Berkeley Varitronics Systems' (BVS) microprocessor-based $3900 Rhino3 is a precision battery-operated signal source, but don't let its internal fast-charge NiMH power source fool you into thinking that it's for field use only. Equipped with a 12-channel GPS receiver, the 8 lb. unit can be useful running continuously in the lab as well as out in the field.
On your bench, the Rhino3's antenna can be placed on a windowsill, for example, feeding constant satellite signal information through a coaxial cable feedline to the Rhino3's receiver. In those kinds of applications you would likely operate the box from the AC line as well.
Of course, in some applications the Rhino3 does indeed extend GPS timing and reference capability where satellite reception isn't available. GPS satellite signals are acquired when they are in view, with the unit or its antenna outdoors; the system then reports latitude, longitude, and time just as any handheld GPS would. The Rhino3 also develops multiple 10-MHz ultra-stabilized outputs, as well as timing pulses.
When the unit is carried indoors to the lab or to a shadowed field application, the Rhino3's oven-heated and temperature compensated crystal oscillator takes over. The box therefore provides a signal accurate to 1-12 with a stability of 1-10. GPS stability can be maintained for an hour or two before GPS re-disciplining might be needed. The spec sheet indicates that the NiMH pack will let the unit run independently for up to three hours.
Note that the holdover stability of the Rhino3 is a whale of a lot better than most ovenized TCXOs (temperature compensated crystal oscillators). Of course, it's lower than a rubidium standard. But, as the man once said, you pays your money and takes your choices. What you use will depend on your needs.
No Rubidium Standard
Significantly, the Rhino3's accuracy and stability is akin to BVS's earlier Rhino1 and Rhino2 products, but because the Rhino3 is disciplined to GPS birds, it doesn't include the expensive rubidium-locked standards of its forebears. As such, its price is roughly half that of the earlier Rhino1 and Rhino2 systems.
Through individually-buffered output ports, the Rhino3 portable provides one TTL-compatible 1 pps signal, and three frequency outputs. These 50-ohm ports are equipped with BNC connectors. For their part, the Rhino3's three 50-ohm sinewave 10-MHz outputs can drive lab equipment that needs phase-locking, such as multiple spectrum analyzers.
According to BVS Chief Technical Officer Gary Schober, the pulse outputs are especially welcome by users developing and deploying CDMA cellphone systems. The pulses can be used to ensure proper timing of CDMA-specific frame rates and short codes, for example.
Processing Input Signals
Notably, the Rhino3 also includes sinewave and TTL-compatible input ports. These permit you to feed in signals of your choice, so that you can actually measure their frequency drift and phase shift.
The Rhino3's internal phase comparator and microprocessor team up to provide an instant display of any error between the system's internal oscillator and your external signal. Moreover, you can feed the system's "smart clock" output data to a PC (usually a laptop), gathering long-term data sets. The box includes an RS-232 port for the purpose.
If you do use the Rhino3 in conjunction with your PC, all of the portable's functions that are usually accessible using the front-panel controls, 2-line x 16-character LCD, and LED indicators are then controllable and readable from your computer. BVS includes PC software for the purpose.
In recent months, we've reviewed a number of cost effective portable test-and-measurement products from BVS. The firm's Rhino3 continues the trend. Contact Gary Schober for more details.