#### How many radio stations can be broadcast by a DAB^{+} transmitter ?

Every participating radio station in a DAB^{+} ensemble is a digital audio stream. Compare it with the radio web stream for Internet listeners.

The higher the bitrate of the stream, the better it could sound. However, this is not always the case, bit compression has evolved, and the truth is that HE-AAC gives better quality than MP3, even at lower bitrates.

DAB^{+} works similarly, although we do not use the Internet but a DAB^{+} channel. The DAB^{+} channel has a higher bitrate than each independent audio channel. The Ensemble MUX will cut Audio streams into chunks and put them each in their time slot allocation (one after the other). We call it TDM or **T**ime **D**ivision **M**ultiplex. Each radio program takes some bits per second in the Ensemble MUX.

Each station can transmit a certain amount of bits per second (bandwidth). We can add up stations to the total capacity of the Ensemble MUX. By making every (local) station sound a little less good, many more (local) radio stations can access the same DAB^{+} Ensemble.

The easiest way to explain this is to start from the bit transfer capacity of a DAB system. Consider the system as a one-way wireless modem: from transmitter to receiver. Better would be to call it a modulator. But we will use the word modem because so many people know it. We understand that a modem has a maximum bitrate (see 1200 bits/s, 2400 bits/s, 4800 bits/s, 9600 bits/s, etc.).

How many bits can the DAB+ system send to the receiver per second? Well, it is precisely **2,400 kbits/s**. However, we will have to reserve **96 kbits/s** (called the Fast Information Channel) for particular data that enables a receiver to start decoding a DAB signal quickly. As a result, the limit for the audio data will be **2,304 kbits/s **(the Main Service Channel).

Please remember at all times that the AUDIO bit transfer rate for DAB+ is equal to 2,304 kbits/s

The number of radio stations fitting into the above DAB^{+} is all the radio station’s bit rates multiplied by the inverse of the “Equal Error Protection (EEP)” factor. Possible EEP efficiency values for DAB+ are 1/4, 3/8, 1/2, and 3/4, meaning redundant error correcting information to the original audio signal.

- For ¼, the original bitrate will be multiplied by 4.

(Each bit will have 3 bits error correction, or the actual data will be ¼ of the final bitrate with the additional error correction). - For 3/8, the original bitrate will be multiplied by 8/3 or 2,6666.

(Each bit will have additional 2,666 bits error correction, or the actual data will be 3/8 of the final bitrate with the additional error correction). - For 1/2, the original bitrate will be multiplied by 2.

(Each bit will have one additional bit error correction, or the actual data will be 1/2 of the final bitrate with the additional error correction). - For ¾, The original bitrate will be multiplied by 4/3 or 1,3333.

(Each bit will have additional 1,3333 bits error correction, or the actual data will be 3/4 of the final bitrate with the additional error correction).

E.g., in the case of an error correcting factor of 1/4 for every bit of the actual number of bits, three redundant ones are added. Most operators use EEP-3A with a value of 1/2. Sum all the multiplied values up, and as long as they fit the maximum of **2,304 kbit/s**, it will work.

For example, take 12 stations with a bitrate of 96 kbit/s and protection EEP-3A (1/2). They will use 12 times 192kbps (*station bitrate multiplied by 2, the inverse of the error correction factor *). This example shows that this configuration just fits into the 12 x 192 kbits/s = **2,304 kbits/s.**

Instead of using a per second approach, One can calculate the capacity using a 24ms time-lapse by using the quantity of the used CU’s.