List of standard steps for on-site debugging of wireless microphone (common for performances/conferences)

Whether it's a big party, a small Shang Yan, a government-enterprise meeting, or a lecture hall training, the off-frequency of the wireless microphone, noise, string of wheat, and howling are all the most fatal rollover accidents at the scene.
90% of audio faults are not the poor quality of microphone hardware, but the lack of a standardized field debugging process. In this paper, the standard debugging list of the whole process, which is common in the industry and suitable for both performances and meetings, is compiled. It covers all aspects, including preliminary equipment inspection, radio frequency band planning, wiring gain calibration, full-court signal traversal, howling suppression, final inspection before performances and on-site emergency treatment. Andhadhun, engineers and venue operation and maintenance can all be collected directly.

I. Spot check of equipment and environment before commissioning (completed 60 minutes before opening)
1. Complete hardware inspection
Receiver host: power-on self-check, check that there is no error on the screen, and the indicator light of diversity RF dual receiving channels is normal; Multi-machine stacked cabinets are equipped with metal shielding partitions, and the equipment spacing is more than or equal to ≥10cm.
Antenna system: All omni-directional antennas are fully unfolded vertically, and are not entangled or attached to the metal cabinet/power amplifier; Multi-channel box/stage is equipped with antenna distributor to prevent cross talk of shared antenna; Long-distance field supporting antenna amplifier, directional flat antenna.
Transmitter (hand-held/pocket collar clip):
Unified replacement of new high-capacity alkaline batteries, full of electricity; Spare batteries are stored in bags, and the replacement period is marked.
Pocket antenna is prohibited from bending, winding, and stuffing into clothes pocket, keeping it hanging naturally; The infrared window at the bottom of the handheld microphone has no wear and tear.
Wire and interface: XLR balanced output cannon wire locking buckle, no loose oxidation; The RF antenna signal line is routed separately from the power line and audio line, and is not bound.
Auxiliary equipment: feedback suppressor, mixer, audio processor and power amplifier are powered on in advance for preheating, and idle channel faders are closed.
2. On-site interference source cleaning (premise of core anti-crosstalk)
The receiver cabinet is far away from WiFi router, LED large-screen power supply, song ordering host, walkie-talkie and charging adapter, and the distance is ≥ 1.5m..
In the stage and podium area, it is forbidden for staff to carry mobile phones and wireless Bluetooth devices with them, so as to avoid 2.4G clutter from interfering with UHF wireless microphones.
In the shielding area of large-area metal truss and metal podium, the antenna erection point should be planned in advance to ensure that the transmitter and antenna can be seen without shielding.
Second, radio frequency band planning and infrared frequency matching (core intermodulation prevention and crosstalk steps)
Standard operating sequence: frequency sweep → frequency alignment → frequency locking → multi-wheat interval check.
All transmitters are turned off, only the receiver of the corresponding channel is turned on, and automatic spectrum scanning SCAN is performed. The equipment automatically filters the frequency points in the red zone of environmental interference, and automatically screens clean channels.
Hard rules for using multiple microphones at the same time:
Within 4 channels: channel interval ≥3 channels; 6 or more, the frequency difference is ≥500KHz, so as to prevent intermodulation noise generated by continuous adjacent frequency points.
Multi-box/multi-stage zones are planned for the whole floor, and the frequency bands in different areas do not overlap at all, so as to prevent cross-site crosstalk.
Standard flow of infrared synchronous frequency matching:
① Select the channel corresponding to the receiver and press and hold SYNC to enter the counter-frequency flashing mode;
② When the transmitter is turned on, the infrared window is facing the IR area of the receiver, with a distance of 10–30cm, and the axes are aligned;
③ The indicator light changes from flash to evergreen, which means that the pairing is successful. Press and hold LOCK to lock the frequency point, and the setting will not be lost when the power is off.
Multi-microphone calibration test: turn off the single microphone in turn, and observe the RF signal strength of other channels. If there is still high RF signal in other channels after turning off the single microphone, it means that there is interference at the frequency point, and re-sweep the frequency to change channels.
Transmission power adaptation: lower the power of the conference box; The 200-meter long-distance large-scale performance is mid-range; It is forbidden to transmit at full power without special requirements, so as to avoid cross-talk of signals overflowing through walls.

Third, fine calibration of wiring and gain of audio system (eliminating distortion, sonic boom and noise floor)
Output wiring specification: In professional scenes, the XLR balanced output of the receiver is used to access the MIC channel of the mixer, and the 6.35 unbalanced interface is rejected to reduce the environmental noise interference.
Standardized adjustment of GAIN gain (universal standard of human voice)
① The channel fader of the mixer returns to zero, and the gain knob is screwed to the lowest;
② The user speaks with normal speech/singing intensity and slowly increases the gain clockwise;
③ The peak indicator light only flashes slightly occasionally (-6dB~-3dB), and the continuous bright red indicates gain overload, and the human voice will be clipped and distorted;
④ The sensitivity of the collar-clamped wheat is higher, and the gain is 3-5dB lower than that of the hand-held wheat, so as to avoid the amplification of friction noise.
Basic EQ Vocal Preprocessing (General for Conference/Performance)
Low cut 80–120 Hz: filter floor resonance and low-frequency noise of footsteps;
Intermediate frequency 2–4 kHz slightly increased by 3dB: enhanced vocal clarity and more transparent speech;
Moderate attenuation of high frequency above 6kHz: reduce sharp howling points caused by stage lighting and metal equipment.
Noise reduction and squelch SQ setting: indoor venue SQ is set to mid-range; Raise the mute threshold in outdoor noisy places, and automatically shield RF clutter when no one makes a sound.
Fourth, the whole field signal traversal test (to prevent the dead angle of the stage from being broken)
With the corresponding transmitter, travel all the use areas: the corner of the stage, the backstage side curtain, the aisle of the audience, the podium in the back row, the entrance and exit of the stairs and so on.
Observe the receiver's RF dual-channel diversity signal indicator lamp in the whole process, and keep more than two full-grid signals in the whole process; Single-point signal is weak, flickering and sound breaking, and there are two solutions:
Add directional receiving antenna nearby;
Re-scan and replace clean frequency points to reduce the interference of surrounding RF shielding.
Synchronous test of multiple people on the same stage: all microphones are turned on at the same time, and people can walk freely in the venue. Only when there is no wheat jumping, noise and signal jump for 5 minutes can they be qualified.
Special test of human body shielding: The user turns his back to the receiver and shields the bodypack antenna to verify that the diversity reception function is normal and the sound will not be interrupted instantly.

Visible unobstructed schematic diagram of antenna

Pocket antenna is placed correctly.
V. On-site debugging of howling suppression (conference speech and stage singing are divided into two sets of standards)
1. Physical noise prevention is preferred (lowest cost and best effect)
The speaker is hung above the human head, facing the audience area, and the microphone should avoid facing the sound surface of the speaker; The horizontal included angle between the microphone and the main amplifier is ≥ 30, and the vertical height difference is ≥ 0.5m..
Users should not speak directly to the speaker on the lecture platform.
2. Equipment parameter debugging process
All microphone channel faders are slowly and synchronously lifted until slight howling occurs for the first time, and then immediately pulled down by 2–3 dB to lock the upper limit of safe volume.
Turn on the feedback suppressor to automatically sweep the frequency, capture 3-5 fixed howling frequency points in the venue, and each frequency point is attenuated by 3-6dB, so as not to blindly cut the frequency greatly and lose the human voice texture.
The stage performance is equipped with independent return speakers, which reduces the dependence on the main amplification volume and greatly reduces the probability of howling in the audience; The meeting scene closes the stage and returns to listen, leaving only the main expansion under the stage.
VI. Final checklist before the official opening (required 10 minutes before the opening of the performance/meeting)
Battery recheck: all transmitters check the power display, and if it is less than 70%, replace it with a new battery to prevent low-voltage noise and frequency cut-off in the middle.
Second confirmation of frequency points: check that all channels lock frequency points, and there are no duplicate and adjacent interference channels.
Full-scale audition: the speaker and singer read/sing completely according to the real process, with no distortion, discontinuity and cross-talk.
Interference retest: turn on all equipment such as large screen, lighting, computer and projector on site, and traverse the whole signal again under full load environment.
Standby equipment is ready: standby microphone, standby receiver and full set of standby batteries are placed in the mixer at a convenient location.
Specification for channel mute: All unused microphones are mute, and no long-term idle standby is used to transmit RF signals, thus reducing spectrum congestion in the air.
VII. On-site operation and maintenance specifications during performance/meeting.
Idle microphones are turned off immediately, and multiple microphones are prohibited from transmitting in standby for a long time at the same time.
Staff regularly check the low battery alarm of the receiver, replace the battery 3-5 minutes in advance, and avoid the key nodes of speech and singing.
Do not arbitrarily change the locked frequency point, gain and EQ parameters; In case of noise and frequency cut-off, check the antenna and battery first, and do not blindly modulate the frequency.
During the intermission, turn off all transmitters to reduce the accumulation of RF signals and reduce the probability of intermodulation interference in the second half.
Eight, common fault quick emergency disposal list (on-site first aid)
Single microphone is broken and RF signal flashes.
Give priority to replacing new batteries; Check whether the pocket/handheld antenna is bent and blocked; Moving the receiving antenna to an unobstructed position; Re-infrared frequency alignment.
Microphones cross each other and the microphone next door makes noise.
Turn off the idle microphone immediately; Re-scan the whole channel spectrum and widen the frequency interval of each channel; Installing antenna distributor to isolate multi-channel receiver.
Scream as soon as you speak
Pull-down channel gain; Fine tuning feedback suppressor; Adjust the speaker orientation, and keep the microphone away from the sound reinforcement box; Attenuate high frEQuency eq.
Continuous noise floor and radio frequency noise.
Check whether the antenna interface is loose; Stay away from routers and LED power supplies; Raise the squelch gear of the receiver SQ; Replace the balanced XLR output line.