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Zaxcom Transmitter Modulation Overview

What is modulation?
Modulation is the way the digital bit stream is transmitted to the receiver. All Zaxcom wireless transmitters have the ability to be set to transmit different modulations types. Each modulation will have different transmission properties for different applications.

What are the available modulations?

  • Stereo – Stereo modulation is used when transmitting a stereo signal from a stereo TRX transmitter.
  • Mono – Mono modulation is used to transmit to legacy receivers and for updating receiver software.
  • XR – XR modulation will have better transmission range than mono modulation.
  • ZHD96 – ZHD96 modulation has a smaller modulation bandwidth and a smaller minimum channel to channel spacing requirement than XR modulation. ZHD96 will perform very well when dealing with reflective surfaces.
  • ZHD48 – ZHD48 modulation has the narrowest modulation bandwidth and the closest minimum channel to channel spacing and the longest transmission latency. ZHD48 will also perform best when dealing with reflective surfaces.
Stereo Mono XR ZHD96 ZHD48
Modulation Bandwidth 200 kHz 200 kHz 200 kHz 96 kHz 48 kHz
Minimum Channel to Channel Spacing 400 kHz 400 kHz 400 kHz 300 kHz 100 kHz*
6 MHz TV Channel Capacity 15 15 15 30 60
Latency 3.5ms 3.5ms 6ms 6ms 18ms
Compatibility with 200 Series Receiver 2 Transmitters 2 Transmitters 2 Transmitters 2 Transmitters 1 Transmitter
Compatibility with QRX300 Receiver no no no no 1 Transmitter

*When used with QRX300 receiver – the minimum spacing is 200 kHz when using all other receivers

What is the modulation bandwidth?
The modulation bandwidth is how much spectrum space the RF signal occupies. The narrower the signal is the more frequencies can fit within a given amount of spectrum space.

What is channel to channel spacing?
If two transmitters are operating too close to each other the signals from the transmitters will interfere with each other. Channel to channel spacing is the minimum number of kilohertz one frequency needs to be set from another frequency to prevent interference. The smaller the spacing, the more frequencies can fit within a given amount of spectrum space.


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