This script is meant to be run with the Motorola SB6121 Surfboard Modem.

Sample a Motorola SB6121 Surfboard's Signal

#!/usr/bin/env python
"""Sample the modem's signal

This script is meant to be run with the Motorola SB6121 Surfboard Modem.

If you run it on a different modem, it might not work, but it's worth a try...

It should be run as a cron job, every minute (or whatever interval you'd like)
into a text file. The file can later be used by a json parser to analyze the
signal over time, which can be used to come to conclusions that you can argue
with the cable company's tech support about when the service goes down.""" 

import sys
import os
from optparse import OptionParser
import fileinput
import logging

from collections import namedtuple
import requests
from bs4 import BeautifulSoup
from datetime import datetime
import json

# Default paramaters to be used by option parser
DEFAULT_SIGNAL_URL = "http://192.168.100.1/cmSignalData.htm"

# Set up logging
log = logging.getLogger(__name__)
hdlr = logging.StreamHandler()
log_formatter = logging.Formatter('%(asctime)s %(levelname)s %(message)s')
hdlr.setFormatter(log_formatter)
log.addHandler(hdlr) 


def set_log_level(verbosity):
    """ 
    Set the log level based on an integer between 0 and 2
    """ 

    log_level = logging.WARNING # default
    if verbosity == 1:
        log_level = logging.INFO
    elif verbosity >= 2:
        log_level = logging.DEBUG

    log.setLevel(level=log_level)

def get_options():
    """ 
    Returns the options and arguments passed to this script on the commandline

    @return: (options,args)
    """ 

    usage = "usage: %prog [options] file1 file2 ..." 
    parser = OptionParser(usage)

    parser.add_option("-u", "--signal-url", dest="signal_url", default=DEFAULT_SIGNAL_URL,
                      help="The signal url Default: [default: %default]")
    parser.add_option('-v', '--verbose', dest='verbose', action='count',
                      help="Increase verbosity (specify multiple times for more)")

    options, args = parser.parse_args()

    return (options, args)

def main(args):
    (options, args) = get_options()
    set_log_level(options.verbose)

    log.debug("Starting with options: %s" % (options))
    
    
    timestamp = datetime.now().isoformat()
    
    try:
        r = requests.get(options.signal_url)
        soup = BeautifulSoup(r.content, 'html.parser')
    except:
        print json.dumps({'timestamp':timestamp, 'res':"error"})
        return
    
    res = {}
    
    for table in soup.find_all("table"):
        if not table.th:
            continue
        
        heading = table.th.font.contents[0]
        
        res[heading] = {}
        
        if heading:
            for table_row in table.find_all("tr"):
                if table_row.th:
                    continue
                
                row_data = []
                
                for s in table_row.stripped_strings:
                    if s.startswith("The Downstream Power Level reading is a"):
                        continue
                    
                    row_data.append(s)
                
                if row_data:
                    res[heading][row_data[0]] = row_data[1:]
    
    print json.dumps({'timestamp':timestamp, 'res':res})
    
    
if __name__ == '__main__':
    sys.exit(main(sys.argv[1:]))

Output looks like this:

{"timestamp": "2015-08-20T20:29:43.386229", "res": {"Signal Stats (Codewords)": {"Total Uncorrectable Codewords": ["2859", "1101", "2811", "1778"], "Total Correctable Codewords": ["473", "261", "307", "340"], "Channel ID": ["201", "202", "203", "204"], "Total Unerrored Codewords": ["629643765", "628717510", "628715909", "628717051"]}, "Upstream ": {"Symbol Rate": ["5.120 Msym/sec", "5.120 Msym/sec", "5.120 Msym/sec"], "Ranging Status": ["Success", "Success", "Success"], "Ranging Service ID": ["1979", "1979", "1979"], "Upstream Modulation": ["[3] QPSK", "[3] 64QAM", "[3] QPSK", "[3] 64QAM", "[3] QPSK", "[3] 64QAM"], "Power Level": ["39 dBmV", "41 dBmV", "40 dBmV"], "Frequency": ["23700000 Hz", "36500000 Hz", "30100000 Hz"], "Channel ID": ["3", "1", "2"]}, "Downstream ": {"Downstream Modulation": ["QAM256", "QAM256", "QAM256", "QAM256"], "Power Level": ["-5 dBmV", "-5 dBmV", "-6 dBmV", "-6 dBmV"], "Frequency": ["711000000 Hz", "717000000 Hz", "723000000 Hz", "729000000 Hz"], "Signal to Noise Ratio": ["37 dB", "37 dB", "37 dB", "36 dB"], "Channel ID": ["201", "202", "203", "204"]}}}

You could use this with a tool like jq to filter for the information that you want. I hope someone other than me finds this useful :)

Made Python3 and PEP 8 fixes in my fork, as well as fixed an issue that caused Downstream and Upstream headings to output with an extra space at the end.

Sweet! I just said to myself that I should write a script like this to sample the status of my modem. And you've already done it! Thank you.