Measurement of Crest Factor at the Output of a Limiter

Abstract

Limiters are used to protect sensitive components such as LNAs and radar receivers. This demonstration shows the effect that limiters have on the crest factor of your signal as its level is increased. The pulse generator has an internal noise source which is used to simulate a WLAN or LTE signal. The UFX7000 is used to simulate an LNA, and shows how crest factor is affected as signal and noise levels are varied.

Test the effect that a limiter has on your Communication Signal

NoisecomUFX7000A and Boonton USB 55000 SeriesDemonstration

Product Demo:

Limiters are used to protect sensitive components such as LNAs and radar receivers.  This demonstration shows the effect that limiters have on the crest factor of your signal as its level is increased. The pulse generator has an internal noise source which is used to simulate a WLAN or LTE signal. The UFX7000 is used to simulate an LNA, and shows how crest factor is affected as signal and noise levels are varied.

Target Users:

Design engineers, production automated test engineers working with wireless communication systems,radar systems and satellite systems for commercial and military applications.

About UFX7000A series:

The Noisecom UFX7000A series broadband noise generatorscreate complex and custom broadband noise signals for advanced test systems. The flexible interface allows control of multiple precision attenuators, switches, and filter banks to provide high output power broadband noise with superior flatness.Noise output level is adjustable in 0.1 dB optional steps withan optional input signal combiner followed by an attenuator that allows control of the noise & signal paths independently to vary SNR or Carrier to Noise signal testing.

Significant Features of UFX7000A series:

• Custom broadband noise frequenciesup to 40 GHz
• Remotely controlled via Ethernet, GPIB or RS232/RS422/RS423.
• Manually controlled by a front panel touch screen display.
• 0.1 dB step attenuator to adjust noise and signal levels (optional).
• 75 ohm or 50 ohm input/output impedance.
• Switchable filters for custom tailored noise bands.
• Front or rear panel input and output connectors. SMA, BNC or N types.
• Removable harddrive (military/defense applications).

About 55 Series Wideband USB Peak Power Sensor& Real Time Power Processing™:

Key benefits of the Boonton 55 Series wideband USB peak power sensor is the processing power and real-time signal acquisition featuring NO GAPS in acquired data. Unparalleled rise time and video bandwidth.

• Risetime: 3 ns
• Video Bandwidth: 195 MHz
• Resolution: 100 picoseconds (125 x faster than competition)
• 100,000 measurements/second. Re-arm trigger in microseconds, versus milliseconds or more
• 100 MSamples/second SUSTAINED sample rate – world’s fastest!
• 10  GSamples/second effective sample rate for repetitive signals (superior resolution)
• Continuous or gated CCDF (multi channel, see amplifier compression)
• Multichannel capability allows delay measurements
• Capture and analyze data 100x faster than conventional power sensors
• Real-time "video" display update rate versus a series of "snapshots"

Measuring Crest Factor by observing the output of a limiter and generating noise using UFX7000A and the Boonton USB55006:

Our test set-up works with a pulsed test signal with simulated OFDM modulation as the input signal to the limiter.  The broadband noise level generated by the UFX7000A is varied using remote or manual commands to change the noise or carrier levelin 0.1 dB steps over the unit’s full dynamic range to generate a desired SNR level. The output of the UFX7000A is connected to a Boonton USB55006 Peak Power Analyzer to display and measure accurate crest factor measurements. UFX7000A series allows the user to characterize Signal to Noise (C/N) performance of their Communication/Radar system by injecting precise AWGN onto the desired signal or provide broadband noise for jamming and interference applications for radar and communication receiver sensitivity measurements. The Boonton USB55006 sensors can measure up to 16 automatic measurements such as Rise time, Average and Peak power for Crest Factor Measurements. You will also be able to measure the rise of the noise floor.

Typical Test Results:

Existing and Comparable Products:

• UFX7000A series is Noisecom's flagship noise generator. With options and customization capabilities Noisecom can configure the unit to the user’s requirements.
• For the state of art the Eb/No testing system Noisecom also offers CNG-EbNo high-end Eb/No measurement instrument.It automates Eb/No(C/N) vs. BER/MER measurements by automatically measuring and controlling signal and noise levels. CNG-EbNo eliminates the need for power meters and test software to control and monitor Eb/No.