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V1.92 Fax decoder

G8JNJG8JNJ
in KiwiSDR Discussion
Hi John,

The beta Fax decoder in V1.92 is very impressive even in its current form :-)

I realise that there is much more work to be done, but I tried the record function and I don't see a thumbnail when I press stop and when I click on the missing thumbnail image space I just get a blank image page.

Checking the size of the stored file fax.ch2.png shows 0KB.

Regards,

Martin - G8JNJ



Comments

  • SWLJO43SWLJO43
    Hello John, here is the same: the fax.ch0.png is empty.

    The Fax decoder is working well. Thank you.

    And now a JT65 decoder with reporting to pskreporter.info :-)

    cu Dirk - SWLJO43
  • G8JNJG8JNJ
    edited June 2017
    Hi John,

    Is it possible to have the option to default to the currently tuned frequency rather than the first pre-set ? 

    This would allow non-standard or newly discovered frequencies to be more easily used.

    Plus can the audio be muted when the Fax decoder is running ?

    Regards,

    Martin - G8JNJ
  • jksjks
    The fax code needs an external program to convert .pgm format files, which is what it records, to the .png file for download. I forgot to include installation of that program in the Kiwi makefile. I'll do that for today's release.

    I can change it to not disturb the initial frequency. I always changed to 7880 Hamburg because that was the best signal during development.

    You can always click the "mute" button while the fax extension is running. Not sure I want to make this the default behavior as it might confuse people. It could be a (future) user preference.

    G8JNJ
  • G8JNJG8JNJ
    edited June 2017
    Hi John,

    Some other suggestions.

    Would it be possible to use something like Shift - Click on FAX to align ?

    It's too easy to accidentally click on the image and mess up the alignment. A double action would fix that problem.

    Would it also be possible to drag the image up / down or resize it in the decoder window in order to view previous parts of the decoded image (or images)  as at the moment it's only possible to see about of the 1/3 height of one full image.

    Regards,

    Martin - G8JNJ
  • jksjks
    I was going to make the image window scrolling, like the waterfall. But the idea of a draggable image is interesting.

  • jksjks
    Question: I've not used external fax programs (I can't get any VAC programs to work on this Mac and the only one that is supposed to work costs USD$100). In those programs, when you adjust the image shearing, does it also adjust what's been previously displayed so you can gauge the correct value? Or does it just adjust newly received lines, so you have to wait a while to see the effect?

  • G8JNJG8JNJ
    Hi John,

    Scrolling of the image would be fine.

    Maybe an Shift-right click on a suitable top alignment reference point (e.g. image border) and an Shift-left click (or similar) on the same point towards the bottom half of the image could be used to set the skew ?

    Understood about everything else.

    Regards,

    Martin - G8JNJ




  • KA7UKA7U
    John, 
    Image adjustment in MultiPSK is done after the image is received. You stop the receiver, adjust the slant and alignment and then save the image. 

    FLDIGI provides adjustment for slant and it is remembered until it is changed. The alignment is either manual or automatic. Automatic works quite well, usually. FLDIGI seems to provide the more adjustable FAX receiver as compared to MultiPSK.

    I am a casual user, so you might want to test them to see. Both of them work well, although on my system FLDIGI occassionally locks up and I need to kill the program and restart.

    Ron - KA7U
  • G8JNJG8JNJ
    Hi John,

    Thanks for all the FAX updates in V 1.93 - that's a lot better :-)

    I've also copied you on some private emails that may be of interest to you.

    Regards,

    Martin - G8JNJ
  • G8JNJG8JNJ
    Hi John,

    I notice that some of the FAX presets are not tuning to the correct frequency.

    e.g. 

    8105 Athens, SVJ4 GR tunes to 8103.10 when it actually needs to tune to 8105.

    12786 Pt. Reyes, NMC US tunes to 12784.10 when it actually needs to tune to 12785.00

    I think this error occurs because of the way that some of the FAX transmission frequencies are specified by the different agencies that operate them.

    Some use the USB carrier frequency, whilst others use the center of the transmitted signal as the reference.

    Regards,

    Martin - G8JNJ


  • WA2ZKDWA2ZKD
    in place of a VAC, you can use a sound dongle and a wired loopback
  • KA7UKA7U
    John,
    Put some more effort into it this morning. MultiPSK does seem to be more stable here than FLDIGI and generally I'm finding the FAX image to be cleaner than the one from FLDIGI. Also the slant and alignment can be adjusted to receive correctly although it takes a bit of fiddling with the controls and requires the registered version of MultiPSK to work. So my vote now goes to the MultiPSK FAX decoder.
    Ron - KA7U
  • jksjks
    8105 Athens, SVJ4 GR tunes to 8103.10 when it actually needs to tune to 8105.
    I'll have to wait for a scheduled transmissions time to check.

    12786 Pt. Reyes, NMC US tunes to 12784.10 when it actually needs to tune to 12785.00
    This worked for me during US daylight hours: http://foxgulch.net:8073/?ext=fax,12786


  • G8JNJG8JNJ
    Hi John,

    I checked 12786 Pt. Reyes, NMC last night and it was correct on 12784.1 

    However there is another Fax signal that is using approximately the same channel but is slightly off-frequency. I've observed that the start tones don't line up correctly in the KiWi Fax pass-band. I'll keep an eye on this on and and try to get a screen grab.

    I've sent a private email with some other related information.

    Regards,

    Martin - G8JNJ




  • G8JNJG8JNJ
    edited June 2017
    Hi John,

    Just a thought - would it be possible to use a different colour font for the Fax presets that we know are good - so that it's easier to concentrate on the ones that haven't so far been confirmed ?

    This is my current list of Fax signals from my own (and a few other KiWi SDR's) that I have been so far able to confirm.

    Frequency MHz Callsign Location User

    2.6261 VMC Charleville, Australia Daytime 1Kw
    3.8530 DDH3 Pinneberg / Hamburg, Germany DWD, FAX
    4.2331 NMF Boston, Massachusetts, USA Daytime 4Kw
    4.2961 NOJ Kodiak, AK/USA USCG (wx fax)
    4.6100 GYA Northwood, UK F1C-120 weather fax
    5.0981 VMC Charleville, Australia All times 1Kw
    5.7530 VMW Wiluna, Australia 1Kw
    6.3300 Unid Unid LSB wx fax
    6.3385 NMF Boston, Massachusetts, USA All times 4Kw
    7.5331 VMW Wiluna, Australia All times 1Kw
    7.7945 JMH Tokyo, Japan FAX/120/576
    7.8781 DDK3 Hamburg / Pinneberg, Germany 20Kw
    8.0381 GYA Northwood, UK Anytime 10Kw
    8.1050 SWA/SVJ4 Athens, Greece Hellenic Meteorological Service 8Kw
    8.4656 JJC Kyodo News Agency, Japan 10Kw
    8.5020 NMG New Orleans, USA All times 4Kw
    8.6751 CBV Valpariso Playa Ancha, Chile 1Kw
    8.6801 NMC Pt. Reyes, California, USA All times 4Kw
    9.1081 NMF Boston, Massachusetts, USA All times 4Kw
    9.1631 HLL2 Seoul, Korea All times 3Kw
    9.9806 KVM70 Honolulu, USA Daytime 4Kw
    10.5531 VMW Wiluna, Australia All times 1Kw
    11.0280 VMC Charleville, Australia All times 1Kw
    11.0846 GYA Northwood, UK Daytime 10Kw
    11.0881 KVM70 Honolulu, USA All times 4Kw
    12.7436 JJC Kyodo News Agency, Japan 15Kw
    12.7481 NMF Boston, Massachusetts, USA Nightime 4Kw
    12.7841 NMC Pt. Reyes, California, USA All times 4Kw
    12.7880 NMG New Orleans, USA All times 4Kw
    13.5681 HLL2 Seoul, Korea 0000-1200 3Kw
    13.8806 DDK6 Hamburg / Pinneberg, Germany 20Kw
    13.9181 VMC Charleville, Australia All times 1Kw
    13.9866 JMH4 Tokyo, Japan All times 5Kw
    15.6135 VMW Wiluna, Australia All times 1Kw
    16.9691 JJC Kyodo News Agency, Japan 15Kw
    17.0677 JJC Kyodo News Agency, Japan 15Kw
    17.4281 9VF/252 Kyodo News Agency, Singapore 0740-1010 1415-1815 10Kw
    22.5401 JJC Kyodo News Agency, Japan 15Kw

    Maybe others can add to the list of confirmed stations and frequencies ?

    Regards,

    Martin - G8JNJ


  • jksjks
    I've never tried changing the font styles of individual menu items. I'll give it a try.
    Some browsers use different styles for the disabled items in the list, so it's probably possible.

  • arniearnie
    Hello John et al,
    got a tension to fiddle around the FAX decoder today and would like to share my notes and suggestions on its work so far.
    Yes, the images are slanted, but I understand the decoder is in an early stage of life and it might be fixed in the future.
    But here are a few less obvious bugs I've encountered:

    1) It seems I cannot run the "recorder" for too long, eg. 20 minutes or more, or, when I click the image, when it seems to be ready to view, I crash the server :( at least it stops playing the audio, the waterfall freezes and I can't download the image. I need to refresh the receiver page after a dozen of seconds to be able to continue to use it. Fortunately, my test signal was JMH on 3622.5 kHz (3620.6 USB) via Chiba, Japan, but what if I chose Kyodo News whose faxes are way longer? And then, trying to refresh the browser tab with, allegedly, my decoded FAX freezes the Kiwi again. But then, I'd rather launch the FAX decoder again and hit the record button to record another image. Would it be successful? ...

    2) ... it depends. If I stopped decoding that image before hitting the record button, then, after I end the recording, all I get is an empty PNG image, 0 bytes of size. That's regardless of whether I start decoding during the FAX or not. I think this is the reason why some of us get nothing instead of decoded images at times.

    3) On the plus side, clearing the decoder's buffer while recording the
    FAX doesn't result in losing anything of actual resulting picture.

    4) A few Japanese Fishery stations have FAX transmissions scheduled too. They're not listed in http://www.nws.noaa.gov/os/marine/rfax.pdf and it's a bit hard to obtain information on them, but I can tell JFX Kagoshima broadcasts a chart on 8658 kHz (tune to 8656.1 USB) eg. at 18:00 UTC. Full schedule, as received by somebody via FAX itself, is as follows: (note that all times are in JST = UTC+9h)
     image

    By the way, could anybody confirm the status of BMF in Taiwan, and CBV and CBM in Chile? They are all listed in that PDF, but, well, I haven't heard BMF for a few years and consider it inactive now. And I know nothing about Chilean stations.

    Best regards,
    Arnie
  • jksjks
    I've never tried capturing a file for a long period of time. Doesn't surprise me it's broken -- the file after 20 mins would be huge. It is recorded on the Kiwi server and that's why it must be downloaded. The download process is supposed to happen at a lower priority on both the server and on your browser so as to not disturb the Kiwi audio/waterfall, but again, it doesn't surprise me there is a problem here.


  • G8JNJG8JNJ
    Hi Arnie,

    Following an analysis made by a friend of mine, he suggests that "The slant would seem to be because the frequency of a streamed demodulated tone from the SDR is is about 90ppm lower than the demodulated tone of the original signal". "if left running, the audio from the SDR demodulation process will eventually overrun the streamed audio going out over the internet. A small amount (1 in 10000) must be lost when a buffer overflows somewhere along the line. "

    In answer to your specific question. I have heard CBV on 8.6751MHz  but nothing from BMF, VFA, VFF, VFR, RBW, JFA or JFW

    This is my current list of Fax stations that I have definitely confirmed as operational over the past 3 months.

    2.6166 GYA   Northwood, UK Night time 10Kw
    2.6261 VMC Charleville, Australia Daytime 1Kw
    3.5831 HLL2 Seoul, Korea 1200-0000 3Kw
    3.6206 JMH Tokyo, Japan All times 5Kw
    3.8531 DDH3 Hamburg / Pinneberg, Germany 10Kw
    4.2331 NMF Boston, Massachusetts, USA Daytime 4Kw
    4.2961 NOJ   Kodiak, Alaska, USA All times 4Kw
    4.3441 NMC Pt. Reyes, California, USA Daytime 4Kw
    4.6081 GYA Northwood, UK Anytime 10Kw
    5.0981 VMC Charleville, Australia All times 1Kw
    5.7531 VMW Wiluna, Australia 1Kw
    5.8051 ZKLF Wellington, New Zealand All times  5Kw
    6.33 UNID UNID LSB wx fax
    6.3386 NMF Boston, Massachusetts, USA All times 4Kw
    7.4316 HLL3 Seoul, Korea All times 3Kw
    7.5331 VMW Wiluna, Australia All times 1Kw
    7.7931 JMH2 Tokyo, Japan All times 5Kw
    7.8781 DDK3 Hamburg / Pinneberg, Germany 20Kw
    8.0381 GYA Northwood, UK Anytime 10Kw
    8.105 SWA/SVJ4 Athens, Greece Hellenic Meteorological Service 8Kw
    8.4656 JJC Kyodo News Agency, Japan 10Kw
    8.502 NMG New Orleans, USA All times 4Kw
    8.6751 CBV        Valpariso Playa Ancha, Chile 1Kw
    8.6801 NMC Pt. Reyes, California, USA All times 4Kw
    9.1081 NMF Boston, Massachusetts, USA All times 4Kw
    9.1631 HLL4 Seoul, Korea All times 3Kw
    9.9806 KVM70 Honolulu, USA Daytime 4Kw
    10.5531 VMW Wiluna, Australia All times 1Kw
    11.0281 VMC Charleville, Australia All times 1Kw
    11.0846 GYA Northwood, UK Daytime 10Kw
    11.0881 KVM70 Honolulu, USA All times 4Kw
    12.7436 JJC Kyodo News Agency, Japan 15Kw
    12.7481 NMF Boston, Massachusetts, USA Nightime 4Kw
    12.7841 NMC Pt. Reyes, California, USA All times 4Kw
    12.788 NMG New Orleans, USA All times 4Kw
    13.5486 ZKLF Wellington, New Zealand All times  5Kw
    13.5681 HLL5 Seoul, Korea 0000-1200 3Kw
    13.8806 DDK6 Hamburg / Pinneberg, Germany 20Kw
    13.9181 VMC Charleville, Australia All times 1Kw
    13.9866 JMH4 Tokyo, Japan All times 5Kw
    15.6131 VMW Wiluna, Australia All times 1Kw
    16.9691 JJC Kyodo News Agency, Japan 15Kw
    17.0677 JJC Kyodo News Agency, Japan 15Kw
    17.1445 NMG New Orleans, USA Nightime 4Kw
    17.1493 NMC Pt. Reyes, California, USA All times 4Kw
    17.4281 9VF/252 Kyodo News Agency, Singapore 0740-1010 1415-1815 10Kw
    22.5401 JJC Kyodo News Agency, Japan 15Kw
    3245.5 ZKLF Wellington, New Zealand Daytime 5Kw


    This is the list I'm still working through and have so far not heard.

    0.0214 GYA Northwood, UK F1C-120 weather fax
    0.1461 PEVEK, CHUKOTKA PENINSULA
    2.0521 NOJ Kodiak, Alaska, USA All times 4Kw
    3.2511 VFF Iqaluit, Canada 5Kw
    3.2511 VFR Resolute, Canada 5Kw
    3.5831 HLL2 Seoul, Korea 1200-0000 3Kw
    4.0121 ZSJ Cape Naval, South Africa 1600-0600 10Kw
    4.2261 CBV Valpariso Playa Ancha, Chile 1Kw
    4.3141 JJC Kyodo News Agency, Japan 5Kw
    4.316 NMG New Orleans, USA All times 4Kw
    4.3201 CBM Punta Arenas Magallanes, Chile 1Kw
    4.4141 VCO Sydney, Nova Scotia, Canada
    4.4141 VFA Inuvik, Canada
    4.481 SWA/SVJ4 Athens, Greece 8Kw
    4.6141 BMF        Taipei, Taiwan All times 10Kw
    4.7775 Rome Meteo Rome, Italy F1C-120 weather fax
    5.25 BMF / Taipei Meteo Taipei, Taiwan Weather Fax
    5.3341 RBW41 Murmansk, Russia
    5.8556 HLL2 Seoul, Korea All times 3Kw
    6.33 UNID UNID LSB wx fax
    6.337 New Zealand NZ Navy, Ice Fax
    6.4145 JFW Kagoshima, Fukushima, Japan FAX
    6.4436 RBW41 Murmansk, Russia
    6.9132 VCO Sydney, Nova Scotia, Canada
    6.9132 VFA Inuvik, Canada
    7.3931 HSW64 Bangkok, Thailand All times 3Kw
    7.5061 ZSJ Cape Naval, South Africa All times 10Kw
    7.7081 VFF Iqaluit, Canada 5Kw
    7.7081 VFR Resolute, Canada 5Kw
    7.9069 RBW41 Murmansk, Russia
    8.1381 BMF Taipei, Taiwan All times 10Kw
    8.14 BMF / Taipei Meteo Taipei, Taiwan Weather Fax
    8.3161 LOR Puerto Belgrano Radio, Argentina
    8.4571 NOJ Kodiak, Alaska, USA All times 4Kw
    8.658 JFA Chuo, Fukushima, Japan FAX
    8.658 JFW Kagoshima, Fukushima, Japan FAX
    8.6941 CBM Punta Arenas Magallanes, Chile 1Kw
    9.4571 ZKLF Wellington, New Zealand All times  5Kw
    10.1281 RBW48 Murmansk, Russia
    12.4106 NOJ Kodiak, Alaska, USA All times 4Kw
    12.6631 PWZ-33 Rio De Janeiro, Brazil 1Kw
    12.6706 LOR Puerto Belgrano Radio, Argentina
    13.5361 ZSJ Cape Naval, South Africa All times 10Kw
    13.8981 BMF Taipei, Taiwan All times 10Kw
    16.0331 9VF/252 Kyodo News Agency, Singapore 0740-1010 1415-1815 10Kw
    16.1331 KVM70 Honolulu, USA Night time 4Kw
    16.3382 ZKLF Wellington, New Zealand Nightime 5Kw
    16.9075 JFW Kagoshima, Fukushima, Japan FAX
    16.9761 PWZ-33 Rio De Janeiro, Brazil 1Kw
    17.1446 CBV Valpariso Playa Ancha, Chile 1Kw
    18.0581 VMW Wiluna, Australia Nightime 1Kw
    18.2361 ZSJ Cape Naval, South Africa 0600-1600 10Kw
    18.5581 BMF Taipei, Taiwan All times 10Kw
    22.5596 JFW Kagoshima, Fukushima, Japan FAX

    Some of these are still listed in the ITU list of Maritime stations but others are not (perhaps because they are military or commercial).

    From the list of confirmed stations it's possible to see that some like ZKLF Wellington are active on some frequencies, but I have not been able to confirm all of the ones listed for that station or others which are operational on some (but perhaps not all of their listed frequencies). 

    Can anyone else identify if any stations on my unconfirmed list are still active, or if I'm missing any others that are definitely operational ?

    Regards,

    Martin - G8JNJ



  • arniearnie
    5857.5 HLL2 switched to voice weather services in, I believe, Korean, Japanese, Chinese and English, a few years ago; it's not continuous but I've seen a carrier on 5857.5 every time I tuned in on Japan SDR. And I confirmed all Kyodo frequencies, except 4MHz one, at Twente when the Sun had been awaken one day this May (in fact, I didn't hear 4314.1 even at Chiba, so I assume it's inactive). Well, 16033.1 transmitted "black" tone only then.

    NOJ Kodiak is certainly active too, on 2052.1 4296.1 8457,1 (though this one is somewhat defective) at 1150z
  • G8JNJG8JNJ
    Hi Arnie,

    OK great - I also heard the Faulty NOJ on 8557.1 this morning - looks like the TX is being overdriven and is producing IMD.

    So including your previous information, my new 'Unconfirmed" list is now:-

    0.0214 GYA Northwood, UK
    0.1461 PEVEK, CHUKOTKA PENINSULA
    3.2511 VFF Iqaluit, Canada
    3.2511 VFR Resolute, Canada
    3.5831 HLL2 Seoul, Korea
    4.0121 ZSJ Cape Naval, South Africa
    4.2261 CBV Valpariso Playa Ancha, Chile
    4.3141 JJC Kyodo News Agency, Japan
    4.316 NMG New Orleans, USA
    4.3201 CBM Punta Arenas Magallanes, Chile
    4.4141 VCO Sydney, Nova Scotia, Canada
    4.4141 VFA Inuvik, Canada
    4.481 SWA/SVJ4 Athens, Greece
    4.6141 BMF Taipei, Taiwan
    4.7401 JFX Kagoshima, Fukushima, Japan
    4.7775 Rome Meteo Rome, Italy
    5.25 BMF / Taipei Meteo Taipei, Taiwan
    5.3341 RBW41 Murmansk, Russia
    6.33 UNID UNID weather chart but using LSB ?
    6.337 New Zealand Navy Ice warning
    6.4145 JFW Kagoshima, Fukushima, Japan
    6.4436 RBW41 Murmansk, Russia
    6.9132 VCO Sydney, Nova Scotia, Canada
    6.9132 VFA Inuvik, Canada
    7.3931 HSW64 Bangkok, Thailand
    7.5061 ZSJ Cape Naval, South Africa
    7.7081 VFF Iqaluit, Canada
    7.7081 VFR Resolute, Canada
    7.9069 RBW41 Murmansk, Russia
    8.1381 BMF Taipei, Taiwan
    8.14 BMF / Taipei Meteo Taipei, Taiwan
    8.3161 LOR Puerto Belgrano Radio, Argentina
    8.658 JFA Chuo, Fukushima, Japan
    8.658 JFW Kagoshima, Fukushima, Japan
    8.6831 JFX Kagoshima, Fukushima, Japan
    8.6941 CBM Punta Arenas Magallanes, Chile
    9.4571 ZKLF Wellington, New Zealand
    10.1281 RBW48 Murmansk, Russia
    12.4106 NOJ Kodiak, Alaska, USA
    12.6631 PWZ-33 Rio De Janeiro, Brazil
    12.6706 LOR Puerto Belgrano Radio, Argentina
    13.5361 ZSJ Cape Naval, South Africa
    13.7021 JFX Kagoshima, Fukushima, Japan
    13.8981 BMF Taipei, Taiwan
    16.1331 KVM70 Honolulu, USA
    16.3382 ZKLF Wellington, New Zealand
    16.9056 JFX Kagoshima, Fukushima, Japan
    16.9075 JFW Kagoshima, Fukushima, Japan
    16.9761 PWZ-33 Rio De Janeiro, Brazil
    17.1446 CBV Valpariso Playa Ancha, Chile
    18.0581 VMW Wiluna, Australia
    18.2361 ZSJ Cape Naval, South Africa
    18.5581 BMF Taipei, Taiwan
    22.5577 JFX Kagoshima, Fukushima, Japan
    22.5596 JFW Kagoshima, Fukushima, Japan

    Regards,

    Martin - G8JNJ



  • UR5VIBUR5VIB
    JMH, Tokyo, Japan fax transmission (5 kW TX) on 3621 kHz USB, was received in KN68BK, Ukraine, 16:58 UTC, with KiwiSDR Fax extension.
    The receiver antenna is Mini-Whip.
    Fortunately, there was no usual QRM at the moment.
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