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What is a Cable Modem Router Combo & What are its Advantages?

February 4, 2020 No Comments

Featured article by Vanessa Rogers, Independent Technology Author

In today’s world of fast-paced internet connectivity, chances are you have already heard about cable modems and ADSL (Asymmetrical Digital Subscriber Lines). The cable modem is a common feature with most cable TV provider nowadays and can provide a high-speed internet connection to their clients. 

If you are planning on getting an ISP to set up your home’s internet network, you will most likely encounter two choices: cable modems and DSL. In this article, we will solely focus on the cable modem router. We will be taking a close inspection as to how a simple coaxial cable can deliver not only hundreds of channels to your television but also allow users to gain access to the infinite treasure trove that is the world wide web. 

What is Inside the Cable Modem Router?

First off, know that there are two variations of the cable modem: the external and internal cable modem. In cases that relate to cable TV services, chances are they will incorporate a device called a set-top cable box. This type of cable modem device only requires your standard keyboard and mouse to gain internet access. 

Upgraded versions of these devices (from standard cable system to digital cable) will be able to connect to the internet by default without needing to connect to the CATV. While best cable modem routers combos typically come in different shapes and sizes, depending on the ISP, all cable modems have the same set of essential components. 

These components are:

– Tuner
– Demodulator
– Modulator
– Media Access Control Device (MAC)
– Microprocessor

Now, let’s take a closer look at the inner workings of a cable modem router to understand what makes it tick fully.

Cable Modem Router Components


– Tuner


The tuner is an integral part of a cable modem router as it separates the data received from CATV program to the Internet data. Think of the tuner as a sort of traffic enforcer that directs Internet data as it exclusively utilizes an unused cable channel; the tuner will then direct the internet data towards the demodulator, which we will be discussing later in this article, as well.

There is also a component called a diplexer which is sometimes used in conjunction with the tuner. The diplexer assists the tuner in utilizing a range of frequencies to segregate downstream traffic and upstream data.


– Demodulator


As we have noted earlier, the tuner works directly with another component called the demodulator. Most demodulators have a total of four functionalities in total. A demodulator takes frequencies sent to it by the tuner. As the radio-frequency received typically contain varying degrees amplitude, it is the demodulator’s job to simplify the signal so that it can be easily read by the A/D converter (Analog to Digital converter). 

The A/D converter will then take the signal sent by the demodulator and convert it into 1s and 0s. To ensure that all data received are error-free, an error correction module will come in to double-check all data collected from the A/D converter. If any error is detected, the module will repair said error in coding as well. 


– Modulator


Some cable modem routers also use a unique cable system to send upstream traffic. In these instances, a modulator is needed to keep the system functioning. The modulator’s job is to convert network data into radio-frequency. Once saved, the radio-frequency signal is then sent through the system. 

The modulator or burst modulator is named as such due to the erratic behavior of data traffic between the user and the internet. Transmission through the modulator goes through three stages:

1. Checking and correction of data/code/information.
2. QAM modulator receives data and sends it to –
3. The D/A converter.

All of these procedures happen almost instantaneously making this process even more impressive.


– Media Access Control Device or MAC


The MAC is an integral part of connecting your system to the internet. It acts as a buffer between the hardware and software interface as well as the various protocols that operate within both systems. Note that while every computer network device utilizes MACs, a cable modem takes the standard functionalities of MACs and puts several extra layers on top. This makes MACs found in cable modems more complex.


– Microprocessor


At the center of it all is the microprocessor. The microprocessor’s responsibility varies depending on what type of cable modem is being used. Specifically, cable modems that work together as part of a more extensive computer system or to provide Internet access on its own.

The Cable Modem Termination System (CMTS)

Over on the cable provider’s side is the Cable Modem Termination System of CMTS. The CMTS features almost similar functionalities as those found in its counterpart in the DSL system called the Digital Subscriber Line Access Multiplexer (DSLAM).  

The job of the CMTS is to take all incoming traffic from all clients from a particular channel and re-route it to the ISP so that the clients gain access to the internet. The cable provider will also provide a lease for third-party ISPs. In turn, this will allow the Dynamic Host Configuration Protocol (DHCP) to assign specific IP addresses to all clients of the cable provider. 

The Advantages and Disadvantages of Using Cable Modem Routers

Of course, Cable modems come with their ups and downs. Understanding the cable modem’s strengths and shortcomings are essential to determine whether this type of Internet network system is the best in your particular case. 

The primary benefit here would be with the first group of users to connect to the internet using the cable provider’s channel. The reason for this is that these lucky clients get access to most of the bandwidth provided by the cable provider. 

Of course, as more clients connect to the cable’s ISP, the more cluttered the traffic will be. This can affect the network speed of all clients across the board unless the cable provider upgrades their system to accommodate the influx of new clients. 

One more notable advantage of using cable modem is that its performance is not affected by the distance between the client and the main cable office. Unlike digital cable, cable modem routers deliver the same level of performance wherever the clients are as long as they can connect directly to the cable lines. 

Final Thoughts

In summary, cable modem routers offer stability and reliability to users that utilize this particular method of connecting to the internet. The only downside here is that the cable provider must regularly upgrade their system as their customer list grows to avoid heavy-traffic and slowdowns.


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