Mercury.... NO AC3 :-(

[wejones]

Well, as mentioned in other two threads, I haven't been able to get AC3 audio out of my new Mercury-II. I had hopes that the problem was due to some issue with the optical input of my Soundblaster Extigy, which I've been using as an AC3 decoder for years via the coaxial input.

UPS FINALLY delivered the optical --> coaxial converter that I ordered, and I just connected it. Unfortunately, STILL NO AC3 AUDIO. The converter works fine on regular digital, but not on AC3. I really had hopes that this would work, but nope.

I hooked up the coaxial cable to my oscilloscope, and first displayed the signal from Montanna PBS, which has regular mpeg audio, and you can see a square wave with ringing, which is stable when there is no audio, but jumps around a lot when there is audio. When I switched to one of the PBS AC3 channels, I still got the square wave, but it doesn't jump around when there should be audio. Also, the Extigy is not detecting any Dolby Digital (it has a light that lights up when it sees Dolby Digital). I've reset the thing to factory defaults several times, and also upgraded to the newest firmware.

I really have to conclude at this point that my new Mercury is just not working right. The Mercury is detecting the channels as AC3, but just not outputting the AC3 signal. I guess I'll have to contact Sadoun to find out what my options are.

[radiobob]

Bill:

There's weirdness afoot! Suddenly I can get AC3 audio on PBS via my optical (toslink) cable where I couldn't before.

Today I was messing around with AMC3, scanning for additional channels and decided (why?) to try one more time to see if I could get AC3 audio. The optical input to the surround receiver was already selected since regular (non-Dolby) sound comes through fine, just as you describe with your Mercury. I hit the Dolby button on the surround unit's remote and switched to "Auto" mode and--VOILA!--for the first time, all the PBS channels now have sound! I'm pretty sure I've tried the "Auto" mode on my surround receiver before, but maybe...

To compound the weirdness, I still don't get AC3 from the "silent Spanish" channels on G10R. I haven't tried Pentagon Dolby on AMC1 yet, but I will after I finish this post.

Since Fortec touts the Mercury as having Dolby (as does Viewsat their box), I'm wondering what's going on. Even though I claim to be an audio engineer, I really know nothing about the actual nature of the AC3 stream. Is it possible that there's something new in the coding that your Mercury/Extigy combo doesn't "like", but my Viewsat/Sherwood combo suddenly does? I'm going to have to ask around on this one...

Meantime...hang in!

[wejones]

Originally Posted by radiobob

Bill:

There's weirdness afoot! Suddenly I can get AC3 audio on PBS via my optical (toslink) cable where I couldn't before.

Today I was messing around with AMC3, scanning for additional channels and decided (why?) to try one more time to see if I could get AC3 audio. The optical input to the surround receiver was already selected since regular (non-Dolby) sound comes through fine, just as you describe with your Mercury. I hit the Dolby button on the surround unit's remote and switched to "Auto" mode and--VOILA!--for the first time, all the PBS channels now have sound! I'm pretty sure I've tried the "Auto" mode on my surround receiver before, but maybe...

To compound the weirdness, I still don't get AC3 from the "silent Spanish" channels on G10R. I haven't tried Pentagon Dolby on AMC1 yet, but I will after I finish this post.

Since Fortec touts the Mercury as having Dolby (as does Viewsat their box), I'm wondering what's going on. Even though I claim to be an audio engineer, I really know nothing about the actual nature of the AC3 stream. Is it possible that there's something new in the coding that your Mercury/Extigy combo doesn't "like", but my Viewsat/Sherwood combo suddenly does? I'm going to have to ask around on this one...

Meantime...hang in!

That's interesting. AC3 is usually associated with Dolby 5.1, and I have heard about something called Dolby 7.1, but don't know what the difference is. Whatever the difference is, I don't think it should matter for the Fortec, since I don't think it's supposed to decode the Dolby, just pass it through, but perhaps it is reformatting the headers or something.

I hooked up the coaxial signal from my new optical-->coaxial converter to my oscilloscope. The trace from Montanna PBS looked like this...



I have the scope on 0.5 uS/div and it looks like about 2/3 cycle/div, so I think this looks like about 1.3 cycles/uS, or 1.3 MHz (if I'm thinking straight this morning). But you see the first 2 (actually 1) cycles are solid, but the cycles after that are kind of scrambled, and jump around with the sound, so that must be where the data is.

Compare that to the signal I got from one of the PBS AC3 channels, ie:



You see that there just doesn't seem to be any data in this signal, or if it is there, it is very low intensity relative to the main carrier.

I don't understand at all how the Dolby digital works, but I think it's looking for phase modulation of this carrier. This is all very interesting, and I'm learing a lot, but I just wish I could hear the audio, because 95% of my satellite viewing is PBS, so I need my AC3.

[radiobob]

Well, the difference between 5.1 and 7.1 is just in the number of surround channels with 5.1 more likely for home use. I found a website that gives some insight into Dolby digital sound (aka AC3):

Dolby Digital - a definition from Whatis.com

It still doesn't answer the mystery of why you're not getting Dolby digital sound now (and I am...sort of), but it does help understand a little more.

I say "sort of", because I verified that while I'm getting the PBS mux, I still don't decode the Pentagon Dolby channel or the G10R canals en Español.

The investigation continues!

[wejones]

Originally Posted by radiobob

Well, the difference between 5.1 and 7.1 is just in the number of surround channels with 5.1 more likely for home use. I found a website that gives some insight into Dolby digital sound (aka AC3):

Dolby Digital - a definition from Whatis.com

It still doesn't answer the mystery of why you're not getting Dolby digital sound now (and I am...sort of), but it does help understand a little more.

I say "sort of", because I verified that while I'm getting the PBS mux, I still don't decode the Pentagon Dolby channel or the G10R canals en Español.

The investigation continues!

Well this is getting stranger. Since Rainman said that his unit worked through a home theater system, I decided to go out to Walmart, and I picked up one of their surround sound systems (only because my wife said that she could get use out of it). It has both optical and coaxial input. I plugged the coaxial line from my converter in, and guess what.... IT WORKS! Plugged back into my Extigy, and it doesn't work. So what you said above, about "something new in the coding" must be true, and it must be something that the Mercury is doing to the signal, because if I take the SPDIF signal on the same channel from either my Lifetime or Ultra, it works fine on the Extigy.

There must be something different in the way that the Mercury handles the AC3.

I am very confused about this. But I'm happy that I may not have to return the Mercury, although this is going to mean that I'm not going to be able to use this thing like my other receivers, since I don't have access to a line level audio signal to feed through my main A/V system.

I'm still hoping that there might be some way to get this thing to work through the Extigy, or perhaps there is some other decoder out there. I'm going to hook both the signal from the Mercury and my Ultra into the scope again, to see if I see any difference. Like maybe the level from my converter is too high or something.

I guess I'll read through the link you posted. Maybe it might suggest something. THanks.

Even more confused.

[melbfla]

Hi Webjones

Could you give the brand and model of the surround sound system you got at Walmart , I have been trying to figure out what to get myself.
Thanks

[wejones]

Originally Posted by melbfla

Hi Webjones

Could you give the brand and model of the surround sound system you got at Walmart , I have been trying to figure out what to get myself.
Thanks

Hi
I get the impression that all WalMarts aren't the same with respect to these things. People have been posting for years about buying cheap home theater systems in WalMart, but I've never seen one in 2 of the 3 Walmarts near me, but this weekend I went to the 3rd one in the area, and it had some.

They had 2, that claimed to do digital Dolby 5.1. The cheapest cost around $60 or $70, but you couldn't tell from the box what type inputs it had, ie optical, coaxial, and whether there were also analog inputs. But this should work, at a minimum by getting a converter.

However, I had to justify the purchase by getting something that my wife could use to plug in her hand held MP3 player, and/or play FM music. So instead of the cheap one, I got an RCA RT2760, 720W. This cost about twice as much, but it had both optical and coaxial inputs, plus analog and AM/FM, and other things. More than I wanted to spend, and it doesn't solve my problem of getting a line level output to go to my main system, but it does work.

I'm still trying to figure out why the Mercury won't work with the Soundblaster Extigy. It really should. I've looked at more oscilloscope traces, this time comparing the output from the Mercury vs the Lifetime receiver, which DOES work with the Extigy. I basically see the same waveform from both receivers, and the only difference I see is that the voltage levels coming out of the optical--->coaxial converter from the Mercury are a bit higher in voltage. I've tried attenuating the signal, but that didn't help. I'm still trying to figure this out.

If anyone knows of another Dolby 5.1 decoder or converter, please post, because at this point, this Mercury will have to be disconnected from my system, because I can't use it unless it can feed audio into my main system.

[Vitruvius]

Ok, I am truly excited. I have found my arc. It has taken me several months of re-adjusting the dish... but now I just use the USALS for any satellite.
I have also tuned into the AMC3 87 and found about 8 PBS stations with the Dolby signal. I've read every forum issue regarding the PBS sound. Like everyone else with the Mercury, I do not get sound from the Dolby stations. I do get sound from the one Montana PBS. Do I need to get a surround sound stereo to get sound for these stations? I really don't want to, because I don't have the space.

Anyway, here is the equipment I have:
Fortec 80cm
DGS2100
Mercury II
LG32LD LCD TV.
LG DVD recorder.

These PBS stations have a higher quality image than a lot of the other stations, and it would be nice to have the sound. The SPDIF thing is really new to me. I understand two line stereo wire a little... well maybe not...

[csmith704]

[quote=Vitruvius;45660] I do not get sound from the Dolby stations. I do get sound from the one Montana PBS. Do I need to get a surround sound stereo to get sound for these stations? I really don't want to, because I don't have the space.[\quote]

I have an A/V receiver so it's not a problem for me, however I've read that others purchased a Sonic Voom headset and took one of the outputs (via a mini Y to RCA adapter) to their receiver. check out fry's, walmart, computergeeks, ebay etc online.... Note you will need an optical cable, for example:
RCA DT6HPL Digital Optical Audio Cable with lighted halo connector 6-ft

[rainman]

Originally Posted by Vitruvius

Ok, I am truly excited. I have found my arc. It has taken me several months of re-adjusting the dish... but now I just use the USALS for any satellite.
I have also tuned into the AMC3 87 and found about 8 PBS stations with the Dolby signal. I've read every forum issue regarding the PBS sound. Like everyone else with the Mercury, I do not get sound from the Dolby stations. I do get sound from the one Montana PBS. Do I need to get a surround sound stereo to get sound for these stations? I really don't want to, because I don't have the space.

Anyway, here is the equipment I have:
Fortec 80cm
DGS2100
Mercury II
LG32LD LCD TV.
LG DVD recorder.

These PBS stations have a higher quality image than a lot of the other stations, and it would be nice to have the sound. The SPDIF thing is really new to me. I understand two line stereo wire a little... well maybe not...

yes you will need some sort of ac3 decoder that will work with optical cable I use a cheap KOSS dvd and surround player it works just fine.

[wejones]

Originally Posted by csmith704

.....
I have an A/V receiver so it's not a problem for me, however I've read that others purchased a Sonic Voom headset and took one of the outputs (via a mini Y to RCA adapter) to their receiver. check out fry's, walmart, computergeeks, ebay etc online........

Well that's certainly a cheap way of doing it. Hope it works. I have been looking and looking for any kind of a 5.1 decoder that isn't part of a high power audio system, that I can use to feed my main stereo or the TV, but I've been unable to find anything. The Soundblaster Extigy, that I use for my other receivers SHOULD work for the Mercury, but for some reason the Mercury just isn't compatable with the Extigy, and I've been unable to figure out why. Makes no sense at all.

Anyway, on reading the above, I just grabbed one of those Sonic Voom things off Ebay. When I get it, I'll report on whether or not it works.

[William Eng]

Depending on your wallet, one can spend anywhere from under 100 to thousands of dollars for a sound system. I brought the Sony system from Sears for $120. Most stereos now have a built in DVD player which I didn't need, since I already have a DVD/VCR recorder. So far, it has been a very reliable system and produces excellent sound. I have the unit intergrated with my Fortec Classic receiver and DVD/VCR unit so that I can get the AC3 via the optical link as well as getting stereo sound from DVD movies. The only thing that is not setup is the TV sound to the stereo, but of course I could always unplug the input from the satellite receiver and plug it into the back of the TV.

[wejones]

Originally Posted by William Eng

Depending on your wallet, one can spend anywhere from under 100 to thousands of dollars for a sound system. I brought the Sony system from Sears for $120. Most stereos now have a built in DVD player which I didn't need, since I already have a DVD/VCR recorder. So far, it has been a very reliable system and produces excellent sound. I have the unit intergrated with my Fortec Classic receiver and DVD/VCR unit so that I can get the AC3 via the optical link as well as getting stereo sound from DVD movies. The only thing that is not setup is the TV sound to the stereo, but of course I could always unplug the input from the satellite receiver and plug it into the back of the TV.

As I've posted before, I actually bought a similar stereo, just to verify that the Fortec was putting out AC3, and I put this small system down in my basement. But I already have a higher quality stereo system, so I was really looking for just a decoder, preferably something that didn't draw much current, and something that put out line level output, not output to speakers. I've been doing this for years with the Extigys, but now there doesn't seem to be anything similar on the market. Ie since all the new stereos apparently have digital inputs, there wasn't a market for digital decoders.

This headphone alternative seems like a nice low cost alternative if it works. I spent about $14 + shipping on Ebay, which seemed like an economical solution.... if it works.