Simple doppler-shift velocity

D

Dan Major

Guest
I was pondering over on the model rocket newsgroup about a simple way to
measure the velocity of a model rocket. One poster had come up with the
idea of using a "surplus" police radar set on e-bay. The problem with this
is the extremely small RCS of a paper-and-balsa rocket traveling away from
the radar. My idea was to put a small fixed-frequency transmitter in the
rocket. A ground-based receiver tuned to the same frequency would notice a
doppler shift as the rocket accellerated away.
Questions:
1) is this practical?
2) could the error signal from a phase locked loop be used to indicate the
doppler shift?
3) can this be easily/cheaply (under $50) implemented?

--
Sooner dot boomer at gbronline dot com
 
Dan Major wrote:
I was pondering over on the model rocket newsgroup about a simple way to
measure the velocity of a model rocket. One poster had come up with the
idea of using a "surplus" police radar set on e-bay. The problem with this
is the extremely small RCS of a paper-and-balsa rocket traveling away from
the radar. My idea was to put a small fixed-frequency transmitter in the
rocket. A ground-based receiver tuned to the same frequency would notice a
doppler shift as the rocket accellerated away.
Questions:
1) is this practical?
2) could the error signal from a phase locked loop be used to indicate the
doppler shift?
3) can this be easily/cheaply (under $50) implemented?
Click to expand...
A Doppler detector only gives you radial velocity- that is the frequency
shift proportional to the time rate of change of straight line distance
to the rocket.
 
On Sun, 28 Nov 2004 16:09:47 -0800, John Larkin
<jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> wrote:

On Sun, 28 Nov 2004 16:57:06 -0700, Jim Thompson
thegreatone@example.com> wrote:

On Sun, 28 Nov 2004 23:43:06 GMT, Dan Major <nospam@this.address
wrote:

I was pondering over on the model rocket newsgroup about a simple way to
measure the velocity of a model rocket. One poster had come up with the
idea of using a "surplus" police radar set on e-bay. The problem with this
is the extremely small RCS of a paper-and-balsa rocket traveling away from
the radar. My idea was to put a small fixed-frequency transmitter in the
rocket. A ground-based receiver tuned to the same frequency would notice a
doppler shift as the rocket accellerated away.
Questions:
1) is this practical?
2) could the error signal from a phase locked loop be used to indicate the
doppler shift?
3) can this be easily/cheaply (under $50) implemented?

The frequency shift will be Vrocket/C(speed of light)*Ftransmitted =
149Hz per GHz of Ftransmitted at 100MPH... not real easy to measure
accurately.

...Jim Thompson


And any oscillator is going to be trashed by the acceleration of the
rocket a lot more than that.

John
Click to expand...
It just occurred to me that the easiest way would be to use an
accelerometer and down-link the data.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
"Dan Major" <nospam@this.address> wrote in message
news:Xns95AFB448476D7soonerboomergbronlin@68.12.19.6...
I was pondering over on the model rocket newsgroup about a simple way to
measure the velocity of a model rocket. One poster had come up with the
idea of using a "surplus" police radar set on e-bay. The problem with
this
is the extremely small RCS of a paper-and-balsa rocket traveling away from
the radar. My idea was to put a small fixed-frequency transmitter in the
rocket. A ground-based receiver tuned to the same frequency would notice
a
doppler shift as the rocket accellerated away.
Questions:
1) is this practical?
2) could the error signal from a phase locked loop be used to indicate the
doppler shift?
3) can this be easily/cheaply (under $50) implemented?

--
Sooner dot boomer at gbronline dot com
Click to expand...
Maybe flash a couple leds on the rocket at a known rate and then video the
event. Calculate speed from a frame by frame replay.
regards
john
 
On Mon, 29 Nov 2004 01:08:48 -0000, "john jardine"
<john@jjdesigns.fsnet.co.uk> wrote:

"Dan Major" <nospam@this.address> wrote in message
news:Xns95AFB448476D7soonerboomergbronlin@68.12.19.6...
I was pondering over on the model rocket newsgroup about a simple way to
measure the velocity of a model rocket. One poster had come up with the
idea of using a "surplus" police radar set on e-bay. The problem with
this
is the extremely small RCS of a paper-and-balsa rocket traveling away from
the radar. My idea was to put a small fixed-frequency transmitter in the
rocket. A ground-based receiver tuned to the same frequency would notice
a
doppler shift as the rocket accellerated away.
Questions:
1) is this practical?
2) could the error signal from a phase locked loop be used to indicate the
doppler shift?
3) can this be easily/cheaply (under $50) implemented?

--
Sooner dot boomer at gbronline dot com

Maybe flash a couple leds on the rocket at a known rate and then video the
event. Calculate speed from a frame by frame replay.
regards
john
Click to expand...
Redshift? :)

- YD.
--
Remove HAT if replying by mail.
 
"YD" <yd.techHAT@techie.com> wrote
john@jjdesigns.fsnet.co.uk> wrote:
Maybe flash a couple leds on the rocket at a known rate and then video the
event. Calculate speed from a frame by frame replay.
Redshift? :)
Click to expand...
Time dilation.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
Remove spaces etc. to reply: n o lindan at net com dot com
 
How about an ultrasonic piezo transmitter on the rocket and a
directional microphone on the ground with a frequency counter. I don't
know if the range will suit the application for any reasonable
transmitter power.
Click to expand...
Why limit yourself to "reasonable" transmit power?

How about a whistle run my the rocket going through the air
or something similar run by the rocket engine?

--
The suespammers.org mail server is located in California. So are all my
other mailboxes. Please do not send unsolicited bulk e-mail or unsolicited
commercial e-mail to my suespammers.org address or any of my other addresses.
These are my opinions, not necessarily my employer's. I hate spam.
 
It might
also be a good idea to put filaments along the bottom of the fins,

And making them a tuned length.
Click to expand...
If the diameter is sufficient, a corner reflector in the nosecone.
 
GPG wrote:
It might
also be a good idea to put filaments along the bottom of the fins,

And making them a tuned length.
If the diameter is sufficient, a corner reflector in the nosecone.
Click to expand...
For a measurement from a satellite ?

Rene

--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net
 
On Mon, 29 Nov 2004 02:47:32 -0800, GPG wrote:

It might
also be a good idea to put filaments along the bottom of the fins,

And making them a tuned length.
If the diameter is sufficient, a corner reflector in the nosecone.
Click to expand...
If he can find a 10 GHz radar gun, a corner reflector could be pretty
small, like 3 CM or so, I think.

Good Luck!
Rich
 
Hal Murray wrote:
How about an ultrasonic piezo transmitter on the rocket and a
directional microphone on the ground with a frequency counter. I don't
know if the range will suit the application for any reasonable
transmitter power.

Why limit yourself to "reasonable" transmit power?

How about a whistle run my the rocket going through the air
or something similar run by the rocket engine?
Click to expand...
That might work as well, but I know less about how the aerodynamics of
such a whistle might affect a rocket than the electronic solution.

--
Paul Hovnanian mailto:paul@Hovnanian.com
------------------------------------------------------------------
Programmers don't die, they just GOSUB without RETURN.
 
"Nicholas O. Lindan" <see@sig.com> wrote in message
news:QByqd.3459$6K5.1372@newsread2.news.atl.earthlink.net...
"YD" <yd.techHAT@techie.com> wrote
john@jjdesigns.fsnet.co.uk> wrote:
Maybe flash a couple leds on the rocket at a known rate and then video
the
event. Calculate speed from a frame by frame replay.
Redshift? :)

Time dilation.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
Remove spaces etc. to reply: n o lindan at net com dot com
Click to expand...
Well go on then! ... I know I was bored at the time and it's a crap idea
anyway but what glaring bollock did I drop that you guys instantly noticed?
:)

Spent ages trying to figure why the idea cant' work, (well, the past 30
seconds). Simplisticly ... . If an insanely bright led, flashes once per
second, for say a 20ms period then only particular video frames will catch
the led as being lit. The 25 frames per second provides a timebase.
No ?.

regards
john
 
"john jardine" <john@jjdesigns.fsnet.co.uk> wrote in message
news:cogoqb$j4g$1@newsg4.svr.pol.co.uk...
"Nicholas O. Lindan" <see@sig.com> wrote in message
news:QByqd.3459$6K5.1372@newsread2.news.atl.earthlink.net...
"YD" <yd.techHAT@techie.com> wrote
john@jjdesigns.fsnet.co.uk> wrote:
Maybe flash a couple leds on the rocket at a known rate and then
video
the
event. Calculate speed from a frame by frame replay.
Redshift? :)

Time dilation.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
Remove spaces etc. to reply: n o lindan at net com dot com
Click to expand...
[clip bollockspeak]
And 30 seconds later realise I've no distance reference :-(
 
In article <41ABC2FB.B6459227@Hovnanian.com>, Paul Hovnanian P.E.
<Paul@Hovnanian.com> writes
How about a whistle run my the rocket going through the air
or something similar run by the rocket engine?
Reminds me of an Idea I patented some years ago only to discover that
Click to expand...
someone filed the previous year. Now in the public domain if anyone
interested:
Add value to vehicle exhaust silencer/muffler by incorporating a
siren/whistle to be bypassed under normal driving conditions but
introduced when required as an anti-theft system.
1 or 2 horsepower dedicated to generating acoustic energy with 80%
efficiency as is possible with sirens would render a vehicle a centre of
attention and undriveable except by the deaf....:)
--
ddwyer
 
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