If there is one thing that system engineers absolutely dislike the sight of, it’s the presence of random signals, like white noise, in a signal of interest. These signals corrupt the signal of interest and cause unnecessary loss of data.
Unfortunately, all systems introduce noise by default during signal transmission. And so, the transmitted signal must be processed and refined to restore it to its undistorted state and to extract the valuable information out of it.
At the same time, there are certain applications, particularly in the domain of testing communication equipment, where these same random signals play a pivotal role in helping engineers to assess the functionality of a device and optimize its performance for better.
PRBS, or pseudorandom binary sequence, is a type of algorithm-generated random signal that is quite extensively used for this purpose.
The signal comprises of lots of 1’s and 0’s, where the bit sequence has no defined (or obvious) pattern, and the correlation between the adjacent bits is completely random, mimicking a Kronecker delta function.
In short, and put simply, PRBS signal emulates white noise to perfection, which makes the signal extremely useful for testing purposes.
Okay…But why a “random” sequence for testing? Why not a clock signal or any other pre-determined, predictable data signal?
That’s because only a random (unpredictable) signal can truly test the functionality of a communication device or system.
During PRBS testing, a known data system is multiplied by a pseudo-random binary sequence, and the resulting signal is transmitted over a RF channel. Once received, the transmitted signal is then studied for anomalies.
Besides being used for device testing purposes, PRBS signal is also used for system identification. A series of tests are performed on the system of interest, and its response to each is noted. Using the information obtained from the tests, an experimental model is generated which reveals the properties of the system, thus helping engineers to better understand the system.
Given the PRBS signal is so useful, it’s worth knowing how to generate one, when and as needed.
There are several ways through which you can generate a PRBS signal. One common method is using a combination of CMOS devices. Other, more preferred, method is using a pre-built PRBS generator.
At ADSANTEC, we stock multiple PRBS solutions, available in as instrumentation, ICs and board products. View our complete line of PRBS generators here.