Sound is fed into the ear down a hollow tube. This allows the transducer to be located away from your ear.
This is used for many covert earpieces. The tube is soft transparent plastic and the transducer is hidden under a collar.
You can hold a normal conversation while for example hammering in a nail or shooting. Each hammer impact or shot fired is suppressed instantly but you can carry on the conversation. You will also be aware of vehicles moving behind you.
A small Mic on each ear cup allows you to hear what is going on around you, however the instant there is a noise above an unsafe level the Mic's shut down and your ears are protected by the defenders.
The other important point is that the Cut Off system operates in stereo so you still have directional hearing, an immense safety advantage when working near moving machinery.
Each radio talks directly to all other radios in range. The most common and simplest radio system where radios are independent of any base radios or repeaters. This radio system is failure robust because no single equipment failure will result in total communications failure.
Some examples of back-to-back systems are Marine VHF radios, the UK Search and Rescue radio system, PMR446 licence free radios.
'Classic' products while conforming to our high standards and with a full 12 month warranty are the lowest cost version of a headset or earpiece. We usually have similar products available which are built to a higher standard of construction and performance.
Continuous Tone Controlled Squelch System is used to keep your radios silent to other users sharing your frequency.
All radio channels are shared to some extent either sometimes locally (within radio range) as in PMR446 or nationally or internationally where geographic location helps prevents interference. Either way it is almost certain your radio would pick up other users now and then.
The main method to silence this interference is CTCSS. It works by setting all radios in your group to transmit a common sub-audible (67 to 250hz) tone whenever the transmit button is pressed. All radios in your group will only un-mute the speaker when this tone is received. The chances are other user groups will not be using the same CTCSS tone so your radio will be silent to their traffic.
All the radios we supply have CTCSS as standard except most Marine VHF and Air band equipment which does not normally use CTCSS for historical and safety reasons.
Conventional radio systems use analogue FM (frequency modulation). Newer digital radios have capability to use FM but also Digital modulation. Digital modulation gives many advantages and few disadvantages.
- Noise-free, clear speech right up to maximum range.
- Encoded speech for voice privacy.
- Digital audio processing removes much ambient noise.
- Two channels in the space of one analogue channel.
- Non-audible signalling for Fleet, Group and Private calling.
- As of 2012 more expensive analogue radio.
- Little warning that maximum range is being reached. Speech is clear or not there at all.
Digital Signal Processing is a term used to cover many forms of electronics but in voice communication is used to refer to circuits and software that improve the voice audio. It usually does this by reducing undesired noise such as background noise picked up by the users Mic.
DSP is particularly useful in industrial and motorsport communications and can be found in many of our industrial communications products.
Full duplex allows communication in two directions at once. A normal telephone conversation is full duplex so callers can interrupt one another. A full duplex intercom allows many users to all talk and interrupt much like a group conversation in the same room.
Inductive loop equipment is a way of sending audio wirelessly over a few metres.
For covert use the loop is worn under clothing around your neck and plugged into a radio, MP3 player or other audio device. A tiny in-ear receiver picks up the loop signal.
Another application is to build the loop into the room. This is a common scenario in cinemas and theatres and is used for feeding speech direct to hearing aid users. Hearing aids usually have a 'T' setting for this purpose.
Intelligent chargers will rapidly charge a battery to full capacity then go into trickle mode keeping the battery topped up without over-charging and damaging the battery. (Mobile phones have intelligent chargers). If the radio is left on charge for long periods, a weekend for example, the battery will not be damaged. Batteries should not normally be left on charge for more than three days however.
Intercom means a two-way communication path just like a conference telephone conversation. All users hear all others and can interrupt at any time. This is the most natural form of wireless (or wired) communication and much like a group of people talking in a room. There is no Press-to-talk and no Voice operated transmit.
Kevlar is high tensile strength fibre. The copper and plastics used in most cables have a relatively low tensile strength which means if they are excessively stretched the copper breaks and the earpiece fails.
A bundle of Kevlar fibres are laid alongside the copper conductors to helps prevent the cable being stretched and making for a more robust earpiece harness.
Lone worker radios have an internal timer which prompts the user to press a button at regular intervals. Failure to press the button triggers an alarm.
Advanced lone worker uses GPS to report the location of the user.
Man-down detects the user/ radio tilting beyond a programmable angle and automatically sends an alarm signal.
Advanced man-down detects lack of movement to trigger an alarm.
Motorcyclists often ask for VOX communications. Unfortunately this almost always not practical with anything other than a dedicated Motorcycle intercom, even reports intercom VOX effectiveness are mixed.
VOX works by making the radio transmit when sound levels reach a preset level. This level is adjusted in the VOX unit (usually the radio). Most radios have a crude VOX with two or three VOX sensitivities. Only Kenwood and newer Icom's have multiple VOX levels and adjustments, ten in the case of Kenwood.
What level is VOX set at? The VOX has to trigger when your voice is louder than other noises. The problem is 'other noises' are variable; Wind noise, engine noise rustling clothing when you move you head, all these vary. Wind noise is a special problem. Our brains are very good at filtering most of the wind noise so we don't notice its large change in volume between say 30 and 70 mph. VOX has no such intelligence just a preset level. Set it high for high speed and turn into a head wind and the VOX triggers, ride slow and you will need to shout to trigger it. Set it low and the radio transmits frequently and randomly. You buddies will not thank you for transmitting nothing but noise.
When using a radio on a bike use Push to Talk (PTT). It is reliable and it works. Using equipment like the Sena Bluetooth hub you can still have all the advantages of wireless helmets but long range bike to many bikes that only radio offers.
Noise Cancelling Microphones are designed to pick up the users voice but reject ambient noise. They work best in noisy applications and where the Mic can be placed very close to the users mouth.
They work in a number of different ways but essentially are very directional responding best to the user when their mouth is very close to the Mic and ignoring interfering sounds which are usually much further away.
Describes an earpiece where there is only one cable between the radio and the user. Usually this cable has the earpiece at the far end and a combined Mic and PTT (transmit button) somewhere along that cable. This is simplest kind of earpiece with the least cabling. The disadvantage of this kind of earpiece is that unless the earpiece has a boom Mic the user must turn their head to the Mic when they talk.
PMR446 is licence free UHF radio system for pan-European use.
It is a simple back-to-back radio system which when correctly set up with quality radios will give superb professional performance for most small business and other simple applications. It is the only radio system you can use across most of Europe without licencing.
PMR446 is not configurable to work with Repeaters or external base aerials so cannot achieve the range obtainable with licensed systems.
PMR 446 radios differ from licenced radios in having a maximum of 0.5watt transmit power, non-removeable aerials and and can only transmit on the 8 PMR446 channels.
Press-To-Talk. This is the system two way radios use. Push the transmit button and talk. Only one user can talk at a time and everyone else hears them.
Also used as jargon for the transmit button.
A repeater is used to improve range and coverage of a radio system.
Basic components are receive and transmit radio with external aerials usually located in a position which overcomes obstacles in the radio coverage area. It receives incoming traffic and rebroadcasts it at higher power levels.
More sophisticated repeaters can handle several user groups and be interconnected by data networks (wired and wireless) to allow radio use across multiple sites.
Selcall or selective calling is a signalling system that gives functionality beyond one to all voice calls. The number of functions supported increases with higher tier radios (as do costs of those radios).
- Receive (and Make) a 'Private' (one to one) calls.
- Receive (and Make) a 'Group' (one to several) calls.
- Receive (and Make) a 'Fleet' (one to everyone) calls.
- Receive (and Make) Private, Group and Fleet messages. Sound or Text.
- Stun, Revive.
- Remote control. Automation.
- Man Down and Loan Worker.
- Emergency Button
- GPS location over radio.
Simplex is the method by which most two-way radios work. Communication is in one direction at a time initiated by pressing the transmit button. Only one person can talk at a time on the radio channel while the other listen.
On this website situational awareness refers to 'Hearing' what is going on around you but with a sense of direction.
If both ears hear a particular noise you quickly can work out which direction it is coming from. This is a huge safety factor when working near moving machinery and vehicles for instance.
Earpieces with this feature do not block ambient sound from either ear.
This is a specialist Covert system where the Mic and PTT and Earpiece are each on their own cable. The Mic must be pinned into clothing as near the users mouth as possible. The PTT can be concealed in pocket which avoids talking to the hand. The disadvantages are that performance depends on Mic placement and there are a lot of cables to hide.
Shortened from CTCSS. Continuous Tone Controlled Squelch System. Also known as Digitally Controlled Squelch, DQT, QT, Sub Channels, PL and other names.
When you transmit your radio sends a sub-audible tone. The recieving radio will only activates its speaker (open ist squelch) if the tone matches its own.
What this means is that you only hear other radios in your group but not other users who might be on you channel. It also keeps the radio quiet from interference caused by other electronic devices.
Used on this website to refer to the earpiece element which generates sound. The technology varies with different earpieces but generally they are moving coil fixed magnet speaker types.
Trickle chargers slowly charge a battery. They will continue to charge the battery as long as the power is applied so there is a danger that they will over charge and damage a battery if the radio is left on charge for long periods, a weekend for example. The duration of a trickle charge should be proportional to the radios use. See the manufacturers instructions for more information. A simple precaution to avoid overcharging is to use a simple security lighting timer to limit the daily time the charger is powered up.
From the radio one wire goes to the earpiece. A second wire goes to a combined Mic and PTT (transmit button).
The advantage of this system is that the combined Mic-PTT can be threaded down a sleeve and the user talks into their hand concealing their mouth.
This makes it very versatile and ideal for covert, head-up or noisy applications because the Mic is very close to the users mouth helping mask background noise. The Mic-PTT can also be worn clipped to a lapel like a one-wire earpiece.
Ultra High Frequency. One of two commonly used radio frequency bands used for mobile communications, the other being VHF. Without going into technical details (see Wikipedia) UHF radios generally perform better than VHF in urban and built environments because it penetrates buildings better.
UHF is commonly used for Industrial, Security and Underground applications.
Very High Frequency. One of two commonly used radio frequency bands used for mobile communications, the other being UHF. Without going into technical details (see Wikipedia) VHF radios generally perform better than UHF in rural and non-urban locations. VHF performs worse than UHF in urban and built environments.
VHF is commonly used for Marine, Search and Rescue and Farming applications.
Voice Operated Transmit
This is usually a function of the radio but usually depends on having a special VOX earpiece. It works by measuring the general noise level from the MIC and causing the radio to transmit when the user speaks above a certain level.
VOX works best where noise levels are steady and predictable. (It is easily triggered by wind noise). It is much easier to set up and sue with radios that have many VOX adjustment levels, variable Mic Gain and VOX delay times.
To get the best from VOX various settings need to be adjusted for the job in hand.
VOX Level. A level somewhat higher than the ambient noise to avoid false VOX triggering.
VOX Delay. The time the radio transmits for after the user stops speaking thereby preventing the radio from ceasing transmit during pauses or gaps in a sentence.
VOX Proceed tone or Sidetone. An audible indication to the user that they have triggered VOX and their radio is transmitting their utterances.
Water damage is not usually caused by water but by corrosion associated with current from the battery AND the water. Salt water corrosion happens extremely quickly, within minutes.
Damage can be minimised or even prevented if URGENT action is taken.
1. REMOVE Battery.
2. Shake out the water.
3. Flush well in drinking water. With low cost radios this is easy as the housing is poorly sealed. With professional quality radios remove the outer housing which is usually just a case of removing a few screws.
4. Flush for 5 minutes with an opened radio or much longer with a sealed radio.
5. Shake out water and dry on top of a radiator for at least 48 hours.
6. Fit the battery and test the radio. Any faults remove the battery and arrange for a repair.