Cable Plant Testing and Maintenance Procedures in Software

Make pdf417 2d barcode in Software Cable Plant Testing and Maintenance Procedures

This driver option is usually preferred because it is specifically written for compatibility with Terminal Services and still has many of the required printer features. CAUTION: It is possible to install directly via Add Drivers or indirectly via an imported network print server a legacy driver (one not certified for Windows Server 2003/Windows XP). In Windows Server 2003, Microsoft changed the print driver mode from kernel mode to user mode. Kernelmode drivers were responsible for the majority of spooler crashes in Windows NT and Windows 2000 when a bad driver was invoked in a multiuser environment. Many of these legacy drivers were never certified for Terminal Services. Bad user-mode drivers will normally only impact printing functionality in the user s session, not globally (all users on the server). Ensure only user-mode drivers are allowed to propagate to the Citrix printing environment.

the optical receivers or transmitters. If this station is simply a receiving station, the optical signals are connected to the receivers, where optical to electrical (electronic) conversion takes place. If the station is a receive-andtransmit station, then communication services can essentially undergo drop or add and be transmitted to other stations. 4.144 Quite recently, the ber-optic coupler or splitter has been perfected. This device is actually an optical fusion of more than just two optical bers. Figure 4-16 illustrates the concept of splitting and coupling the optical signal. Because this device is made from optical ber itself, it is quite small and physically compact. Such optical signal splitters can be placed in either aerial splice closures or aerial optical receivers. They can also be found in terminating stations where an optical signal enters at a high level, drops off a low level signal, and exits on another optical cable to another receiver station. A device that is often needed is an optical attenuator used to reduce a signal into a receiver so as not to overdrive it. Optical attenuators are made by a calibrated bend in the optical ber. Here, light escapes from the ber right through the cladding and plastic coating. Lost light results in an attenuated signal into the device connector. The devices are constructed with a plastic form with a bending channel radius built in with the calibrated bend. The ber is placed in the groove and the cover is closed. Another method of making an attenuator is with some fusion splicers. Here, the core of the joined bers is offset an appropriate amount, causing a misalignment that decreases the signal the desired amount.

The following sections will discuss how you initially create your contexts so that you can set up security policies and move traffic through them.

Notice that the certificate has a serial number at the top, which was assigned by the CA. Below this is who issued the certificate (Issuer section) and whom the certificate is for (Subject section). In the preceding example, the Issuer and Subject information is the same, meaning that this is the certificate of the CA. Troubleshooting Certificate Problems One of the most common problems of obtaining and using certificates involves the date and time. When validating a certificate, two things are required, and a third thing is optional. The first two things are comparing the device current time with the beginning and ending time on the certificate (if the device current time falls between these two, then the first authentication step passes), and validating the signature on the certificate. Optionally the device can check to see if the certificate has been revoked by using CRLs or OCSP. Since the date and time are important in validating certificates, I highly recommend that you don t statically define the date and time, but use the Network Time Protocol (NTP) to make sure your CA and devices acquiring and using certificates are in synch with each other. The configuration of NTP on the appliances is discussed in 26. To troubleshoot all other problems related to obtaining and/or using certificates, use the following command:

Ill 14-6

RS is a.c. series resistance caused by wires, in ohms. XL is a series inductive reactance caused by twisted wires. RP is insulation leakage resistance between conductors. XC is capacitive reactance caused by capacitance between conductors. It can be shown that ZO

the cadmium sul de photocell that varied its resistance with changes in light levels. The silicon solar cell produces an electrical voltage when light rays fall on the cell s photosensitive area. Most of the photo or lightsensitive devices previously discussed either require signi cant amounts of light or are too slow to be of much value in ber-optic communication applications. 4.132 Solid-state photodiodes are used as the light detector or receiver in ber-optic communication systems. The photodiode s p-n junction is reverse-biased, which removes current carriers out of the depletion region that blocks current until light enters that frees electron s hole pairs, causing the current to ow through the junction. Doping can change the dark current of the photodiode and thus low light level operation can be improved. Since the transistor consists of either an n-p-n or p-n-p junction, if one of the junctions, usually the base emitter junction, becomes the photodiode, the photo transistor results. Furthermore, if the phototransistor is placed with a second transistor into a Darlington circuit, the Darlington photo detector results. As might be suspected, all of the gain results in an increase in responsiveness. Again, it might seem that this type of light detector would indeed be superior, but the junction capacitance causes the rise time to increase. This, of course, affects the high-speed pulse (data) response and highfrequency response. Phototransistor detectors are ideal for high sensitivity and medium-to-low speed applications. 4.133 The pin-photodiode does not have the responsiveness of ampli edphoto detectors, but it has a very small rise time and can be used for highspeed, high-frequency applications. The pin-photodiode is usually used for single-mode operations for cable television optical receivers. Usually, an optical receiver circuit uses an operational ampli er following the pinphotodiode, which does not load the photodiode output and provides some power gain as well as a low impedance output to the following circuitry. Companies that manufacture optical transmitters and receivers for cable television applications usually offer optical transmitters with input levels and a number of cable channels speci ed. Optical receivers are usually paired with the optical transmitter. The cable operator has to design for a given power budget calculated by the system losses, the transmitter output, and the receiver threshold sensitivity. An example of an optical transmitter and receiver fundamental circuit is shown in Figure 4-12. A listing of various photodiode detector characteristics is shown in Table 4-1.