Wireless question
Archiver
Posts: 46,084
Hello all,
I have a project which I would appreciate any input on...
I would like to use a stamp to control a motor and its operational state
based on inputs from two substations. If a signal is received from
substation A But not substation B, then the motor @mainstation would run for
10 additional minutes, then if no other signal is received shut off. If
during that 10 minute period A reactiveates, then the kill process is
stopped. If during the 10 minute period a signal is received from
substation B, then the motor is stopped immediately.
The killer is that the substations/mainstation are a half mile apart. I
have used buried cable in this area before, but have quit because prarie
dogs/gophers always chew the line.
I hope this gives a fairly clear picture of what I would like to accomplish,
but would be happy to answer any questions.
Some current considerations
...How to cover the distance wirelessly?
...How to distinguish between Stations A and B and perhaps an additional
station later.
...The "best" overall design.
Substation A <
1/2 mile
>(Mainstation)<
1/2
mile
>Substaion B
I am in the preliminary stages of thinking through this.. i.e. nothing is
set in concrete so any thoughts would be appreciated.
Thanks for your assistance.
Vince
I have a project which I would appreciate any input on...
I would like to use a stamp to control a motor and its operational state
based on inputs from two substations. If a signal is received from
substation A But not substation B, then the motor @mainstation would run for
10 additional minutes, then if no other signal is received shut off. If
during that 10 minute period A reactiveates, then the kill process is
stopped. If during the 10 minute period a signal is received from
substation B, then the motor is stopped immediately.
The killer is that the substations/mainstation are a half mile apart. I
have used buried cable in this area before, but have quit because prarie
dogs/gophers always chew the line.
I hope this gives a fairly clear picture of what I would like to accomplish,
but would be happy to answer any questions.
Some current considerations
...How to cover the distance wirelessly?
...How to distinguish between Stations A and B and perhaps an additional
station later.
...The "best" overall design.
Substation A <
1/2 mile
>(Mainstation)<
1/2
mile
>Substaion B
I am in the preliminary stages of thinking through this.. i.e. nothing is
set in concrete so any thoughts would be appreciated.
Thanks for your assistance.
Vince
Comments
I can write a program that will accomplish what you want, but as you point
out, interstation communication is the problem. What is the topography
between the main and sub-stations ? Where do A and B get their power
from ? Are "relay" stations feasible ?
RF equipment to cover that distance is available but quite expensive.
I have written several programs using RF and IR for remote control of relays
but all for shorter disances.
Sid
[noparse][[/noparse]Non-text portions of this message have been removed]
Thanks for the reply.
You are correct in that the communications part of the equation may be the
toughest to whip.
The area between the station/substations are relatively flat and level. With
few to no obstructions. Power is available at all stations. Relay stations
would not be feasable for a number of reasons.
Thanks again.
VF
Original Message
From: Newzed@a... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=9vOYRCGp0SBS-D5LepWdeTnxZH1gmlaays8hVT4-0VD-XKy-oz2zGTm5il5SNvxvbdR8OYAF]Newzed@a...[/url
Sent: Thursday, July 18, 2002 2:13 PM
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] Wireless question
For Vince
I can write a program that will accomplish what you want, but as you point
out, interstation communication is the problem. What is the topography
between the main and sub-stations ? Where do A and B get their power from ?
Are "relay" stations feasible ?
RF equipment to cover that distance is available but quite expensive.
I have written several programs using RF and IR for remote control of relays
but all for shorter disances.
Sid
[noparse][[/noparse]Non-text portions of this message have been removed]
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A few things came to mind about the wireless solution when I read
your post. It's fairly trivial really to send low speed data over a
distance of a mile or so, the only question is how fancy you want to
get which ultimately dictates how much money you plan to spend. One
thing you might try if you plan to use a basic stamp is to pick up a
couple TNC's (Terminal Node Controller) like what is used for data
communication in the amateur (HAM) radio scene. Check out eBay and
do a search for 'TNC' or maybe 'packet radio'. A search for 'packet
radio' found this TNC for around 20-30 bucks:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1366706725
You'd then need a couple transceivers and antennas to hook em up to
and a frequency to operate on that would be approved by the FCC for
such a purpose (I'd recommend the 433mhz range like the RF modules
from Parallax). Most likely you'll be in violation of some FCC rule
or regulation for even attempting this without a license, but if it
doesn't cause any interference to a commercial entity or government
agency you won't have any problems. After all this you'll have to
play around with getting the stamp to talk to the TNC which should be
fairly trivial since it has a serial interface anyway. You could
easily cover several miles this way, especially if you had decent
output power on your transmitters and good antennas.
Another solution that may work is just modifying the RF modules that
Parallax has. The ones with the wire antennas look promising. Looks
like you could remove the wire antennas and probably intall a BNC,
UHF, or N connector. The fixed antenna modules might even have
removable antennas already. In either scenario, once you have a
connector in place, you can run it directly to an external anteanna
with some coax or through an amplifier first if you need more power.
This has probably already been done or attempted by someone out
there, maybe asking around on this list or searching the web would
yield some results.
Good luck with the project. Remember this is all theoretical!
--- In basicstamps@y..., "Fell, Vince" <vince.fell@t...> wrote:
> Hello all,
> I have a project which I would appreciate any input on...
> I would like to use a stamp to control a motor and its operational
state
> based on inputs from two substations. If a signal is received from
> substation A But not substation B, then the motor @mainstation
would run for
> 10 additional minutes, then if no other signal is received shut
off. If
> during that 10 minute period A reactiveates, then the kill process
is
> stopped. If during the 10 minute period a signal is received from
> substation B, then the motor is stopped immediately.
> The killer is that the substations/mainstation are a half mile
apart. I
> have used buried cable in this area before, but have quit because
prarie
> dogs/gophers always chew the line.
> I hope this gives a fairly clear picture of what I would like to
accomplish,
> but would be happy to answer any questions.
> Some current considerations
> ...How to cover the distance wirelessly?
> ...How to distinguish between Stations A and B and perhaps an
additional
> station later.
> ...The "best" overall design.
>
> Substation A <
1/2 mile
>(Mainstation)<
1/2
> mile
>Substaion B
>
> I am in the preliminary stages of thinking through this.. i.e.
nothing is
> set in concrete so any thoughts would be appreciated.
>
> Thanks for your assistance.
>
>
> Vince
that are being resold for cheap are 1200 baud units.
If that is acceptable then the next question is what
radios and frequencies are going to be used. If
reliability is a concern, 433MHz may not be the ideal
frequency to use as the US Government and licensed
Amateur Radio operators have precedence to the range
of frequencies in that neighborhood (420-450MHz). They
may not welcome your presence as packet activity is
not used in that part of the frequency spectrum. (Long
haul Single Sideband Voice is normally operated here.)
Alternatives - 49MHz walkie talkies?
From a packaging perspective, things start to get
kludgy as a TNC may be as small as a pack of
cigarettes but are often much bigger, about the size
of an old Hayes modem. Combine that with a radio and
you may decide to stick with an already built,
integrated, and neatly packaged part 15 solution that
could support data rates up to 19.2Kbps.
The best way to increase range for a part 15 device is
to mount the antennas up as high and in the clear as
possible. Using beam antennas will decrease the amount
of unintended interference; both transmitted and
received along the signal path to both of your
stations. In doing so, though, you may be in violation
of FCC rules. Just a word of warning. It is possible
that you can do this and never bother anyone or get
caught in the act (just not in LA!).
Kevin K Asato
KC6POB
--- tilrock <tbanez@h...> wrote:
> Vince,
>
> A few things came to mind about the wireless
> solution when I read
> your post. It's fairly trivial really to send low
> speed data over a
> distance of a mile or so, the only question is how
> fancy you want to
> get which ultimately dictates how much money you
> plan to spend. One
> thing you might try if you plan to use a basic stamp
> is to pick up a
> couple TNC's (Terminal Node Controller) like what is
> used for data
> communication in the amateur (HAM) radio scene.
> Check out eBay and
> do a search for 'TNC' or maybe 'packet radio'. A
> search for 'packet
> radio' found this TNC for around 20-30 bucks:
>
>
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1366706725
>
> You'd then need a couple transceivers and antennas
> to hook em up to
> and a frequency to operate on that would be approved
> by the FCC for
> such a purpose (I'd recommend the 433mhz range like
> the RF modules
> from Parallax). Most likely you'll be in violation
> of some FCC rule
> or regulation for even attempting this without a
> license, but if it
> doesn't cause any interference to a commercial
> entity or government
> agency you won't have any problems. After all this
> you'll have to
> play around with getting the stamp to talk to the
> TNC which should be
> fairly trivial since it has a serial interface
> anyway. You could
> easily cover several miles this way, especially if
> you had decent
> output power on your transmitters and good antennas.
>
> Another solution that may work is just modifying the
> RF modules that
> Parallax has. The ones with the wire antennas look
> promising. Looks
> like you could remove the wire antennas and probably
> intall a BNC,
> UHF, or N connector. The fixed antenna modules
> might even have
> removable antennas already. In either scenario,
> once you have a
> connector in place, you can run it directly to an
> external anteanna
> with some coax or through an amplifier first if you
> need more power.
> This has probably already been done or attempted by
> someone out
> there, maybe asking around on this list or searching
> the web would
> yield some results.
>
> Good luck with the project. Remember this is all
> theoretical!
>
> --- In basicstamps@y..., "Fell, Vince"
> <vince.fell@t...> wrote:
> > Hello all,
> > I have a project which I would appreciate any
> input on...
> > I would like to use a stamp to control a motor and
> its operational
> state
> > based on inputs from two substations. If a signal
> is received from
> > substation A But not substation B, then the motor
> @mainstation
> would run for
> > 10 additional minutes, then if no other signal is
> received shut
> off. If
> > during that 10 minute period A reactiveates, then
> the kill process
> is
> > stopped. If during the 10 minute period a signal
> is received from
> > substation B, then the motor is stopped
> immediately.
> > The killer is that the substations/mainstation are
> a half mile
> apart. I
> > have used buried cable in this area before, but
> have quit because
> prarie
> > dogs/gophers always chew the line.
> > I hope this gives a fairly clear picture of what I
> would like to
> accomplish,
> > but would be happy to answer any questions.
> > Some current considerations
> > ...How to cover the distance wirelessly?
> > ...How to distinguish between Stations A and B and
> perhaps an
> additional
> > station later.
> > ...The "best" overall design.
> >
> > Substation A <
1/2
> mile
>(Mainstation)<
1/2
> > mile
>Substaion B
> >
> > I am in the preliminary stages of thinking through
> this.. i.e.
> nothing is
> > set in concrete so any thoughts would be
> appreciated.
> >
> > Thanks for your assistance.
> >
> >
> > Vince
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed.
> Text in the Subject and Body of the message will be
> ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
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