PPS Sources
Novus PPS Sources
Pulse Per Second (PPS) is often a critical signal in many system applications. When selecting or implementing a PPS source, there are several significant parameters to consider:
Key Parameters
Signal Type
Novus PPS sources are available with CMOS levels (3.3V and 5V) as well as LVDS output.
Drive Levels
Supports both high impedance loads (Z < 1000 Ohm) and 50 Ohm drive capability.
Pulse Width
Programmable from 100 ns to 500 ms, offering flexibility for varied timing requirements.
Understanding Jitter
Jitter is one of the more complex and critical parameters of a PPS system.
Radio Source PPS
Most GNSS receivers offer a PPS output, though performance can vary widely:
- Jitter is often specified as a sigma level dependent on signal strength.
- Most radios exhibit a 1-sigma jitter between 5 ns and 30 ns.
- Some receivers may not follow a Gaussian distribution, potentially introducing significant bias.
- PPS position can be influenced by cable lengths — though many radios provide compensation features.
Examples of radio PPS distributions are shown below.
Synthesized PPS
Another approach is to synthesize the PPS from a disciplined time source. Selection of the time base depends on holdover accuracy and jitter requirements:
- OCXO: ~1 ms/day holdover
- Rubidium: <20 μs/day holdover
A complex algorithm disciplines the synthesizer using weighted characteristics of the radio PPS signal. In advanced Novus units, thermal and mechanical isolation are employed to minimize jitter.
Typical pulse-to-pulse jitter performance for a standard Novus unit is shown below.
PPS Distribution Considerations
Distributing PPS signals introduces its own challenges:
- Latency can be managed via programmable delay sources.
- Skewing must be minimized, especially in complex systems.
Below is typical skewing data for the Novus ND3623 Distribution Amplifier.
Get in Touch
Contact Novus today to discuss your PPS source and distribution needs. We’re here to help you design and implement precision timing solutions.