Pendulum Instruments · Frequency Distribution Amplifiers
FDA-301A
Point-to-multipoint distribution amplifier for reference frequency and timing, reaching remote sites up to 2 km away over fiber
When the reference has to reach a room that is not the one it lives in, coax length becomes the first problem: attenuation, ground loops and pickup all grow with distance. The FDA-301A covers that stretch with fiber. One reference source is distributed to remote sites up to 2 km away, through up to 18 fiber outputs (3 modules of 6) or 12 coax outputs (3 modules of 4). Sine distribution spans 100 kHz–60 MHz (10 MHz default), pulse distribution handles up to 20 MHz bandwidth, including 1-pps and IRIG-B DCLS. Before planning, decide for each remote site whether it needs frequency, timing pulses or both; that decides how the modules are combined.
Overview
Two things get underestimated in multi-site time and frequency distribution. The first is distance: after a few hundred meters of coax, loss and noise are hard to accept, while fiber is nearly indifferent to length and holds signal quality to 2 km. The second is grounding: equipment spread across buildings and chained with coax readily picks up ground potential differences and loop noise; fiber is electrically isolated, so the problem simply goes away. The FDA-301A supports both media, so nearby equipment can stay on coax while remote sites go over fiber, and one unit covers the whole facility. Outputs grow in modules, up to 3 per unit, 6 fiber or 4 coax outputs each, so you configure to the number of sites you actually have rather than paying for unused channels. Beyond sine frequency (100 kHz–60 MHz) it also distributes pulses; 1-pps and IRIG-B DCLS are the usual timing formats, with a 20 MHz bandwidth ceiling. Typical homes are observatories, test ranges, large calibration facilities and lab networks that span several buildings.
Key specifications
| Sine frequency distribution range | 100 kHz to 60 MHz (10 MHz default; other frequencies on request from the factory) |
|---|---|
| Pulse distribution bandwidth | Up to 20 MHz (1-pps, IRIG-B DCLS) |
| Maximum outputs (fiber) | 18 (3 × 6-output fiber modules) |
| Maximum outputs (coax) | 12 (3 × 4-output coax modules) |
| Maximum fiber distance | 2 km |
| Input configuration | Dual master-slave inputs with automatic change-over |
| Dimensions (H × W × D) | 90 mm × 210 mm × 395 mm (2U, half 19" rack) |
| Operating temperature | 0°C to +50°C |
| Storage temperature | -40°C to +70°C |
| Shock | Half-sine 30G (MIL-PRF-28800F) |
| Safety | EN 61010-1:2011 |
| EMC | EN 61326:2013-6, increased test levels (EN 61000-6-2:2008) |
Features
2 km over fiber
Remote sites are no longer limited by coax loss; signal quality stays consistent across the whole facility.
Electrical isolation
Fiber has no ground loop, so runs between buildings do not bring ground potential differences into the measurement.
Coax and fiber together
Coax for nearby equipment, fiber for remote sites; one unit serves both needs across the facility.
Modular expansion
Up to 3 modules, 6 fiber or 4 coax outputs each, sized to the number of sites you really have.
Frequency and time on one box
Besides 100 kHz–60 MHz sine, it distributes 1-pps and IRIG-B DCLS pulses.
Cascades for larger sites
One unit gives up to 18 fiber outputs, and a fiber output can feed the fiber input of another FDA-301A within 6 dB of optical attenuation and 2 km, so large research facilities and telecom rooms scale without redesigning the distribution.
Typical applications
Metrology lab
One frequency standard driving several instruments in step
With a rubidium clock or a GNSS timing receiver as the master reference, the FDA-301A distributes the 10 MHz sine and the 1-pps signal to counters, phase noise analyzers, signal generators and other instruments at the same time, so every measurement shares one low-jitter timebase and timing error between instruments falls.
Telecom network
Synchronized frequency distribution across floors and buildings
Telecom rooms and data centers need to deliver synchronization clocks, including 2.048 MHz E1 timing, 1-pps and serial time messages, to other floors or to remote nodes up to 2 km away. The FDA-301A extends the reference point-to-multipoint over fiber to as many as 18 remote sites, and its dual inputs switch over automatically so a master failure does not interrupt service.
Aerospace / defense
Isolated time and frequency distribution in EMI-sensitive environments
Satellite ground stations, radar test ranges and defense labs suffer from ground potential differences between racks and are exposed to electromagnetic pulse. The FDA-301A replaces long coax runs with fiber, giving full electrical isolation that removes ground loops and interference pickup, so each remote site receives a reference with the same low jitter as the source.
Options and configuration
Tick the options you need; we compile the configuration list and carry it into the quote form.
Standard equipment (included)
Input options
Output module options (up to 3)
Mounting and transport options
Downloads
This page describes the FDA-301A, the model Pendulum Instruments sells today. The earlier FDA-301 is on the factory discontinued-products list; its datasheet and user manual are still available for download from that page. Please quote new projects as the FDA-301A.
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