The processing of the various signals is carried out through implements that are together called as DSP hardware. This includes the hardware that is used for transmission of signals, various devices that are used to enhance or filter the signals, analogue to digital and digital to analogue converters and other processing equipment such as computers.
Among the hardware mentioned above, digital signal processors are the ones in which the actual processing takes place. Usually the digital signal processors today have the following characteristics:
They are equipped to handle real time processing i.e. they can give the optimal performance even when streaming data is being fed into them.
The memories that are used to store programs are different from the ones used to store data.
They do not provide hardware that supports multitasking.
It can be used as a direct memory access device in supporting or host environments.
They take analogue signals as input, convert them into the digital form, process the signals and then, convert them back into the analogous form.
They make use of Direct Memory Access technique.
The digital signal processors usually have architecture so as to optimise the following features:
- A unit that can handle floating numbers is present directly in the data flow path.
- The accumulators or multipliers that are present are highly parallel in nature.
- Special hardware is included in order to carry looping at a very low cost.
- Their architecture is specially designed so that fetching multiple data at the same time is possible.
- The calculations are usually carried out by fixed point arithmetic process in order to speed them up.
- Most of the registers present in computers today move the data to the lower-most bit if an overflow occurs. However, in case of digital signal processors, the overflow is retained at the maximum point itself.
- Specialised instructions are present for modulo and reversed bit addressing.
These days, large amount of modifications are being made on in the digital signal processors so that they can function at a higher speed. The speed however, varies from one processor to the other. Some of the fastest ones are capable of processing over 8000 million instructions per second.
The quality digital signal processors can be interfaced with a variety of other devices, buses etc. Even though they can be modified to handle floating point numbers, many of them are capable of performing only fixed point arithmetic as the range provided by the fixed point numbers is sufficient to handle all the signal data. Usually, when a floating point system is integrated, the software comes cheaper however; the cost of the hardware is greater.
The DSP hardware is usually in the form of ICs or Integrated Circuits however, they can also be constructed using Field Programmable Gate Arrays. In the times to come, digital processors are sure to undergo a large amount of changes to support the growing needs generated by other developments in technology.