The AM Forum

Does anyone have any further information on what digital mode is used on 3710 ?

I found it very odd that this ends up 5kHz away from 3705, a a commonly used AM calling frequency.

That garbage has been showing up a lot down thare.

Nice working ya on the big oh-five.

klc

Nice working you too !

I figured out what it is....

HIGH RESOLUTION SSTV  (EZPAL)

A number of guys were sending pictures back and forth to each other. While I was listening, one of them made a comment, "Guys, you hear that scratching noise, it sounds like somebody off frequency". ROTFLH !!!!!!!!

Another one, replied, its those crazy AM guys.....

Those knot heads usually hang out 3713. They don't care if the freq is in use or not. They just fire up. Knot heads.

Usually tweek the EQ to give a little more shhhhhhh sound to get the hint across.
QRO and a good aerial is the only way to squash the problem...coz we know many others are doing the same thing beyond legal limit!!!! But The bigger TX they have, the bigger they fall when there's a crap out from a bad RF connection!!!!

There's always a contaminated freq where ever we go. 3705 was dead for a long time and that's "Advance Class" folks........now this digital stuff. The beauty of SDR makes it no problem for me.
I wonder if the HD pictures are the usual trash that is sent over the air......???

I'll be looking at 3705 later this evening.......
Fred

A couple of weeks ago one of their number came down where I was calling CQ on 3705Kc, he switched to AM, and said I was wiping them out on 3710 and could I "narrow it up."

Uh, no.  But I did give it up for the evening because he was actually nice about it.

They then continued to send what they described as photos of onetime singer Judy Collins.

Turns out there's a bunch of them, mostly really weak when they are on a voice mode, and I suspect the "problem" was the difference in signal strength between a reported 30+ on my station, versus the S-7 I was registering among them to my location.

Saturdays when I run the W3AOA memorial net on 3.858 a bunch fire up with the same type of digital transmission.  Pretty nasty QRM so we usually move up or down to get away from it.  Never use to hear fast scan stuff on 75 in the past.  

Joe, W3GMS  

Meet the new QRM, same as the old QRM.

Maybe its time for some NBFM down there ::)

My Hallicrafters HT-19 did come with an 80 meter output coil :)

Given the generally high QRN on 80 it would be my last choice for any image mode.

You can usually hear this mode on 14.233, where the analog SSTV hang out is 14.230. the majority of ops are decent about how they operate. Most newbees adjust their transmissions incorrectly and end up over modulating the SSB rig. The PC software for this stuff is mostly EZPAL as mentioned by Stephanie. It is a derivation from WinDRM software. Both are free to download and use. The WinDRM was initially set up for digitized voice transmission/reception. It uses 16 BPSK tones spread from 300 Hz to 2500 HZ or thereabouts. The problem is that even when you set up a rig for 100 W pep output, the meters will show 10W or less when sending the stuff. SO a lot of guys who do not know better crank up the audio and then splatter. This stuff sounds like the old Russian Airplane sounding jammers. A raspy buzz saw that lasts up to a minute or more depending upon file size. WinDRM, when doing audio is continuous for the transmission. There is another sound, a kind of musical chirpy sound that usually lasts a few seconds. That is usually a waterfall ID. These programs have a waterfall display to adjust tuning so that the three pilot type tones fall into place. A software module takes the station's call sign and creates a sequence of sounds so that your call sign, or even other text, will magically appear to flow down in the waterfall display. Not quite the same as Hellscriber. EZPal will even take a jpg or other image file and create a longer sound sequence to paint out the image in the waterfall display. naturally, sweep rates of the waterfall display needs to be adjusted for the correct aspect ratio, especially if you are using some other waterfall display capable program like Spectran.

But, the data transmission of the image files is quite robust. To demonstrate the mode at our local group meeting, we had  two laptops running EZPal and used only their built in mic and speakers to send images acoustically across the room. no radio at all. one merely listened to the other. We even talked during the transmission and it still got the images across. There is so much error correction in the transmission that when you have a clean signal, it only takes about 3/4 of the transmission to get the image.

This mode is susceptible to interference from say, a station tuning up in the middle of the signal. I have often observed this when trying to receive and decode signals. The image material seems to be: still life; natural scenes; pets or other animals; and women.  I have intercepted a fair number of suggestive images.

You don't need a computer/radio interface, or a CAT capable radio. Just a stable receiver and a PC with a soundcard and microphone plugged in. Just stick the mic in front of the speaker and run one of the programs.

One last point, if anyone even reads this, is that it is interesting to watch the broad signal in the waterfall display in late afternoon. as the conditions change on 20M the waves of fading show up tin the display in very interesting patterns.

I like watching the MSC window to see how the signal is propagating though, it's pretty interesting to watch.

I enjoy the mode. We sometimes use it on FM locally to move pictures or really any type of file around. You can send .exe files and whatever via it, not just images.

I've run a fair amount of DSSTV with the group on 7173. The free EasyPal software is very cleverly written and the learning curve is not very steep as far as getting it up and running. That being said, if you want to roll your sleeves up and go deeper there's plenty there to learn. The error correction scheme for missed data resembles PAR files in some ways (for those who grab files off the newsgroups) except the EasyPal software sends a reply transmission that identifies the exact segments needed to complete the file you have received. The sending station then replies with a small data package that fills in the missing data. The picture quality is excellent and doesn't resemble the grainy analog stuff sent back and forth with SSTV. The guys who play with this on 7173 are quite nice and help out anyone who gives it a shot. They also suffer from the same intrusions we experience, with people sliding up on an overlapping frequency and diddling around.

There are several DSSTV web receivers around the country and across the pond that automatically receive and post pictures that are sent back and forth. They are helpful when you're setting audio levels and determining how much picture compression to use when sending. One example is this site:   http://www.n8mdp.com/easypalpix.html

For those who like to experiment with different modes it's fairly amusing and the software is free. If you are already using any of the digital modes then you already have all the hardware you need. It's too bad that they are running so close to 3705, but I've noticed that they run on 3715 or higher when they see an established QSO on 3705. I give them room and slide down to 3695 if they're already there when I'm in that section of the band. There's plenty of room for all of us.

Rob W1AEX

Ive the HT-18 on one of the HT-9's, a Meissner EX Signal Shifter with the NBFM module and Band F 160M coil set on the other, plus the CE-100V for all modes (its actually Phase Modulation).

It is a fun mode if you're into digital stuff.  Those guys go up a few kc's because the EasyPal software really needs a clear signal to decode well... so they are more bothered by QRM than AMers are even.... I don't know about the 3.713 group, but the groups on higher bands are pretty good guys and if they are the same guys, I bet simply asking them to move up a bit would work.

I'm game. Let me know when.  ;)

Phil - AC0OB

THe problem is 3710 or so will be vacant, we'll have a QSO there, then these idiots just start right up on top with no ID, no request, etc.  This seems to happen every time someone happens to use "their" frequency.  I have heard them go for hours with no voice ID.  They are, in my experience, some of the most arrogant and selfish group of knotheads (as Steve said) I've had the displeasure to encounter on ham radio.

Or just a couple of strapping AM signals.  But in any case, make sure the frequency is indeed clear before transmitting. You don't want to be guilty of the same tactic, i.e. starting up on top of an existing QSO.

By "existing QSO" I mean when at least two stations are actively engaged in transmitting and talking to each other.  This does NOT mean a "dead-air group" where one or two members monitor the frequency 24/7 but hours may pass without transmitting, yet the instant someone outside their group happens to transmit on or near the frequency, it suddenly becomes "in use".

I simply do not recognise dead-air groups.  Use it or lose it. You don't queue up at the bank teller's, then suddenly decide to leave to tend to some other business, and come back a few minutes later and expect to return to your same spot.  You start all over again at the end of the line.

I wonder if those guys ID with their digital mode.  I was under the impression that when running SSTV you were supposed to ID at least every 10 minutes using voice, and when running RTTY and other digital modes you were supposed to ID with CW. Or has the FCC deleted that rule, as they did with the prohibition against modulating more than 100%, simultaneous amplitude and frequency modulation, and the requirement to possess instruments capable of "accurately measuring" transmitter power if you run more than 90% the legal power limit?

"By existing QSO... dead air groups...." etc, etc...

Sometimes I call CQ for a minute or two and then say "now listening for any AM station".   I then wait about a minute and call again....   Inevitably, moreso on 40 meter I notice... someone will come in on ssb and start calling CQ without asking if the frequency is in use.... this usually happens after maybe 45 seconds of silence while I await a response.  I will then say "the frequency is in use, I am and have been calling CQ" then continue calling. 

Do I own this frequency at this point?  I always assumed I did since I am actively using it for a CQ call.  What do you all think?

As far as digital mode ID... I am fairly certain that one can now ID in the mode, voice (which is illegal in most digital mode frequencies) or CW ID is no longer necessary.  I can tell you that the SSTV (and the Digital SSTV) modes are run in the phone bands due to the bandwidth necessary, (they run with transceivers in SSB mode) and most groups do chat in phone between SSTV transmission, if nothing else to ID and say they are about to transmit in a certain format, but often they chat about the picture about to be sent or just sent.

John

I think it's a grey area, regarding calling CQ.  If you call CQ, and no-one comes back to the call, does that mean you have established presence on that frequency, and have priority over someone else slipping in with their own CQ while you are listening, before you make another call?  You haven't yet established any communication for the other station to be interfering with. I suppose calling CQ on top of another station while he is still calling CQ could be construed as wilful interference.  But would that be any different from participating in a DX pile-up?

Maybe the FCC has relaxed the rules for identification, but I seem to recall that when analogue SSTV first started to be used, one had to ID on voice or CW.  I also recall that RTTY operators had to ID on CW as well as Baudot. That may have all changed with the advent of the digital modes used to-day.  Since I don't presently work those modes, I haven't bothered to keep up with the pertinent rules in Part 97.

Same here. I called CQ one evening on 3.705 as it appeared to not have had any activity whatsoever for 30 minutes.  I identifed and asked if the freq was clear, etc. No response so I called CQ. All at once this SSTV signal jumped right on about 3.708 or so. I continued calling CQ and had a short QSO and finally the SSTV moved up to about 3.713 or thereabouts. No ID from the SSTV, no announcement they might beginning a QSO, no nuttin.'

Phil - AC0OB  

What country are you from?

8-land

Typos and bad proofreading  :'(

some sstv and digital mode programs provide the option of a trailing CW ID.

Seems to be the case -- ID is required, but it can be within the mode of operation, or some combination of modes as long as they're "specified" or "applicable."  That seems NOT to rule out IDs in a proprietary system, such as the automated email system WinLink found on HF.  That's where I first heard it was legal to not identify in-the-clear.  Nice.  These automatic store and forward stations are thus harder to identify as the source of interference they may cause.  Probably won't be long until the guys sending pictures of Judy Collins just shoot a photo of their call sign and play it out every so often.

http://www.w5yi.org/page.php?id=124

Sounds like a very different group from the 40 meter bunch that does a voice ID before every digital transmission and has a very pleasant demeanor. Some DSSTV stations do a visible text ID in the waterfall, but since they are in the voice portion of the band I don't think that cuts it. At any rate, your description of the 3710 group indicates unwelcome moronic behavior in an area of the band that has generally been a peaceful place to chat. From experience I can tell you that it doesn't take much to make make a mess of that mode as the SNR needs to be quite high for error-free transmissions. With that in mind I would imagine they would be motivated to not snuggle up too close to a strapping and well-filled out AM signal. Time will tell I suppose!

73,

Rob W1AEX

They took Saturday night -> Sunday morning off, or else they moved.

Or maybe the Aurora creeped them out.

Apparently, that would be enough to satisfy the legal requirement.

I have no dealings with the 3713 Digi SSTV group but I do know the fellas on 7.173 are a good group of considerate operators.  Rob is right and this is what I was alluding too in a previous post... Strapping AM would be more of a problem to them than the digital hash is to us... just saying...not avocating malicious interference.  :-\