| Compander |
| Also known as noise reduction system. A system which improves the signal-to-noise ratio by compressing the dynamics on the transmitter side using a compressor, and subsequently restores the normal dynamics on the receiver side using an expander. |
| Connector |
| A standardised single or multi-pole plug for connecting units or accessories. |
| Dynamic range |
| The "bandwidth" of the differences in level between the quietest and loudest passages of a sound event, given in dB. Recording and transmission media must be able to process the dynamics without interference. The dynamic range of a microphone is limited at the lower level by its so-called self-noise and at the upper level by overload distortion or clipping. The dynamic range is determined from the difference between the maximum sound pressure level and the A-weighted equivalent noise level (evaluated in accordance with DIN/IEC 651). Studio microphones, for example, can process a dynamic range of up to 126 dB. The dynamic range of an RF system is the range between the inherent noise and the start of clipping, given in dB. |
| Frequency response (microphone) |
| The frequency response of a microphone is given within the limits defined by the manufacturer. In studio condenser microphones it is generally within the range of between 20 Hz and 20 kHz. |
| Input voltage range (bodypack transmitter) |
| Indicates the voltage range of the input signal within which a unit will work properly, i.e. as specified in its technical data. |
| Modulation |
| The process in which one wave is varied by some parameter of another wave, for example, an RF carrier frequency that is modulated by an audio signal. Types of modulation include amplitude modulation, frequency modulation, pulse code modulation and pulse width modulation. |
| Nominal deviation |
| Also known as reference deviation. The nominal deviation has been fixed at 40kHz to be able to give comparable technical data. |
| Number of channels |
| Frequencies which are available to transmit a signal. |
| Operating temperature |
| Gives the range of temperatures at which a unit can be operated without damage. |
| Peak deviation |
| Maximum permissible deviation for FM. |
| Power supply (bodypack transmitter) |
| Description of the power source used for powering a unit, for example mains, battery, rechargeable accupack, etc. |
| RF frequency range |
| The range of frequencies to which a unit (e.g. a receiver) can be tuned. |
| RF output power |
| Output power measured at the antenna socket. |
| Spurious emission |
| Unwanted by-products in the transmission of RF. |
| Switching bandwidth |
| The frequency band in which frequencies can be switched directly. |
| Total harmonic distortion (THD) |
| Total harmonic distortion is a measure of non-linear harmonic distortion and is given in %. Non-linear harmonic distortions are signals which were not present in the original before the signal was converted by the headphones. These unwanted signals are caused by the diaphragm, whose movements do not precisely move in time with the electric signals that cause it to move. Unfortunately, this is a feature of all electroacoustic transducers. Although it cannot be completely eliminated, suitable steps can be taken to minimise it. However, the user is not interested in why this distortion takes place but in how great the level of distortion must be for it to become perceptible. According to the findings of several research projects, a total harmonic distortion of 1% in the frequency range of 100 to 2000 Hz is imperceptible. Below 100 Hz, the perceptibility threshold lies at 10%. |
