RF dual circuits
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Posts: 46,084
Hi everyone,
I need to build an application which has two different sets of stamps
chatting via RF at the same time. Since there are two independent
communications, I can't use a single frequency. Should I purchase a
trans/receive set at 418 and at 433? Any advice on who to purchase from?
I've been looking at the Linx products and at Rentron. The Linx products
seem much more expensive, does anyone have an opinion on this?
Also, is there any disadvantage to using the SIP and a whip antenna over
the "all in one" modules? I have to fit my circuit into a weird space, and
I thought having a exterior antenna might help my range.
Finally, if anyone has any general advice on this topic I'd certainly
appreciate it
Thanks!!
I need to build an application which has two different sets of stamps
chatting via RF at the same time. Since there are two independent
communications, I can't use a single frequency. Should I purchase a
trans/receive set at 418 and at 433? Any advice on who to purchase from?
I've been looking at the Linx products and at Rentron. The Linx products
seem much more expensive, does anyone have an opinion on this?
Also, is there any disadvantage to using the SIP and a whip antenna over
the "all in one" modules? I have to fit my circuit into a weird space, and
I thought having a exterior antenna might help my range.
Finally, if anyone has any general advice on this topic I'd certainly
appreciate it
Thanks!!
Comments
>Hi:
>
> First bit of advice, stop thinking in analouge terms, this is a digital
>application you are talking about.
>
> You can have as many "radios" on the same freq as you like. Why?
>Because they can be addressed seperately in the message stream. If the
>message is not for a particular radio have it ignore it. The radios have a
>"busy" indication so if a radio wants to transmit but there is a signal
>present it can be made to wait until the channel is clear.
In this case the transmitters will be sending data almost continuously and
often at the same time, so I can't have them wait until the channel is clear.
First bit of advice, stop thinking in analouge terms, this is a digital
application you are talking about.
You can have as many "radios" on the same freq as you like. Why?
Because they can be addressed seperately in the message stream. If the
message is not for a particular radio have it ignore it. The radios have a
"busy" indication so if a radio wants to transmit but there is a signal
present it can be made to wait until the channel is clear.
I don't know what your application is, but you can extend the range by
using repeaters spaced along the intended path.
Go to the Parallax web site and download some of the sample code that
ships with the radios and you will see an excellent example of a message
protocol to use with these guys.
By the way, I have a brand new set of the 433 Mhz transcievers, never
used, that I would trade for a BS2P40 chip if you are interested..
Let me know.
Mike B.
Original Message
From: "raoul vaneigem" <raoul@c...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, August 21, 2002 11:10 AM
Subject: [noparse][[/noparse]basicstamps] RF dual circuits
> Hi everyone,
>
> I need to build an application which has two different sets of stamps
> chatting via RF at the same time. Since there are two independent
> communications, I can't use a single frequency. Should I purchase a
> trans/receive set at 418 and at 433? Any advice on who to purchase from?
> I've been looking at the Linx products and at Rentron. The Linx products
> seem much more expensive, does anyone have an opinion on this?
>
> Also, is there any disadvantage to using the SIP and a whip antenna over
> the "all in one" modules? I have to fit my circuit into a weird space, and
> I thought having a exterior antenna might help my range.
>
> Finally, if anyone has any general advice on this topic I'd certainly
> appreciate it
>
> Thanks!!
>
>
> 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/
>
>
data comms field for over 40 years and the reality is you are going to need
to have the recieving stations acknowldge your transmissions if you hope to
ever have any kind of reliability in the data. The simple fact is that the
unlicensed devices you are likely to use occupy the same frequency with
MILLIONS of part 15 devices and you are very likely to experience
interfence. These devices range from key fob transmitters to unlock your car
to Radio Shack R/C cars and everything in between. Just transmitting
blindly and hoping the data gets there will doom the project to failure.
ACK transmissions take only miliseconds and the initiating station should
keep repeating the data UNTIL it gets confirmation from the recieving
station that the data arrived intact. This can be done on the same freq
(simplex) or two seperate freqs (duplex). I am using this method (simplex)
in a R/C submarine project with 5 watt transcievers (commercial units) and
the range to the sub is usually less than300-400 feet and I still
occasionally get "hits" from various outside sources..
Enjoy.
Mike B.
Original Message
From: "raoul vaneigem" <raoul@c...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, August 21, 2002 11:43 AM
Subject: Re: [noparse][[/noparse]basicstamps] RF dual circuits
> At 12:18 PM 8/21/2002 -0700, you wrote:
> >Hi:
> >
> > First bit of advice, stop thinking in analouge terms, this is a
digital
> >application you are talking about.
> >
> > You can have as many "radios" on the same freq as you like. Why?
> >Because they can be addressed seperately in the message stream. If the
> >message is not for a particular radio have it ignore it. The radios have
a
> >"busy" indication so if a radio wants to transmit but there is a signal
> >present it can be made to wait until the channel is clear.
>
> In this case the transmitters will be sending data almost continuously and
> often at the same time, so I can't have them wait until the channel is
clear.
>
>
> 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/
>
>
Electronics. They are very inexpensive. What is the
range you looking at? These products work pretty good
upto 300 ft.
--- raoul vaneigem <raoul@c...> wrote: > Hi
everyone,
>
> I need to build an application which has two
> different sets of stamps
> chatting via RF at the same time. Since there are
> two independent
> communications, I can't use a single frequency.
> Should I purchase a
> trans/receive set at 418 and at 433? Any advice on
> who to purchase from?
> I've been looking at the Linx products and at
> Rentron. The Linx products
> seem much more expensive, does anyone have an
> opinion on this?
>
> Also, is there any disadvantage to using the SIP and
> a whip antenna over
> the "all in one" modules? I have to fit my circuit
> into a weird space, and
> I thought having a exterior antenna might help my
> range.
>
> Finally, if anyone has any general advice on this
> topic I'd certainly
> appreciate it
>
> Thanks!!
>
>
> 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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>data comms field for over 40 years and the reality is you are going to need
>to have the recieving stations acknowldge your transmissions if you hope to
>ever have any kind of reliability in the data. The simple fact is that the
>unlicensed devices you are likely to use occupy the same frequency with
>MILLIONS of part 15 devices and you are very likely to experience
>interfence. These devices range from key fob transmitters to unlock your car
>to Radio Shack R/C cars and everything in between. Just transmitting
>blindly and hoping the data gets there will doom the project to failure.
Sorry Mike, no disrespect intended. Believe it or not, the application is
in an underground setting that I can't imagine would be getting any
interference, but on the other hand, I really don't have any idea what I'm
doing [noparse];)[/noparse] so I certainly would be advised to take your advice. I was hoping
to use transmitters on one side and receivers on the other to save on costs
since it seems like the transmit/receive units cost more. Can I ask you
what you are using for transmitters in your product? Would you advise
purchasing the ones that parallax sells, or going somewhere else? I'm
looking for a fairly easy solution, and don't need more than 100 feet of
range.
Thanks!
You can get RF transceivers for less than $20 a pop.
Cheers,
Nick
on 21/8/02 2:10 PM, raoul vaneigem at raoul@c... wrote:
> Hi everyone,
>
> I need to build an application which has two different sets of stamps
> chatting via RF at the same time. Since there are two independent
> communications, I can't use a single frequency. Should I purchase a
> trans/receive set at 418 and at 433? Any advice on who to purchase from?
> I've been looking at the Linx products and at Rentron. The Linx products
> seem much more expensive, does anyone have an opinion on this?
>
> Also, is there any disadvantage to using the SIP and a whip antenna over
> the "all in one" modules? I have to fit my circuit into a weird space, and
> I thought having a exterior antenna might help my range.
>
> Finally, if anyone has any general advice on this topic I'd certainly
> appreciate it
>
> Thanks!!
>
>
> 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/
>
>
>Ok, but you sure dimissed theconcept pretty quickly.. I have been in the
>data comms field for over 40 years and the reality is you are going to need
>to have the recieving stations acknowldge your transmissions if you hope to
>ever have any kind of reliability in the data. The simple fact is that the
>unlicensed devices you are likely to use occupy the same frequency with
>MILLIONS of part 15 devices and you are very likely to experience
>interfence. These devices range from key fob transmitters to unlock your car
>to Radio Shack R/C cars and everything in between. Just transmitting
>blindly and hoping the data gets there will doom the project to failure.
>
> ACK transmissions take only miliseconds and the initiating station should
>keep repeating the data UNTIL it gets confirmation from the recieving
>station that the data arrived intact. This can be done on the same freq
>(simplex) or two seperate freqs (duplex). I am using this method (simplex)
>in a R/C submarine project with 5 watt transcievers (commercial units) and
>the range to the sub is usually less than300-400 feet and I still
>occasionally get "hits" from various outside sources..
Hi Mike,
Everything you say is true, but depending on the intelligence and whether
or not there is data buffering in the radios, what you suggest could really
tie up a Stamp if the RF link isn't solid. If that's OK, then all is well.
If not, then if the economics of the project justify it, I'd suggest
looking into using old Amateur (Ham) packet radio Terminal Node Controllers
(TNCs) at each end of the data link. The Stamp would talk to the TNCs and
the TNCs (via the radios) will assure error-free exchange of data free of
extra Stamp overhead. For the serial link to the Stamp the TNC can run all
standard baud rates from 300 up to anything the Stamp can handle. The RF
link typically runs 1200 baud, but many TNCs also do 300 baud and some do
4800/9600 baud.
Problems? Any sort of data buffer in the radio would be a big problem
since the TNC has it's own send/receive buffer and only wants to
send/receive an audio stream to/from the radios.
If interested, feel free to ask more. TNCs should be available on eBay for
$50 and preferably much less. The "Tiny Two" is about the size of a pack
of cigarettes and is "polite" when it comes to being battery operated -
it's designed for battery operation. Most others are about the size of or
a bit smaller than old external phone modems and are power hogs - 700 ma -
1 amp at 12 volts being normal.
Jim H
I have used the Lynx transceivers with the stamp with some reservation.
The problem with "duplex" comms with the Lynx unit is that it must change
state on two pins on the module using the Stamp to receive and then
transmit. It is not a full duplex link that has paths open both ways at all
times. It's o.k. for some uses, but you have to make sure you add code that
will change the pin's mode at the correct sequence. Take a look at the
Melexis units. I think it is www.melexis.com as these units are similar to
the Lynx units, but better as they are FSK type meaning that a carrier is
present all the time and the noise floor is significantly reduced. When
you=\ send a command over the link, it rides above the carrier and the
receiver can decode it better than the Lynx type. They are a single chip
device, but buy the demo boards for $50 as they can be used as a completed
part for your application. If you need more info, e-mail me direct:
mocenter@e... and I will share my experiences
cya
mike m
Original Message
From: raoul vaneigem <raoul@c...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, August 21, 2002 2:10 PM
Subject: [noparse][[/noparse]basicstamps] RF dual circuits
> Hi everyone,
>
> I need to build an application which has two different sets of stamps
> chatting via RF at the same time. Since there are two independent
> communications, I can't use a single frequency. Should I purchase a
> trans/receive set at 418 and at 433? Any advice on who to purchase from?
> I've been looking at the Linx products and at Rentron. The Linx products
> seem much more expensive, does anyone have an opinion on this?
>
> Also, is there any disadvantage to using the SIP and a whip antenna over
> the "all in one" modules? I have to fit my circuit into a weird space, and
> I thought having a exterior antenna might help my range.
>
> Finally, if anyone has any general advice on this topic I'd certainly
> appreciate it
>
> Thanks!!
>
>
> 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/
>
>
>
I have a BS2P24 that I can trade you if interested. Never used in sealed
package. Let me know
mocenter@e...
mike m
Original Message
From: Mike Blier <w6ffc@p...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, August 21, 2002 3:18 PM
Subject: Re: [noparse][[/noparse]basicstamps] RF dual circuits
> Hi:
>
> First bit of advice, stop thinking in analouge terms, this is a digital
> application you are talking about.
>
> You can have as many "radios" on the same freq as you like. Why?
> Because they can be addressed seperately in the message stream. If the
> message is not for a particular radio have it ignore it. The radios have
a
> "busy" indication so if a radio wants to transmit but there is a signal
> present it can be made to wait until the channel is clear.
>
> I don't know what your application is, but you can extend the range by
> using repeaters spaced along the intended path.
>
> Go to the Parallax web site and download some of the sample code that
> ships with the radios and you will see an excellent example of a message
> protocol to use with these guys.
>
> By the way, I have a brand new set of the 433 Mhz transcievers, never
> used, that I would trade for a BS2P40 chip if you are interested..
>
> Let me know.
>
> Mike B.
>
Original Message
> From: "raoul vaneigem" <raoul@c...>
> To: <basicstamps@yahoogroups.com>
> Sent: Wednesday, August 21, 2002 11:10 AM
> Subject: [noparse][[/noparse]basicstamps] RF dual circuits
>
>
> > Hi everyone,
> >
> > I need to build an application which has two different sets of stamps
> > chatting via RF at the same time. Since there are two independent
> > communications, I can't use a single frequency. Should I purchase a
> > trans/receive set at 418 and at 433? Any advice on who to purchase from?
> > I've been looking at the Linx products and at Rentron. The Linx products
> > seem much more expensive, does anyone have an opinion on this?
> >
> > Also, is there any disadvantage to using the SIP and a whip antenna over
> > the "all in one" modules? I have to fit my circuit into a weird space,
and
> > I thought having a exterior antenna might help my range.
> >
> > Finally, if anyone has any general advice on this topic I'd certainly
> > appreciate it
> >
> > Thanks!!
> >
> >
> > 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/
> >
> >
>
>
>
> 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/
>
>
>
Mike B.
Original Message
From: "M. E. M. Electronics" <memelectronics@e...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, August 21, 2002 5:40 PM
Subject: Re: [noparse][[/noparse]basicstamps] RF dual circuits
> mike,
> I have a BS2P24 that I can trade you if interested. Never used in
sealed
> package. Let me know
> mocenter@e...
> mike m
>
Original Message
> From: Mike Blier <w6ffc@p...>
> To: <basicstamps@yahoogroups.com>
> Sent: Wednesday, August 21, 2002 3:18 PM
> Subject: Re: [noparse][[/noparse]basicstamps] RF dual circuits
>
>
> > Hi:
> >
> > First bit of advice, stop thinking in analouge terms, this is a
digital
> > application you are talking about.
> >
> > You can have as many "radios" on the same freq as you like. Why?
> > Because they can be addressed seperately in the message stream. If the
> > message is not for a particular radio have it ignore it. The radios
have
> a
> > "busy" indication so if a radio wants to transmit but there is a signal
> > present it can be made to wait until the channel is clear.
> >
> > I don't know what your application is, but you can extend the range
by
> > using repeaters spaced along the intended path.
> >
> > Go to the Parallax web site and download some of the sample code that
> > ships with the radios and you will see an excellent example of a message
> > protocol to use with these guys.
> >
> > By the way, I have a brand new set of the 433 Mhz transcievers, never
> > used, that I would trade for a BS2P40 chip if you are interested..
> >
> > Let me know.
> >
> > Mike B.
> >
Original Message
> > From: "raoul vaneigem" <raoul@c...>
> > To: <basicstamps@yahoogroups.com>
> > Sent: Wednesday, August 21, 2002 11:10 AM
> > Subject: [noparse][[/noparse]basicstamps] RF dual circuits
> >
> >
> > > Hi everyone,
> > >
> > > I need to build an application which has two different sets of stamps
> > > chatting via RF at the same time. Since there are two independent
> > > communications, I can't use a single frequency. Should I purchase a
> > > trans/receive set at 418 and at 433? Any advice on who to purchase
from?
> > > I've been looking at the Linx products and at Rentron. The Linx
products
> > > seem much more expensive, does anyone have an opinion on this?
> > >
> > > Also, is there any disadvantage to using the SIP and a whip antenna
over
> > > the "all in one" modules? I have to fit my circuit into a weird space,
> and
> > > I thought having a exterior antenna might help my range.
> > >
> > > Finally, if anyone has any general advice on this topic I'd certainly
> > > appreciate it
> > >
> > > Thanks!!
> > >
> > >
> > > 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/
> > >
> > >
> >
> >
> >
> > 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/
> >
> >
> >
>
>
> 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/
>
>