Jitter Measurements

This simple Python script, measure-jitter.py, makes some Jitter measurements.

Script

measure-jitter.py

#!python3

"""This program illustrates making Jitter measurements in
the Infiniium XR8 oscilloscope.
"""

# Import modules.
import pyvisa
import sys
from matplotlib.ticker import EngFormatter

# Global variables.
oscilloscope_visa_address = "TCPIP0::localhost::hislip0,4880::INSTR"
timeout = 20000  # 20 seconds.
eng_s = EngFormatter(unit="s", places=2, sep=" ")
eng_V = EngFormatter(unit="V", places=2, sep=" ")

# Files location.
standard_folder = "C:\\Users\\pw5670\\Documents\\Keysight\\Infiniium\\"

def exit_program():
    """Exit program."""

    # Close connection to oscilloscope.
    sys.stdout.write("Closing oscilloscope connection.\n")
    Infiniium.write(":SYSTem:GTLocal")  # Unlock GUI.
    Infiniium.clear()  # Clear oscilloscope communications interface.
    Infiniium.close()  # Close communications interface to oscilloscope.
    rm.close()  # Close resource manager.
    print("End of program.")
    sys.exit()


def check_error_queue(when):
    """Check error queue."""

    errors_found = False
    while True:
        # Keep reading errors until "No error".
        error_string = Infiniium.query(":SYSTem:ERRor:NEXT? DIAGnostic")
        if error_string:  # If there is an error string value.

            if error_string.find("0,", 0, 2) == -1:  # Not "No error".
                errors_found = True
                print(f"ERROR: {error_string}")

            else:  # "No error"
                break

        else:  # :SYSTem:ERRor:NEXT? DIAGnostic should always return string.
            errors_found = True
            print("ERROR: :SYSTem:ERRor:NEXT? DIAGnostic returned nothing.")
            break

    if errors_found:
        print(f"Exited because error(s) found when: '{when}'")
        exit_program()


# ==========================================================
# Main program:
# ==========================================================

# Connect and initialize oscilloscope.
rm = pyvisa.ResourceManager("C:\\Windows\\System32\\visa64.dll")
try:
    Infiniium = rm.open_resource(oscilloscope_visa_address)
except Exception:
    print(
        f"Unable to connect to oscilloscope at {oscilloscope_visa_address}. Aborting program."
    )
    sys.exit()

Infiniium.timeout = timeout  # Set global timeout.
Infiniium.clear()  # Clear the instrument bus.
# Lock GUI happens automatically.

# Move waveform file to oscilloscope disk.
wfm_data_file = "Jitter_Noise.h5"
wfm_data_file_local = f"../{wfm_data_file}"
wfm_data_file_osc = f"{standard_folder}{wfm_data_file}"
f = open(wfm_data_file_local, "rb")
file_bytes = f.read()
f.close()
message = f':DISK:FILE:WRITe? "{wfm_data_file_osc}",'
Infiniium.write_binary_values(message, file_bytes, datatype="s")
success_or_failure = Infiniium.read().strip()
if success_or_failure == "1":
    print(f"Local file copied to oscilloscope disk: {wfm_data_file_osc}")
else:
    print(f"FAILURE copying local file to oscilloscope disk: {wfm_data_file_osc}")

# Default Setup.
print("Default Setup.")
Infiniium.write(":SYSTem:DEFault")

# Stop acquisitions and clear the display.
Infiniium.write(":ACQuire:STOP")
Infiniium.write(":ACQuire:CDISplay")

# Load waveform data from oscilloscope disk into waveform memory.
Infiniium.write(f':WMEMory1:FILE:NAME "{wfm_data_file_osc}"')
Infiniium.write(":WMEMory1:FILE:LOAD")
print(f"Waveform data loaded from oscilloscope disk: {wfm_data_file_osc}")

# Turn off channel 1.
Infiniium.write(":CHANnel1:DISPlay OFF")

# Make jitter measurements.
Infiniium.write(":MEASure:JITTer1:JITTer:RJBandwidth NARRow")
Infiniium.write(":MEASure:JITTer1:JITTer:TJBer 1E-12")
Infiniium.write(":MEASure:JITTer1:JITTer:EDGE BOTH")
Infiniium.write(":MEASure:JITTer1:JITTer:SMEThod SPECtral")
Infiniium.write(":MEASure:JITTer1:JITTer:MODE TPHase")
Infiniium.write(":MEASure:JITTer1:JITTer:EOPening SER")
Infiniium.write(":MEASure:JITTer1:JITTer:PTYPe PERiodic")
Infiniium.write(":MEASure:JITTer1:SOURce WMEMory1")
Infiniium.write(":MEASure:JITTer1:JITTer:UNITs SECond")

jitter_results_dict = {}
Infiniium.write(f":MEASure:JITTer1:JITTer:ANALysis ON")
jitter_measurements = ["EWIDth", "TJ"]
for meas in jitter_measurements:
    result = float(Infiniium.query(f":MEASure:JITTer1:JITTer:{meas}?"))
    status = Infiniium.query(f":MEASure:JITTer1:JITTer:{meas}:STATus?").strip()
    reason = Infiniium.query(f":MEASure:JITTer1:JITTer:{meas}:STATus:REASon?").strip()
    jitter_results_dict[meas] = (result, status, reason)

# Make noise measurements.
Infiniium.write(":MEASure:JITTer:NOISe:RNBandwidth WIDE")
Infiniium.write(":MEASure:JITTer:NOISe:MLOCation 50")
Infiniium.write(":MEASure:JITTer:NOISe:UNITs VOLT")

noise_results_dict = {}
Infiniium.write(f":MEASure:JITTer1:NOISe:ANALysis ON")
noise_measurements = [
    ["EHEight", ""],
    ["TI", "LEVel1"],
    ["TI", "LEVel0"],
]
for meas, level in noise_measurements:
    if level != "":
        Infiniium.write(f":MEASure:JITTer1:NOISe:{meas}:LEVel {level}")
    result = float(Infiniium.query(f":MEASure:JITTer1:NOISe:{meas}?"))
    status = Infiniium.query(f":MEASure:JITTer1:NOISe:{meas}:STATus?").strip()
    reason = Infiniium.query(f":MEASure:JITTer1:NOISe:{meas}:STATus:REASon?").strip()
    noise_results_dict[(meas, level)] = (result, status, reason)

# Print selected results.
print("Jitter measurement results:")
for meas in jitter_measurements:
    (result, status, reason) = jitter_results_dict[meas]
    if status != "CORR":
        print(f"{meas}: {eng_s(result)}, status: {status}, reason: {reason}")
    else:
        print(f"{meas}: {eng_s(result)}")

print("Noise measurement results:")
for meas, level in noise_measurements:
    (result, status, reason) = noise_results_dict[(meas, level)]
    if level != "":
        if status != "CORR":
            print(
                f"{meas} ({level}): {eng_V(result)}, status: {status}, reason: {reason}"
            )
        else:
            print(f"{meas} ({level}): {eng_V(result)}")
    else:
        if status != "CORR":
            print(f"{meas}: {eng_V(result)}, status: {status}, reason: {reason}")
        else:
            print(f"{meas}: {eng_V(result)}")

# Check error queue.
check_error_queue("End of program")

# Exit program.
exit_program()