It is very basic and has to do with the RPM that the prime power producer spins at. There are 2 basic types of Frequency Converters: Rotary Frequency Converters , manufactured with the use of a Motor Generator and Solid State Static Frequency Converter , manufactured with the use of semi-conductors and power stages.
The Rotary machine is brute force as opposed to the Static machine. The static unit is for non industrial applications. There are other factors to considered when deciding on a Frequency Converter. One factor is if you need the converter to also maintain power output when the utility is no longer available.
If the Frequency Converter also needs to clean up a non stable input frequency like accepting a poor frequency range on the input and produce a stable output frequency and voltage, a Dynamic Frequency Regulator should be used. This unit allows for a very unstable utility, while producing the required output. There are several factors which will help identify which frequency conversion solution is right for your project. Skip to content.
Examples of Frequency Converters:. The cable company must ensure that the cable system is in proper working order. Beyond that, most cable operators are willing to help a customer resolve a problem concerning the quality of the received service. It is costly to leave an interference problem unresolved. Dissatisfied viewers can cancel their subscriptions and, if the interference problem is caused by a cable system leak, the FCC can levy fines or shut down channels.
Consumer electronic equipment manufacturers also share in the responsibilities. In , Public Law became law. Among other things, this legislation gave the FCC the authority to regulate consumer electronic equipment susceptibility. The FCC chose to implement a program of voluntary immunity standards and allow the manufacturers to devise a program of voluntary compliance.
The non-technical side--diplomacy. There are occasional misunderstandings between the cable subscriber, the cable company services personnel and the transmitter operator who is involved in the problem.
The subscriber often feels that the transmitter is to blame. After all, if the radio transmitter wasn't on the air, there wouldn't be a problem. The station operator often feels that the problem is always the responsibility of the cable company, and that it can always be fixed if the cable system shielding is improved. The cable company repair personnel are often stuck in the middle.
This scenario is sometimes compounded by hostility, hurt feelings and a hostile posture adopted by everyone who is involved. This creates an atmosphere in which the problem cannot be solved. At this point, the subscriber, the ham and, if necessary, the cable company staff must decide to put aside bad feelings and approach the situation with an open mind. There are three components to any interference problem: 1 a source of radio-frequency energy or electrical noise, 2 a piece of susceptible equipment and 3 a path over which the unwanted energy is propagated.
Any solution to an interference problem is going to involve a change made to one or more of these three factors. In most cases of cable systems ingress, the source is difficult to control. If the source is a transmitter of a licensed radio service this includes Amateur Radio, among many others operating in compliance with the appropriate regulations, there may be little justification to ask the operator to make any changes to the station. Under some circumstances, however, it may be possible to improve the situation by making changes to the source.
Ensure that the transmitting station is installed and operated using good engineering practice. The equipment should be properly grounded and installed so that the transmitted signal is coming from the antenna, not the transmitter chassis or ground.
Transmitter output power and the proximity of the antenna to the susceptible equipment or the cable distribution system can all affect the severity of an interference problem. There is little that can be done by the cable repair personnel to improve susceptible equipment. Most states have laws and licensing requirements that regulate the electronic equipment repair industry.
In addition, most cable companies have policies that prohibit the cable company service staff from repairing or modifying any subscriber-owned equipment. The best source of help with susceptible equipment is the equipment's manufacturer. Interference can propagate via several different possible paths.
Take a look at Figure 7. In the direct path, the interfering signal travels directly from the transmitting station's antenna to the susceptible equipment.
Conducted interference travels from the source to the susceptible equipment by wires. Most of the time, however, the conducted signal is one that has been induced into the external or internal wiring of the susceptible equipment. All electronic circuits require two wires or their equivalents - one wire for the signal to travel on and another for the signal return. In the differential mode a signal travels down the center conductor of a coaxial cable and uses the inside of the shield as its return path.
In the common mode, the shield and center conductor act as if they were one wire, with the return path being earth ground usually through the ac wiring. Figure 7. Most signal-leakage cures will be applied to the path. The most important of these cures involve filtering and shielding.
If a shield is placed between the source and the susceptible equipment, the effect of the interfering signal can be significantly reduced. Unfortunately, shielding is not a practical solution in most cases. It is difficult to imagine convincing a subscriber that the entire video system including the viewers! Another means of affecting the path is the use of filters to attenuate unwanted energy.
Part 2 of this article will discuss the practical steps that should be taken to cure interference problems, concentrating on the use of the necessary filters. Part 1 of this article appeared last month. It discussed the nature of the interference problem, ways to deal effectively with the subscriber and the radio operator, and electromagnetic compatibility technical fundamentals.
It is time to outline some standard approaches that usually result in a solution to the problem. The first technical step toward finding a solution to an interference problem is for the cable company service personnel to determine if there is any leakage in the cable system wiring.
If the interfering radio signal is leaking in, it will, in most cases, be impossible to filter. Fortunately for troubleshooting purposes , if a signal is leaking in it others are leaking out. Cable operators have many good methods for measuring leakage, -although a passing cumulative leakage -index CLI figure on the Federal Communications Commission's Form does not ensure that leakage and ingress are completely under control.
The radio operator can do a quick check for leakage in the VHF ham bands by using a receiver designed for the Amateur Radio Service.
A local ham can often be of help here. If a strong carrier is heard in the subscriber's home on the frequency of the video carrier in the or MHz amateur bands, then leakage is indicated. On the other hand, if no carrier is heard, then the cable system assuredly does not leak at that point.
In some cases, it may be possible to hear a signal when the receiver's antenna is placed within inches of the cable. It may, however, be leaking elsewhere in the neighborhood and being delivered to the subscriber's drop.
The accompanying table shows the frequencies of the video and sound carriers that can be found in, or adjacent to, the amateur bands. Another effective way of evaluating leakage is to use a spectrum analyzer. Spectrum analyzers are usually well-shielded and filtered, and can be relied upon to measure only signals inside the cable. Under some conditions, an in-band, spurious signal that is 60 dB weaker than the video carrier can cause just-perceptible interference. If the in-channel radio transmitter's fundamental signal is weaker than this, then cable system leakage is not contributing to the problem, so other causes should be investigated.
Many cases of ingress can be traced to something the subscriber has done. It is not rare for a subscriber to add additional cable and splitters to the installation to save monthly fees for additional outlets. It is not unheard of for subscribers to run cables to a neighbor's house, to give away free cable, or to take advantage of free cable with or without the other party's consent.
As if this weren't bad enough, this if often done using substandard cable, splitters or installation techniques check the crimps. Even worse, they may use wires such as twin-lead or zip cord, or even hook up an external TV antenna in parallel with the cable. Even if the subscriber has done none of these things, substandard cables may have been substituted for the quality jumper cables used at the time of installation, or the subscriber may have repaired a broken connector using parts and techniques not up to industry standards.
Look for these things --you may fix your problem without having to go any further. All of these defects can result in severe leakage. Not only can they be the direct cause of the interference problem, but they can have quite the impact on your system's cumulative leakage performance.
Some of them also represent a significant revenue loss. This should be tested early in the trouble-shooting process. Disconnect the TV set from the cable system and terminate its input with a 75 ohm terminator or ohm carbon resistor as appropriate for its input impedance. Select the channel the TV set is normally tuned to--usually Ch. With the consumer as priority, our customer-made durable and reliable equipment ensure the end product freshness and flavor.
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