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From: email@example.com (john jardine)
Subject: Re: Help - Power mosfets - difficult load
Date: 29 Oct 2002 12:27:03 -0800
References: <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org> <email@example.com>
NNTP-Posting-Date: 29 Oct 2002 20:27:03 GMT
firstname.lastname@example.org (Bill Allison) wrote in message news:<email@example.com>...
> "Phil Allison" wrote in message news:...
> > "Bill Allison" wrote in message
> > news:firstname.lastname@example.org...
> > > Phil
> Phil that's absolutely not the case. An uninterrupted stream of good
> pulses to the servo is guaranteed by the program code in the receiver
> decoder's microcontroller section - and is verifiable by CRO
> observation :)
> > . . . . .............. Phil
Each individual element may appear invincible but the comms channel
must be looked at as a 100% complete system, including its
susceptibility to external unwanted inputs.
Spent time working on a high data integrity, distributed, (UHF and
microwaves) telemetry system. The computer mainframe and data
processing systems were a primarily a copy of the gun laying systems
used on larger British warships. Every year, at the start of June,
spurious and invalid data readings would begin to appear in the
system. Eventually correlated with the yearly visit of the Russian
trawler fleet to the local port of Scarborough. Receiver to modem
symptoms were long bursts of high level audio noise as against the
usual low level 2 tone fsk. A test using an noise source (0-100kHz)
plugged into the setup could turn up a valid telemetry command 'poll'
every 30mins (wide StanDev). A valid (wanted) poll consisted of a
serial string of 36 bits (12 command, repeat of the 12, inverse of the
The random noise was managing (how?) to replicate a valid string of 36
bits!. The system of course responded in a normal manner. Error
checking technology has improved vastly but systems are still liable
to random failure and can never be 'guaranteed'.
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