Chip with simple program for Toy

[Miles Harris]

On Mon, 17 Jan 2005 01:09:34 GMT, Rich The Newsgropup Wacko
<wacko@example.com> wrote:

Oh, well you need a flyback diode for that, to guard against the back
EMF. Don't take any notice of the other posters here, I know what
you're really asking. The answer basically to your question is the
answer basically to your question is you need a flyback diode for
that, to guard against the back EMF. Don't answer basically your
question is any notice of the other posters here, I know what you're
really asking. The answer basically to your question is you need the
answer basically to your question is a flyback diode for that, to
guard against the back EMF. Don't take any notice of the other posters
here, I know.
The answer basically to your question is what you're really asking.
The answer basically is your question.
HTH.

Can I have a hit of that?

Sure. Go nuts. Save it to a file and repost it to every dumb assohole
that posts here. There are plenty. Start with John Fields.

>

 

I stated earlier that i connected the output to only ONE point 1 or 4
or 3 or 6 but i wonder if the 2nd interval circuit requires a load
also such that TWO output is (1 or 4) AND (3 or 6) , could this be why
the long interval is not ending properly?

the diagram shows both but what where would I connect the other OUT?







On Sun, 16 Jan 2005 23:49:40 GMT, urjant@mail.com wrote:

On Sun, 16 Jan 2005 17:49:52 GMT, "CWatters"
colin.watters@pandoraBOX.be> wrote:


urjant@mail.com> wrote in message
news:AoLqQWk9h2iYQ2NTSA6G4ySLx8Vr@4ax.com...

toggleing doesnt work at all timer does not function at all if no
power to A and B

The Contol switch is the same as the start switch? No other switch on the
unit?

no switch at all ...thats added by the user

ftp://partsarts@divxdude.dyndns.org/internal.jpg

i took it apart. heres what it looks like.

if i can find my meter i can test some stuff like resistors caps
diodes.

 

whats bugging me is that the configuration jumpers inside
could have been tampered or were even prepared by some
stoner at the factory or distributor level at purchase time.
and Eagle Signal doens't and won't provide that setup
chart such that i can check it.

it would be quit simple to check the cuts in the 3 SEVERABLE JUMPER
BLOCKS to be sure thats its not accidentally set for 0-60 hours
instead of minutes.

I asked..the guy wouldn't give.










On Sun, 16 Jan 2005 23:49:40 GMT, urjant@mail.com wrote:

On Sun, 16 Jan 2005 17:49:52 GMT, "CWatters"
colin.watters@pandoraBOX.be> wrote:


urjant@mail.com> wrote in message
news:AoLqQWk9h2iYQ2NTSA6G4ySLx8Vr@4ax.com...

toggleing doesnt work at all timer does not function at all if no
power to A and B

The Contol switch is the same as the start switch? No other switch on the
unit?

no switch at all ...thats added by the user

ftp://partsarts@divxdude.dyndns.org/internal.jpg

i took it apart. heres what it looks like.

if i can find my meter i can test some stuff like resistors caps
diodes.

 

[John Fields]

On Sun, 16 Jan 2005 16:47:48 GMT, Miles Harris <mazzer@yahoo.com>
wrote:

On 15 Jan 2005 11:24:31 -0800, ngdbud@hotmail.com wrote:

i mean the flybacks from the link in William j. beaty's posting.

Oh, well you need a flyback diode for that, to guard against the back
EMF. Don't take any notice of the other posters here, I know what
you're really asking. The answer basically to your question is the
answer basically to your question is you need a flyback diode for
that, to guard against the back EMF. Don't answer basically your
question is any notice of the other posters here, I know what you're
really asking. The answer basically to your question is you need the
answer basically to your question is a flyback diode for that, to
guard against the back EMF. Don't take any notice of the other posters
here, I know.
The answer basically to your question is what you're really asking.
The answer basically is your question.
HTH.

---
HTH???

THC!!!

http://www.bitoffun.com/weirds-Dont_Bogart.htm
--
John Fields

 

On Mon, 17 Jan 2005 20:25:35 GMT, urjant@mail.com wrote:


the whole thread can be found here
http://groups-beta.google.com/group/sci.electronics.design/browse_thread/thread/e31958e5b764562b/04d50d6fe6e2a0d8?q=timer+relay+help+needed&_done=%2Fgroup%2Fsci.electronics.design%2Fsearch%3Fgroup%3Dsci.electronics.design%26q%3Dtimer+relay+help+needed%26qt_g%3D1%26searchnow%3DSearch+this+group%26&_doneTitle=Back+to+Search&&d#04d50d6fe6e2a0d8
if this link works hopefully.

in a nutshell

is this timer broken?

am i not using it correctly?

was it just configured wrong at order time?
(since it is an internally custom configurable device.)

and probably how can i use it with another timer relay device
to get a recycling timer with different ON and OFF ranges
since half of this one seems to be broken or not up to my
needs.

 

[RichK]

thanks
"Andrew Holme" <andrew@nospam.com> wrote in message
news:csjmlq$n2q$1$830fa7a5@news.demon.co.uk...

RichK wrote:
I have a broken small appliance (food processor) where I think the
problem may be with the motor start capacitors. When I try to use
the unit, there is a buzz, but the motor doesn't run. There are 2
capacitors labeled "motor start". Both are rated for 170 VIC. One
is 100 mF; the other is 130 mF. All I have for testing is a digital
multi-meter. When I test both of the capacitors on a high-resistance
scale, they seem to pass current for about 15 seconds. (On the 200k
ohm scale, the resistance slowly rises until it shows "open".) Does
this mean that they are bad?

No, on the contrary: it's normal. You're charging the capacitor up.
Current slows and finally stops as the voltage on the capacitor approaches
that of your multimeter. Try measuring the voltage across the capacitor
afterwards: you'll see it discharge through the meter.

 

[Cmd Buzz Corey]

Jerry Gardner wrote:

William L. Bahn said:

But let's be consistent and ban listening to music or talking to
passengers. And why should someone that uses a cell phone get five
years
just for using it but someone putting on makeup should walk free?

They shouldn't! Anyone willing to do dumb, distracting things while
driving
should be punished. Removing their driving privledges for a few
months
would send a message to people that would be hard to ignore.

Just to move this thread onto a ligher vein, what's the dumbest thing
you've seen someone do while driving? Here's my list:

1. Putting on makeup/shaving.
2. Changing clothes.
3. Watching TV (Saw a guy watching Monday Night Football, while
driving, on
a TV mounted on the passenger-side dashboard).
4. Talking on two cell phones simultaneously--one in each hand.

So how many people do you see everyday:

1. Putting on makeup/shaving.
2. Changing clothes.
3. Watching TV (Saw a guy watching Monday Night Football, while
driving, on
a TV mounted on the passenger-side dashboard).
4. Talking on two cell phones simultaneously--one in each hand.

and how many people do you see everday using a cell phone while
driving?

 

[Anthony Fremont]

<gaurav.patil@gmail.com> wrote

hello,
i want to construct a circuit which will be able to measure distance
between two moving cars.The two cars are needed to maintain a fixed
distance between each other.
if the distance between them increases or decreases the circuit
should be able to detect this change and notify the amount of change
in the distance to both cars.
i want to construct this circuit using infrared LEDS ,so if any one
can help me out with this(circuit idea) please mail it to me .

Usenet is not a write-only medium. You post your questions here and you
get your answers here, otherwise the only person that gains anything
from it is you. That's not the way a public forum works. If you'd
rather work this issue via e-mail, then feel free to e-mail your
question to as many people as you like.

Now to the question at hand. You need to specify the distance, weather,
and other operating conditions that you expect this to work in. You are
not likely to get this to work in the bright sun without allot of
effort.

 

[Andrew Holme]

gaurav.patil@gmail.com wrote:

hello,
i want to construct a circuit which will be able to measure distance
between two moving cars.The two cars are needed to maintain a fixed
distance between each other.
if the distance between them increases or decreases the circuit
should be able to detect this change and notify the amount of change
in the distance to both cars.
i want to construct this circuit using infrared LEDS ,so if any one
can help me out with this(circuit idea) please mail it to me .

It might be easier with microwaves than infra-red:

Measure relative velocity using the Doppler effect. By integrating
this, you get a running estimate of the change in distance. Weird
things might happen when you go around corners!

Unfortunately, absolute measurement of short distances using
electromagnetic waves is difficult / impossible due to the speed of
light.

 

[peterken]

"Andrew Holme" <ajholme@hotmail.com> wrote in message
news:1106310278.349514.124760@z14g2000cwz.googlegroups.com...

gaurav.patil@gmail.com wrote:
hello,
i want to construct a circuit which will be able to measure distance
between two moving cars.The two cars are needed to maintain a fixed
distance between each other.
if the distance between them increases or decreases the circuit
should be able to detect this change and notify the amount of change
in the distance to both cars.
i want to construct this circuit using infrared LEDS ,so if any one
can help me out with this(circuit idea) please mail it to me .

It might be easier with microwaves than infra-red:

Measure relative velocity using the Doppler effect. By integrating
this, you get a running estimate of the change in distance. Weird
things might happen when you go around corners!

Unfortunately, absolute measurement of short distances using
electromagnetic waves is difficult / impossible due to the speed of
light.

microwave is indeed more reliable
using a bursting microwave gives an indication of absolute distance and
speed between objects

timing between start of burst and start of reception of it is a measure for
absolute distance
doppler frequency gives relative speed

 

[Richard Harris]

I can't help you with an electronic way of doing the task you require but I
just happen to have worked with some computer software and hardware that can
do this task very well.

What you are looking for is a "Stereo Vision Pair" (two cameras feeds) and
some software that works out the distance between the cameras and a selected
object. The software is a little complex but I have written some code that
does the trick with simple math. This is all done using trigonometry.
The most complex part of the software is object tracking, once you have
zero'd onto the object you can take the displacement of the object from the
two image frames and use trigonemetry to workout the distance between the
cameras (which are normaly 90 degree and 6 degree with a spacing of 60mm) .
It's very processor intensive but there are a number of algorithms that are
required to do this task optimally. Once you have this all working you can
even tell the size of objects and distance from with great accuracy (down to
about 1mm depending on the total distance range required.).

I have a technique and system I developed from scratch, If you are
interested I could give you a head start with information on object
tracking, stereo vision metrics and optimizing algorithms for image
processing. My system is developed using the C programming language and on
the WIN32 API.

The only down side to this all is that the software is rather complex when
you put all the components together.

Hope this may help.

"peterken" <peter273@hotmail.com> wrote in message
news:8f8Id.912$gX.230449@phobos.telenet-ops.be...

"Andrew Holme" <ajholme@hotmail.com> wrote in message
news:1106310278.349514.124760@z14g2000cwz.googlegroups.com...

gaurav.patil@gmail.com wrote:
hello,
i want to construct a circuit which will be able to measure distance
between two moving cars.The two cars are needed to maintain a fixed
distance between each other.
if the distance between them increases or decreases the circuit
should be able to detect this change and notify the amount of change
in the distance to both cars.
i want to construct this circuit using infrared LEDS ,so if any one
can help me out with this(circuit idea) please mail it to me .

It might be easier with microwaves than infra-red:

Measure relative velocity using the Doppler effect. By integrating
this, you get a running estimate of the change in distance. Weird
things might happen when you go around corners!

Unfortunately, absolute measurement of short distances using
electromagnetic waves is difficult / impossible due to the speed of
light.


microwave is indeed more reliable
using a bursting microwave gives an indication of absolute distance and
speed between objects

timing between start of burst and start of reception of it is a measure
for
absolute distance
doppler frequency gives relative speed

 

[mike]

gaurav.patil@gmail.com wrote:

hello,
i want to construct a circuit which will be able to measure distance
between two moving cars.The two cars are needed to maintain a fixed
distance between each other.
if the distance between them increases or decreases the circuit
should be able to detect this change and notify the amount of change
in the distance to both cars.
i want to construct this circuit using infrared LEDS ,so if any one
can help me out with this(circuit idea) please mail it to me .

One can only imagine what you're trying to do.
If you're gonna use the information to CONTROL the cars, you're
absolutely (fill in the blank with your favorite expression of dementia).
You're quite likely to get sued by the estate of the person(s) you kill
using your contraption...assuming you survive. Suggest you get a
different hobby.
mike

--
Return address is VALID.
Wanted, PCMCIA SCSI Card for HP m820 CDRW.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
http://nm7u.tripod.com/homepage/te.html
Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121
Bunch of stuff For Sale and Wanted at the link below.
http://www.geocities.com/SiliconValley/Monitor/4710/

 

[Dan Ritter]

mike wrote:

gaurav.patil@gmail.com wrote:

hello,
i want to construct a circuit which will be able to measure distance
between two moving cars.The two cars are needed to maintain a fixed
distance between each other.
if the distance between them increases or decreases the circuit
should be able to detect this change and notify the amount of change
in the distance to both cars.
i want to construct this circuit using infrared LEDS ,so if any one
can help me out with this(circuit idea) please mail it to me .


One can only imagine what you're trying to do.
If you're gonna use the information to CONTROL the cars, you're
absolutely (fill in the blank with your favorite expression of dementia).
You're quite likely to get sued by the estate of the person(s) you kill
using your contraption...assuming you survive. Suggest you get a
different hobby.
mike

Actually I can just imagine that I wouldn't mind a device to tell me how

far exactly the car is behind or in front of me. I wouldn't use it in
repacementment of looking with my eyes though. But it might be nice for
talking about those talegaters that come up behind you. Like "this guy
actually got within 10 feet behind me on the highway" for example.
Perhaps thats an extreme example though.

 

[Mac]

On Fri, 21 Jan 2005 04:24:38 -0800, Andrew Holme wrote:

gaurav.patil@gmail.com wrote:
hello,
i want to construct a circuit which will be able to measure distance
between two moving cars.The two cars are needed to maintain a fixed
distance between each other.
if the distance between them increases or decreases the circuit
should be able to detect this change and notify the amount of change
in the distance to both cars.
i want to construct this circuit using infrared LEDS ,so if any one
can help me out with this(circuit idea) please mail it to me .

It might be easier with microwaves than infra-red:

Measure relative velocity using the Doppler effect. By integrating
this, you get a running estimate of the change in distance. Weird
things might happen when you go around corners!

Unfortunately, absolute measurement of short distances using
electromagnetic waves is difficult / impossible due to the speed of
light.

It is not difficult at all. It just requires bandwidth. Before anybody
jumps on my case about detecting short CW pulses, let me point out that
short CW pulses have a LOT of bandwidth, and the shorter they are the more
bandwidth they have.

The same rules would apply to a modulated IR signal. There is no way the
OP is going to get any kind of high resolution ranging using IR alone
because there is just not enough bandwidth. (Some laser diodes have more
than enough bandwidth to do this, but I don't think they put out enough
power)

Ultrasound might work well. You could have a transponder on the back of
the car in front and a range-finder on the front of the car in back.

--Mac

 

[Mac]

On Fri, 21 Jan 2005 01:31:11 -0800, gaurav.patil wrote:

hello,
i want to construct a circuit which will be able to measure distance
between two moving cars.The two cars are needed to maintain a fixed
distance between each other.
if the distance between them increases or decreases the circuit
should be able to detect this change and notify the amount of change
in the distance to both cars.
i want to construct this circuit using infrared LEDS ,so if any one
can help me out with this(circuit idea) please mail it to me .

This won't work.

I suggest you try to think of a different approach. It seems to me as
though radar is the best approach.

Ultrasound might work, but high frequency ultrasound attenuates rapidly in
air.

You might be able to use two LED's on the rear of the car in front, and a
video camera on the car in back. The distance would be calculated from the
angular separation of the LED's. The LED's would have to be mounted with a
carefully measured separation.

Good luck. You're going to need it.

--Mac

 

[keith]

On Sat, 22 Jan 2005 07:32:19 +0000, Mac wrote:

On Fri, 21 Jan 2005 04:24:38 -0800, Andrew Holme wrote:


gaurav.patil@gmail.com wrote:
hello,
i want to construct a circuit which will be able to measure distance
between two moving cars.The two cars are needed to maintain a fixed
distance between each other.
if the distance between them increases or decreases the circuit
should be able to detect this change and notify the amount of change
in the distance to both cars.
i want to construct this circuit using infrared LEDS ,so if any one
can help me out with this(circuit idea) please mail it to me .

It might be easier with microwaves than infra-red:

Measure relative velocity using the Doppler effect. By integrating
this, you get a running estimate of the change in distance. Weird
things might happen when you go around corners!

Unfortunately, absolute measurement of short distances using
electromagnetic waves is difficult / impossible due to the speed of
light.

It is not difficult at all. It just requires bandwidth. Before anybody
jumps on my case about detecting short CW pulses, let me point out that
short CW pulses have a LOT of bandwidth, and the shorter they are the more
bandwidth they have.

Ok, what's the bandwidth of a kHz modulated ~2GHz carrier (wherever there
is some free bandwidth). It should be trivial to measure the round-trip
delay to withing a nS, which is about six inches. At a kHz,
that gives us a distance measuremnt every millisecond, which should be
enough for distance and differentiate to give a relative velocity
number.

The same rules would apply to a modulated IR signal. There is no way the
OP is going to get any kind of high resolution ranging using IR alone
because there is just not enough bandwidth. (Some laser diodes have more
than enough bandwidth to do this, but I don't think they put out enough
power)

Since it *is* done, I'm not sure why you contend that it can't.

Ultrasound might work well. You could have a transponder on the back of
the car in front and a range-finder on the front of the car in back.

It's *is* done without any transponder, which would make the idea useless.

--
Keith

 

[keith]

On Sun, 23 Jan 2005 17:51:45 +0000, Mac wrote:

On Sat, 22 Jan 2005 23:41:45 -0500, keith wrote:

On Sat, 22 Jan 2005 07:32:19 +0000, Mac wrote:

On Fri, 21 Jan 2005 04:24:38 -0800, Andrew Holme wrote:


gaurav.patil@gmail.com wrote:
hello,
i want to construct a circuit which will be able to measure distance
between two moving cars.The two cars are needed to maintain a fixed
distance between each other.
if the distance between them increases or decreases the circuit
should be able to detect this change and notify the amount of change
in the distance to both cars.
i want to construct this circuit using infrared LEDS ,so if any one
can help me out with this(circuit idea) please mail it to me .

It might be easier with microwaves than infra-red:

Measure relative velocity using the Doppler effect. By integrating
this, you get a running estimate of the change in distance. Weird
things might happen when you go around corners!

Unfortunately, absolute measurement of short distances using
electromagnetic waves is difficult / impossible due to the speed of
light.

It is not difficult at all. It just requires bandwidth. Before anybody
jumps on my case about detecting short CW pulses, let me point out that
short CW pulses have a LOT of bandwidth, and the shorter they are the more
bandwidth they have.

Ok, what's the bandwidth of a kHz modulated ~2GHz carrier (wherever there
is some free bandwidth). It should be trivial to measure the round-trip
delay to withing a nS, which is about six inches. At a kHz,
that gives us a distance measuremnt every millisecond, which should be
enough for distance and differentiate to give a relative velocity
number.

Are you talking about on/off modulation of a 2GHz carrier at a 1KHz
rate? How long is the "on" time?

Yes, pick your poision.

The same rules would apply to a modulated IR signal. There is no way the
OP is going to get any kind of high resolution ranging using IR alone
because there is just not enough bandwidth. (Some laser diodes have more
than enough bandwidth to do this, but I don't think they put out enough
power)

Since it *is* done, I'm not sure why you contend that it can't.


Please elaborate. What is done? Are you saying that there is an IR diode
based system that can give precise range information? I am very interested
in this system.

I was referring more to the RADAR range finders that Merc is using for
"smart" speed control. IR diodes may have different problems (ambient
noise, etc).

Ultrasound might work well. You could have a transponder on the back
of the car in front and a range-finder on the front of the car in
back.

It's *is* done without any transponder, which would make the idea
useless.

I admit that the transponder is not essential. It just makes it easier
to detect the signal, and increases the range over which the system
would work.

It also adds an unknown and significant delay into the path.

--
Keith

 

[Mark Jones]

keith wrote:

On Fri, 21 Jan 2005 12:41:48 -0500, Mark Jones wrote:


Or use something much slower than light - ultrasonics.


Why? If better than a few inch resolution is needed, which doesn't seem
to be the case here, use interferometry or as another poster said,
stereoscopic vision. The guts of a few optical mice may do a decent
stereoscope.

I'd think ultrasonics would be dicy in a noisy environment.

The design of an ultrasonic rangefinder would be trivial in
comparison to a laser rangefinder.

But of course, the OP may do what he likes.

 

[Mac]

On Sun, 23 Jan 2005 14:07:55 -0500, keith wrote:

On Sun, 23 Jan 2005 17:51:45 +0000, Mac wrote:

On Sat, 22 Jan 2005 23:41:45 -0500, keith wrote:

On Sat, 22 Jan 2005 07:32:19 +0000, Mac wrote:

On Fri, 21 Jan 2005 04:24:38 -0800, Andrew Holme wrote:


gaurav.patil@gmail.com wrote:
hello,
i want to construct a circuit which will be able to measure distance
between two moving cars.The two cars are needed to maintain a fixed
distance between each other.
if the distance between them increases or decreases the circuit
should be able to detect this change and notify the amount of change
in the distance to both cars.
i want to construct this circuit using infrared LEDS ,so if any one
can help me out with this(circuit idea) please mail it to me .

It might be easier with microwaves than infra-red:

Measure relative velocity using the Doppler effect. By integrating
this, you get a running estimate of the change in distance. Weird
things might happen when you go around corners!

Unfortunately, absolute measurement of short distances using
electromagnetic waves is difficult / impossible due to the speed of
light.

It is not difficult at all. It just requires bandwidth. Before anybody
jumps on my case about detecting short CW pulses, let me point out that
short CW pulses have a LOT of bandwidth, and the shorter they are the more
bandwidth they have.

Ok, what's the bandwidth of a kHz modulated ~2GHz carrier (wherever there
is some free bandwidth). It should be trivial to measure the round-trip
delay to withing a nS, which is about six inches. At a kHz,
that gives us a distance measuremnt every millisecond, which should be
enough for distance and differentiate to give a relative velocity
number.

Are you talking about on/off modulation of a 2GHz carrier at a 1KHz
rate? How long is the "on" time?

Yes, pick your poision.

It looks like it doesn't really matter, anyway. The Fourier transform is
just a sum of two sinc() functions, one shifted right and one shifted left
by the carrier frequency. The pulse duration controls the magnitude of the
FT.

I believe the total bandwidth is infinite, but any finite signal has
infinite bandwidth, so that doesn't really help us.

Unfortunately, I'm not sure I know how to answer the question myself.

I'll try to remember to ask some people who might know tomorrow and get
back to you. (It also might pay to ask in the radar/sonar newsgroup.)

But the more you constrain the bandwidth, the more difficult it will be to
identify exactly where the pulse starts or stops. So for precise ranging,
you need more BW, regardless of pulse duration.

The same rules would apply to a modulated IR signal. There is no way the
OP is going to get any kind of high resolution ranging using IR alone
because there is just not enough bandwidth. (Some laser diodes have more
than enough bandwidth to do this, but I don't think they put out enough
power)

[snip]

Ultrasound might work well. You could have a transponder on the back
of the car in front and a range-finder on the front of the car in
back.

It's *is* done without any transponder, which would make the idea
useless.

I admit that the transponder is not essential. It just makes it easier
to detect the signal, and increases the range over which the system
would work.

It also adds an unknown and significant delay into the path.

Depending on exactly how the system is set up, the delay could be
completely neutralized by using a PLL.

--Mac

 

[keith]

On Mon, 24 Jan 2005 00:09:10 +0000, Mac wrote:

On Sun, 23 Jan 2005 14:07:55 -0500, keith wrote:

On Sun, 23 Jan 2005 17:51:45 +0000, Mac wrote:

On Sat, 22 Jan 2005 23:41:45 -0500, keith wrote:

On Sat, 22 Jan 2005 07:32:19 +0000, Mac wrote:

On Fri, 21 Jan 2005 04:24:38 -0800, Andrew Holme wrote:


gaurav.patil@gmail.com wrote:
hello,
i want to construct a circuit which will be able to measure distance
between two moving cars.The two cars are needed to maintain a fixed
distance between each other.
if the distance between them increases or decreases the circuit
should be able to detect this change and notify the amount of change
in the distance to both cars.
i want to construct this circuit using infrared LEDS ,so if any one
can help me out with this(circuit idea) please mail it to me .

It might be easier with microwaves than infra-red:

Measure relative velocity using the Doppler effect. By integrating
this, you get a running estimate of the change in distance. Weird
things might happen when you go around corners!

Unfortunately, absolute measurement of short distances using
electromagnetic waves is difficult / impossible due to the speed of
light.

It is not difficult at all. It just requires bandwidth. Before anybody
jumps on my case about detecting short CW pulses, let me point out that
short CW pulses have a LOT of bandwidth, and the shorter they are the more
bandwidth they have.

Ok, what's the bandwidth of a kHz modulated ~2GHz carrier (wherever there
is some free bandwidth). It should be trivial to measure the round-trip
delay to withing a nS, which is about six inches. At a kHz,
that gives us a distance measuremnt every millisecond, which should be
enough for distance and differentiate to give a relative velocity
number.

Are you talking about on/off modulation of a 2GHz carrier at a 1KHz
rate? How long is the "on" time?

Yes, pick your poision.

It looks like it doesn't really matter, anyway. The Fourier transform is
just a sum of two sinc() functions, one shifted right and one shifted left
by the carrier frequency. The pulse duration controls the magnitude of the
FT.

Sure. I'm looking at launching a ~2GHz (wherever the FCC allows) CW pulse
and measuring its time in flight. At a ns/ft that's 6"/ns round-trip.
Some tricks should be able to get this down significantly less than this.
A ns is a long time these days.

I believe the total bandwidth is infinite, but any finite signal
has infinite bandwidth, so that doesn't really help us.

Sure. I don't see a few kHz on either side of 2GHz to be a big deal
though. It might be a challenge to gate an uwave tranmsitter on in a
millisecond, but...

Unfortunately, I'm not sure I know how to answer the question myself.

I'll try to remember to ask some people who might know tomorrow and get
back to you. (It also might pay to ask in the radar/sonar newsgroup.)

RADAR was my primary interest here. Measuring ns delays is rather trivial
these days. ...and that gets us to 6" distance resolution. Put enough of
these together with a (very) little computation and we get velocity. I
don't see how the mechanics of a couple of cars will exceed the physics or
computational needs.

But the more you constrain the bandwidth, the more difficult it will be
to identify exactly where the pulse starts or stops. So for precise
ranging, you need more BW, regardless of pulse duration.

Ok. We can measure more points of the envelope. The question is where is
the bandwidth limitation. I suspect it will be in the transmitter,
though I don't know. Again, a few kHz isn't a lot of bandwidth.

The same rules would apply to a modulated IR signal. There is no way
the OP is going to get any kind of high resolution ranging using IR
alone because there is just not enough bandwidth. (Some laser diodes
have more than enough bandwidth to do this, but I don't think they
put out enough power)

[snip]

Ultrasound might work well. You could have a transponder on the back
of the car in front and a range-finder on the front of the car in
back.

It's *is* done without any transponder, which would make the idea
useless.

I admit that the transponder is not essential. It just makes it easier
to detect the signal, and increases the range over which the system
would work.

It also adds an unknown and significant delay into the path.

Depending on exactly how the system is set up, the delay could be
completely neutralized by using a PLL.

How? The PLL has to capture the signal and then re-launch the "answer".
That's time. If we're measuring the round-trip delay of two cars ten
meters apart on the Autobahn, the capture/retransmit time is an error I'd
rather not make.

--
Keith
> --Mac