Finding symbol sequences within a pattern waveform

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
""" Script on PC controls FlexDCA or N1000A from PC).
This script demonstrates locating and displaying symbol sequences
within a pattern waveform in Oscilloscope mode. The script opens
a connection to FlexDCA and installs a simulated module.
Requires a  N1000A with precision timebase option.
"""
import pyvisa as visa  # import VISA library

ADDRESS = 'TCPIP0::localhost::hislip0,4880::INSTR'
#ADDRESS = 'TCPIP0::K-N1000A-00003::hislip0,4880::INSTR'  # DCA-X
CHANNEL = '5A'


def open_flexdca_connection(address):
    """ Opens visa connection to FlexFlexDCA. """
    print('Connecting to Flexdca ...')
    try:
        rm = visa.ResourceManager()
        connection = rm.open_resource(address)
        connection.timeout = 20000  # Set connection timeout to 20s
        connection.read_termination = '\n'
        connection.write_termination = '\n'
        inst_id = connection.query('*IDN?')
        print('\nFlexDCA connection established to:\n' + inst_id, flush=True)
    except (visa.VisaIOError, visa.InvalidSession):
        print('\nVISA ERROR: Cannot open instrument address.\n', flush=True)
        return None
    except Exception as other:
        print('\nVISA ERROR: Cannot connect to instrument:', other, flush=True)
        print('\n')
        return None
    return connection


def all_channels_off(FlexDCA):
    """ Turns all available channels off. """
    for slot in '12345678':
        for letter in 'ABCD':
            channel = slot + letter
            FlexDCA.write(':CHANnel' + channel + ':DISPlay OFF')


def install_simulated_module(FlexDCA, channel, model, signal='NRZ'):
    """ Simplified installation of a simulated FlexDCA module.
    model is type of simulated module. "DEM" is a dual-electrical module.
    "QEM" is a quad-electrical module. "DOM" is a dual-optical
    module. "QEM" is a electrical-optical module.
    signal if format of signal: NRZ or PAM4.
    """
    slot = channel[0]
    FlexDCA.write(':EMODules:SLOT' + slot + ':SELection ' + model)
    if signal in 'NRZ':
        FlexDCA.write(':SOURce' + channel + ':FORMat NRZ')
    else:
        FlexDCA.write(':SOURce' + channel + ':FORMat PAM4')
    FlexDCA.write(':SOURce' + channel + ':DRATe 9.95328E+9')
    FlexDCA.write(':SOURce' + channel + ':WTYPe DATA')
    FlexDCA.write(':SOURce' + channel + ':PLENgth 127')
    FlexDCA.write(':SOURce' + channel + ':AMPLitude 90E-3')
    FlexDCA.write(':SOURce' + channel + ':NOISe:RN 3.0E-6')
    FlexDCA.write(':SOURce' + channel + ':JITTer:RJ 4.0E-12')
    FlexDCA.write(':CHANnel' + channel + ':DISPlay ON')


def setup(FlexDCA):
    FlexDCA.query(':SYSTem:MODE OSCilloscope;*OPC?')
    FlexDCA.query(':TRIGger:PLOCk ON;*OPC?')
    FlexDCA.query(':SYSTem:AUToscale;*OPC?')
    FlexDCA.write(':ACQuire:EPATtern ON')
    FlexDCA.write(':ACQuire:RUN')


def view_entire_pattern(FlexDCA):
    PatternLength = FlexDCA.query(':TRIGger:PLENgth?')
    FlexDCA.write(':TIMebase:UIRange ' + PatternLength)
    print('\nThe entire {0} symbol pattern is displayed.'
          .format(PatternLength))


def waveform_acquisition(FlexDCA):
    """ Performs waveform acquisition limit test. """
    FlexDCA.write(':ACQuire:STOP')  # single acquisition mode
    FlexDCA.write(':ACQuire:CDISplay')  # Clear display
    FlexDCA.write(':LTESt:ACQuire:CTYPe:WAVeforms 32')
    FlexDCA.write(':LTESt:ACQuire:STATe ON')
    print('\nAcquiring 32 waveforms. Please wait...', flush=True)
    FlexDCA.query(':ACQuire:RUN;*OPC?')
    FlexDCA.write(':LTESt:ACQuire:STATe OFF')


def find_bit_sequence(FlexDCA, channel):
    print('*' * 30)
    print('A symbol sequence is a string of "1" and "0" characters.\n' +
          'For example: 1110')
    sequence = input('Enter a symbol sequence using symbols 0 and 1: ').strip()
    if (sequence in 'qQ') or (sequence == ''):
        return
    sequence = sequence.strip('"')
    sequence = sequence.strip("'")
    FlexDCA.write(':TIMebase:UNITs UINTerval')
    FlexDCA.write(':TIMebase:FIND:SIGNal CHAN' + channel)
    FlexDCA.write(':TIMebase:FIND:SEQuence "' + sequence + '"')
    i = float(FlexDCA.query(':TIMebase:UIPosition?'))
    pattern_start = int(i)
    total = 0
    print('*' * 30)
    while True:
        FlexDCA.write(':TIMebase:FIND:NEXT')
        i = float(FlexDCA.query(':TIMebase:UIPosition?'))
        bit_offset = int(i)
        bit = bit_offset - pattern_start
        if bit == 0:
            print('The bit sequence was not found.')
            break
        total += 1  # found sequence
        if total == 1:
            print('\nDisplayed span for "' + sequence + '" sequence is ' +
                  str(len(sequence)) + ' symbol.\n')
            print('REPEATEDLY PRESS ENTER KEY until all sequences are found.')
            print('Or, press "q" to exit.\n')
            print('Symbol Sequences Found'.center(30, ' '))
            print('-' * 30)
            print('      Number    Symbol Offset')
            print('-' * 30)
            first_found = bit
        elif bit == first_found:  # starting to repeat from beginning
            print('\n' + str(total-1) + ' sequences have been found.')
            break
        s = str(total).rjust(3, ' ') + '      '
        s += str(bit).ljust(5, ' ')
        print(s.center(30, ' '), end='')
        s = input()
        if (s == 'q'):
            break


FlexDCA = open_flexdca_connection(ADDRESS)
FlexDCA.query(':SYSTem:DEFault;*OPC?')
all_channels_off(FlexDCA)
install_simulated_module(FlexDCA, CHANNEL, 'DEM')
FlexDCA.write(':CHANnel' + CHANNEL + ':DISPlay ON')
setup(FlexDCA)
view_entire_pattern(FlexDCA)
waveform_acquisition(FlexDCA)
find_bit_sequence(FlexDCA, CHANNEL)
FlexDCA.write(':SYSTem:GTLocal')
FlexDCA.close()