Wednesday 15 April 2015

2-Way Radio QUICKGUIDE

Confidently, painlessly and quickly sift through all technical specifications, facts and figures to get the core information you need to make an informed purchase of two-way radios. Clear up "data confusion" and glean the most relevant information from manufacturer tech sheets.

FACTOR 1: RF Power

RF Power is a good indicator of the distance a 2-way radio can transmit, as well as a more important factor: the strength of a 2-way radio's signal under optimal transmission conditions. In general, customers don't use their 2-way radios at the upper limits of the transmission range. Most customers transmit from a relatively close proximity between 2-way radios, roughly the size of your "average" construction site - one-half to one mile. Transmitting a distance of that average construction jobsite requires much less than 1 watt of output power.

When do you need 5 watts of RF output power? You need it to overcome interference in the real world. In the real world, 2-way radio users aren't dealing with an optimal situation - a clear line of sight with nothing in between the user and the persons they are communicating with. Buildings, terrain and everything else between you and the receiving parties will create interference and degrade your transmitted signal.

When taking into account real world factors, 1 watt may not be strong enough to overcome interference; any signal that reaches the intended receivers will be very weak and difficult to understand. Models that feature low/high power options allow you to choose when to save power and when to crank it up.

FACTOR 2: Battery (type / capacity / voltage):

Everything begins with the battery when it comes to portable (handheld) 2-way radios. If battery isn't good enough, then nothing else within the 2-way radio can be work well enough. You want a rechargeable battery technology that does not hold memory and can be recharged many times, which is why a high-capacity Li-ion is better than NiMH. Battery capacity, measured in milliamps per hour (mAh), indicates how long the 2-way radio can operate between charges. The higher the number, the longer the run time.

Battery voltage is also directly related to the 2-way radio's RF output power. If a 2-way radio has 5 watts of output power (efficiently) it needs to be backed by at least a 7 volt DC battery pack. TIP: If a two-way radio technical specs sheet claims 5 watts of output power, but only has a 3 volt DC battery pack, it's either a typographical error or an outright lie.

FACTOR 3: Dimensions and Weight:

This one's pretty obvious, and it's the same reason we wear watches instead of carry clocks. Toting around a large, heavy two-way radio all day long creates unnecessary fatigue. A compact, lightweight radio that is rugged and durability is ideal.

There's a pretty wide range between competing models. I have seen differences of ten ounces or more in weight between comparable models. Remember to take the battery and antenna into consideration if the spec sheets don't specify the total weight of the radio.

FACTOR 4: Channels:

If channels aren't programmable, they don't do you a lot of good. Most 2-way radios on the market today feature programmable channels. The more channels your 2-way radio has, the more frequencies you can program, and thus the more options you have to avoid interference from other groups of people using the same frequency. That may be important in congested areas. I recommend a minimum of a dozen programmable channels for real-life convenience.

For example, if you are using a 2-way radio with only 1 or 2 channels and there are other people using those frequencies you may not be able to "get away" from the busy channels, making your 2-way radios fairly useless. Having more channels gives you more frequency options so you can easily and quickly switch to open channels. Again, the number of channels and the number of programmable channels varies depending on the make and model of the radio.

FACTOR 5: Frequency Range:

Frequency range details which frequencies the 2-way radio will transmit and receive. This feature is very much controlled by the FCC within the US. The FCC details which frequency ranges are for which type of activity and radio type, along with which frequencies require an active license to use.

FACTOR 6: Channel Spacing (Bandwidth):

This is related to frequency range. A radio frequency signal occupies more than just the frequency it transmitting on. The signal takes up space on the frequency above and below its transmit frequency. How much of the frequencies above and below are affected is what we call "bandwidth" or "channel spacing".

In an effort to make more efficient use of available frequencies, the FCC recently created a narrowbanding rule requiring all radios to have channel spacing of 12.5 kHz or less. To repeat: to be narrowband compliant with FCC regulations, a two-way radio MUST have a channel spacing of 12.5 kHz or less.

FACTOR 7: Audio Output:

Audio output (typically measured in mW) measures your 2-way radio's audio amplifier output power (the loudness of your two-way radio's volume). Construction and industrial environments are loud in and of themselves, so professional users need their 2-way radio volume (audio output) to be loud enough to hear the received signal over the ambient noise.

A 500mW rating is good. Generally speaking, the higher the mW audio output is above 500mW, the more likely your two-way radio's volume will be measurably louder and clearer. Extreme military radios have an audio output of around 1000mW.

Taking these six factors into consideration should result in a the purchase of a 2-way radio that will function well for professional purposes. Other features you many see on spec sheets will be optional "convenience" factors such as programmable squelch, programmable buttons, headset accessory jacks, universal compatibility, VOX (voice activated transmit), busy channel lockout, channel scan, and privacy settings (though privacy even among the most expensive models is questionable).

Among these options, my Must-Have features are "Emergency Call Out" and "Group Call" features that allow immediate critical communication that saves time, and sometimes lives.


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