The stray off subject isn't really. More like relevant comparison side note.
Agreed.
"with a batch file or something; have both pc's start their identical playlist at the exact time, then both of the xmtr audio feeds would be synchronized.. or so it seems."
With that kind of setup, you would need something to ensure that the co-located systems remain alive if mains goes down. Although a computer can be configured to auto-start everything needed if power glitches, ain't nothing there to "bump" up that schedule script or the program mp3/wav/ogg file to advance it so that everything is back in time and on schedule when power returns.
So to overcome that, each site would need an UPS capable of maintaining power for at least 30 or more minutes.
At that point, again expense becomes a major factor.
And it's been said that Part 15 is cheap.
HA!
RFB
Although a computer can be configured to auto-start everything needed if power glitches, ain't nothing there to "bump" up that schedule script or the program mp3/wav/ogg file to advance it so that everything is back in time and on schedule when power returns
Well, maybe something like this would be a work around the problem of power glitches.. and this is off the top of my head, but it seems reasonable;
Make the automation programs (at both locations) depended upon time scheduled downloads as opposed to a basic playlist?
Both locations would still be playing the exact same audio files at the exact same time, even after a power failure.
Hows that sound?
I think the discussion has been circling around the idea that audio streams played from computers can be time compensated in some way, but (if that is the topic) I don't think so.
Every computer sends audio from point A to point B at its own delay-rate, which varies based on what other tasks are being done in the background, and over an internet line or LAN would have further variable delays.
I started back at the beginning of this entire thread and have been carefully studying everything that has been said and linked. There is a lot of information here on the subject of multiple-transmitters.
In his opening post, Lefty mentioned possibly starting with three transmitters, and, realizing I may have missed something, I think that all examples given have been for two transmitters.
Unexpected was the link to Chez Radio's pages regarding their guidelines on synching transmitters, based on two out of three adjustments: 1) adjust the frequencies of all transmitters so they are dead-on; 2) using Exstreamers they mention that the Barix Exstreamer CAN be time adjusted for audio, which I did not realize. The missing agility is a setting for phase flutter, but Chez is very clear about this so there can be no misunderstanding.
How difficult would it be to have a phase adjustment added to a part 15 AM transmitter for manual control?
"Make the automation programs (at both locations) depended upon time scheduled downloads as opposed to a basic playlist?"
Hmm...now that is an interesting approach! Sort of like an on-demand thing from a secured server. The script could be written so that it's looking at actual time and comparing that actual time with the run time of the program. If a glitch occurs, it instructs the playback system to pick up the on-demand source in correlation to the real time, and advance accordingly based on the "gap" time of the glitch, and pick up at the proper moment and resume playing the program, so the next program starts at the correct time and prevents throwing off an entire day's schedule!
Just might work!
RFB
"I think the discussion has been circling around the idea that audio streams played from computers can be time compensated in some way, but (if that is the topic) I don't think so."
Actually I think considerations to audio synchronization as well as carrier synchronization are hand in hand. And both are quite relevant to the subject of synchronization of multiple transmitters.
Either method of audio delivery is going to require synchronization no matter what.
Now add the third approach of End80's idea with scripts controlling and monitoring real time and run time and compensating for any glitching which may shift a day's schedule out of whack.
"How difficult would it be to have a phase adjustment added to a part 15 AM transmitter for manual control?"
Well not that difficult..but you need a reference for a starting point to each TX site. As to manual adjustments, maybe the same approach of Rich's time controlled on-demand sourcing, another program can be monitoring the carrier and incoming reference and do the adjustments automatically, or access the remote site with something like log me in and make the manual adjustments remotely.
RFB
i have some long distance 802.11 stuff available. 2 yagis 4 radios 4 base units, 3 psu's.
$ale.... or Trade to THIIv5 and external ATU.
the price quoted at http://denvercoyardsale.tk is not the part15us price. i give forum members a discount.
on audio linkage you are best using a hardware solution such as barix boxes to lower connection latency.
maybe send an audio sync pulse over one stereo channel and the regular mono audio over the other channel or use WWV as a carrier sync source.
Tonight I was researching these inexpensive RUKO internet streaming players intended for TV's, but it looks like they can be used as a standalone shoutcast receiver to feed audio to a transmitter. Any shoutcast stream can be specified in the settings.
The RUKO LT sells for less than $50, does not require a computer, only an internet connection - So in essence it seems very similar in capability to the Barix instreamer http://www.roku.com/roku-products
Somewhere I read something about adjusting the audio stream in the case of an out of sync video.. which implies to me synchronization capability for audio feeds in multiple transmitter installations.
I need to research it a little more, and what I'm suggesting is half documentation and half speculation, but the primary points are this:
A computer is not required.
It's wifi ready.
Any shoutcast stream can be received.
Standard rca jack audio outputs.
No subscription costs.
It may have some synchronization capabilities.
It cost less than $50!
The Roku idea sounds like an idea to explore.
As it uses Shoutcast streams maybe something can be surmised by looking at their behavior.
When my Winamp Player feeds to an AM transmitter it comes from the computer in what appears to be real time.
For comparison, I am able to use a Flash Player to receive my audio after it has departed the building, gone out from the Shoutcast Server, gone out somewhere on the internet and re-connected back into the Flash, where the audio is delayed by many seconds in comparison to the "in-house" audio feed. That's all at 48kbps.
A second Flash Player can be set to receiving my other Shoutcast Stream, the slow one at 16kbps, and it is many many seconds behind the other two streams.
I will guess that the Roku will exhibit whatever the delay factor may be inherent to Shoutcast streaming, but that could be o.k. if each transmitter was receiving the exact same delay via its dedicated computer.
The question at that point would be one of whether the delay between one Roku and another remains exactly in step, and probably the only way to find out is to have two Roku's and two AM transmitters in a laboratory study.
We are assuming in this scenario that the wifi reception at each Roku is dependable.
My part 15 installation does not lend itself to adding additional transmitters at distant locations, but the technical puzzle presented by the idea is very interesting to imagine.
Already having spent several days following this thread and trying to visualize solutions that would be available to part 15ers, I have decided how I'd begin.
I would begin by having two transmitters at different frequencies as a way of establishing the two antenna sites.
Finding two adjacent frequencies would be most desirable in this approach, recalling that at one time MICRO1700 switched from 1690 to 1700 for day & night signals, but my closest open frequencies are 1640 and 1680, and we are talking about full-time operation on both frequencies.
Without having yet synchronized the two transmitters we already have the need to establish two links to the farther transmitter; an audio link and remote control link for carrier off/on.
Once the links and the remote installation exist, further experiments can be done with the eventual goal of synchronizing on a single frequency.
Toward this objective a spare transmitter would exist at the remote site site to share a same frequency with the nearer transmitter. This would set the stage for upgrading by experiment.
There would inevitably be many trips to the remote location for equipment management, so it would need to be a very accessible spot.
Due to the difficulty of attaining a line-of-sight for my second transmitter, and some more research, I decided to purchase a Roku as a Barix alternative.
On ebay I bought an older model for $38.
A couple days later, decided I wanted a second unit for personal enjoyment..
Well, http://www.roku.com is having a Black Friday sale, and a few minutes ago I bought a brand new Roku HD unit for $39 and free shipping!
Tonight (Monday) is the last chance for this deal, ebay auctions with multiple bidders for used units are at this very moment selling for over $50!
So if anyone else is interested, you only have a few hours left.. get the $59 Roku HD which also has the rca outputs(it deducts $20 during checkout) free shipping
Roku HD - Grand total $39 http://www.roku.com
It's a poor mans Barix
Wow great find !!!!
I will use these for sure !!!
Thanks Rich.
Because of poor vision, I am not that computer
literate.
So how do you send your own original studio
programming content from your audio chain through
a Roku unit, and how do you receive that audio in another
location?
I am absolutely clueless on this, but if it is an inexpensive
way to send my audio programming from my studio to
another location, I am very interested.
I understand the Roku sends audio and video - do you
stream a "blank" video screen and just send audio???
You can see how foreign this is to me, I guess.
Best Wishes, and Thanks
Bruce, W 60 HZ Carrier Current AM 1020 and
X-13, 13.560 MHz Experimental Radio
Bruce, I haven't received my unit yet to explain first hand (it should be here tommorow), but basically what is going on is this..
You set up a stream of your station from your computer through a Shoutcast server, just the same as if you are doing it to hear your station on your webpage or something.
Then on the Roku Shoutcast Channel you are able to play your stream.. there is some basic configurations you need to do to pull in a specific user defined stream, but it's pretty simple..
The Roku Shoutcast channel has an "ECP interface" for adding custom URLs...
(Here's a simple interface to add a custom URL to Roku: http://roku.permanence.com/shoutcast.htm )
- You enter your Rokus IP address, the name of the channel you want to add along with the URL, then once entered it will start playing through the Roku box, then you "Add to Favorites" so the Roku has a stored direct link or it.
For the initial set up you need to have the video jack connected to a TV so you can see what your doing, but once set up you can just use the rca audio out to feed your transmitter -- By the way, if you get one, make sure its one that has the rca jacks (also less expensive) and not one that only use a HDMI cable.
Just consider the Roku as a wifi radio, which happens to have an added feature of being able to receive video too.
Does that clear it up any?
I will be more precise about the installation and implementation of using the Roku as a remote audio feed as soon as I receive and set it up, but I'm pretty sure what I described is accurate.
Ok.. Above I said to get the cheapest one that has the RCA jacks, but now that the black friday sale is over, it's not the cheapest one anymore!
What you'd need is the "Roku HD" for $59 and free shipping ( http://shop.roku.com ).. or get a used unit on ebay.
It does not matter what generation or model you get, any one of them will work with shoutcast, but just be sure it's one that has RCA outs on it.
BUT!!..
Don't go spending money based only on what I've described! Remember that I haven't even actually used one yet.
Although I feel sure this will work for my intended purpose, I can't be certain until I do it and have first hand experience in the real world.