Compact Airborne Timing Unit

The Brandywine Communications Compact Airborne Timing Unit is a robust time reference LRU designed for airborne environments.

The CATU processes time of day from an internal GPS receiver (either Commercial or Military), while generating precise dual 10MHz frequency references and dual UTC-aligned ICD-GPS-060B-compliant one-pulse-second signals (1PPS).   In addition, the CATU LRU features IEEE 802.3ab (1GbE) Stratum 1 NTP Server functionality.


  • Ruggedized
  • Flight Qualified
  • Available with vibration-isolated OCXO or CSAC Oscillator options
  • Gigabit Ethernet
  • GNSS, SAASM, or M-Code supported
  • Designed for GPS denied environments

This versatile timing unit employs its GPS for basic disciplining of its internal Oven Controlled Crystal Oscillator (OCXO), and an – optional – Chip Scale Atomic Clock (CSAC), providing holdover capabilities in a GPS denied environment in excess of 20 hours.  Complimented by a low phase noise, vibration compensated 10MHz reference output locked to the 1PPS ICD-GPS-060B compliant output, the Brandywine Communications Compact Airborne Timing Unit provides unparalleled availability of reliable TOD in highly demanding fixed, and rotary-wing applications.

A commercial version with GNSS Receiver is also available.


GPS Antenna Input
Signal Type GPS CA
GPS P(Y) (optional)
GPS M-Code
Input Signal Level (at receiver RF connector) P(Y) on L1:    -153 dBW to -121 dBW
P(Y) on L2:    -153 dBW to -124 dBW
C/A on L1:    -150 dBW to -119 dBW
Minimum Operating Bandwidth L1 1575.42 MHz ± 10.23 MHz
L2 1227.60 MHz ± 10.23 MHz
Input Impedance 50 Ω (nominal)
Input VSWR 2.5:1 maximum at center frequency of L1 and L2.
Number of Inputs 1
Voltage 28VDC per MIL-STD-704F
Rated Current Draw 1A
Interface Type IS-GPS-154
Phase Noise
G-sensitivity 5x10-11/G
Vibration Frequency Range 10Hz-2000Hz
Allan Deviation 1 second 1x10-11
10 seconds 1x10-11
100 seconds 5x1011
1PPS Output
No. of Outputs 2
Signal Type Per ICD-GPS-060B
Signal Rate 1 pulse per second
Rising Edge On Time
Rise Time <50ns
Signal Type Sinusoid
Fall Time <100ns
Pulse Width 20 µs ±5% default
Output Amplitude 10V ±10%
Coherency 1PPS = 10MHz/106
10 MHz Output
Signal Type Sinusoid
Output Frequency 10 MHz
Output Amplitude 13dBm/1Vrms
Harmonic Distortion -30dBc
Frequency Accuracy (Locked) 1x10-12 avg. over 24 hours
Holdover 1µSecond 24 hours
Ethernet Interface
Signal Type Gigabit Ethernet (IEEE 802.3ab)
Protocols Supported NTPv4, SNMPv3, SSH
Dimensions 7.29” x 4.52” x 2.36”
(185.166mm x 114.808mm x 59.944mm)
Weight 3 lbs. (1.36 kg) nominal
Connectors J1        Antenna, SMA
J2, J3  1PPS SMA
J4, J5  10 MHz SMA
J6        D-Sub17 for KLIF, DS/101-232
J7        1Gb Ethernet
Battery MMCx
Antenna Supply 5V @ 35mA
Operating Temperature -40°C to +55°C
Altitude 41000 ft.
Humidity 95% non-condensing
Environmental Certifications Tested to the following specifications:
MIL-STD-810F, MIL-STD-461: CS101, CS114, CS115, CS116

Resources & Downloads

Data Sheets