Hi
It is sort of an " everybody does it " sort of thing. Various justifications:
Less power is used / less heat in the drivers and terminations.
Transformer coupling works better ( lower delay ) with narrow pulses
Anything over 1 us has been "really long" in terms of logic speeds
since the 1960's
A definite duty cycle "bias" let's you detect an inverted pulse.
The only real reason is "that's the way it's done". Big Customers ask for it
that way. Suppliers deliver what is asked for. Nobody complains, nothing
changes.
Bob
> On Sep 16, 2016, at 7:44 PM, Peter Vince <petervince1...@gmail.com> wrote:
>
> Can I ask why PPS pulses are so narrow? It makes them difficult to see on
> a 'scope, and difficult to detect on a PC. And, as Bob said, far less
> obvious if you trigger off the wrong edge.
>
> Peter
>
>
>
>> On 16 September 2016 at 23:55, Bob kb8tq <kb...@n1k.org> wrote:
>>
>> Hi
>>
>> Most PPS signals these days are very low duty cycle. If you AC couple
> them, you can easily be triggering on the wrong edge. With the narrow pulse
> it may not be very obvious.
>>
>> Bob
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