<div dir="ltr"><div>Thanks, good info. But I disagree about the resolution. *most* presentations I see are very wasteful of fonts. They use big fonts and maybe only 4 bullets per slide. On the other hand some slides use painfully small font that are ridiculous. <br><br></div><div>I always toke care to use large font, and big ideas and graphics that are representative of concepts and do not need detail resolution.<br></div><div>I think my slides would work OK via SSTV resolution.<br><br></div><div>But I agree too many presentations are unreadable even at normal resolution anywhere in the room but the front row. People just dont have a clue when they prepare such unreadable presentations.<br><br></div><div>Bob<br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, May 4, 2020 at 4:51 PM Stephen H. Smith <<a href="mailto:wa8lmf2@aol.com">wa8lmf2@aol.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">On 5/4/2020 12:45 PM, Robert Bruninga wrote:<br>
> The local radio club wants to move to on-line technical talks but got bogged <br>
> down in arguments over teleconferingin protocols and security..<br>
> <br>
> I's like to transmit my presentation as SSTV FAST mode (13 seconds per slide) <br>
> and give the talk on the local repeater. The FAST FM mode premiered in the <br>
> (decades ahead of its time) Kenwood VC-H1 And generally has to connect to the <br>
> modulator and discriminator and not the voice circuits.<br>
> <br>
> Has anyone used FAST FM mode for SSTV? Can it be received by most folks <br>
> without having to get to the discriminator for receive?<br>
> <br>
<br>
<br>
1) NO! The fast mode is a failed protocol that never gained acceptance. No <br>
one except owners of the now rare VC-H1 that also have the only radio that <br>
worked with the VC-H1 in fast mode (the TH-D700) can send/receive it. NO SSTV <br>
software supports the fast mode.<br>
<br>
<br>
2) The resolution of any normal SSTV frame (including the fast mode) is only <br>
320x240 pixels -- far far too low to reproduce any kind of presentation with <br>
text or detailed graphics such as maps or schematic diagrams.<br>
<br>
The only modes to go above the quarter-VGA 320x240 are some of the PD modes <br>
that can do a standard 640x480 VGA (2-3 mins/frame) or SVGA 800x600 (4.5 <br>
mins/frame) image.<br>
<br>
Consider that normal PowerPoint presentations typically expect a 1024x768 XGA, <br>
1280x1024 SXGA, 1280x720 half-HD or even 1920x1080 full HD display. At least <br>
3/4 of them use far too small text (to cram more onto each page), resulting in <br>
the text being unreadable to anyone but the first row of the audience . Sent <br>
over low-def bandwidth-limited 320x240 analog SSTV will guarantee that NO one <br>
will be able to read them!<br>
<br>
Further, the only way to create "fast mode" images is the unbelievably bad <br>
low-res camera head of the VH-C1. I radically improved the sent image quality <br>
of the VC-H1 (on standard SSTV modes) by connecting an external NTSC camera to <br>
it in place of the OEM head. (The jack on the VC-H1 for the camera is actually <br>
a standard NTSC 1-volt P-P composite video input.)<br>
<br>
<br>
3) The only way to get the fast mode out of a radio is via the raw FM <br>
discriminator. Radios that have the 6-pin mini-DIN "packet" or "data" port <br>
make this easily - one of the 6 pins is the discriminator-out connection, <br>
sometimes labeled "9600 baud packet". Full details on the port here on my website:<br>
<<a href="http://WA8LMF.net/6-Pin-MiniDin-Data-Connector" rel="noreferrer" target="_blank">http://WA8LMF.net/6-Pin-MiniDin-Data-Connector</a>><br>
<br>
Unfortunately, fewer and fewer radios are now coming with this port. I am <br>
painfully aware of this as I struggle to acquire basic monoband radios with the <br>
din port for APRS applications. NONE of the Chinese radios now flooding the ham <br>
market have the DIN port. Not to mention the god-awful BaoFeng disposable <br>
handhelds that more and more entry-level hams struggle to use on non-voice <br>
modes, usually with lousy results.<br>
<br>
FM/digital Transceivers are evolving toward entire radio-systems-on-a-chip that <br>
include RF, synthesizer, mixers, detector and audio on a single IC, These <br>
chip-sets are intended for high-volume cellular devices, but are now <br>
increasingly appearing in two-way radios as well. This type of design makes it <br>
increasing difficult to "tap the discriminator" (if in fact they even have an <br>
IF & discriminator). More often they are now direct-conversion DSP devices. <br>
(Nearly all the cheap Chinese radios are of this type.)<br>
<br>
I wind up having to pick up second-hand Yaesu FT-1500 2M monobanders off eBay <br>
or at swapmeets for building ammo-can trackers or ammo-can porta-digis. Jusat <br>
last month, I discovered that one of the last small-footprint VHF-UHF FM-only <br>
radios with the DIN port (the Yaesu FT-8900 10-6-2-70cm quad-bander) has just <br>
been discontinued with no replacement in sight.<br>
<br>
_____________________________________________<br>
Stephen H. Smith wa8lmf (at) <a href="http://aol.com" rel="noreferrer" target="_blank">aol.com</a><br>
Skype: WA8LMF<br>
EchoLink: Node # 14400 [Think bottom of the 2-meter band]<br>
Home Page: <a href="http://wa8lmf.net" rel="noreferrer" target="_blank">http://wa8lmf.net</a><br>
<br>
----- NEW! 60-Meter APRS! HF NVIS APRS Igate Now Operating ------<br>
<<a href="http://wa8lmf.ddns.net:14447/" rel="noreferrer" target="_blank">http://wa8lmf.ddns.net:14447/</a>><br>
<br>
<br>
<br>
Live Off-The-Air APRS Activity Maps<br>
<<a href="http://wa8lmf.net/map" rel="noreferrer" target="_blank">http://wa8lmf.net/map</a>><br>
<br>
Long-Range APRS on 30 Meters HF<br>
<<a href="http://wa8lmf.net/aprs/HF_APRS_Notes.htm" rel="noreferrer" target="_blank">http://wa8lmf.net/aprs/HF_APRS_Notes.htm</a>><br>
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</blockquote></div></div>