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How far/fast?

The first two questions asked by many novice users of wireless communications is always:

  1. How fast does it go?
  2. How far does it cover?

The answers are not practical to answer for a device like the ADALM-PLUTO, or any other SDR since you can gain distance by giving up datarate, gain data rate by increasing bandwidth, gain data rate by changing modulation scheme. The performance (how far/fast) of the system will depend heavily on everything from the choice of carrier frequency, modulation type, bandwidth, antennas, local environment (topography, vegetation, weather), just to name a few.

Data Links vs Radios

One of the first things to understand from a novice standpoint is the difference between a data link and a radio.

At the top level, a data link connects one location to another for the purpose of transmitting and receiving digital information. In most instances, we have a transmitter and a receiver and the channel. These are governed by a link protocol enabling digital data to be transferred from a data source (transmitter) to a data sink (receiver). The data link specifies everything that both the transmitter and a receiver need to know to communicate effectively. This includes such things as:

  • Simplex, Half-duplex or Duplex communication links
  • occupied bandwidth
  • center frequency
  • modulation types supported
  • negotiation of modulation types (if supported)
  • MAC protocol (multi-master, master-slave, CSMA, etc)

When asking questions about how far, how fast, bit error rate - these are characteristics of a data link, not a radio.

Since the ADALM-PLUTO is a radio, not a datalink, it is difficult to answer those questions.

For analyzing data links, there is a great article at AFAR Communications which reviews these sorts of things.

university/tools/pluto/users/far_fast.1491844899.txt.gz · Last modified: 10 Apr 2017 19:21 by Robin Getz