Wednesday, June 10, 2015

Battleship Iowa Wefax Reception Update

For those that have asked about the problems I was having receiving weather fax transmissions using our Signalink and fldigi, I found the problem today, and "fixed" it.

Turns out there was a sample-rate mismatch between what Windows was using for the Signalink USB Audio Codec, and the settings in fldigi.

The settings Windows uses for "Recording" is normally something like 2 channel, 16-bit 44.1khz, the same as it uses for "CD Quality" audio playback, which makes sense since most consumers would want to record something that they could burn to CD and play.

After doing a Google session, and experimenting in fldigi by watching the signal "quality" in the waterfall display, I decided to switch to 2-channel, 16-bit, 48kHz, which Windows calls "DVD Quality".

This made the waterfall look much better as far as Signal-to-Noise ratio, but I still couldn't decode anything.

Somehow, I had it stuck in my mind that regardless of what Windows was using, the Signalink was using something else and passing the data directly to fldigi.

UH.....no, that's not how it works.

As soon as I went into the "Modems" setting on fldigi, and set the rate to 48000, I started getting picture decoding, and now we're getting usable weather maps.


Why didn't I have this trouble here at my home station? Well, I'm not using a Signalink on my Flex Radio 5000.

Since the "radio" is running on the same PC that the fldigi software is, I don't need an additional hardware box to digitize the audio from the Flex, and feed it to the program. The audio stays in the digital domain from the "radio" directly to the program using a pair of Virtual Serial Ports, connected together with a Virtual Serial Cable.

And in setting up the two ports and their "cable", I set the bit rate to be the same, so "it just worked".

Just one of the pitfalls of having one foot in the Analog Domain, and the other in the Digital Domain, I guess!


And for those that have asked about why we weren't on for Museum Ships Weekend.....


Well, we had to cancel at the last minute. There was a major film project for an upcoming TV program that resulted in the ship being pretty much shutdown for that complete weekend, as well as the entire week following.

Parking was a major hassle as the parking lot was used for the filming of the event (the ship was basically a backdrop), and access to and from the ship was severely restricted.

We talked with the Museum Ships people, and they would have allowed  us to operate from shore, BUT...we had to be in sight of the ship to do it.

That would have meant operating "mobile" from on-street parking, or finding another lot in sight of the ship where we could overnight with a generator,

It would have been just too much hassle, so we requested the Museum Ships people remove us from the list.

It's kind of a bummer because we were going to use this as a "full-up" test for Field Day, but the welfare of the Iowa comes first, so we accepted it without any bad feelings. They've been so good to us, that we have absolutely no reason to complain about missing a weekend "playing radio"!

6 comments:

  1. Glad you got it sorted... one of those 'Doh! moments...

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    1. Or as one of buddies calls it, a "Senior Moment"!

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  2. Good deal. I am lucky. My computer connects directly to the Kenwood TS-480 and just uses the soundcard with fldigi. Works the same with WSPR and MMSSTV.
    Terry
    Fla.

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    1. I could have done something like that with a simple interface to the radio.

      There's audio in/out available at one to the TS-850 accessory ports (it's where you plug in the Signalink), and I could have just made some cables to go to it. BUT, then you need some way to key the rig up for transmit, as the VOX circuitry doesn't work on the audio in of that accessory port.

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    2. Bummer on the VOX. I use CAT control with fldigi and VOX with WSPR (works on the 480 assy input). Can't beat dumb luck. I would have never found the problem you originally had.
      Terry

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    3. I just installed a USB Rig Control cable so the logging program we use can talk to the radio. It works fine with N3FJP's "AC Log", but when I try and set up the rig control section of fldigi, it locks up fldigi, and I have to use the Windoze task Manager to kill fldigi.

      And this is with fldigi running by itself, after a reboot to make sure AC Log wasn't still holding on to the COM8 port that Windoze reports the USB rig control cable is using.

      COM8 shows up in fldigi, and I've tried using both the hamlib interface, and their own RigCat interface, and every time after I enter all the required info, and hit "Initialize" to tie it to the port, it locks up solid. Even tried waiting 10 or 15 minutes, but no joy.

      I wanted to get fldigi set up by itself to confirm the USB rig control cable worked with it, and if it did I was going to set up a couple of "Virtul Serial Ports" so both programs could share the data coming from/going to the rig.

      I've got a real Kenwood IF232 PC interface box (actually I've got three or four leftover from my Kenwood days), but seeing as the IF232 boxes go for over $125 on eBay, while a good quality USB cable is about 35 bucks, I just couldn't bring myself to use one on the Iowa!

      I might just take one in anyway to see if fldigi still locks up the PC when configuring it for rig control.

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Keep it civil, please....