Reading Frequencies
Archiver
Posts: 46,084
Hello,
I am developing a remote control system that works like this:
There are 5 transmitters placed in a circle some 30 ft apart.
each sends a steady signal at a specific frequency. A receiver is
placed at the center of the circle. When the receiver is pointed at
any of the transmitters it can read that signal and distinguish which
transmitter it is listening for.
I would appreciate any help
Al Najjar
I am developing a remote control system that works like this:
There are 5 transmitters placed in a circle some 30 ft apart.
each sends a steady signal at a specific frequency. A receiver is
placed at the center of the circle. When the receiver is pointed at
any of the transmitters it can read that signal and distinguish which
transmitter it is listening for.
I would appreciate any help
Al Najjar
Comments
>Hello,
>
>I am developing a remote control system that works like this:
>
>There are 5 transmitters placed in a circle some 30 ft apart.
>each sends a steady signal at a specific frequency. A receiver is
>placed at the center of the circle. When the receiver is pointed at
>any of the transmitters it can read that signal and distinguish which
>transmitter it is listening for.
>
>I would appreciate any help
>
>Al Najjar
Hi Al -
The problem with that, as I found out, when I proposed to an RF
engineer - was that omni-directional antennas are difficult and
expensive to design. I even proposed a small parabolic, but the
size was prohibitive for the size of the platform. I've no idea
how large your platform is, but mine was over 24" x 24" in size.
The antenna I would have needed was over 3 feet in diameter for
the frequency I had in mind. From what he told me, NOT that I
understand it, but 1/4 and 1/2 wave dish antennas are to prone to
"losses" - I think he said.
With THAT width, and the HEIGHT I would require, the platform would
have needed a concrete block on it to keep it STABLE. At that juncture
I gave up. Perhaps you'll do better than I did : )
Regards,
Bruce Bates
antennas switched with PIN diodes. Then you can switch the antennas rapidly
and compute the doppler to tell you the bearing to the transmitter.
This is commonly used in RDF equipment these days.
Read:
http://www.pe.net/~dopplers/index.html
http://homes.aol.com/homingin/newdopant.html
http://members.aol.com/bmgenginc/index.html
http://www.silcom.com/~pelican2/
http://colba.net/~jacbro/index/projpic/doppler/mtl_dopl.html
QST ran, years ago, a DoppleScant or something like that, that had the short
whips built into an auto roof and a bearing display in the vehicle.
Probably not a simple design project, but there are plenty out there for the
taking.
Regards,
Al Williams
AWC
* Connect a PS/2 keyboard to your microcontroller project!
http://www.al-williams.com/awce/pak6.htm
>
Original Message
> From: Bruce Bates [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=HpIpJQftrd-hATvj87k5TclAv83I-ctDr4SNAzMw1WM-k-BRyvf_l7Cqz3TKPdKxuowKUU4H_zfwlqO88y3Ayw]bvbates@u...[/url
> Sent: Sunday, January 07, 2001 1:07 PM
> To: basicstamps@egroups.com
> Subject: Re: [noparse][[/noparse]basicstamps] Reading Frequencies
>
>
> At 1/7/2001 Sunday 04:11 PM +0000, alnajjar@s... wrote:
> >Hello,
> >
> >I am developing a remote control system that works like this:
> >
> >There are 5 transmitters placed in a circle some 30 ft apart.
> >each sends a steady signal at a specific frequency. A receiver is
> >placed at the center of the circle. When the receiver is pointed at
> >any of the transmitters it can read that signal and distinguish which
> >transmitter it is listening for.
> >
> >I would appreciate any help
> >
> >Al Najjar
>
> Hi Al -
>
> The problem with that, as I found out, when I proposed to an RF
> engineer - was that omni-directional antennas are difficult and
> expensive to design. I even proposed a small parabolic, but the
> size was prohibitive for the size of the platform. I've no idea
> how large your platform is, but mine was over 24" x 24" in size.
> The antenna I would have needed was over 3 feet in diameter for
> the frequency I had in mind. From what he told me, NOT that I
> understand it, but 1/4 and 1/2 wave dish antennas are to prone to
> "losses" - I think he said.
>
> With THAT width, and the HEIGHT I would require, the platform would
> have needed a concrete block on it to keep it STABLE. At that juncture
> I gave up. Perhaps you'll do better than I did : )
>
> Regards,
>
> Bruce Bates
>
>
>
frequency of each of the 5 transmitters, i.e. the "boundary conditions" of
the problem. Record the angular position of the rotating receiver using an
optical encoder (or digital compass). When it points at the known position
of one of transmitters, program the receiver to receive only at that
frequency.
Dennis
Original Message
From: alnajjar@s... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=pmmOo4H_2fpftjXpggwnnyttJJfjetysQWop4WWL5o3HLZ3zpwU0ZxQBDD9qKvAzLa9RJM5OVeY4hg]alnajjar@s...[/url
Sent: Sunday, January 07, 2001 8:11 AM
To: basicstamps@egroups.com
Subject: [noparse][[/noparse]basicstamps] Reading Frequencies
Hello,
I am developing a remote control system that works like this:
There are 5 transmitters placed in a circle some 30 ft apart.
each sends a steady signal at a specific frequency. A receiver is
placed at the center of the circle. When the receiver is pointed at
any of the transmitters it can read that signal and distinguish which
transmitter it is listening for.
I would appreciate any help
Al Najjar
That's a brilliant idea. Where do you recommend getting optical
encoders or digital compass, and find out how they work?
I assume that this could be done with BS2 using the pulseIn command!
Also, I need to find a chip that can produce a sine wave on command
from the BS2. The BS2 generates square waves which is difficult to
convert into sine. I think I have run in the past into a chip that
can act as wave generator.
Any ideas? and thanks again
Al Najjar
--- In basicstamps@egroups.com, "Dennis P. O'Leary" <doleary@h...>
wrote:
> The solution is simplified if you know both the position and
transmission
> frequency of each of the 5 transmitters, i.e. the "boundary
conditions" of
> the problem. Record the angular position of the rotating receiver
using an
> optical encoder (or digital compass). When it points at the known
position
> of one of transmitters, program the receiver to receive only at that
> frequency.
> Dennis
>
>
Original Message
> From: alnajjar@s... [noparse][[/noparse]mailto:alnajjar@s...]
> Sent: Sunday, January 07, 2001 8:11 AM
> To: basicstamps@egroups.com
> Subject: [noparse][[/noparse]basicstamps] Reading Frequencies
>
>
> Hello,
>
> I am developing a remote control system that works like this:
>
> There are 5 transmitters placed in a circle some 30 ft apart.
> each sends a steady signal at a specific frequency. A receiver is
> placed at the center of the circle. When the receiver is pointed at
> any of the transmitters it can read that signal and distinguish
which
> transmitter it is listening for.
>
> I would appreciate any help
>
> Al Najjar
and pulse waveformes), but it does require an ADC as well as a -5vdc
source
-Ian Bobbitt
On Mon, 8 Jan 2001 alnajjar@s... wrote:
> Thanks Dennis,
>
>
> That's a brilliant idea. Where do you recommend getting optical
> encoders or digital compass, and find out how they work?
>
> I assume that this could be done with BS2 using the pulseIn command!
>
> Also, I need to find a chip that can produce a sine wave on command
> from the BS2. The BS2 generates square waves which is difficult to
> convert into sine. I think I have run in the past into a chip that
> can act as wave generator.
>
> Any ideas? and thanks again
>
> Al Najjar
>
> --- In basicstamps@egroups.com, "Dennis P. O'Leary" <doleary@h...>
> wrote:
> > The solution is simplified if you know both the position and
> transmission
> > frequency of each of the 5 transmitters, i.e. the "boundary
> conditions" of
> > the problem. Record the angular position of the rotating receiver
> using an
> > optical encoder (or digital compass). When it points at the known
> position
> > of one of transmitters, program the receiver to receive only at that
> > frequency.
> > Dennis
> >
> >
Original Message
> > From: alnajjar@s... [noparse][[/noparse]mailto:alnajjar@s...]
> > Sent: Sunday, January 07, 2001 8:11 AM
> > To: basicstamps@egroups.com
> > Subject: [noparse][[/noparse]basicstamps] Reading Frequencies
> >
> >
> > Hello,
> >
> > I am developing a remote control system that works like this:
> >
> > There are 5 transmitters placed in a circle some 30 ft apart.
> > each sends a steady signal at a specific frequency. A receiver is
> > placed at the center of the circle. When the receiver is pointed at
> > any of the transmitters it can read that signal and distinguish
> which
> > transmitter it is listening for.
> >
> > I would appreciate any help
> >
> > Al Najjar
>
>
>
>
Original Message
From: alnajjar@s... <alnajjar@s...>
To: basicstamps@egroups.com <basicstamps@egroups.com>
Date: Monday, January 08, 2001 6:17 AM
Subject: [noparse][[/noparse]basicstamps] Re: Reading Frequencies
>Thanks Dennis,
>
>
>That's a brilliant idea. Where do you recommend getting optical
>encoders or digital compass, and find out how they work?
DigiKey has encoders, and Horowitz & Hill "Art of Electronics" is a good
reference. But since you only want 5 positions, such as at 2, 4, 6, 8, and
10 o'clock, you don't really need the high resolution provided by encoders.
So you might try biasing a 1-turn pot that is capable of continuous
rotation, and then using the Stamp to "watch" the voltage with the pulsein
command. Assign a voltage range to each of the known transmitter positions.
>
>I assume that this could be done with BS2 using the pulseIn command!
>
>Also, I need to find a chip that can produce a sine wave on command
>from the BS2. The BS2 generates square waves which is difficult to
>convert into sine. I think I have run in the past into a chip that
>can act as wave generator.
>
>Any ideas? and thanks again
There are various hardware sine chips, and choosing among them depends on
your specs regarding 1) how clean the sine wave must be, 2) its frequency,
and 3) how precisely you want to control phase (or starting point on the
sine wave). The only one that I've worked with is a Burr-Brown UAF42, which
is actually a filter design chip. The application notes show how to use it
as a sine wave generator.
Dennis
You are a wealth of information.
I never heard of a one turn pot capable of coninous rotation. Can you
recommend a source?
The sine wave doesn't have to be clean, in fact some noise will be
fine. Does digiKey have those?
Al
--- In basicstamps@egroups.com, "Dennis O'Leary" <doleary@h...> wrote:
> Al, See below
>
Original Message
> From: alnajjar@s... <alnajjar@s...>
> To: basicstamps@egroups.com <basicstamps@egroups.com>
> Date: Monday, January 08, 2001 6:17 AM
> Subject: [noparse][[/noparse]basicstamps] Re: Reading Frequencies
>
>
> >Thanks Dennis,
> >
> >
> >That's a brilliant idea. Where do you recommend getting optical
> >encoders or digital compass, and find out how they work?
>
> DigiKey has encoders, and Horowitz & Hill "Art of Electronics" is a
good
> reference. But since you only want 5 positions, such as at 2, 4, 6,
8, and
> 10 o'clock, you don't really need the high resolution provided by
encoders.
> So you might try biasing a 1-turn pot that is capable of continuous
> rotation, and then using the Stamp to "watch" the voltage with the
pulsein
> command. Assign a voltage range to each of the known transmitter
positions.
> >
> >I assume that this could be done with BS2 using the pulseIn
command!
> >
> >Also, I need to find a chip that can produce a sine wave on command
> >from the BS2. The BS2 generates square waves which is difficult to
> >convert into sine. I think I have run in the past into a chip
that
> >can act as wave generator.
> >
> >Any ideas? and thanks again
>
> There are various hardware sine chips, and choosing among them
depends on
> your specs regarding 1) how clean the sine wave must be, 2) its
frequency,
> and 3) how precisely you want to control phase (or starting point on
the
> sine wave). The only one that I've worked with is a Burr-Brown
UAF42, which
> is actually a filter design chip. The application notes show how to
use it
> as a sine wave generator.
>
> Dennis
Newark Electronics (800-463-9275) has Spectrol 132 series and 157 series
single-turn precision pots with continuous rotation. A stock no. is
12F4048R10.0K for a 132 series 10K wirewound pot. Not cheap though -- about
$30. Some other interesting possibilities from www.mouser.com are 1)a
motor-driven PC mount 10K pot (stock no. 316-1020-10K for about $10,
including the motor, and 2)Model DE2 incremental encoder (No. 594-DE2-0132)
for $49.
Yes, Digikey has the Burr-Brown UAF42AP filter chip in a 14-Dip package
for about $15. You can download the application notes from
www.burr-brown.com.
Dennis
Original Message
From: alnajjar@s... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=v-8i720KXSeoAZ4ctSZvwcc332-MxocBES9HQZCLnga42q2O1bkn0LeYb3KK4ouM3f3X9hss5C7fEw]alnajjar@s...[/url
Sent: Monday, January 08, 2001 4:53 PM
To: basicstamps@egroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Reading Frequencies
Thanks Dennis,
You are a wealth of information.
I never heard of a one turn pot capable of coninous rotation. Can you
recommend a source?
The sine wave doesn't have to be clean, in fact some noise will be
fine. Does digiKey have those?
Al
--- In basicstamps@egroups.com, "Dennis O'Leary" <doleary@h...> wrote:
> Al, See below
>
Original Message
> From: alnajjar@s... <alnajjar@s...>
> To: basicstamps@egroups.com <basicstamps@egroups.com>
> Date: Monday, January 08, 2001 6:17 AM
> Subject: [noparse][[/noparse]basicstamps] Re: Reading Frequencies
>
>
> >Thanks Dennis,
> >
> >
> >That's a brilliant idea. Where do you recommend getting optical
> >encoders or digital compass, and find out how they work?
>
> DigiKey has encoders, and Horowitz & Hill "Art of Electronics" is a
good
> reference. But since you only want 5 positions, such as at 2, 4, 6,
8, and
> 10 o'clock, you don't really need the high resolution provided by
encoders.
> So you might try biasing a 1-turn pot that is capable of continuous
> rotation, and then using the Stamp to "watch" the voltage with the
pulsein
> command. Assign a voltage range to each of the known transmitter
positions.
> >
> >I assume that this could be done with BS2 using the pulseIn
command!
> >
> >Also, I need to find a chip that can produce a sine wave on command
> >from the BS2. The BS2 generates square waves which is difficult to
> >convert into sine. I think I have run in the past into a chip
that
> >can act as wave generator.
> >
> >Any ideas? and thanks again
>
> There are various hardware sine chips, and choosing among them
depends on
> your specs regarding 1) how clean the sine wave must be, 2) its
frequency,
> and 3) how precisely you want to control phase (or starting point on
the
> sine wave). The only one that I've worked with is a Burr-Brown
UAF42, which
> is actually a filter design chip. The application notes show how to
use it
> as a sine wave generator.
>
> Dennis