Recommend the latest -102 professional wireless monitoring system, it uses UHF signal transmission, has Bluetooth function, can connect multiple bodypack receivers for wireless monitoring, with high-fidelity HIFI headphones, used for recording studios, stage performances, classroom teaching, conferences speech, etc. The transmitter and antenna should in the relative position of accessibility of the straight line. Don't put the receiver close to the radio wave emission source, with magnetic objects or most digital devices(such as the CD player, computer, speaker, wifi etc). Try to place the receiver in height of 1.5 meters from the ground and the position of a distance of 1 meter away from the wall. Receiver Specifications: Frequency range:530-580MHz Signal transmission range: 300m (in an open environment) Receiving mode: Super heterodyne double-conversion Frequency vibration: PLL lock loop Sensitivity: -93 dBm Audio output: XLR balance output:0-500mV / ф6.35 unbalance output:0-500 mV Rated power consumption:3W Transmitter Specifications: Modulation Method:π/4-DQPSK Frequency Range:530-580MHz,1x100CHs (Please refer to the actual product for the frequency of some orders) Transmission power: 10mW Sampling Ratio:48KHz Transmission Rate:204.8Kbps Dynamic Range: 90dB Total Harmonic Distortion:Less than 0.1% Delay Time of Audio Transmission:Less than 3ms S Ratio: 96dB Frequency Response:30-20Khz RX Sensitivity:Less than -94dBm Color:Black Material:plastic Package Contents: 4 * receivers 1 * Transmitter Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.