Here are a few things to keep in mind when designing the MAX2982 for long cable lengths applications:
1. The distance depends on attenuation of used cable for 4-20MHz frequency range.
Below is a link to how to calculate attenuation of 24AWG twisted pair cable.
source: http://www.interfacebus.com/24AWG_Attenuation-vs-Frequency.html
Another table for coaxial and UTP cables:
source: https://solutions.borderstates.com/resource/attenuation-for-coaxial-and-utp-cables/
2. Now, let’s consider a maximum attenuation at 20MHz is 6dB per 30 meters for 24AWG twisted pair cable.
Distance = 500m
Total attenuation: 6dB * (500m/30m) = 100dB
This attenuation is too high!
The UTP and coaxial cables attenuation is much lower.
The MAX2982/81 receiver sensitivity limits total attenuation to 75-80dB.
Customers need to calculate attenuation of the cable for the desired distance or measure it by testing.
Keep in mind that 7Mbps (UDP) is a maximum application data rate at maximum Ethernet packet size and best channel condition.
When designing with the MAX2982 the customer should consider reasonable data rate margin for possible channel degradation and delay due to packet loss/retries etc.