Mobile phones have undergone remarkable changes over the past three decades. They have gone from those analogue car phones the size of a suitcase to tiny, digital and multimedia companions with built-in camera, MP3 player, games console and mobile Internet access. Despite such progress, the speech quality of mobile phone systems is at present significantly poorer than that of landline telephones. Today, in the era of UMTS, a bound in quality is possible though not yet realised.
Mobile phones are frequently used in noisy environment. Speech intelligibility suffers because of this. The shape and size of the device can have a further negative impact, both in terms of operability, ergonomics and speech quality. For instance, very small phones do not fully cover the outer ear, even when the unit is pressed closely to the ear. An acoustic leak results, causing a shrill sound and poor sound insulation.
We take into account and assess the diverse qualities and vast requirements of mobile phones according to the following aspects: acoustics, ergonomics, reception quality (antenna quality), power management, as well as measurements of electromagnetic energy absorption by human tissue (SAR measurement). The user’s perspective is of primary importance in all investigations.
Measurement of the reception and emission characteristics of a mobile phone in an RF test chamber