What time in the morning does the vendor begin transmitting real-time quotes on each market you are interested in?

Do EOD quotes include evening trades, or GLOBEX? (Hopefully not, unless you know what you are doing.)

Phone Line Transmission

Of the several media available, telephone lines provide the most elementary, easiest to set up, portable and often most reliable way to connect to a data provider. With the recent advent of the Internet and its escalating use by data providers, the telephone is often the only way to access some of these varieties of market data. The data providers offering service via telephone line typically allow a subscriber to either dial into their data server directly, or access the data via a Web site using an Internet connection. Generally, the users target application for the data in some way dictates whether telephone access is practical, or even possible.

Line speed and data error rates are the key factors to consider when using a phone line to access market data. Several options are available, starting with the standard phone line connected to a residence or business. Generally, although it varies considerably by locality, it is possible to acquire data with minimum error rates at speeds up to 56Kb using a standard phone line (slower, however, is much more typical). The next better alternative is the ISDN line, more expensive (2-5 times the cost of a standard line) and not available in all locations, especially away from larger population centers. Finally, the direct Tl connection offers the subscriber very clean data at speeds up to 1.4 MB, at correspondingly higher fees and complexity of installation.

FM Transmission

FM transmission is the second oldest method of market data delivery, following telephone lines. Typically, the data provider leases bandwidth from one or several FM broadcast stations in a city or region, and supplies the data to the broadcaster via leased phone line. The broadcaster then multiplexes the data onto the broadcast FM signal, which is then received and de-multiplexed at the users end. The output from this receiver is typically a serial data line that is then fed into the users computer.

A limited amount of data can be delivered on the FM sideband via this method. Since most of the bandwidth available at the broadcast FM frequency is used by the radio station for its own programs, only a small amount remains for dedication to other purposes, the data provider in this case. As market data volumes have increased, less of that data, and in a less timely fashion, can be delivered via this medium.

As a result of the data delivery mechanism, data is received by the end user at a much slower baud rate than typically available via other media. There is constant criticism from the trading community about the data delays via FM. For example, DBC Signals reporting of SP futures real-time via FM is reported by users to arrive several minutes behind a direct audio squawk box, and in fast markets, from 5 to 8 minutes

late. Nonetheless, some users rely on FM as an emergency backup should their primary method (cable, satellite, etc.) fail.

Users have complained formally about the delays inherent in this medium, by bringing a class action lawsuit against DBC and its Signal subsidiary. The basis for this complaint is that Signal has historically advertised "real-time" quotes via this service, at a substantial increase in subscription rates over its delayed quote service. But due to the delays in this medium (and the slow baud rate of the receivers used to capture the data), data arrived with unacceptable delay.

Questions to Ask

If you purchase satellite or cable transmission, will the vendor provide you for /free a means to receive FM as a backup measure? \

/ Will the vendor guarantee a no-hassle refund if nondelayed data frequently ar- J I rives too late to be reliable?

Cable Transmission

Data arrives via cable in "packets" that are spaced apart in time. Technically, the vendor collects data and queues them prior to insertion into an analog TV signal. The data is transmitted in the vertical blanking interval space in the TV signal between video frames on a commercial cable broadcast channel. Data must be queued, because vertical intervals come only once every Mo of a second and last about 1 msec. In that interval, only about one-fifth is normally available for data transmission, even less when the interval is shared with other digital information. Therefore, incoming data must be queued at least until the next vertical interval, and, just as lines at banks grow very large on Friday afternoons (payday), the data queue grows longer during fast markets. Thus, both the signals bandwidth (speed at which data can be pumped through the cable) and the queue process contribute to the cables signal throughput speed, and the faster the signals bandwidth, the less data queuing is needed.

The local cable station has the option of preempting the national feed for commercials, and when they do, the feed is disrupted for up to 60 seconds, or more. They have no fixed schedule for such interruptions, and so it can be difficult to forecast when this will happen. During that time all data that you would have received is lost until the interruption ceases. It is not delayed or stored. You will know when this is happening when the "data" light goes out on your receiver box. And of course if your TV is running on that station, you can also see when a commercial is running. Not all commercials cause a blackout, though. The national commercials are not likely to disrupt the feed; rather the local commercials sold and broadcast by the local cable TV station are the culprits.

Cables unique advantage is that you can hook up and trade anyplace that receives any of the appropriate cable channels. On the other hand, cable has its own set of problems:

• There are blackout interruption periods, as just discussed.

• Service by the local cable company may be very poor. The cable signal can be down for days. (So can leased lines, for that matter.)

• Cable companies will, without warning, retune their amplifiers, corrupting the signal.

• The local cable channel may not allow the datafeed signal to travel over its network. For example, vendors are losing lines in many markets to closed captioning, and so on. This is bad news if all of a sudden your signal is gone for good and you took out a nonrefundable lease for your receiver box.

You can counter some of these problems:

• Ask your cable company about these issues. Insist on speaking to an engineer, not the first customer service representative who answers the phone.

• Some cable channels are more likely to insert blackouts than others are. Test all the available channels recommended by the vendor. Sometimes transmission is blocked during sports games only after trading hours. Nonetheless, this will still impact Globex trading.

• Try getting your cable signal by using a satellite dish. The DBC Signal International feed via private satellite hookup is purported to be a great method. Use the new small-footprint direct-TV type of dish.

• Place the receiver box in plain view so when the signal is cut off, you can detect the data light go out. Some software will alert you when there have been no data changes for an unusual period of time, even though the reception is good. Most software products do not.

• Employ the squawk box service from the S&P pit and the T-bond pit over the phone during such outages. When there is no outage, the telephone squawk box gives a good way to check the speed of your feed.

Questions to Ask

Vendors may not realize that closed captioning has blanked out your neighborhoods transmission of the datafeed. Ask that you be given a trial period so you can test all the available channels.

Ask if you can get the cable signal via a satellite dish, which will bypass the cable companys interference.

Satellite Transmission

The overall advantage with satellite transmission is that there is less to go wrong except for the weather. Advantages include avoiding blankouts by local commercial