Jackson Labs FireFly-1A GPSDO, User Manual

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FireFly-1A User Manual
4 © 2011 Jackson Labs Technologies, Inc.
Table 2.1 shows the FireFly-1A revision 2.0 hardware connectors
Table 2.1 FireFly-1A hardware connectors
2.2 Coaxial Connector types
There are three coaxial connectors on the FireFly-1A board. They are the following types:
J1, antenna: MMCX
J3, 1PPS output: SMB
J4, 10MHz sine output: SMB
2.3 Connecting the GPS Antenna
Connect the GPS antenna to the BNC to MMCX cable adapter. Caution: use a Lightning Arrestor on
your Antenna setup. Use an amplified GPS antenna that is 3V LNA compatible. The FireFly-1A GPS
receiver is a 50 channel high-sensitivity GPS receiver with very fast lock time. It does not require any
self-survey or position-hold mode (auto survey), and thus can be used in mobile platforms.
FireFly-1A is capable of generating standard navigation messages (see GPS:GPGGA and
GPS:GPRMC RS-232 commands) that are compatible with most GPS based navigation software.
Please note that FireFly-1A indicates MSL height (rather than GPS height) in its GPGGA, GPS? and
syst:stat? output strings.
The GPS receiver generates a 1PPS time signal that is phase synchronized to UTC. This 1PPS signal
is used to frequency-lock the 10MHz Sine-Wave output of the FireFly-1A GPSDO to UTC, thus
disciplining the unit’s 10MHz frequency output to the US Naval master clock for very high
frequency accuracy (typically better than 1ppb of frequency accuracy when locked to GPS). Over the
long term, the FireFly-1A will out-perform free-running Cesium Atomic Frequency Standards.
Ref Name Function
Specification
Pinning
J5 +12V Clean +12V Supply 8.0V-14.0V DC, <0.5A, <10mVac 3 +12V, 2-GND, 1-GND
J4 Sine Out 10MHz Output +11dBm +/-3dB 10MHz Output Center-Sine Output, Shield-GND
J3 1PPS Out 1PPS Output 3.3V CMOS, Rising Edge
Synchronized Center-1PPS Output, Shield-GND
J6 RS-232 RS-232
Communication 115Kbaud, 8N1, RS-232 3-RX, 2-GND, 1-TX
J1 Antenna GPS Antenna 3.0V Amplified Antenna MMCX
connector
Center-RF Input, Shield-GND
J2 ISP/Status Alarm/Lock Status
indicators, and
Enable-ISP Flash
Download Mode
Pin 3: 3.3V CMOS output
Pin 2: 4.7Kohm pull-up on open
collector to 3.3V 3-LOCK-OK indicator, can drive an
LED
2-ALARM (unlock) indicator, needs
buffering
1-GND
[Connect pin 2 to ground during
power-on to enter ISP
flash-firmware-download mode]