Prelim: If anyone remembers me from previous posts, please note 
that constraints imposed by my location dictate that I use, as 
far as possible, only long-established standard components in my 
projects.

I want to send two independent unidirectional pulsed signals over 
a distance of about 500 meters and I'm considering my options. 
The signals will be single triggering pulses with long irregular 
intervals in between pulses. The primary requirement is that 
interference should not cause false triggering, and the two 
channels must not interfere with each other.

I've considered optical fiber cable and RF, but am currently 
thinking that CAT5 cable might offer the best compromise of 
simplicity, cost and reliability. I'm always open to alternative 
suggestions though. Where I'd like to ask for your inputs is:

1. Is my scheme at all feasible with fairly simple circuitry?

2. I've never made a study of the electronics that drives 
computer network lines, and I can't do it now because my ISP is 
working in sporadic bursts (I had to wait >1 hr to post this). I 
could drive each twisted pair as balanced differential lines 
instead of using one wire as ground. Is this likely to be 
necessary?

3. What factors do I need to know and consider? 

pimpom wrote:
> Prelim: If anyone remembers me from previous posts, please note 
> that constraints imposed by my location dictate that I use, as 
> far as possible, only long-established standard components in my 
> projects.
> 
> I want to send two independent unidirectional pulsed signals over 
> a distance of about 500 meters and I'm considering my options. 
> The signals will be single triggering pulses with long irregular 
> intervals in between pulses. The primary requirement is that 
> interference should not cause false triggering, and the two 
> channels must not interfere with each other.
> 
> I've considered optical fiber cable and RF, but am currently 
> thinking that CAT5 cable might offer the best compromise of 
> simplicity, cost and reliability. I'm always open to alternative 
> suggestions though. Where I'd like to ask for your inputs is:
> 
> 1. Is my scheme at all feasible with fairly simple circuitry?
> 
> 2. I've never made a study of the electronics that drives 
> computer network lines, and I can't do it now because my ISP is 
> working in sporadic bursts (I had to wait >1 hr to post this). I 
> could drive each twisted pair as balanced differential lines 
> instead of using one wire as ground. Is this likely to be 
> necessary?
> 
> 3. What factors do I need to know and consider? 
> 
> 

What does "long" mean in this context? Milliseconds? Minutes?

What's the minimum such interval?

What delay can you tolerate between sending the pulse, and receiving it?

Sylvia.

pimpom wrote:
> Prelim: If anyone remembers me from previous posts, please note
> that constraints imposed by my location dictate that I use, as
> far as possible, only long-established standard components in my
> projects.
>
> I want to send two independent unidirectional pulsed signals over
> a distance of about 500 meters and I'm considering my options.
> The signals will be single triggering pulses with long irregular
> intervals in between pulses. The primary requirement is that
> interference should not cause false triggering, and the two
> channels must not interfere with each other.
>
> I've considered optical fiber cable and RF, but am currently
> thinking that CAT5 cable might offer the best compromise of
> simplicity, cost and reliability. I'm always open to alternative
> suggestions though. Where I'd like to ask for your inputs is:
>
> 1. Is my scheme at all feasible with fairly simple circuitry?
>
> 2. I've never made a study of the electronics that drives
> computer network lines, and I can't do it now because my ISP is
> working in sporadic bursts (I had to wait >1 hr to post this). I
> could drive each twisted pair as balanced differential lines
> instead of using one wire as ground. Is this likely to be
> necessary?
>
> 3. What factors do I need to know and consider?

You haven't told us anything about frequencies or time periods you are 
deailing with. That will pretty much dictate what's easily possible over 
500m.

Standard differential RS485 for example is simple to implement and capable 
of more than 1km at low enough data rates.

Dave.


-- 
---------------------------------------------
Check out my Electronics Engineering Video Blog & Podcast:
http://www.eevblog.com 

Sylvia Else wrote:
> pimpom wrote:
>> Prelim: If anyone remembers me from previous posts, please 
>> note
>> that constraints imposed by my location dictate that I use, as
>> far as possible, only long-established standard components in 
>> my
>> projects.
>>
>> I want to send two independent unidirectional pulsed signals 
>> over
>> a distance of about 500 meters and I'm considering my options.
>> The signals will be single triggering pulses with long 
>> irregular
>> intervals in between pulses. The primary requirement is that
>> interference should not cause false triggering, and the two
>> channels must not interfere with each other.
>>
>> I've considered optical fiber cable and RF, but am currently
>> thinking that CAT5 cable might offer the best compromise of
>> simplicity, cost and reliability. I'm always open to 
>> alternative
>> suggestions though. Where I'd like to ask for your inputs is:
>>
>> 1. Is my scheme at all feasible with fairly simple circuitry?
>>
>> 2. I've never made a study of the electronics that drives
>> computer network lines, and I can't do it now because my ISP 
>> is
>> working in sporadic bursts (I had to wait >1 hr to post this). 
>> I
>> could drive each twisted pair as balanced differential lines
>> instead of using one wire as ground. Is this likely to be
>> necessary?
>>
>> 3. What factors do I need to know and consider?
>>
>>
>
> What does "long" mean in this context? Milliseconds? Minutes?
>
> What's the minimum such interval?
>
Sorry about omitting the info. I noticed it after posting my 
message. It will be of the order of minutes with a minimum of 
perhaps 1 minute.

> What delay can you tolerate between sending the pulse, and 
> receiving
> it?
1 millisecond max, preferably less. 

David L. Jones wrote:
> pimpom wrote:
>> Prelim: If anyone remembers me from previous posts, please 
>> note
>> that constraints imposed by my location dictate that I use, as
>> far as possible, only long-established standard components in 
>> my
>> projects.
>>
>> I want to send two independent unidirectional pulsed signals 
>> over
>> a distance of about 500 meters and I'm considering my options.
>> The signals will be single triggering pulses with long 
>> irregular
>> intervals in between pulses. The primary requirement is that
>> interference should not cause false triggering, and the two
>> channels must not interfere with each other.
>>
>> I've considered optical fiber cable and RF, but am currently
>> thinking that CAT5 cable might offer the best compromise of
>> simplicity, cost and reliability. I'm always open to 
>> alternative
>> suggestions though. Where I'd like to ask for your inputs is:
>>
>> 1. Is my scheme at all feasible with fairly simple circuitry?
>>
>> 2. I've never made a study of the electronics that drives
>> computer network lines, and I can't do it now because my ISP 
>> is
>> working in sporadic bursts (I had to wait >1 hr to post this). 
>> I
>> could drive each twisted pair as balanced differential lines
>> instead of using one wire as ground. Is this likely to be
>> necessary?
>>
>> 3. What factors do I need to know and consider?
>
> You haven't told us anything about frequencies or time periods 
> you are
> deailing with. That will pretty much dictate what's easily 
> possible
> over 500m.
>
Sorry about such a glaring omission. I'm talking intervals of 
minutes. Pulse duration is not yet decided but not critical in 
any case - may be of the order of a millisecond. Triggering is 
most likely to be with the rising edge. Exact triggering level is 
also not critical as long as rise time can be kept below 1 msec.

> Standard differential RS485 for example is simple to implement 
> and
> capable of more than 1km at low enough data rates.
>
> Dave. 

On Fri, 8 Jan 2010 15:57:40 +0530, "pimpom" <p...@invalid.invalid>
wrote:

>Prelim: If anyone remembers me from previous posts, please note 
>that constraints imposed by my location dictate that I use, as 
>far as possible, only long-established standard components in my 
>projects.
>
>I want to send two independent unidirectional pulsed signals over 
>a distance of about 500 meters and I'm considering my options. 
>The signals will be single triggering pulses with long irregular 
>intervals in between pulses. The primary requirement is that 
>interference should not cause false triggering, and the two 
>channels must not interfere with each other.
>
>I've considered optical fiber cable and RF, but am currently 
>thinking that CAT5 cable might offer the best compromise of 
>simplicity, cost and reliability. I'm always open to alternative 
>suggestions though. Where I'd like to ask for your inputs is:
>
>1. Is my scheme at all feasible with fairly simple circuitry?
>
>2. I've never made a study of the electronics that drives 
>computer network lines, and I can't do it now because my ISP is 
>working in sporadic bursts (I had to wait >1 hr to post this). I 
>could drive each twisted pair as balanced differential lines 
>instead of using one wire as ground. Is this likely to be 
>necessary?
>
>3. What factors do I need to know and consider? 
>

Pulse specifications (pulse width)? Rise time? Fall time? Pulse width?
Minimum 'off' time? Maximum 'off' time? Signal level of pulse? 

PeterD wrote:
> On Fri, 8 Jan 2010 15:57:40 +0530, "pimpom" 
> <p...@invalid.invalid>
> wrote:
>
>> Prelim: If anyone remembers me from previous posts, please 
>> note
>> that constraints imposed by my location dictate that I use, as
>> far as possible, only long-established standard components in 
>> my
>> projects.
>>
>> I want to send two independent unidirectional pulsed signals 
>> over
>> a distance of about 500 meters and I'm considering my options.
>> The signals will be single triggering pulses with long 
>> irregular
>> intervals in between pulses. The primary requirement is that
>> interference should not cause false triggering, and the two
>> channels must not interfere with each other.
>>
>> I've considered optical fiber cable and RF, but am currently
>> thinking that CAT5 cable might offer the best compromise of
>> simplicity, cost and reliability. I'm always open to 
>> alternative
>> suggestions though. Where I'd like to ask for your inputs is:
>>
>> 1. Is my scheme at all feasible with fairly simple circuitry?
>>
>> 2. I've never made a study of the electronics that drives
>> computer network lines, and I can't do it now because my ISP 
>> is
>> working in sporadic bursts (I had to wait >1 hr to post this). 
>> I
>> could drive each twisted pair as balanced differential lines
>> instead of using one wire as ground. Is this likely to be
>> necessary?
>>
>> 3. What factors do I need to know and consider?
>>
>
> Pulse specifications (pulse width)? Rise time? Fall time? Pulse 
> width?
> Minimum 'off' time? Maximum 'off' time? Signal level of pulse?

I provided most of the specs in reply to the others - in 
approximate terms since most of them are either not critical or 
not yet decided. Here's a summary:

Width - 1-10 msec
Rise time - fraction of a msec at Tx, max 1 msec at Rx
Fall time - not relevant as triggering will be by the rising 
edge, may be several msecs.
Pulse width - milliseconds, variable. Single pulse.
Minimum off time - 1 minute
Max off time - indefinite
Signal level - at least 4.5V. May also be from 12V logic circuit. 

On a sunny day (Fri, 8 Jan 2010 15:57:40 +0530) it happened "pimpom"
<p...@invalid.invalid> wrote in <hi71au$jh9$1...@news.albasani.net>:

>Prelim: If anyone remembers me from previous posts, please note 
>that constraints imposed by my location dictate that I use, as 
>far as possible, only long-established standard components in my 
>projects.
>
>I want to send two independent unidirectional pulsed signals over 
>a distance of about 500 meters and I'm considering my options. 
>The signals will be single triggering pulses with long irregular 
>intervals in between pulses. The primary requirement is that 
>interference should not cause false triggering, and the two 
>channels must not interfere with each other.
>
>I've considered optical fiber cable and RF, but am currently 
>thinking that CAT5 cable might offer the best compromise of 
>simplicity, cost and reliability. I'm always open to alternative 
>suggestions though. Where I'd like to ask for your inputs is:
>
>1. Is my scheme at all feasible with fairly simple circuitry?
>
>2. I've never made a study of the electronics that drives 
>computer network lines, and I can't do it now because my ISP is 
>working in sporadic bursts (I had to wait >1 hr to post this). I 
>could drive each twisted pair as balanced differential lines 
>instead of using one wire as ground. Is this likely to be 
>necessary?
>
>3. What factors do I need to know and consider? 

Risetime?
Frequency?
Amplitude?
Pulse width?
Electrical and magnetic noise in environment? 
Price.
Delivery times?
Availability?

As a cheap solution for low frequency and good noise immunity some pieces of rope will do.

Jan Panteltje wrote:
> On a sunny day (Fri, 8 Jan 2010 15:57:40 +0530) it happened 
> "pimpom"
> <p...@invalid.invalid> wrote in 
> <hi71au$jh9$1...@news.albasani.net>:
>
>> Prelim: If anyone remembers me from previous posts, please 
>> note
>> that constraints imposed by my location dictate that I use, as
>> far as possible, only long-established standard components in 
>> my
>> projects.
>>
>> I want to send two independent unidirectional pulsed signals 
>> over
>> a distance of about 500 meters and I'm considering my options.
>> The signals will be single triggering pulses with long 
>> irregular
>> intervals in between pulses. The primary requirement is that
>> interference should not cause false triggering, and the two
>> channels must not interfere with each other.
>>
>> I've considered optical fiber cable and RF, but am currently
>> thinking that CAT5 cable might offer the best compromise of
>> simplicity, cost and reliability. I'm always open to 
>> alternative
>> suggestions though. Where I'd like to ask for your inputs is:
>>
>> 1. Is my scheme at all feasible with fairly simple circuitry?
>>
>> 2. I've never made a study of the electronics that drives
>> computer network lines, and I can't do it now because my ISP 
>> is
>> working in sporadic bursts (I had to wait >1 hr to post this). 
>> I
>> could drive each twisted pair as balanced differential lines
>> instead of using one wire as ground. Is this likely to be
>> necessary?
>>
>> 3. What factors do I need to know and consider?
>
> Risetime?
> Frequency?
> Amplitude?
> Pulse width?

All given before.

> Electrical and magnetic noise in environment?

Car/bike ignition, cellphones and the like. No strong EMI 
expected. At least the cable will not pass through a microwave 
oven.

> Price.

No stringent constraint.

> Delivery times?

No strict deadline. Preferably within a couple of weeks.

> Availability?
>
See my introductory lines. Preferably built out of common 
general-purpose components.

> As a cheap solution for low frequency and good noise immunity 
> some
> pieces of rope will do.

Try tugging on 500m of rope with less than 1msec delay at the 
other end. 

On a sunny day (Fri, 8 Jan 2010 20:40:07 +0530) it happened "pimpom"
<p...@invalid.invalid> wrote in <hi7hsm$g5d$1...@news.albasani.net>:

>Jan Panteltje wrote:
>> On a sunny day (Fri, 8 Jan 2010 15:57:40 +0530) it happened 
>> "pimpom"
>> <p...@invalid.invalid> wrote in 
>> <hi71au$jh9$1...@news.albasani.net>:
>>
>>> Prelim: If anyone remembers me from previous posts, please 
>>> note
>>> that constraints imposed by my location dictate that I use, as
>>> far as possible, only long-established standard components in 
>>> my
>>> projects.
>>>
>>> I want to send two independent unidirectional pulsed signals 
>>> over
>>> a distance of about 500 meters and I'm considering my options.
>>> The signals will be single triggering pulses with long 
>>> irregular
>>> intervals in between pulses. The primary requirement is that
>>> interference should not cause false triggering, and the two
>>> channels must not interfere with each other.
>>>
>>> I've considered optical fiber cable and RF, but am currently
>>> thinking that CAT5 cable might offer the best compromise of
>>> simplicity, cost and reliability. I'm always open to 
>>> alternative
>>> suggestions though. Where I'd like to ask for your inputs is:
>>>
>>> 1. Is my scheme at all feasible with fairly simple circuitry?
>>>
>>> 2. I've never made a study of the electronics that drives
>>> computer network lines, and I can't do it now because my ISP 
>>> is
>>> working in sporadic bursts (I had to wait >1 hr to post this). 
>>> I
>>> could drive each twisted pair as balanced differential lines
>>> instead of using one wire as ground. Is this likely to be
>>> necessary?
>>>
>>> 3. What factors do I need to know and consider?
>>
>> Risetime?
>> Frequency?
>> Amplitude?
>> Pulse width?
>
>All given before.
>
>> Electrical and magnetic noise in environment?
>
>Car/bike ignition, cellphones and the like. No strong EMI 
>expected. At least the cable will not pass through a microwave 
>oven.
>
>> Price.
>
>No stringent constraint.
>
>> Delivery times?
>
>No strict deadline. Preferably within a couple of weeks.
>
>> Availability?
>>
>See my introductory lines. Preferably built out of common 
>general-purpose components.
>
>> As a cheap solution for low frequency and good noise immunity 
>> some
>> pieces of rope will do.
>
>Try tugging on 500m of rope with less than 1msec delay at the 
>other end. 

There was no mention of 1ms in your post.
For 1ms delay you need a risetime of 10x better.
Your limit is about 10ns / meter for a signal to travel...

Ah, I have it, a big stroboscope flash, and a photo detector with lens pointed at the stroboscope :-)
Or just use a coax.
Or optical.
Sound is too slow ... only 300m / second, so are pigeans.
But pigeons can carry an SDcard or USB stick with a lot more data.
LOL