Sunday, 29 September 2013

CW Decode from HO-68 using MultimonNG - Update II

(This is an update to this post)

I tweaked the string that my stupid search script uses to be "BJ1SA " - this should then take into account the proper spacing of the characters. The best result I got out from that was this (I used the data to which I'd applied a narrow band filter):

 J1RA XW XW AAA TTT AW- ATE ETT TTT TTT TTT TTT TTT TTT TTT TTT XW XW EE
BJ1SA XW XW AAA TTT AU4 TBE ETT TTT TTT TTT TTT TTT TTT TTT TTT XW XW
BJ1SA XW XW AAA TTT AU4 TNT ETT TTT TTT TTT TTT TTT TTT TTT TTT XW XW
BJ1SA XW XW AAA TTT AU4 AVT ETT TTT TTT TTT TTT TTT TTT TTT TTT XW XW
BJ1SA XW XW AAU T5H H 5 <._.......>DHSH IIIEIS

BJ1SA XW XW AAA TTT AU4 AVE ETT TTT TTT TTT TTT TTT TTT TTT TTT XW XW
BJ1SA XW XW AAA TTT AU4 TBE ETT TTT TTT TTT TTT TTT TTT TTT TTT XW XW E
BJ1SA XW XW AAA TTT AU4 AVT ETT TTT TTT TTT TTT TTT TTT TTT TTT XW XW EIE
BJ1SA XW XW AAA TTT AW4 TDT ENTTTT TTTETTNTTTTTNAAAVATUA<....._>


This appears to be better than the previous decoding. The graphical representation of the search space is show here:

As you can see there is a much smaller range of parameters where the best decoding occurs.

I have now integrated in the multimonNG decoding of CW signals into my GroundStation software and have decoded signals in realtime from a number of satellites including FO-29 and CO-55. The current implementation I use is far from optimum as I have around 2.5kHz of audio going into multimonNG, so as mentioned previously I'll be able improve the performance by additional filtering.

I've also improved the calibration of one of my RTLSDR receivers such that I can receive meteor signals from the GRAVES transmitter - more data to follow on that subject at a later date.


2 comments:

  1. Hi Matt,
    I'm looking for someone to write a simple python script to use with MultimonNG, i need it to listen to MultimonNG and activate a GPIO output for a set period of time when it reads a specific POCSAG address.

    Willing to pay.

    contact me at kglover21@me.com if you're interested.

    ReplyDelete
  2. Great work. I only ever see numbers come up, like this:

    12045.034180,339
    12045.080078,288
    12045.125000,229
    12045.170898,164
    12045.215820,94
    12045.260742,18
    12045.306641,-62
    12045.351562,-143
    12045.397461,-228
    12045.442383,-316
    12045.488281,-403
    12045.533203,-490
    12045.579102,-574
    12045.624023,-658

    What am I doing wrong here? 73s Chris 2E0OBC

    ReplyDelete