Talk button on the Callbox. You can use it to record instructions for the user to follow such as “Welcome to our facility. An attendant will be with you shortly.
  • Identification (ID) Message: The ID message is transmitted automatically when the Talk button is first pressed.  This message identifies which Callbox has been activated. A typical message might be, “South delivery entrance” or “Main Gate.” The message will be retransmitted every time the Callbox is pressed until it is answered. If the Greeting Message is used, the ID message is transmitted after the greeting is played. The ID message can be periodically until the Callbox is answered. It is also sent ahead ahead of a Sensor Detect or Low Battery/Power Fail messages.
  • Low Battery/Power Fail Message: This message is automatically transmitted when low voltage is detected on the Callbox. The message may say something like “Power failure” or “Low Battery.” The ID Message is sent immediately before this message.
  • Sensor Detect On Message: This message is automatically transmitted when a switch attached to the Sensor Input is closed. A typical message may be something like, “Door opened,” “Motion detected,” or “Vehicle present.” The ID Message is sent immediately before this message. A typical message may be something like, “Main Gate,” Vehicle present.
  • Sensor Detect Off Message: This message is automatically transmitted when a switch attached to the Sensor Input is opened. A typical message may be something like, “Door opened,” “Motion detected,” or “Vehicle present.” The ID Message is sent immediately before this message.

Click on the link in the first paragraph to learn more about how a wireless callbox can help you. You can also visit www.IntercomsOnline.com to see these wireless call boxes.

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Rechargeable Two Way Radio

A rechargeable two way radio lets you plug in to AC power after using the radio instead of having to throw away batteries whenever the radio’s charge is low. Following are some things to consider when looking for a rechargeable two way radio.

Batteries

Some two-way radios take standard AA batteries that allow you to use rechargeable batteries, but in event of a long power outage, you can use off the shelf AA batteries when your rechargeable batteries die. Other radios use a custom size battery. For these you can purchase spare batteries that you can have charged and ready to go in the event your primary battery charge runs out. Two-way radios come with a charger unit to keep the primary batteries charged, and in the case of custom batteries, they usually include a slot for the backup battery too.

There are three types of batteries that are typically used for rechargeable two-way radios: nickel cadmium (NiCAD), nickel metal hydride (NiMH), and lithium ion (LiION). You can’t typically choose the type of battery you use for most two-way radios. The manufacturer does that for you. Following are some of the advantages and disadvantages of each type.


Advantages


Disadvantages



NiCAD
Good at low temperatures, resistant to overcharging, long life expectancy, low cost. Larger and heavier, memory effect reduces effectiveness if not fully
discharged,

NiMH
No memory effect, lighter than NiCAD Shorter life expectancy, special charger required to limit overcharging.


LiION
HTML clipboardFast charging, no memory effect, slow loss of charge when not in use, lighter than other batteries. Higher cost, after a number of maximum number of charges they no longer accept a charge (typically 500 to 1000).

Drop-In Charger

Some two way radios simply have an AC adapter that plugs in the phone which recharges its battery. Other radios have a drop-in recharger cradle that lets you neatly store the unit, plus they allow for charging a backup battery as well. That way if you run out of charge on one battery you simply swap it out for the charged one.

Multi-Charging Units
While each radio comes with its own recharging unit, the higher quality radios have multi-unit chargers available that enable you to have up to six radios charging at one time. If you are keeping the radios all in one place, the advantage of this is that you don’t have to use a large outlet strip to plug in multiple AC transformers for each radio.

Depending on the type of rechargable two way radio you choose you may not be given the choice of some of the above options, but if you look around, you can find the radio that best suits your application.

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Emergency Call Box

There are several types of Emergency Call Boxes. The most familiar are the emergency call boxes you see along side the highways in some states. These callboxes usually have a phone-type handset and they tie into some sort of central emergency assistance command center either through wires or a wireless link.

Another type of call box just has a push button and it allows the user to speak into it without holding a handset. These too may be wired or wireless. This article discusses the type of wireless call boxes without a handset.emergency call box

When someone presses a button on a wireless Emergency Call Box it transmits an alert tone to a two way radio or wireless base station intercom. Right after the sent alert tone this person can also speak a message. Whoever receives the tone and message can then respond by pressing the Talk button on their wireless device. A conversation can then be held between the two parties.

The benefit of an emergency wireless callbox is that you save money by not having to do trenching and running expensive cable to the unit. You also don’t have to pay any air-time or telephone service fees with these wireless systems. As mentioned, another benefit is that since the unit is wireless, people monitoring the units can carry handheld radios that communicate with the callbox. That allows your monitoring people to be mobile.

The range of these units is several miles, which can be extended by adding an external antenna. Some units can use radio repeaters to extend this range even more.

If you have existing two-way business radios, you’ll want a system that can integrate with them. Some emergency callboxes can be programmed to be compatible with virtually any brand of VHF or UHF business band radio.

You can get call boxes that require an FCC license, or you can get units that are certified for use on special FCC License-Free MURS Business Frequencies. If you choose a licensed version, the license is usually not too difficult or expensive to obtain.

If no AC power is available, then choose a system that lets you use battery or AC power. You can also get units that have optional solar power so that they can run for several days on a single day of sunshine.

If you need to remotely control gates, magnetic door locks, or barrier arms from your portable 2-way radio or desktop base station intercom, then select a unit that has this capability. With this ability you can let someone in a gate or door when they call you. There are units that also let you turn on a strobe light at the callbox location to help draw attention to it.

Another useful feature is the ability for call boxes to store a voice message that is played when someone presses its button. This could be a message that gives the caller specific instructions on what to do. These units can also send a second and different voice message alert to the monitoring central location or portable radios. This message could give the callboxes location or it could be an emergency message of some type.

If you have several callboxes in use and you need to know the location of the unit calling in, then you can get a call box that transmits a unique numeric identifier to a radio that has the ability to decode this identifier. This is like having a telephone with Caller ID capability.

These emergency callboxes are used for applications like parking lots, college campuses, airports, hospitals, construction sites, manufacturing facilities, resorts, hotels, farms, warehouses, delivery docks, campgrounds, gated facilities, or anywhere people may need emergency assistance. So by using an emerency call box, you can put clear wireless voice communication anywhere you need it, quickly, without expensive trenching and monthly air-time fees.

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Long Range Two Way Radio

Before you can choose a long range two way radio, you first need to understand about radio frequencies so you can make an intelligent choice.Handheld two way radio

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, read the free book titled: Two-Way Radio Success: How to Choose Two-Way Radios, Commercial Intercoms, and Other Wireless Communication Devices for Your Business.

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Two Way Radio Walkie Talkie

Two way radio walkie talkie radios are the type of radios you see people carrying around. As ruled by the FCC (Federal Communications Commission), handheld radios may not have more than 5 watts of power.

There are two major formats for walkie talkie type 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. See this article for a more detailed description about which radio is right for you: UHF versus VHF.two way radio walkie talkie kit

If you go down to your local building supply or discount store you will see two way radio walkie talkie radios that say they have a range of 14 miles, 22 miles, or something like that. Yet when you take them home you find that they don’t even go a mile. Why is that?

One of the biggest factors to reducing range is the obstacles in the path of transmission. These obstacles absorb and reflect the radio waves so while a radio advertised to go 22 miles may actually do that if both users are standing on peaks of a mountain with nothing in between, the same radio can’t go a half mile through a forest. Two-way radios communicate “line of sight,” which means that if you can see between two points, the radio should be able to communicate between these two points. Consider that the radio the Apollo astronauts on the moon used to communicate only used one watt of power and you’ll get the picture on this.

If you consider that two points on land or water become invisible after about five miles between them because of the curvature of the Earth, you can understand that communicating more than five miles becomes difficult even if there are no obstacles between the radios. The key to getting more range is either to raise the height of the antenna, increase the power of the radio, or both.

For a more detailed discussion on two way radio walkie talkies, read the free book Two-Way Radio Success: How to Choose Two-Way Radios, Commercial Intercoms, and Other Wireless Communication Devices for Your Business .

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Two Way Radio Base Station

Two way radio base stationWhile the mobility of handheld two way radios is a good thing, there are times when you need a least one radio that is stationary. That’s where a two way radio base station comes in handy.

Desktop two way base station radios use wall AC power and they may have a built-in antenna, but this antenna may be disconnected and then connected to cable that leads to an external-mounted antenna. The higher the antenna is mounted, the better the range.

These radios are available in FCC-licensed UHF and VHF frequencies as well as the unlicensed MURS radio frequencies.

Like two-way radios, these base stations can have multiple channels. In some cases like the MURS radios, there are only 5 channels available. Other radios typically have up to 10 channels available, or you can program them to only use one channel.

One thing about a base station two-way radio is that when you press the Talk button and speak, everyone on that channel will hear you. If you have individual departments in your business that you want to separate, then this isn’t the ideal solution.

That’s where you can use the multiple channels on the base station radio. If you are in a manufacturing environment for instance, you could set up Channel 2 for Shipping, Channel 3 for the Office, Channel 4 for Manufacturing, and so on.

MURS Two way radio base station

You can use the channels sort of like an intercom system that lets call individual people or groups instead of broadcasting a message to everyone. So the Shipping people keep their radios on Channel 2, but if they need to talk to people in the office, they change to Channel 3.

Some handheld radios also have a scanning capability that also works well for this type of application. You

can actually program the channels you want to scan, and the radio will only pick up conversations for the channels you have programmed.

In the example above say you add a Channel 1 as the Broadcast, Paging, or All Call channel. Now you set each radio to scan not only their department channel, but also the Paging channel as well. So if there is need to broadcast a message then anyone can change to Channel 1 and everyone hears the message. This is a great emergency notification system.

Some base station two-way radios in the VHF band allow you to receive weather broadcasts from the NOAA Weather Radio service if you are in a broadcast area.  With this feature you’ll know instantly of approaching bad weather so you can alert others.

The two base station radios on the market right now are the MURS Multi-Mile Intercom and the MURS Commercial Intercom.

So when you need a two way radio that sits on someone’s desk, or mounts on a wall, a two-way radio base station may be the device you are looking for.

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Wireless Two Way Radio

A wireless two-way radio is essentially available in three types: hand-held portable, vehicle-mounted mobile, and desktop base station. There are also unique wireless two-way radio devices called wireless call boxes you can get as well.

handheld wireless two way radioHandheld portable wireless two-way radios are the walkie talkie type of radios you see people carrying around. As ruled by the FCC (Federal Communications Commission), handheld radios may not have more than 5 watts of power.Mobile wireless two way radio

Vehicle-mounted mobile two-way radios mount in a car or truck and they use the vehicle’s battery for power. They may have their own antenna, but better range is achieved by using an externally-mounted antenna.Base station wireless two way radio

Desktop base station radios use wall AC power and they too may have a built-in antenna, but this antenna may be disconnected and then connected to cable that leads to an external-mounted antenna. The higher the antenna is mounted, the better the range. The vehicle-mounted mobile radios are usually used as base stations by just adding an AC to DC power converter.

Mobile and Base station radios are usually more powerful than hand-held radios and may have as much as 100 watts of power.

Top wireless two way radio devices are available at www.IntercomsOnline.com.

You can get a free wireless two way radio book just by clicking the highlighted link in this sentence.

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Wireless Call Boxes

When you need a way for clients, students, employees, or anyone else to communicate with you from distant areas of your campus or property, a wireless call box or callbox is one way to do it. A call box is a box made of metal or fiberglass that contains electronic circuitry that enables someone to press a button or pick up a handset and call a central location for assistance. Some callboxes also allow calling a handheld two way radio so that assistance can be mobile.Wireless Callbox

There are two main types of call box units available, wired and wireless. A wired callbox involves running a cable to it from the central location.This section is about the other kind, the wireless units.

The benefit of a wireless callbox is that you save money by not having to do trenching and running expensive cable to the unit. You also don’t have to pay any air-time or telephone service fees with these wireless systems. As mentioned, another benefit is that since the unit is wireless, people monitoring the units can carry handheld radios that communicate with the call box. That allows your monitoring people to be mobile.

The range of these units is several miles, which can be extended by adding an external antenna. Some units can use radio repeaters to extend this range even more.

If you have existing two-way business radios, you’ll want a system that can integrate with them. Some call boxes can be programmed to be compatible with virtually any brand of VHF or UHF business band radio.

One problem you may have in placing a call box is the lack of available power. You’ll want to choose a system that lets you use battery or AC power. You can also get units that have optional solar power so that they can run for several days on a single day of sunshine.

If you need to remotely control gates, magnetic door locks, or barrier arms from your portable 2-way radio or desktop base station intercom, then select a unit that has this capability. With this ability you can let someone in a gate or door when they call you. There are units that also let you turn on a strobe light at the callbox location to help draw attention to it.

Another useful feature is the ability for call boxes to store a voice message that is played when someone presses its button. This could be a message that gives the caller specific instructions on what to do. These units can also send a second and different voice message alert to the monitoring central location or portable radios. This message could give the call boxes location or it could be an emergency message of some type.

If you have several callboxes in use and you need to know the location of the unit calling in, then you can get a call box that transmits a unique numeric identifier to a radio that has the ability to decode this identifier. This is like having a telephone with Caller ID capability.

By adding a motion detector or some other detection device, you can be alerted when that detection device is activated. Some callboxes will send either a tone alert or a custom voice alert when the detection sensor status changes. If this voice message is not immediately answered, the alert message is resent multiple times.

If you are running your system on battery power, you need a unit that has battery conservation mode. In this mode, only the absolute necessities for operation are powered, and the unit can not accept calls to it; it can only make calls. You can attach an external sensor to automatically put the unit into full power mode when someone is detected near the box. This will allow you to make a call to it.

Other useful features:

  • If you want to listen to what’s happening around the call box, then you’ll need a unit that can be paged so you can use the callbox microphone to monitor the sound around it.
  • A low battery alert or external power fail tone is sent to the monitoring portable radio or base intercom.
  • A paging feature allows selective calling of individual boxes or a group of callboxes simultaneously.
  • The busy channel feature prevents someone from transmitting if someone else is using the radio channel.
  • Wireless callboxes have fast installation since no wiring is required.
  • Entry keypad with built-in relay lets people enter a code at the call box to open a gate or door. Remote opening of the gate by monitoring personnel can still happen also.

These wireless call boxes are being used for applications like parking lots, college campuses, airports, hospitals, construction sites, manufacturing facilities, resorts, hotels, farms, warehouses, delivery docks, campgrounds, gated facilities, or anywhere people may need assistance. So by using call boxes, you can put clear wireless voice communication anywhere you need it, quickly, without expensive trenching and monthly air-time fees.

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