Receiver Navigates Precision Time Keeping

Receiver Navigates Precision Time Keeping

This compact receiver works with signals from various navigation satellite systems, providing precision frequency and time output signals for synchronization purposes.

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Frequency and time are two ways of looking at the same time, and both require stable clocks for accuracy. The model ptf 3207A GlobalTyme2 receiver from Precise Time and Frequency is a combination frequency reference and time-keeping standard with dependably stable output signals. It operates with a choice of internal local oscillator (LO)—a temperature-compensated crystal oscillator (TCXO), for example—or oven-controlled crystal oscillator (OCXO).

The receiver incorporates circuitry to lock the LO to signals from a satellite-based navigation system, such as Global Positioning System (GPS) satellites, or Russia’s version of GPS, the Global Navigation Satellite System (Glonass). The receiver can also be equipped to operate with Galileo QZSS (in Japan), and SBAS (WAAS, EGNOS) system signals. It performs Global Navigation System (GNS) tracking on 34 parallel channels for reliable time and frequency precision.

Fig. 1
The model ptf 3207A GlobalTyme2 receiver provides precise frequency and timing output signals for synchronizing test equipment, communications networks, and other systems.

The ptf 3207A receiver (see figure) offers a variety of performance options and features depending upon the amount of precision required. In addition to TCXO and standard or low-noise OCXO internal oscillators, it can be equipped with rubidium or low-noise rubidium oscillators. It provides 10-MHz sinewave outputs for frequency, with options for 100 kHz, 1 MHz, and 5 MHz, as well as IRIG-B and 1 pulse-per-second (PPS)/minute (PPM), pulse per half hour (PHH), or pulse per hour (PPH) output signals for time synchronization.

The 1PPS output is accurate within 20 ns or better of the Universal Time Code (UTC). For system flexibility and redundancy, the receiver can be equipped with 1PPS, IRIG, and 10-MHz input ports as an option.

For monitoring and control, the ptf 3207A includes a front-panel membrane keypad with tactile feel for ease of programming and setup. For security, the front panel control can be locked by means of a four-digit personal-identification-number (PIN) access code. For remote control, the receiver incorporates RS-232 serial and Telnet 100/10 BaseT (RJ-45) Ethernet interfaces supporting a wide range of protocols.

Table

Frequency stability and noise performance is a function of the choice of LO for each receiver, with the single-sideband (SSB) phase noise lower at a given offset frequency for an OCXO source than for a TCXO source (see table). Spurious output levels for OCXO-equipped receivers are better than -80 dBc for all offsets.

The receiver produces four individual digital outputs, with each producing a 5-V TTL/CMOS-compatible signal into a 50-Ω load. In addition, each of the outputs can drive multiple distributed outputs. These programmable clock outputs can be set in frequency from a high of 10 MHz to a low of 0.5960 Hz with 24-b resolution. Frequency can be tuned in steps as fine as 10,000,000 (for the 10-MHz reference) divided by 16,777,215 (for the 24-b resolution).

The ptf3207 is available in 1U and 2U rack-height versions with lengths and widths of 19 × 16 in. It includes front-panel light-emitting-diode (LED) indicators for power, lock, and fault warnings. The receiver runs on 90 to 264 V ac or, optionally, on +18 to +72 V dc. It has an operating temperature range of -25 to +55°C and an operating temperature range of -40 to +85°C for the antenna and cable included with the receiver.  The receiver can be equipped with a second GNS/Galileo receiver as an option

Precise Time and Frequency, Inc., 50L Audubon Rd., Wakefield, MA 01880; (781) 245-9090.

Looking for parts? Go to SourceESB.

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