Industrial Communications Handbook

industrial communications handbook 2016

(military), their combination is often troublesome.

Since the 2,45 GHz band, in particular, is extremely

noisy and busy, each additional transmitter simply

increases the ‘noise floor’, thus making it more dif-

ficult for yet another transmitter to successfully gain

access. Hence data throughput rates drop, and an-

noyingly, that temperature transducer sometimes

works, and sometimes doesn’t …

It is extremely important to note that the network-

ing systems we have were designed for different pur-

poses, and we ought not to use them for things they

were not designed for. Of course, that is a red flag to

a bull …Therefore many systems are inappropriately

used. Bluetooth was not designed for video stream-

ing. Internet protocol was not designed for low la-

tency communications.

Remember that in the 1980s, Ethernet was all con-

nected to the same network segment, and essentially

all communication occurred by talking to everyone

on that bus. When the jabber got too much, one

put a bridge in, and separated the network into two

smaller sub-networks, so that only communication

that had to go over the bridge to the other side did

so, freeing up each side of the bridge to allow more

local communication speed.

Eventually, when costs plummeted, switches ar-

rived, allowing each segment to be quite small, with

only a few machines on a common bus. These days,

it would be odd to have more than one machine on

its own segment, with ALL communication effective-

ly switched over a very fast backbone, such that few

collisions occur.

Wireless takes us Forward, slap bang into 1980 all

over again. Unswitched hubs is all the atmosphere

offers, (OK, there are a FEW non overlapping chan-

nels).

In ordinary Telecomms, when bandwidth be-

comes an issue, lay another cable, it is a tad more

difficult to lay another electromagnetic spectrum.