The transmission rate of a modem refers to the amount of data transmitted per second. What we usually refer to as 14.4K, 28.8K, 33.6K, 56K, etc., refers to the transmission rate of the modem. The transmission rate is measured in bps (bits per second). Therefore, a 33.6K modem can transmit 33600 bits of data per second. Due to the compression of data during transmission by current modems, the data throughput of a 33.6K modem can theoretically reach 115200bps, or even 230400bps.

The transmission rate of a modem is actually determined by the modulation protocol supported by the modem. The V.32, V.32bis, V.34, V.34+, V.fc, and so on that we usually see on the packaging box or manual of the modem refer to the modulation protocol used by the modem. Among them, V.32 is a non synchronous/synchronous 4800/9600bps full duplex standard protocol; V. 32bis is an enhanced version of V.32, supporting a transmission rate of 14400bps; V. 34 is a synchronous 28800bps full duplex standard protocol; And V.34+is a synchronous full duplex 33600bps standard protocol. The above standards were developed by ITU (International Telecommunication Union), while V.fc is a 28800bps modulation protocol proposed by Rockwell, but it has not been widely supported.

When it comes to the transmission speed of modems, we cannot ignore the currently popular 56K modem. In fact, the 56K standard has been proposed for many years, but due to the long-standing existence of K56flex led by Rockwell and U S. The two incompatible standards led by Robotics and X2 have hindered the widespread adoption of 56K modems. Fortunately, in February of this year, with the efforts of the International Telecommunication Union, the 56K standard was finally unified to ITU V9.0. Many modem manufacturers have also introduced upgrade measures, and modems that truly support V9.0 have also blossomed everywhere. 56K is expected to become mainstream in the market within one to two years. By the way, it should be noted that many ISPs in China currently do not provide 56K access services. Therefore, it is best to inquire with your service provider before purchasing a 56K modem to avoid waste.

The transmission rates we mentioned above are all obtained under ideal conditions. In actual use, the speed of the modem often cannot reach the nominal value. The actual transmission rate mainly depends on the following factors:

1. The quality of telephone lines

Because the modulated signal is transmitted over a telephone line, if the quality of the telephone line is poor, the modem will reduce the speed to ensure accuracy. Therefore, when connecting to the modem, we should try to minimize the length of the connection, cut off excess connections, and avoid stacking them in a circle. In addition, it is best not to use extensions, and connections should also avoid passing through sources of interference such as televisions.

2. Is there sufficient bandwidth available

If there are many people accessing the internet at the same time, it will cause congestion and blockage of the line, and the transmission speed of the modem will naturally decrease accordingly. Therefore, whether the ISP can provide sufficient bandwidth is crucial. Additionally, avoiding surfing the internet during peak hours is also a solution. Especially when downloading files, the time spent downloading during busy and non busy periods can differ by several times.

3. The other party's modem speed

The modulation protocol supported by the modem is backward compatible, and the actual connection rate depends on the lower speed party. Therefore, if the other party's modem is 14.4K, even if you are using a 56K modem, you can only connect at a speed of 14400bps.