By Michael Lemm

Don’t be confused about the difference between DS3 and T3 circuits. These terms are really synonymous. Instead you should focus on what they can do for you…and the best scenarios for application.

Digital Signal (DS) is a system of classifying digital circuits according to the rate and format of the signal (DS) and the equipment providing the signals (T). DS and T designations have come to be used synonymously so that DS1 implies T1, and DS3 implies T3.

A DS3 line (also known as a T-3) is an ultra high-speed connection capable of transmitting data at rates up to 45 Mbps. A DS3 line is equal to approximately 672 regular voice-grade telephone lines, which is fast enough to transmit full-motion, real-time video, and very large databases over a busy network. A DS3 line is typically installed as a major networking artery for large corporations and universities with high-volume network traffic. Other example applications include large call centers, enterprise wide VoIP and IP PBX systems, Internet service providers, research labs, video conference centers and software development companies. A DS3 is the second fastest, non optical connection offered in North America. A DS3 line is comprised of 28 T1 lines, each operating at total signaling rate of 1.544 Mbps.

DS3 circuits provide businesses and Internet Service Providers (ISPs) with up to 45 Mb/s of dedicated Internet connectivity. This is an ideal solution for users who have outgrown their T1 connections and are in search of unlimited, high-capacity access. A DS3 line actually consists of 672 individual channels, each of which supports 64 Kb/s. DS3 lines are extremely high bandwidth connections into a carrier’s backbone. They typically include SLAs (Service Level Agreements) that guarantee uptime and performance.

The DS3 signal itself is composed of 28 DS1 signals and is constructed using a two-step multiplexing process. First, the 28 DS1 signals are multiplexed into seven DS2 signals. Second, the seven DS2 signals are multiplexed into one DS3 signal. Each multiplexing step uses bit stuffing to handle the different input frequencies. Overhead bits provide alignment, error checking, in-band communications, and bit stuffing control information.

Line rate: 44,736,000 b/s
Signals: 7 DS2 signals = 28 DS1 signals
Overhead bits:
56 bits total/frame
F-bits (framing) 28 bits/
M-bits (multiframing) 3 bits/
C-bits (stuffing) 21 bits
X-bits (message) 2 bits/
P-bits (parity) 2 bits/
Data bits between overhead bits 84

A DS3 connection is comprised up of two monthly charges: the local loop and the port charge. The local loop charge is the cost of the circuit provided by the Local Exchange Carrier (LEC) that allows DS3 access into the carrier’s network. The loop charge is based on the distance from the customer’s location to the edge of the carrier’s network; the farther the customer is from the network, the more the loop will cost. Nearly every carrier prices loops differently so it is in your best interest to price DS3 service with several providers to ensure that you get the best deal.

DS Internet Access is the ideal solution for businesses that require high-bandwidth access at a reduced price. Whether you host high-traffic Web sites, support Web hosting or need high-capacity bandwidth on an as-needed basis, there’s a level of DS3 service (Full or fractional) that will meet your needs. Fractional to full DS3 or T3 circuits run from speeds of 3 Mbps up to 45 Mbps.

For customers that require more bandwidth than a T1 line can provide but do not yet require the capacity of a full DS3 line, a fractional DS3 connection is the ideal solution. A fractional DS3 is similar to a full DS(T)3, only with some of the channels turned off. This reduces the total monthly cost and provides additional capacity that can be turned up in a matter of days. Unfortunately, the DS3 (T) loop is still required for this service.

If a full DS3 line is more bandwidth that you really need, it is also possible to get Fractional DS3, which gives you a portion of full DS3 bandwidth at a lower cost. Of course, DS3 is also available in multiples to increase bandwidth, similar to bonded T1 service.

DS3 service can be deployed for a wide verity of applications. The most common uses are DS3 point-to-point, DS3 internet, DS3 frame relay, DS3 voice and DS3 VPN. The pricing for these connections varies widely depending on the carrier, location of service and the application for which the connection is being used. Visit DS3 Bandwidth to obtain current “real time” rate quotes for your location.

By Jason Cole

Moving on down the line, today we continue our series on audio effects and editing tools. In the past few articles we’ve such effects as reverb, flange, delay, and noise gate. If you enjoy dabbling in audio production, you’re going to enjoy today’s article. We’ll be discussing compression, which is instrumental in the audio production arena. And also we will also be discussing ring modulation, which is a bit more fun and flexible audio effect. So, in today’s article get ready to learn about both, compression, and ring modulation. Let’s discuss how these effects work and why they work the way they do.

Compression
Compressors reduce the dynamic range of an audio signal, if its amplitude exceeds a set threshold. The amount of range reduction is determined by a set ratio. If the ratio was set to 6:1, the dB would need to be increased by 6 to increase the output signal by 1 dB over the threshold. The way that a compressor reduces dynamic range is by using a variable-gain amplifier, which reduces the gain of an audio signal. Analog compressors typically carry this out by using a voltage controlled amplifier, which reduces the gain as the input signal’s power increases. Digitally, compression is carried out via DSP (digital signal processing), and this is the most modern version of the effect. The main use of compression is to make music sound louder without increasing its peak amplitude. Compressing the peak, (loudest signal), allows you to increase the overall gain without exceeding the dynamic limits of your reproduction device. Compression is widely used in TV and radio, allowing maximum perceived volume, without going over the strict limits imposed by most broadcasting companies.

Ring Modulation
Ring modulation is achieved by multiplying two audio signals, with one signal being a simple waveform such as a sine wave. They combine the two signals, outputting the sum and difference of said signals. Ring modulation is related to amplitude modulation and frequency mixing, and it produces a signal rich in overtones. It is well suited to produce metallic and bell-type sounds. Modern ring modulators, like modern compressors, use digital signal processing to produce the effect. Using DSP to do this produces a mathematically perfect signal output, which some musicians do not like. You can come up with some interesting harmonics using a ring modulator by changing the frequency of the two input waveforms.

This is the third installment in my continuing series on audio effects and engineering tools. We discussed compressors and ring modulators today, a couple of very interesting and deep effects. I learned a lot myself, so I hope that you did as well. We will be continuing this series indefinitely, until we run out of effects! I hope that this has shed a little light on these two amazing pieces of equipment, ultimately making your next music project a bit more interesting and productive.

By Jason Morris

Analogue is the process of taking an audio or video signal and then turning it into electronic pulses. Digital is the process of turning the signal into a binary format, represented by a string of 1’s and 0’s. Analogue technology has been around for a long time now. It really isn’t that complicated and is fairly inexpensive. The problem with analogue signals lies in their size limitations regarding the amount of data they can carry.

Because of the way digital works by breaking a signal into 1’s and 0’s and then re-assembling it exactly at the other end, it gives you clear and distortion free cordless conversations. A digital signal knows what it should be when it reaches the other end, through the arrangement of the binary code. This means it can correct any errors that may have occurred during the transmission of the data (signal). All this means that in most cases clarity of the signal is maintained, offering distortion free telephone conversations or clearer television pictures.

Digital technology is also more compact, allowing you to cram much more data into the same space as an analogue signal, meaning more features can be crammed into the digital signal. Though digital signals offer great clarity, they don’t always offer the same rich sound quality as analogue for now.

Cordless phones

Because of the way digital works by breaking a signal into 1’s and 0’s and then re-assembling it exactly at the other end. It gives you clear and distortion free cordless conversations. Digital cordless phones also encrypt the binary data during transmission, making your call safe from eavesdroppers. With digital more power can be applied to the signal allowing you greater range on cordless conversations.

If you are in a small office or in your home, it may be that you don’t require a big range and security isn’t an issue, in which case you may find that a cheaper analogue cordless system will fulfil your needs. Check out the features at the end of this article to help you decide if a digital cordless phone will benefit you. You will need to keep in mind that when using digital or analogue signals for cordless phone calls, the handsets themselves are still analogue devices that can only be used on analogue lines. Also the range of your cordless phone, whether using analogue or digital signals will always depend on the environment in which you are using it.

Phone systems

When considering which type of phone system is best suited to your business, digital or analogue. Many companies are now choosing hybrid systems, which allow you to use both digital and analogue peripherals, giving you the benefits of a digital system while offering the flexibility to implement any existing analogue equipment.

Benefits of digital and hybrid phone systems

1. Computer Telephony Integration (CTI) – Digital systems allow better implementation of Desk Top Assistant (DTA) software.

2. Allow you to integrate your telephone system with your computer network.

3. Offers greater clarity of call signal (no distortion).

4. Easily adapts to the use of DECT cordless technology, giving your employees the freedom to roam, while still receiving a clear distortion free signal.

5. Allow better integration with advanced features such as voicemail auto attendants and other call handling features.

Benefits of digital handsets

1. Allow better integration of advanced features such as voice mail and auto-attendants.

2. Offer greater internal memory for better call handling.

3. Caller Line Identification (CLI). Allowing you to view the identity of any callers before answering the call.

4. Offer clear distortion free calling.

5. Offer high capacity name and number directories.

Benefits of digital (DECT) cordless handsets

1. DECT cordless offers increased range over analogue sets. Up to 50m indoors and up to 300 outdoors, which can be increased with the use of strategically placed repeaters.

2. DECT cordless offers better security through signal encryption, stopping eavesdroppers.

3. Offer clear distortion free calling.

4. Allows the use of extra handsets without the need for extra wiring.

5. Calls can be transferred between handsets.

6. Caller Line Identification (CLI). Allowing you to view the identity of any callers before answering the call.

7. Offer high capacity name and number directories.