NTSC DigiLite

[g8ajn]

I have had a number of enquiries regarding using DigiLite boards with NTSC video.
The simple answer is yes,you can if you use the correct (i.e. NTSC) WinTV capture card. This applies to most broadcast formats, provided the WinTV capture card will handle it the system is ok with it. Once the card converts whatever video signal it is designed to work with into a mpeg2 stream it is exactly the same to the DigiLite software and hardware.
The capture card needs to produce program stream rather than transport stream. DL Transmit inputs the former and outputs the latter. Some cards do output transport stream, but DL transmit can’t use that.
There are often NTSC cards on EBay.
Dave G8AJN

[w0fms]

Well.. I picked up a NTSC Hauppage PVR-150 Low Profile card for my "shack" PC which-- is a second hand HP Pentium-D-- from E-bay (US). The low profile ones are now going for less than $20 US on E-bay US. (I might buy a second one for my kid's small form factor PC for that price-- but if I do every episode of SpongeBob ever made will fill up the hard drive!) -- of course a week ago I paid $23 and $7.69 for the cable to hook composite video and audio to the cards screwy audio and s-video connectors. The price of the cable dropped a buck too... see deflation is starting to happen in the US ... For now, I running a US "Government Cheese" ATSC converter box into it on Analog Channel 3 and it's working fine, since I don't yet have the composite video/audio cable. The LP PVR-150s could probably work in a normal PCI slot if you were to re-engineer a blank rear panel slot thinggy... but if not.. the full sized ones are going for about $10 more in the US e-bay.

Anyway.. setting GBPVR 1.4.7 the same way as described (fixed 2K bit rate) on the DigiLite web site seems to work -- I don't have the board quite built up enough yet to power the DSPic33 but at least it doesn't crash the TX app. Well.. actually I do but there isn't much of a reason to do so until I get the AD8346 which I'm still waiting for. Otherwise it's fully populated and the FT-2232H Mini Mod's Serial is set to "DATV" and FT245 FIFO on channel "A"as needed.

What I shouldn't be amazed at is how little CPU the PVR-150 takes up when in "Live TV" mode or in Manual record (about 7% in Live TV, 5% in record on the older Pentium-D machine it's running in). I wonder if the Hauppage "Collossus" card-- the H.264 card for $159 US wouldn't work the same for DVB-S2. I'd need a new PC to set that up (full sized PCI-E).. so maybe as a later project.

By the way, look at "digital-digest.com" for GBPVR10407.msi for 1.4.7 or "digital-digest.com" or "videohelp.com" for GBPVR10311.msi instead of C-Net Download.com. At least for me the file there was corrupt.

Also.. if you want to be able to stop the manual record easily on GBPVR... look for "Slimm-GBPVR" which will give you the capability to kill an existing recording.. it's a real pain otherwise to stop one, say scheduled for an hour...

But overall the thing appears to be far more stable than I'd have expected and the low rate video looks better than expected as well.

Like I said.. I'll attempt to document the usage of the BATC DigilLite in the US with "Never Twice the Same Color" video.. I do want to be careful not to step on anything that might be considered proprietary in the CQ-TV issue. Let me know if I say too much.

What is really "cool" about this project is that if I even include the 2nd hand PC in the price, I'm still at less than $300 US for the modulator project. (About $225 otherwise) I was fairly well stocked on parts but most of the parts ordered from Mouser for this effort were the more expensive ones.

73, Fred W0FMS

[g8ajn]

Thanks for the gen, Fred. Glad to hear that you are getting sorted out ok. There is quite a lot of initial software to get through and if one can use WinTV6 successfully that is probably better than using GB PVR. Let us know how it performs when you get it running ok on an NTSC video signal.
This is an amateur project for the very simple reason that we want everyone to 'play' with it and hopefully move it on and perhaps in a year or so we might be looking at a much more sophisticated system. However we have already compromised somewhat on the physical design in order to keep it as a 'homebrew' project, I believe that this is the correct approach in the early days to enable the maximum number of people to get on board.
Dave G8AJN

[w0fms]

Yeah.. I'm having fun with it, alright. I still have a bit to go, like getting up a 23cm signal source into it (which might be a sig gen at first since my old 141T spec an cuts off at about 1200 MHz it might be "used out of band" or at 902-928 MHz to initially set up into a dummy).

I do have the same oscillator as the "Ultram Tech" one I bought as a signal marker at 1152 MHz (at the time it was from Leitner Computers in Isreal but they seem to be out of business now-- off of e-bay). I will probably use that and the little PIC I2C generator you guys came up with for a LO. In the US we can use 902-928 MHz and big surplus cell site amplifiers (only some are linear though without major mods) and I might try that too... I can see that directly on my 141T so it's a intersting plan.

I might buy another of those PLL oscs from the BATC though as I rarely see them on e-bay anymore. Id guess though to follow the ARRL's bandplands the center freqs would need to be moved a bit.

Also I am still awaiting an AD8346... I have samples coming in theory.. but if they are delayed much longer I'll have to buy...

I am still not certain (though some are doing it) that DATV is legal in the US on 70cm. AM NTSC has been allowed in the US since 1959 and I find it ironic that one can have a 6-8 MHz wide image transmission on the 70 cm band. Yet at the same time there is a 56 kilobaud speed / 100 Khz bandwidth data rule for 70cm.

FCC Part 97.307(f)(6) States; “A RTTY, data or multiplexed emission using a specified digital code listed in 97.309(a) of this Part may be transmitted. The symbol rate must not exceed 56 kilobauds. A RTTY, data multiplexed emission using an unspecified digital code under the limitations listed in 97.309(b) of this Part may also be transmitted. The authorized bandwidth is 100 Khz.”

So although I'd love to run this on 70cm it does NOT appear to be legal to do so in the US! I know on the US DATV Yahoo list there is a ham now selling a DVB-C transmitter on 70cm that SHOULD be legal, IMHO it is not. I'm seriously thinking on petitioning the ARRL and the FCC personally if I have to to change this. Going from 6 MHZ AM to 2(ish) MHZ DVB-S (Or -C but maybe not 6 MHz wide -T or even ATSC) is really a no brainer here.

Sadder still is that 70cm is "under threat" now, do you'd think that somehting like this project would help us protect it.

One other thing I've been playing with is generating test cards with FFMPEG and I think I can generate a valid PS now in NTSC (PAL isn't really any different) from a .MP3 and a .JPG file).. once I verify it works, I'll pass that on. The command stucture is tricky and I have to verify that the CBR given is the same as the Conexant MPEG-II chip puts out. I'll try a PAL test card too and write it up on my 'blog.

I'm looking for an original WINTV CD-ROM now though.. If my fellow ham friends locally can't find one I'll have to shell out the $15 or so to Hauppage for a new one. The card I got is a MCE card but I'm lucky I found it as it is. GB-PVR does work and it works well.. but the interface isn't ideal for this project, true.

Lots of fun though. Maybe I can get some interest in ATV here in the Cedar Rapids, IA area again.. if not we can use for "special events" and demos.. but really I'm interested in making this take off in the US. Some of the ATV "Hotspots" like CA, Indianapolis and Dayton I could see this taking off in...

Thanks again guys.. 73 Fred W0FMS

[G4EWJ]

Another option for recording the program stream is GraphEdit (GraphEdt) which is in the Windows SDK. It's a lot more techy than GBPVR, but more flexible. Setting it up is a cross between Lego and join the dots. You connect a few software modules together graphically and the output is written to a hard drive or as UDP.

Well worth a look for the adventurous experimenter.

Brian

[w0fms]

I can confirm that the serializer and the BATC software does not care that the video is NTSC.

I don't have the Ultram Tech oscillator yet.. so I ran the board w/o the MMIC and the LO in place.

But here is a link to a video of an "ATSC" government sponsored (i.e. "government cheese" if you are American) SD converter box feeding NTSC analog video into a small form factor PVR-150MCE NTSC card and what the Digilte thinks it modulating.. or is trying to modulate with no LO or whatever. Looks fine. Figured I'd confirm this for you.

http://www.youtube.com/watch?v=QlvKGLl5aNs

Shows an interesting test of PBS's version of the Antique Road Show in of all places Iowa and then it's showing civil war era operating tools... so appropriate on so many levels!

73, Fred W0FMS

[G4EWJ]

Fred,

The video bit rate in the recording program needs to be a bit lower, to bring the padding up. The TS needs a bit of elbow room to cope with the varying incoming data rate. It's only approximately constant bit rate. It's not even constant over a 15 frame group of pictures. DigiLite Config suggests 2140 as the video bit rate for SR3000, FEC 1/2. I've calculated it to give 5% of padding, but that's only a ballpark figure and is open to experimentation.

The calculation also assumes an audio bit rate of 192k. I found that reducing it below that value had no effect or actually increased the amount of audio data. Some recording programs don't show anything below 192k in the setup for the PVR150.

Brian

[w0fms]

Yeah.. I was pushing it as close as I could when I took that video. If you saw one of my two 'blog posts about it I mention "about 100K less was more appropriate". It is interesting to note the Audio issue you mention though. Good to know, I guess. The couple of programs I've looked at the recorded data with seemed to indicate 128K CBR in the stream but I will investigate further. I was trying to fiddle with that setting because we don't need HiFi audio as hams! But MPEG-1 layer 2 audio isn't nearly as good as even MP3 so I doubt if you'd ever want to go below 96K with it even for "voice quality" anyway.

Thanks. I'm looking forward to getting this project even closer to completion.

Fred, W0FMS