Service / Repair

1. Troubleshooting tips

Despite our best efforts in preventative maintenance and monitoring, our technology is destined to fail – “Stuff breaks”. This is where the art of troubleshooting comes in. While there are many variations on troubleshooting methods and models, and many training courses and certification paths that cover steps to troubleshooting, the best troubleshooters don’t necessarily follow a strict manual or script. They use their knowledge of the working system, past experience and a little intuition, to determine the root cause and a path to a solution. It’s not always a straight path. Here are some tips to help you work through a challenging repair, reaching a solution without much wasted time and resources.

1.1. What’s wrong? Talk to your customer!

It’s nearly impossible to properly fix a problem if you cannot see the problem. That’s why we have field test equipment (RF signal meters) to help in the diagnosis process. Knowing how they work and what to look for is critical for restoring proper service to the customer. However, it is equally important to speak with the customer as part of the troubleshooting process, since one of the ways a technician can “see” the problem is, to have the customer explain it to you in detail. This can be a time saving process as it would allow you to narrow down the problem even before you start to physically troubleshoot.

1.2. Keep it simple

It’s just an expression. However, it is easy, as we get more technical knowledge and experience, to get really creative in our troubleshooting and seek out complex solutions. Finding simple solutions can aid in making the troubleshooting process more effective and efficient. Don’t forget about the “simple stuff”.

1.3. “I don’t know”

No one likes to admit when they are in over their head. But a good technician doesn’t run from lack of knowledge. Instead, not knowing something should drive you to learn. It makes no sense wasting time pretending to fix something even though you have no idea what you are doing. But, if you are unsure, where might you get the information that you need?

1.3.1. Vendor documentation

Product manuals often have a troubleshooting section with some common issues and possible solutions.

1.3.2. Ask your peers

Maybe there’s a more senior technician who has experienced this before and can offer some guidance. A word of warning for the less experienced: don’t ask the same question more than once. It makes it look like you either weren’t listening or you didn’t really understand and perhaps aren’t up for the task. Take good notes and pay attention to what is said. If you’re a peer being asked for help, this is not a time to hoard information. Often, there is a misguided belief that if you are the only one who knows how to fix it, you are therefore invaluable and have greater job security. In reality, you are putting your organization at great risk. Be a team player. Share information with your colleagues.

1.3.3. Have you Googled it yet?

Another great resource is the internet. User and technician forums are an excellent place to get help. You can enhance your job performance and your enjoyment of the job by learning all aspects of what you do. This includes technical information such as how signals are transmitted on cable right down to installation and service techniques. The more you learn the more comfortable you will feel during your field work. There is a wealth of information available online on almost any topic one can imagine. All you need is the drive to learn.

2. Tools and Materials

Having worked with your tools and materials for some time, safety and efficiency should become second nature. Establishing high standards and consistent habits of care and good workmanship are essential to customer satisfaction and your own satisfaction for a job well done. Proper storage of equipment is of the utmost importance since these can be damaged easily and be of no use. The following are some suggestions for proper care and storage of set top boxes (STBs) and Cable Modems.

• Ensure that STB and MODEMS are kept in a dry place and are not exposed to hazardous elements e.g., water, dust, direct sunlight, chemicals to name a few.

• Keep STB and Modems stored so that the equipment will not move around while driving, equipment being tossed around, often becomes faulty and of no use.

• Always keep tools and materials in a safe place to ensure they are not misplaced and minimize the chances of theft.

• Ensure proper inventory of equipment for accountability at any time.

3. HFC Network

FLOW services operate on a HFC (Hybrid fiber coaxial) network. HFC is a telecommunications industry term for a broadband network that combines optical fiber and coaxial cable. It has been commonly employed globally by cable television operators since the early 1990s. In a hybrid fiber-coaxial cable system, the television channels are sent from the cable system's distribution facility, the headend, to local communities through optical fiber subscriber lines. At the local community, a box called an optical node translates the signal from a light beam to radio frequency (RF) and sends it over coaxial cable lines for distribution to subscriber residences. The fiberoptic trunk lines provide adequate bandwidth to allow future expansion and new bandwidth-intensive services such as internet access.

An HFC network may carry a variety of services, including analog TV, digital TV (SDTV or HDTV), video on demand, telephony, and internet traffic. Services on these systems are carried on RF signals in the 5 MHz to 1000 MHz frequency band. The HFC network is typically operated bi-directionally:

• The forward-path or downstream signals carry information from the headend/hub office to the home, such as video content, voice, and Internet traffic.

• The return-path or upstream signals carry information from the home to the headend/hub office, such as control signals to order a movie or internet upstream traffic.

The forward-path and the return-path are carried over the same coaxial cable in both directions between the optical node and the home. To prevent interference of signals, the frequency band is divided into two sections: 108–1000 MHz for forward-path signals, and 5–85 MHz for return-path signals.

4. Drop Cable Electrical Characteristics

4.1. Attenuation

One of the greatest contributors to cable signal loss is the coax itself. On our digital system no Amplifiers are used, so signal loss is a major concern. Attention should be paid to the type of cable used and the distance of the cable used to maintain sufficient signal levels throughout the system.

Attenuation can be calculated for all plant components, and it is expressed in units of decibels or dBmV. dBmV (decibels relative to one millivolt) is a measure of the signal strength in wires and cables at RF frequencies. A millivolt is 1/1000 of a volt. The five major contributors to attenuation are as follows:

• Frequency: The higher the frequency the greater the signal loss in dBmV.

  • Channel 14 attenuation at (121 MHZ.) is 1.95 dBmV per 100ft on RG 6 cable.

  • Channel 135 attenuation at (861 MHz) is 6.1 dBmV per 100ft on RG 6 cable.

• Size of cable: The longer the length of the cable based on its size will determine its loss in dBmV.

• Temperature: The hotter the temperature, higher the resistance, the greater the lost in dBmV level.

• Insertion loss: Loss incurred due to any addition of passive devices added to cable.

• Dielectric material: The type of material used for the dielectric could cause a percentage of attenuation or form some resistance to RF transmission.

  • Plastic poses the highest resistance in dielectric materials.

  • Foam poses a lesser resistant to RF transmission.

  • Air poses little or no resistance to RF transmission.

Note: Foam dielectric is the material used in our cable and is most commonly found in cable companies throughout the world.

4.2. Signal Loss Calculation

All coaxial cable is subject to cable loss over distance. Below are typical examples of signal loss that occurs over 100 feet of coaxial cable.

4.3. Drop cable Distance Specification

The following table identifies the maximum drop length from the tap to Drop Enclosure box (PRIMEX).

• All deviations from the guidelines above shall be reported to FLOW and authorization given whether to proceed or not. No two installations are the same, therefore situations may occur that require a different approach e.g., distribution lines to customer (540 cables).

• These are the standards for minimal acceptable performance.

• These standards are based on cable and splitter losses only.

4.4. 75 Ohm Coax Cable Components

Drop cable is made up of several components. The center conductor is copper coated steel for transmitting the signal and voltage. The foam dielectric maintains a consistent physical separation between the center conductor and the shield, ensuring stable characteristic impedance and minimizing signal loss, while also acting as an insulator grading it as 75 ohms coax. The aluminum foil acts as shielding material protecting the RF signal that is being transmitted on the center conductor from leaking out and preventing other signals from leaking into the cable. These two processes are called egress and ingress respectfully. The steel brays also act as another form of shielding, but also give the cable a form of strength when connectors are placed on the cable the brays bonds with it to have continuous shielding. The polythene jacket protects the cable from the element’s moisture and ultraviolet heat rays. All these components are very flexible which makes the cable workable and would not break when in use. See figure 1 below for further description.

Please note that when installing cable remember to observe the manufacture’s specification for bending cable. When forming loops or routing cables around corners the cable should not be bent or curved less than 10 times its size. If the cable is bent smaller the recommended specification, it will cause the cable to kink changing the impedance of the cable, increasing the ohms from 75ohms hence creating more electrical resistance to the signal. This is represented in the figure below.

4.4.1. Check Your Connectors

If connectors are not installed properly, reception problems will occur. For example, signal leakage causing egress and ingress, moisture migration, cable suck out etc. This can result in the customer having poor/no reception, scrambling pictures, freezing or complete loss of all three services (video, voice, and data).

However, if the connector is installed properly none of the above should occur and your F connector is now ready to deliver quality service. To ensure the proper installation of the ‘F’ connector, the following table identifies the steps that must be adhered to:

5. Service Operating Frequencies

There are three services that FLOW provides to our customers, Video, Data and Voice. The following table represents the operating frequencies and signal parameters for each service:

5.1 Spectrum Usage

Below is a graphical representation of the all the services offered by FLOW Trinidad and where they sit in the RF signal 0 MHz to 1000 MHz frequency band.

NOTE: The frequency and channel ranges specified above are for reference purposes. They are subject to change as there is always work taking place in the back end to further optimize the services offered by FLOW. (See Appendix 1 for full list of channels and corresponding frequencies)

5.1. BER

One of the most important ways to determine the quality of a digital transmission system is to measure its Bit Error Ratio (BER). The BER is calculated by comparing the transmitted sequence of bits to the received bits and counting the number of errors. The ratio of how many bits received in error over the number of total bits received is the BER. A bit error ratio of 10-9 is often considered the minimum acceptable BER for telecommunication applications. A BER of 10-9 means that 1 bit out of every 1,000,000,000 bit is, on average, read incorrectly ({1.0e-9 or 1E-9} -> represented in this format on most signal meters).

5.2. MER

MER stands for Modulation Error Ratio. It is a measure used to quantify the performance of a digital TV transmitter or receiver in a communications system using digital modulation. Acceptable operational MER levels should be above 35dB on the FLOW network. Once MER drops down to 28 dB and below, data transmission can be lost, thus delivering poor quality service.

6. Frequency-Division Multiplexing (FDM)

In telecommunications, frequency-division multiplexing is a technique by which the total bandwidth available in a communication medium is divided into a series of non-overlapping frequency bands. Each of these bands is a carrier of a different signal that is generated and modulated by a sending device. This allows a single transmission medium such as a cable or optical fiber to be shared by multiple independent signals.

The modulated signals are combined using a multiplexer (MUX) in the sending end. The combined signal is transmitted over the communication channel, thus allowing multiple independent data streams to be transmitted simultaneously. At the receiving end, the individual signals are extracted from the combined signal by the process of demultiplexing (DEMUX).

7. What is Channel Bonding?

Channel bonding is when a cable modem combines multiple channels to increase the amount of traffic that it can comfortably support. The best example for how channel bonding works is to look at a highway with heavy traffic:

On a highway, there are multiple lanes to allow traffic through to reduce traffic jams. In this example, the lanes are a cable modem’s channels, and the traffic jam is buffering and lag when your modem isn’t performing fast enough. The traffic congestion happens because you don’t have enough lanes (channels) to let the cars (data) through.

You can prevent issues like buffering with a cable modem that has a higher amount of channel bonding. There are different amounts of channel bonding that a cable modem can have to boost your Internet speeds.

7.1. Channel Bonding and How it Affects Speeds

Cable modems have downstream and upstream channels. These channels are what allow you to download and upload data. And the more channels you have, the faster you can do this. Back to the highway:

A cable modem’s downstream and upstream channels are like the lanes going in and out of a city. A cable modem with 1×1 channel bonding is like a two-lane highway with 1 lane going into the city and 1 lane going out. This means that there is 1 downstream channel and 1 upstream channel. This is the exact format for all channel bonding offerings. Here is a variety of DOCSIS 3.0 channel bonding you will come across:

• 4×4 = (4 downstream, 4 upstream)

• 8×4 = (8 downstream, 4 upstream)

• 16×4 = (16 downstream, 4 upstream)

• 24×8 = (24 downstream, 8 upstream)

• 32×8 = (32 downstream, 8 upstream)

8. Wi-Fi Tips for your Customer

8.1. Reboot your modem

A regular restart helps your modem and other devices perform at their fastest speeds and sometimes can resolve issues.

8.2. Placement

If you can adjust the placement of your modem, move it to an elevated, central spot about 1.5m off the ground and at least 1.5m away from electronics and metal appliances. It is also best to place your modem in a spot as central as possible in the home to have the Wi-Fi signal evenly dispersed.

8.3. Refresh your software

If you have 3rd party apps or software installed on your devices, ensure to keep them updated to achieve maximum speeds. To check for updates, visit the “settings” or “system preferences” on your device. Set up automatic updates for apps, antivirus programs, and other software you have installed on your devices.

8.4. Manage your devices

Turn off other internet-enabled devices and applications when they are not in use to maintain higher speeds. Consider adding a Wi-Fi extender to your home to increase your modem’s reach. Upgrading your plan to higher speeds may be needed if you’re using multiple data intensive devices.

8.5. Use Hard Wire for bandwidth intensive devices

As much as possible, devices such as Smart TVs and Gaming consoles should be connected via Hard Wire (your Ethernet Cable) instead of Wi-Fi. Streaming and gaming over Wi-Fi consumes a lot of bandwidth which may cause intermittent connection to other devices connected via Wi-Fi on your network. Additionally, hard wire is a more stable form of internet connection than Wi-Fi resulting in a better gaming and streaming experience.

8.6. Know your frequencies

Try to use both 2.4Ghz and 5Ghz frequencies on your modem. By connecting devices to both frequencies, it will prevent congestion on any one network and give you an overall better Wi-Fi experience.

2.4Ghz vs 5Ghz:

2.4Ghz – this frequency provides slower speeds but a wider range in distance from the modem. i.e., you can connect devices further away from the modem.

5Ghz - this frequency provides faster speeds but a shorter range in distance from the modem. i.e., devices need to be connected closer to the modem. Also, some older devices will not detect the 5Ghz frequency.

When doing speed tests, you should connect your device to the 5Ghz frequency as the 2.4Ghz is limited in attaining higher speeds.

8.7. Check your device storage

Device Health and maintenance is extremely important. Mobile phones and tablets with limited amounts of storage will experience issues when connecting to Wi-Fi.

8.8. Routers & Modems

If a router is being used next to a modem, this can cause interference and possible service issues. Customer should be informed of same and be advised that their router should be moved to another location if they are experiencing Wi-Fi issues.

9. Wi-Fi Power Levels

-67 dBm is a reliable signal strength. This is the minimum for any online services that require a reliable connection and Wi-Fi signal strength. The following table depicts a quick overview of the required Wi-Fi signal strength for different online activities.

A general rule of thumb in home networking says that Wi-Fi routers operating on the traditional 2.4 GHz band reach up to 150 feet (46 m) indoors and 300 feet (92 m) outdoors. As mentioned before routers that run on 5 GHz bands reached approximately one-third of these distances.

Appendices

Appendix 1