What do you think ?? BUC or Transceiver
Asanka Liyadipita
RF Engineer | Enabling greater connectivity in the Telecommunication Industry | Technology for better future | ?? ?? ?? ??
Actually, it’s all about how to select the most suitable devices using many practical parameters. In an early era like 2000 when installing VSAT for clients installers always installed a 70 MHz modem with a C band or Ku band transceiver, but time converts technology and everyone observed in satellite markets fever transceivers and many more BUCs. So let’s discuss this interesting topic.
The Transceiver
In a typical VSAT installation, the amplifier mount very close to the antenna feed as possible but the modem and other electronic stuff are connected by using cable to the equipment room or operation room. If cable had to carry 4-5-6Ghz signals it requires thicker one which is much expensive . So in order to reduce or cutdown costs, RF engineers came up with a system where the modem could communicate with the transceiver using lower frequencies . They called this lower frequency Intermediate Frequency, and it can be carried over long distance using cheap cables.
If we take standard C band amplifier it required RF frequency input and not the IF frequency . So designers of the transceivers installed an up-converter within the transceiver to change frequency IF to C band or Ku band.
To discuss more about two technologies let’s take simple example: 70 MHz modem and transceiver setup using C band.
The receive frequency of 4 GHz is collected by LNA on the antenna and passed to the receive port of the transceiver. Normally transceiver mounted on the antenna and very short thick cable is sufficient for the setup. Now transceiver received C band signal and it converts signal to Immediate Frequency (IF) of 70 MHz and then the signal can be carried by standard coaxial cable long way from the antenna to Operation room. Generally transceivers waterproof and impervious heat and cold . Transceiver has all the frequency control and input /output power controls that needed to send and receive signals.
The Block up converter
In early 2000, design engineers struggled to reduced price of transceiver making new device. So they developed new scheme that used a higher intermediate frequency in the 900 MHz - 1750 MHz range. Even though much higher than 70 MHz, this L band frequency still can be carried long distance using standard cheap cables. The other change was to replace transceiver with a simple and cheap unit called Block up converter. The BUC converts low frequency to high frequency and act as an amplifier transmitting signals to the satellite . The early BUC are dumb devices compared to transceivers, but now thanks to the technology and engineers who work hard on this BUC’s are becoming more sophisticated, and also having many smart control options . The BUC power supply, tx power settings, frequency selections were moved into the L band modem. So then indoor modem doesn’t required much environmental protection like BUC. Remember everything has positive and negative because this is real world . The penalty is that the L band modem costs more than a similar 70 MHz modem. Anyway the cost of combination BUC, LNB L-band modem was many thousands of dollars less than the transceiver system.
Finally I’m not an enemy of transceivers