Help with EasyPal SSTV software
We have a local two meter SSTV net on Sundays. We mostly use mmsstv software and have had great success. Recently we tried EasyPal digital software. We downloaded the software from KC1CS, set it up as best we knew how and it worked perfectly the first week. The results were amazing. The next week I could not make it work nor could the only other person using it. I can't figure out why, especially since we didn't change any thing that we know of. When I am in receive mode, I can see the callsign of the sending station and see the segment numbers changing, etc. However at the end, no picture. All I get is a message that says "Failed to encode". When I transmit, everything appears to be transmitting fine, but the other person gets nothing at all. Any ideas of what we are doing wrong? We are completely stymied on this one. Any advice would be greatly appreciated. Thanks for reading and 73s. K8LPD, Lansing, MI.
Have you tried to get a "fill", obtained by sending a BSR to the originating station ?
How many segments are reported as "missing" after the originating station finishes transmitting ? You should be able to recover a picture when around 85% of the segments are received.
Was the same station transmitting each and every time? Or did you take turns trying to transmit and receive. There should have been at least one station that could decode the picture transmitted by another station.
What version of EasyPal are you using? How are you determining the amount of modulation that you are using?
When your audio level is OK from the receiver to the soundcard input, the audio level should be about 75% of full scale, and the S/N should be about 10-15 dB , possibly better on FM . How does yours compare?
Inquiring minds want to know ! 73, and good luck, Jim
Last edited by AG3Y; 08-14-2008 at 10:59 PM.
Jim certainly knows much more about this than I do, but here are a few random thoughts:
1. When the other guy is sending, you'll see three little green boxes (about 2mm square at the top of your watrerfall, and you should see three white lines descending from those little squares and lined up with them. Do you see that? If not or if they don't line up pretty close, you may be on slightly different frequencies and that can cause problems.
2. In the box above the waterfall, you should see 5 little boxes, about 1/4 in square. All of those need to be green after the first few seconds. If not, but if #1 is OK, adjust your audio levels, either with the RX gain or the soundcard settings. Don't over drive the sound card!
3. In the Box above the waterfall, check "encode 2". Not exactly sure what this does, but it seems to help, tho that may be mostly on xmit.
4. at the bottom of your waterfall, you'll see a "ribbon bar" that's mostly red. It's a progress indicator and should gradually, from left to right turn green as the picture comes in. If you miss segments, you'll see some red marks in it indicating the missed segments. What does it look like?
5. Be sure you have "progressive receive" turned on (in setup).
6. In the box above the wqaterfall, you should see small boxes indicating level and S/N ratio. Are these OK? (S/N greater than 12dB is mostly OK.
I'm assuming you're using FM. If you're using SSB, I suspect a tuning problem. Let the program autostart the pic. The first few segments of the pic are some sort of header, and you must copy them to get the rest of the pic to decode. You'll start out with 4 of the 1/4" boxes green, and once you get the header, the top box will turn green. Thjis is NOT like MMSSTV, where you can start copying a pic in the middle!
I do this mostly on HF, but it should be the same on VHF. If I've made any errors, I hope Jim will correct them for me.
[EDIT]. The more I think about it, the more I suspect one of you is overdriving / underdriving a sound card. Again, assuming this is on FM.
Last edited by k3wrv; 08-14-2008 at 11:58 PM.
Ham radio is something you DO and LEARN. NOT something you BUY!
Pretty good summary, Bob, except since they are using FM, unless the tuning is really a lot off, and the audio is distorted as a result, they should NOT be having any frequency problems.
It would be a good idea to check the calibration of your soundcard against WWV, however. If you have been using MMSSTV, you should already be familiar with the procedure.
If you have two computers, two radios, etc. you should be able to send from one of the setups to the other and see what is happening. I have run two instances of these programs on one computer using two soundcards with great success.
Bob is perfectly correct in that you MUST have your soundcard levels correct on both receive and transmit sides. If you over-deviate the FM signal, you will be losing too many digital streams to decode the audio properly.
How does that little blue-green amplitude vs frequency line in the small box above the waterfall look ? It should be almost perfectly flat from the lowest frequency ( around 500 hz ) to the highest one ( 2500 hz ) and fairly low in amplitude. Your waterfall should show a somewhat mottled appearance ( hard to explain, but NOT solid , which would indicated overdriving the card )
Please let us know the results of any further test you are doing. Bob and I have both had fairly good success, even in these terrible conditions on the HF bands, and you should be able to recover an FM signal almost perfectly! I have even sent a signal across a small FM part 15 device to a portable radio and the results have been stunning!
Good luck, 73, Jim