Jan 24 (edited) • Audio 🎶
RF/Wireless 101
Here’s a great video from Shure on radio frequencies and wireless kit best practices.
Here’s my summary if the video is too long for you:
(Keep in mind I’m paraphrasing)
Omni are good for indoors because they capture surface reflections and aren’t directionally biased but generally less powerful and less reliable over longer distances. Each whip should be facing 45 degrees to the side of the receiver to increase the range of movement of the transmitter without signal loss.
Directional are great for outdoors especially over longer distances but need to be high enough to gain clear line of sight with no people in the way and directly aimed at the transmitter.
Conical/helix are great for when transmitters have to be in isolated zones or are expected to move and shift position a lot (in degrees).
High gain is more important for analog kits. Gain doesn’t matter as much for digital kits. This is due to the linearity of the receivers and the nature of the data transmission. Analog data is based mainly on frequency, amplitude, and phase modulation, subject to noise that needs to be squelched when present, and is generally just lower quality.
Digital data transmission involves binary bitstreams that represent the same analog information as well as information about the reliability of the data in antenna A versus antenna B, or in all 4 antennas as a majority consensus in Quadversity mode.
1/4 wave, 1/2 wave, and full wavelength are lengths of antennas and the waves they are sensitive to. Smaller wavelengths use smaller lower power antennas. The converse is true as well.
You want to keep your antennas as far away from each other as possible, but at least their respective full wavelength. One full wavelength is 3-4 feet, so 1/2 wavelength would be 1.5-2 feet, and 1/4 wavelength would be 0.75-1 foot. Best practice is at least 10 feet though as the further the better. But you also need to consider signal loss and type of antennas. It’s best not to mix and match. Use the same type in A and B to avoid drop out.
But you also don’t want antennas to be too close together either, especially high powered ones. This results in RF Overload. You don’t want your transmitters close together either, especially when they don’t have external medium-long antennas.
Both Shure analog and digital have blue lights to indicate antenna connectivity, and orange bars to indicate signal strength. Analog receivers gradually lose signal and introduce noise as distance between transmitter and receiver increases. Digital receivers are all or nothing. They sound great regardless of distance until they’re out of range and drop entirely. But they don’t have the same noise issues and don’t have a squelch feature. Digital receivers also have a Q (Quality) bar which is measure 0 (no data reliability) to 5 (perfect reliability). This is their most important metric because the RF bar is just signal strength and there’s no relationship between strength and quality like there is with analog.
Wireless kits may also have filters, whether built-in or custom. Built-in would be the frequency range they use, custom would be like wireless work bench allowing only certain frequencies to be used. You can also encrypt frequencies so that devices can’t use them without directly syncing via IR (ie no manual frequency setting). This is important for high-profile clients like the government and high-traffic areas.
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RF/Wireless 101
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