The Optix™ remote antenna distribution system eliminates the need for expensive, fragile, and lossy coaxial cable by converting RF signal into light. Long runs of up to 10,000 meters are possible with nearly lossless transmission over 1310nm single mode fiber cable. Optix works with any simplex (one-way) 50 ohm radio signal between 450 MHz and 850 MHz.
Each system includes a transmitter and receiver. The transmitter is deployed at the remote antenna site and converts incoming RF from the antenna into an optical signal. The signal travels via fiber optic cable to the Optix receiver module placed near the rack. The receiver converts the optical signal back to RF, through a BNC connector.
Optix is primarily designed for wireless audio receive applications. It has been used in a wide range of signal chain configurations. With appropriate in-line attenuation and re-amplification, it can be used for transmit applications as well. The dynamic range of 60dB is more than adequate for most applications as long as the user does not exceed the dynamic range limits.
Tips for Successful Use
The physics of broadband RF over fiber circuit limits its use to signals that fall within the dynamic range of the device. For example, any signal above -75 dBm and below -15 dBm would be considered to be within the usable range. There are many instruments that can measure well below the -75 dBm level and see various forms of noise. Most of that noise is typically ingress-type noise that is expected in a broadband system.
The same limitations are found in a broadband receiver front end, or an IF strip. The dynamic range, though considerable, is always limited.
Some things to keep in mind:
1. The maximum input and output levels are nearly the same, that is -15 dBm. Any signals exceeding that level will clip and produce noise.
2. Within the dynamic range of the system, which is 60 dB, the total system gain is unity to 10 dB, subject to fiber losses either via attenuation or connector contamination. Don't expect perfect unity gain unless all fiber interconnections and loss is accounted for.
3. Ingress can occur through the case, around the coax connections and at the DC power input. If you operate a transmitter of any kind (cellular, walkie-talkie, wireless mic - anything) within a few meters of the Optix, you will see it in the passband, as the system is necessarily sensitive. In most normal cases that signal will be low.
4. No bandpass filtering is included. We recommend the user employ the narrowest possible external filter for the lowest noise and highest dynamic range. Hint: At narrow bandwidth the observable noise floor is lower than -85 dBm, and can be used under controlled engineering conditions, with the above cautions.
High sensitivity spectrum analyzers are great! They have sensitivities far below the noise floor of many closed systems, including the Optix. If you look low enough, you will start to see signals. More often than not these are signals that exist in your environment (ingress) or are mixing products (sometimes called "intermod") caused by one or more signals in the Optix passband that exceed the -15 dBm clipping level.
Remember that the dynamic range is 60dB, and the operating floor is -75dBm.