Recommended Maximum Cable Lengths for Different Signals Used for Time Synchronization

In general, the maximum cable length also depends strongly on the quality of the cable, the strength of electrical environmental noise, and the maximum baud rate / pulse rate to be transmitted.

So the really useable maximum length can e.g. be less than the respective value given below, if used in an environment with heavy electrical noise, or more than the given length if e.g. a cable type of higher quality is used, or the pulse rate is low.

Using a fiber optic connection instead of a copper cable usually requires mor effort, but has some advantages:

• Not susceptible to electrical noise
• Isolation of receiver from transmitter
• Allows for much larger distances

TTL Signals (TC-DCLS, PPS, PPM, DCF_MARK) via Coaxial Cable (RG58)

• Maximum cable lengh 50 m
• Compatibility of input and output levels as well as impedances needs to be accounted for.

RS-232 Signals (Serial Ports, COM Ports) via Shielded Data Cable

• Depending on cable quality and baud rate, e.g. 15 m at 19200 Baud

RS-485 / RS-422

• Maximum cable length 500 m
• Depending on the baud rate of the signal

Modulated IRIG Signal (TC-AM/IRIG-B)

• Maximum cable length 300 m (typical

E1/T1 Telecom Signals

• Maximum cable length 200 m (655 feet) with CAT5, twisted pair or coax cable

Ethernet (NTP, PTP, IEEE1588)

• Maximum cable length of a segment 100m
• Longer distances when using switches, hubs, or fiber optic connections
• Important: For highest accuracy with PTP/IEEE1588, all switches must be PTP aware

Multi-Mode Fiber Optic Cable 850 nm (TC-DCLS, PPS, PPM, DCF_MARK)

• Maximum 2000 m end-to-end per segment

Single-Mode Fiber Optic Cable 1310 nm

• Maximum 10000 m end-to-end per segment