PortableAudio Frequency Induction Loop Kits
PortableAudio Frequency Induction LoopKits
Incorporating:
PortableInduction LoopKitA,i.e. the PL1/K1
Portable Induction LoopKitB, i.e. the PL1/K3
Consultants Specification
Approved Document No. DFS0000567 Rev 1
CONTENTS
1Scope of work......
2STANDARDS AND regulations......
3Amplifier features / SPECIFICATION......
3.1Amplifier Components......
3.2Supplementary Specification......
4Charging the Amplifier......
5Amplifier Shut-Off Timer......
6Documentation......
1Scope of work
1.1To design and supply the following equipment which shall form part of an audio frequency induction loop system (AFILS).
1.1.1Portable Induction Loop Kit A shall include:
- 1 x amplifier c/w internal battery
- 1 x plugtop battery charger
- 1x cardboard carry case
1.1.2Portable Induction Loop Kit B shall include:
- 1 x amplifier c/w internal battery
- 1 x plugtop battery charger
- 1x robust plastic carry case
1.1.3Spares and accessories including amplifiers, batteries,plastic carry case, remote desk/tie microphone, plugtop charger,induction loop testing equipment and induction loop ancillaries.
1.2The amplifier shall be suitable for counter, table or desktop use. It shall be suitable for restricted person to person contact inareas such as banks, post offices, small meeting rooms, reception desks, open plan offices andticket booths.
1.3The amplifier shall be a portable, lightweight design with a simple one button operation. It shall be movedeasily from location to location and ready for use within seconds.
2STANDARDS AND regulations
2.1Where applicable, the induction loop amplifier shall comply fully with the following British Standards and/or other nominated rules and regulations. The equipment manufacturer shall confirm compliance with the standards.
2.2The equipment manufacturer shall be approved to BS EN ISO 9001 quality system standard for the design and manufacture of the equipment. The product shall be manufactured in conformance with the requirements of all applicable EU directives.
2.3The induction loop driver, i.e. amplifier, shall be designed to assist hearing aid users to communicate more effectively and facilitate compliance with the Disability Discrimination Act.
2.4The amplifier shall be designed to comply with BS 7594 - Code of practice for audio-frequency induction-loop systems (AFILS).
2.5The current standard BS EN 60118-4 recommends that the achievable magnetic field strength of an AFILS over a ‘covered area’ shall be 400mA RMS per metre.
3Amplifier features / SPECIFICATION
3.1AmplifierComponents
The amplifier’s rear shall incorporate the following components, as a minimum:
3.1.1Internal Microphone
The amplifier shall contain an internal speech compressor / automatic gain control (AGC), therefore, the user shall not have to direct his/her voice directly towards the microphone. For optimum performance the microphone shall located at speaking distances of approx. 0.5m. Refer to the AFILS Working indicators, section 3.1.8, toensure best performance.
3.1.2Remote Socket
A 3.5mm jack socket shall be provided for connection of optional equipment, e.g. a tie/desk microphone (not supplied). Note that inserting ancillary equipment into this socket shall disable the amplifier’s internal microphone.
3.1.3On/Off Button
Momentarily pressing the On/Off buttonshall turn the amplifier on. Pressing theOn/Off button again shall turnthe amplifier off.The amplifier shall have a default shut-off time of 10 minutes. Refer to section 5 for details.
3.1.4Charger Socket
A 2.5mm jack socket shall be provided for connection to the amplifier’s plugtop battery charger (supplied).
3.1.5Charging Indicator
A single indicator shall illuminate steady green when the battery is being charged. Refer tosection4.3 for details.
3.1.6Battery Status Indicator
A single indicator shall illuminate steady yellow when the amplifier’s battery is low and requires recharging. The indicator shall flash yellow when the unit is recharging andextinguishwhen the amplifier is fully charged.Refer tosection4 for details.
3.1.7AFILS On Indicator
A single indicator shall illuminate steady green when the amplifier is switched on and ready to use.
3.1.8AFILS Working Indicators
Threeindicators (1-green, 2-yellow, 3-red) shall illuminate steady to confirm the system is working correctly when the user speaks into the amplifier. Theindicators shall follow the user’s speech pattern and shall indicate the electrical current in the induction loop.
- Two indicators (1 & 2)shall illuminate steady to indicate acceptable speech levels, i.e. ‘OK’.
- Three indicators (1, 2 & 3)shall illuminate steadyto indicate non-acceptable speech levels, i.e.‘too loud’.
- Two indicators (2 & 3) shall illuminate predominantly if the amplifier’s position and/or the speech direction is not ideal.
3.1.9Labels
A shortform user instruction and model number label shall be provided.
3.2Supplementary Specification
3.2.1Power
- 230Vac plugtop battery charger UK type (supplied)shall connect to a standard 13A mains socket. Do not used any other charger. Refer to section 4 for details.
- Internal 12V VRSLA (Valve Regulated Sealed Lead Acid)battery shall be monitored against deep discharge. Expected battery life shall be five years (under normal operating conditions).
3.2.2Coverage
The approximate coverage provided by the amplifier shall be 1.2m2.
The amplifier shall have a nominal one metre operating range at 1kHz providing an AFILS field strength of >300mA/m. For optimum performance the amplifier’s internal microphone shall be located at speaking distances of approx. 0.5m.
3.2.3Overspill and ‘cross-talk’
If multiple portable loop systems are to be used in close proximity, it is possible that the ‘field’ generated by one system may be picked up by a hearing aid user stood at another. To guard against this, there shall be a gap of at least two metres between each system.
3.2.4Performance
- Frequency response: 100Hz to 5kHz.
- Fully automatic compressor (up to 5:1 max).
- Less than 1% Total harmonic distortion of output current @1kHz, 1m distance and AFILS field strength >300mA/m.
- Signal-to-noise ratio: -60dB A weighted (reference maximum RMS current, maximum gain).
- AGC range (3dB change in output current), reference rated input voltage: 10dB.
3.2.5Amplifier Dimensions & Weight
- Dimensions (H x W x D): 250mm x 300mm x 100mm.
- Weight (including battery): 1.7kg.
4Charging the Amplifier
4.1A plugtop battery charger shall be supplied with the amplifier. Do not used any other charger.
The charger’s lead shall connect to the Charger socket on the rear of the amplifier and the charger plugged into a standard 13A mains socket.Note there are no user-serviceable parts in the charger and in the event of failure a replacement charger must be purchased.
4.2The amplifier shall be charged for up to 24 hours upon delivery and shall be regularly charged to ensure it is ready for use at short notice.The amplifier shall be used as normal whilst charging or, if required, remain permanently connected to the charger with no adverse effects.
4.3Whilst charging, the Charging indicator on the rear of the amplifier shallilluminatesteady green and the Battery Status indicator shall flash yellow. When the BatteryStatus indicator extinguishes the amplifier is fully charged and ready for use.The Battery Status indicator shall illuminate yellow when the battery is low.
4.4To maintain the battery in good condition the amplifier shall be charged overnight at leastonce a month, or more regularly if its usage demands it.
Note: If left unused for long periods, e.g. six months, a fully charged battery will slowly discharge itself.If the amplifier is stored away for over a year without recharging, the battery WILL completely discharge itself and will need replacing. This shall be indicated by the yellow Battery Status indicator being permanently lit after repeated attempts to fully recharge it. Note that a fully discharged battery shall be replaced by a suitably qualified engineer.
5AmplifierShut-Off Timer
5.1The amplifier’s automatic shut-off timer shall be factory set to 10 minutes and shall commence the moment theOn/Off button is released. 10 seconds before the end of its session, a beeper shall sound to indicate automatic shut off is imminent. Pressing the On/Off button again before the 10 seconds has elapsed shall extend the session by a further period. If the On/Off button is pressed whilst the unit is on and NOT in the last 10 seconds of its session time, it shall immediately turn off.
5.2It shall be possible, using the amplifier’s On/Off button and AFILS Working indicators, to change the amplifier’s default shut-off time from 10 minutes to 30 or 60 minutes, as required.To assist partially sighted users, the amplifier shall also sound a stepped frequency beep when setting the default shut-off time.
6Documentation
6.1The following documentation shall be provided to the user, as a minimum:
- User Instructions
Consultants SpecificationApproved Document No. DFS0000567Page 1 of 6