Precise Time and Frequency, Inc. GPS Receiver VF-3201B

Features GPS Tracking: 12 parallel channels Ovenized quartz oscillator 7 μs over 8 hours 1 PPS and 10MHz outputs GPS antenna and cable included Convenient 1U, 19" rack mount package Applications GPS Satellite Systems Wireless Applications Sub-microsecond Timing Description The VF-3201B offers monitor/control on both RS-232-C and Ethernet ports plus a “time print” RS-232-C port allowing interfacing to a wide range of equipment. This functionality comes in a package which is still offered at a low cost to the end user. At its heart, the VF-3201B uses a microprocessor/CPLD combination interfacing to a 12-channel GPS receiver, control circuitry and a high-quality ovenized oscillator all on a single board. The result is high integrity and reliability. The level of integration of the VF3201B makes it the perfect solution for precise timing applications within the wireless industry. Among its uses are synchronizing and maximizing bandwidth for wireless local loop. The VF-3201B’s GPS clock outputs a 10MHz reference signal and a 1 PPS signal with an over-determined solution synchronized to GPS or UTC time. The 10MHz reference accommodates applications requiring sub-microsecond timing. The microprocessor/CPLD combination performs both the GPS navigation and oscillator disciplining functions. The GPS receiver is driven directly by the 10MHz output signal of the oscillator. This is calibrated against the incoming GPS signal, with the resulting clock and frequency measurements entered into the oscillator frequency control algorithm. The VF-3201B operates on the coarse acquisition (C/A) code transmitted from each satellite. This C/A code, which is unique for each satellite, contains information on the satellite identity for acquisition and tracking. The C/A pseudo random number (PRN) code is a 1023 bit code that repeats at the rate of every millisecond. Operating on the L1 band and utilizing the C/A code transmissions, the VF-3201B determines time and frequency by measuring the time of arrival of a precise timing mark transmitted by each of the satellites, and computing the time against its known (previously determined or entered) position. This is the basis for the VF-3201B's one pulse per second (1 PPS) output.