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apt-x PulseCom STL

C

ChiefOperator

Folks-

I've heard that AT&T is offering a 15kHz digital program loop using Pulsecom cards on each end. Apparently, the cards use the apt-x codec (Rolf??) and the entire system offers total latency of about 10ms (4ms encode/decode at each end and 2ms from network). And the best part if true, the monthly lease is comparable to the old equalized program loop. I briefly spoke to AT&T but couldn't find anyone who knew what I was asking about (not surprising).

Is anyone using the set-up?

Thanks...
 
Hey folks

Yes, these cards are real and are perfect for Telco's wishing to offer analog program loops in a digital word. The fit in a standard telco frame and convert a copper pair to digital audio. Yes, they do use APT-X

As to whether or not AT&T is using these in any given locality I don't know. I Presume the tarriff would be the same as for an analog loop, which does still exist in many areas. The key is that these cards allow the Telco to provide the service with no knowledge of analog!

Rolf
 
AT&T?You are kidding aren't you? Last dealing i had with them can be described as pathetic at best.Want STL, buy your own units (several brands available) Ethernet radios(getting cheaper everyday) and do your own thing.AT&T is a huge JOKE.
 
I'm using this setup for 2 AM stations that couldn't get a reliable 950mhz STL shot. AT&T installed a T1 circuit and the Pulsecom cards at each end. We opted for 8.5khz audio, but 15khz is available. Works great... haven't had any issues with either installation. Monthly cost for the circuit is reasonable too.

RFB
 
Really, for AM? If you don't mind could you share that monthly RECURRENT cost? Last AM i used a non loaded dry pair with bridge taps cutoff (burgular alarm circuit)and the old western electric EQ's on each end..less than 20 bucks a month,sounded great.
 
Recurrent cost is around $90 per month for the point to point T1 circuit.

RFB


oldiesstation said:
Really, for AM? If you don't mind could you share that monthly RECURRENT cost? Last AM i used a non loaded dry pair with bridge taps cutoff (burgular alarm circuit)and the old western electric EQ's on each end..less than 20 bucks a month,sounded great.
Click to expand...
 
These have been avalable for years in Los Angeles. They sound quite good. They work over a 56 kbps data line. The cool thing is that they can be reversed by flipping a switch on each end.
 
All-

Everyone, Thanks for the replies. These sound promising.

rfburns or LA_Guy, do you know what AT&T calls this system? The AT&T folks I've talked to don't know what I'm talking about. I've asked them about "digital program loops," "Digital STL," and even "the program loop that uses the Pulsecom units."

Also, is the latency truly so low that off-air monitoring is still possible?
 
rfburns said:
Recurrent cost is around $90 per month for the point to point T1 circuit.

RFB


oldiesstation said:
Really, for AM? If you don't mind could you share that monthly RECURRENT cost? Last AM i used a non loaded dry pair with bridge taps cutoff (burgular alarm circuit)and the old western electric EQ's on each end..less than 20 bucks a month,sounded great.
Click to expand...
Click to expand...

Is that a fractional T1? I thought the typical cost for a T1 was hundreds of dollars per month.
 
A couple of points

The tarriff will most certainly be for analog program loops. When they install the loop they will use whatever technology they are using that day/week/month/year. I don't think you will be able to determine if the Pulsecoms are used prior to installation.

If I recall correctly (I am 90% sure) the PCAUs provide their own digital modulation and are not used on a T1 but rather on an unloaded copper pair. IIRC it uses 2B1Q but I can't recall for sure.
 
Anyone ever get an AT&T(Bell South) USOC code for this? Realtychecker, according to Mr.Burn's post he uses them with a t1.Maybe he could clarify that and also come up with a USOC.From what i read, for stereo FM, you would need to have a pair of these at each end.
 
Arghh

I Had a lot of links that were lost when I changed employers...

I did some searching and found a BellSouth document on 8kHz program circuits here:

http://wholesale.att.com/reference_library/guides/tech_ref/TR-73546.pdf

Paragraph 1.4 (shown below) clearly states that:

<quote from above link>
Unless otherwise specified a variety of two and four-wire channels may be provided by various types of multiplex systems...
<end quote>

Thus I concur with Realitychecker that even if you fidn the correct USOC that it will merely determine the end-to-end characteristics and will not assure that any given technology will be used (analog OR digital) to achieve (or hopefully exceed) those characteristics.

oldiesstation said:
Anyone ever get an AT&T(Bell South) USOC code for this? Realtychecker, according to Mr.Burn's post he uses them with a t1.Maybe he could clarify that and also come up with a USOC.From what i read, for stereo FM, you would need to have a pair of these at each end.
Click to expand...
 
Regarding the "T1" question. Look at the FAQ here:

http://pulse.com/ba_faq.html

This implies that it could be used on T1.

However it requires converting to a "U interface" which is 2B1Q as realitychecker states.
 
I can't believe that broadcast engineers are actually touting APT-x compression for broadcast lines. If it sounds good to you, fine. But I'll use 15 kHz analog or uncompressed digital, thank you.
 
Bill, the point is, when you request 15KHz analog from Mother Bell, this is one of the solutions they may use to get it for you. There aren't, to my knowledge, any more analog trunks between switches in the Bell system. They're gonna digitize it with >something< and then turn it back to analog for you. The APT-X CODEC seems to do a better job than many when it's cascaded with csomething else (like the HD CODEC). You don't have a lot of control over what's done with the noise after it hits the demarc.
 
littlejohn said:
<SNIP>The APT-X CODEC seems to do a better job than many when it's cascaded with csomething else (like the HD CODEC). You don't have a lot of control over what's done with the noise after it hits the demarc.
Click to expand...

Even better than the fact it cascades well, is the fact that it is impossible to abuse since it has a fixed compression ratio. You choose your desired audio bandwidth and that is it.

Bandwidth is supposed to be getting cheaper but a lot of bad rap for coding algorithms comes from the fact that everyone insists on using them "to the max" without regard to the particular need.

It is no accident that apt-X and enhanced apt-X have the reputation they have with the Broadcast Community as well as the Post Pro Industry.

Perhaps Bill would like to explain his experience and or pre-judgment of using it for STLs?
 
The Pulsecomm PCAUs actually work really well. I have 10 pairs of them in New York for backup STLs. They have razor flat frequency response and the necessary amount of headroom all the way out to 15 KHz, which is something you rarely, if ever, got with the 'older' style of 15 KHz lines from Telco (using Telabs 4008 cards on either end). They actually sound pretty good too.
 
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