fix: the format for comparison between RTCM packet preamble and current byte(#14)

[JeffYoung17]

As mention in #14,
the parsed RTCM packets are empty, by debugging, in rtcm_parser.py we found that combined_buffer[index] is str but _RTCM_3_2_PREAMBLE is int which make this judgment unsuccessful.
if combined_buffer[index] == _RTCM_3_2_PREAMBLE:

[robbiefish]

Thanks so much for providing this fix. One change is required before merging.

[robbiefish]

For me the buffer still comes in as a byte array by default, and this causes the node to crash for me. so we should have some logic in here to handle both cases. Also I think that you could use the encode function instead of looping. I had success with the following implementation, but as I said, my buffer is already bytes, so please let me know if this works for you

if isinstance(combined_buffer, str):
  ascii_values = combined_buffer.encode('utf-8')
elif isinstance(combined_buffer, bytes):
  ascii_values = combined_buffer
else:
  raise Exception('Buffer type is "{}" not a string or bytes, so we cannot parse it.'.format(type(combined_buffer)))

Also I think a better name for ascii_values would be combined_buffer_bytes

[robbiefish]

Closing this for now. If this is a problem for anyone else feel free to reopen