Remote Broadcast Access
Newsletter Issue 3
Inside this issue:
- Comrex Comments
- A Week in the life of a Vector Demo
- Types of Digital Circuits - what are they and what can they do for you?
- ISDN Backup to T1
- Ask the Codec Answer Guy
- NAB 99 and Comrex
- Cool Email
Comrex Comments
by Lynn Distler
President, Comrex Corporation
A couple of months ago, I attended the Great Lakes Broadcasting Conference and EXPO to talk abot our new Vector POTS codec. One of the exhibitors, WSGW Saginaw MI, was doing a live broadcast of their morning show from the convention floor with a Comrex PTLX Two Line Frequency Extender that had to be over 15 years old. When I mentioned that they were using an antique, the talent shot back: "maybe, but it works and sounds good!" On reflection, I realized he had paid us a great compliment ... it was very satisfying to see that old PTLX still in use.
Later that day, the WSGW morning guy came over to see the Vector with his GM. They were impressed: much better audio quality; only 1 phone line to order (they were using 3 on the PTLX remote); and a lot less to carry around. But, if they decide to invest in POTS codec technology, we urge them to also invest some time and effort to learn how to use it effectively. They could also take advantage of our demo program to see if this were the right approach for them.
In this edition of ACCESS, the "Codec Answer Guy" covers some of the issues that need to be considered. We also look at a few of the new digital telephone services and assess their potential for real-time audio applications. Finally, our web site and Fax-on-Demand system are constantly being updated with new material to help our customers become "informed consumers" of the neat new tools that are becoming available.
A Week in the Life of a Vector Demo
KYKY FM in St. Louis, MO is just one of the many radio stations that have taken advantage of Comrex’s demo program. This CBS station tried the new Vector POTS codec that provides 15 kHz two-way audio on a single average phone line for great sounding, dial-up remotes. The station really put the Vector to the test with a challenging international broadcast from the Dominican Republic and a second remote later that week from the Grammy Awards in LA. Both remotes were smashing successes, and we’d like to share them with you.
Several of KYKY’s listeners won a contest to be married in a Mega-Wedding in the Dominican Republic. The Vector traveled there, along with the station’s engineer, Joe Raftery. "While the telephone system in the Dominican Republic seemed less than par, the Vector came away with flying colors," stated Raftery. The Vectors connected at 19.2 kb/s, a very respectable rate given the poor phone system, and delivered 11 kHz two-way audio. Raftery reported that "one very cool thing" was the high quality return feed. Obviously, all music for the broadcast originated from the studio in St. Louis. But the Vector allowed that music to be sent back to the wedding and sound great over the PA system. Raftery added, "All of the newlyweds were very happy, and KYKY was thrilled with their Vector experience in the Dominican Republic."
The Vector was then off to the Grammy Awards in Los Angeles with afternoon drive host, Craig Cornett. Raftery appreciated that the Vector is very talent friendly. "I gave Craig a five minute training session on the Vector before he left town. He had no problems setting the unit up or dialing the studio." The Vectors kept KYKY listeners back in St. Louis up to date on all the stars at the Grammy Awards. After these remotes, Raftery said, "I look forward to owning a Vector in the future and will recommend it to colleagues."
We love hearing about the travels of our demo units, and we thank Joe Raftery and KYKY for the glowing tribute to the Vector. Our demos are intended to allow prospective customers to use our equipment in real life situations to help them decide what is appropriate for their operation. Contact Comrex or your broadcast dealer to learn more about this program.
Types of digital circuits - What are they and what can they do for you?
Key to our symbols:
= Good chance for real-time audio applications
= Possibilities for real-time audio applications
= Not suitable for real-time audio applications
Recently there’s been a lot of talk about new digital telephony technologies. Lots of work has been done to deliver higher speed data to the home or desktop than is available via ISDN or 33.6 kb/s modems. Some of these technologies hold promise for real-time audio connections, and some don’t. Here’s a sampling of some of the systems or circuits you may have heard about and what they really mean to you in terms of real-time audio.
56K modems- If you’re still surfing the internet on a 28.8K modem, these new modems (V.90, X2, and K56 Flex) can really make a difference. They are great for applications (like navigating the web) where a user, connected to an analog line, downloads more than he uploads. Unfortunately, they work the wrong way for remote audio because the high speed would only be available from the digital to the analog side (i.e. only to the remote site).
xDSL- Ma Bell’s foray into internet access. They take an existing analog telephone line and put very high-speed data on it, often leaving the line usable for telephone service as well. The important thing to understand about these new internet connection technologies is that one end terminates on premises, and the other end lands on a TCP/IP server. In the case of xDSL, the server may be at the telco central office, or the line may "pass through" the telco to an Internet Service Provider. Either way, any point to point connections must be internet based, with all the delays, packet loss, and congestion issues associated with the internet.
Cable modems- Like the telephone company, the cable company would like to provide your internet service. Your modem is tied directly to an internet server at your ISP who, in this instance, is your cable company. For real-time audio, cable modems have the same limitations as other internet access options.
Frame Relay- This service is being offered in lieu of dedicated digital circuits in some areas. It’s similar to a packet based protocol which runs over a private network (not the Internet) and provides "guaranteed" data throughput, specified as average kb/s over a certain period of time. The throughputs it offers are typical audio codec data rates (56-256 kb/s) and the cost is lower than dedicated links. The fact that "frames" are "relayed" between network routers implies some time delay, so its duplex applications may be limited, but keep watching for audio applications using frame relay.
3G and GPRS- Lots of work is being done to turn cellular and PCS networks into high sp for the yet-to-be standardized "third generation wireless". There isn’t any deployment yet, and it remains to be seen which technology will find its market, bueed data networks. GPRS is an interim solution, while 3G is the working namet wireless networks hold out the hope for wideband digital audio with mobility. The ultimate solution will be network based, although hopefully not inexorably tied to the Internet.
ISDN Back-up to T1
Most stations are concerned about the integrity of a single Studio-to-Transmitter link. At Big City Broadcasting, each station needs to maintain several STLs. They need more than one transmitter because Big City has pioneered STMC, Synchronous Total Market Coverage, as a way to add a large signal to a market where only small signals are available. Big City considers the Comrex Nexus to be a valuable tool for keeping the same signal on air from multiple transmitters.
Big City utilizes 12 radio transmitters in the top three markets to deliver 4 formats. Each "station" utilizes medium power FM transmitters on the same or first adjacent frequencies to cover LA, New York and Chicago with a signal that sounds like a single powerful signal. Because a listener may well be receiving a signal from two transmitters at once, a sophisticated synchronization of signals is required to reduce the inevitable multipath problems.
"We worked with Intraplex to install a system based on multiple T1 lines," says Al Kirschner, Director of Engineering for Big City, "but we found that T1’s are less than perfectly reliable." With each station requiring 2 to 4 of these links, an automated backup system proved necessary.
Enter the Nexus ISDN audio codec. "We chose the Nexus for several reasons. First of all, since all (the stations) are FM, the 15 kHz response was essential. Secondly, with multiple signals it is essential to minimize delay. We found the Nexus to be a cost effective solution to the problem,"says Kirschner.
The Nexus is capable of sending a 15KHz audio signal over an ISDN line with delays of only a few milliseconds. It incorporates an "STL backup mode" which will automatically dial a predetermined phone number on an external trigger. Kirschner simply wired the external trigger to the "alarm" signal on the T1 line. This way the Nexus will dial only when the T1 line goes down, providing a near-seamless backup path.
At $34 per month for an ISDN line, the Nexus provides an inexpensive "peace-of-mind backup" for Kirschner and Big City. "It has become part of our standard operating system" he notes. A side benefit to the backup system quickly became apparent. "My ISDN calls are itemized on my bill," says Kirschner. "This provides evidence to the telephone company of the frequency and length of our T1 outages." Armed with his ISDN phone bill, Kirschner can get credit for the time the T1 is down, further reducing costs.
Ask the Codec Answer Guy
We have assembled a collection of frequently asked codec questions some of which are presented here. For a complete list of the Answer Guy questions and answers, either give us a call or send us a completed reply card.
Q. The phone line for our studio HotLine (or Vector) is also used for talk shows and the modem in the control room computer. Is this a good idea?
A. Go to the hardware store. Buy an inexpensive crowbar. Bring it back to work and use it to pry open the boss’ wallet, and then order a separate phone line for the POTS codec. Seriously, we highly recommend that nothing else be connected to that line. Make sure that your inside wiring is done with good twisted pair phone cable (Category 3 or higher computer network cable is great). If you must share a line with other equipment, try to actually disconnect the other stuff when you are using the HotLine or Vector.
Q. I’m doing a remote at a location that has a digital phone system. There’s a jack right at the broadcast location. Can I plug my HotLine or Vector into it?
A. If there’s any chance that this isn’t a plain old direct phone line, don’t risk damaging your codec. The high-tech solution would be to get an IBM Modem Saver or similar test gadget to test the line first. The low-tech approach would be to bring a cheap "plain old phone" along, and see if it works. If you get normal-sounding dial tone and can place calls, you should be all set. If the phone blows up, you have saved many bucks in HotLine or Vector repairs. One other note: modems usually work better on direct phone company lines than on in-house phone systems.
Q. This audio codec stuff is great, but how do we get rid of echo at a remote sites?
A. The concept is simple. Don’t send the audio from the remote back to the remote. Give them everything else they need to hear, but not their own audio. This means that the "cure" is at the studio end, not at the remote. See Tech Tip 220 (Mix-Minus...), available on our web site or Fax-on-Demand system.
Q. We have a lot of older Comrex stuff that came from a station we just bought. How can I find out if it works, and what I can use it for?
A. They should have clauses in radio station purchase and sales agreements that require manuals to be provided for all equipment! Anyway, Comrex has manuals and advice for all of our stuff, right back to the dawn of time (1961, by our reckoning). Just call us and ask for Tech Support. We can get you started. And if the gear was sitting on a shelf because it didn’t work, we can see if we can fix it. Unless parts are no longer available, we should be able to help.
NAB 1999
NAB '99 is rapidly approaching... April 19th through the 22nd to be exact. We hope you will come and visit us in booth #L13180. (Translation - just to the right of the main entrance to the Radio/Audio Hall. We are near Orban and next to Broadcast Electronics.)
We will be demonstrating the Vector POTS codec, so if you’ve never heard 15 kHz on a plain phone line, this is your chance!
Nexus or HotLine Owners
We will also have the Nexus ISDN codec and the HotLine POTS codecs on line to demonstrate. If you have a HotLine or a Nexus, stop by and dial up your station (and we’ll even pay for the call!) Here is your chance to check up on the crew back home.
Free Passes
We have exhibit passes for NAB, so contact us if you’d like a free pass and we’ll be happy to send you one.
FYI - FOD
Have you used our Fax-On-Demand system lately? If so, you may have received the incorrect document. We have recently upgraded the system and completely changed the document numbers in the process. For example, the article "You Can Perform Magic on a POTS Line" had been #402 and is now #310. Confusing, huh? We also have some cool new articles like #200 "POTS vs. ISDN & Some Tips for Both" and #202 "Modem Line Checklist." To get a new index either contact us or call our Fax-On-Demand System directly at 978-264-9973 and request document #100.
Cool email
We get some great email. Here are some samples of what our international "pen pals" are writing.
From: <Our dealer in Australia>
To: <complaints@comrex.com>
Subject: Vectors
There seems to be a problem with these Vectors... No one will give them back!! (A customer) has had a demo pair ...and will not give (them) back until we send their new ones. Pretty please is there any chance of getting our order (early?)
Hope you can help,
AND
From: Arnold
To: <remotes@comrex.com>
Subject: St. Lucia
On Sunday I did a live broadcast of a Valentines’s day edition (of) my Sunday show from Castries, St. Lucia. On my return our news editor advised me never to use the Vector on any other overseas broadcast. Why? Because listeners actually thought we were either playing a trick on them from studio or had pre recorded the stuff and sent back the tapes. ... I had to keep saying "we’re live in St. Lucia" (I’m still not sure everyone believes we were.) One of our sponsors met us at the airport just to congratulate us, some think she came to ensure we were really coming off the plane. I am really satisfied with what we have been able to accomplish with this animal...
Thanks again,
Arnold
Thank you Arnold! It’s great to hear comments like yours! If anyone else would like to tell us about their experiences, please feel free to write to us at <remotes@comrex.com>
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