Overview
The Time & Frequency Distribution Amplifier FDA-301A is a very versatile fiber and coax Distribution Amplifier designed to distribute various signal types from a central frequency standard, and/or a central timing source, to multiple remote receiving points. It has a modular output design, with three output module slots at the rear, giving up to 18 fiber connections or 12 coax connections from a single unit.

It offers narrowband sine reference frequency distribution via optical fiber, or coax cable, with minimal jitter and is designed for reference signals between 100 kHz and 60 MHz. The default frequency is 10 MHz. The sine distribution is completely analog, without the use of PLLs or other types of frequency recovery circuits that may introduce jitter or wander. The signal is filtered in a narrow-band, high-Q filter, which heavily suppresses noise and distortion.

FDA-301A also offers distribution of Time Synchronization signals via the Pulse inputs/outputs of for example 1-pps and unmodulated IRIG time code (DCLS). The pulse distribution is broadband, allowing any pulse input signal up to 20 MHz.

Furthermore, the FDA-301A has separate inputs for distributing serial (RS232) Time-of-Day messages (NMEA or user defined), which together with 1-pps pulse distribution will distribute a precise time scale.

The 10 MHz sine inputs are standard, other inputs are optional.

All inputs are dual, in a master-slave configuration, with automatic change-over if the master fails, providing fail-safe input source redundancy.

FDA-301A has 3 output slots for various optional output modules. All coax and Time-of-Day output modules have 4 connectors. All fiber output modules have 6 connectors.

There is also an option for external DC power, to provide power redundancy.

An Example: Using one FDA-301A close to the frequency reference (the transmitter unit), you can distribute the 10 MHz reference, plus the 1-pps signal, to 6 remote sites via fiber. Each remote site has its own FDA-301A receiver and can distribute 10 MHz to 8 local users, plus 1-pps to 4 local users. Thus, with just 7 units of FDA-301A, you can provide 48 local users with 10 MHz reference, plus another 24 users with 1-pps.

The maximum number of users with just one transmitting FDA-301A can be extended to up to 218 local users using 18 remote FDA-301A receivers.

There is also an option for external DC power, to provide power redundancy.

Fiber Distribution
The fiber distribution of FDA-301A has many advantages over coax distribution:

• Distribution up to 2 km for sine and pulse
• No Electro-magnetic noise pick-up
• No ground-current loops
• Smaller cables, lower weight, and lower cost
• No information “sniffing” possible
• EMP-proof distribution to sheltered areas

System Structure
The FDA-301A is designed to work with any Pendulum Frequency Standard (GPS-12R, 6688/89, GPS-88/89), any Fluke Frequency standard (908/909, 910, 910R) and with any reference clock from Orolia/Spectracom. It will also work with all other brands that produce a sine wave reference with amplitude between 0.2 and 2 Vrms.

The FDA-301A will accept all pulse sources producing a TTL or CMOS 5V signal, for example the 1-pps outputs of all Pendulum, Fluke and Orolia/Spectracom clocks