rf distance measurement...

H

Hul Tytus

Guest
Anyone know of any ICs designed for measureing distances with RF? I\'m
thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one
foot. The basic method of one device emitting a signal and another echoeing it
back would be attractive.
Any recommendations?

Hul
 
On Friday, September 9, 2022 at 8:40:00 AM UTC+10, Hul Tytus wrote:
Anyone know of any ICs designed for measureing distances with RF? I\'m
thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one
foot. The basic method of one device emitting a signal and another echoeing it
back would be attractive.
Any recommendations?
Click to expand...

https://en.wikipedia.org/wiki/Tellurometer

Complex modulation and phase-sensitive decoding is popular.

The speed of light is about 1nsec per foot, so you are talking about round trip times of 20nsec, 200nsec and 1usec.

It\'s easy enough to create a 1nsec wide pulse, but detecting it after it has been reflected from something 500 feet away trickier.

--
Bill Sloman, Sydney
 
On 9/8/2022 3:39 PM, Hul Tytus wrote:
Anyone know of any ICs designed for measureing distances with RF? I\'m
thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one
foot. The basic method of one device emitting a signal and another echoeing it
back would be attractive.
Any recommendations?
Click to expand...

You\'ve not been specific about your needs -- which may be as
unconstrained as \"how far is X from here?\" Or, (in my case)
where is X in the context of this arena?\"

TI makes some kit that might fit your needs, depending on your
actual specifics (IIRC, most of their solutions were geared towards
optical sensing).

[note that there may be other (more reliable/cheaper) options
depending on your goals]
 
On Thursday, September 8, 2022 at 8:10:27 PM UTC-7, bill....@ieee.org wrote:
On Friday, September 9, 2022 at 8:40:00 AM UTC+10, Hul Tytus wrote:
Anyone know of any ICs designed for measureing distances with RF? I\'m
thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one
foot. The basic method of one device emitting a signal and another echoeing it
back would be attractive.
Any recommendations?
https://en.wikipedia.org/wiki/Tellurometer

Complex modulation and phase-sensitive decoding is popular.

The speed of light is about 1nsec per foot, so you are talking about round trip times of 20nsec, 200nsec and 1usec.

It\'s easy enough to create a 1nsec wide pulse, but detecting it after it has been reflected from something 500 feet away trickier.
Click to expand...

Probably one uses a corner-cube retroreflector as a target, if you want good signal/noise.
That\'s how this one is set up; give it a try!

<https://www.jpl.nasa.gov/news/apollo-11-experiment-still-going-strong-after-35-years>

Distance is likely to be over 500 feet.
 
On Thursday, September 8, 2022 at 10:40:16 PM UTC-4, jla...@highlandsniptechnology.com wrote:
On Thu, 8 Sep 2022 22:39:52 -0000 (UTC), Hul Tytus <h...@panix.com
wrote:
Anyone know of any ICs designed for measureing distances with RF? I\'m
thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one
foot. The basic method of one device emitting a signal and another echoeing it
back would be attractive.
Any recommendations?

Hul
Reflections will be a big error source.
Click to expand...

Not if an active transponder retransmits the received signal with a fixed delay. That\'s how they measure distance in the TACAN system on airplanes. They use different frequencies which prevents an issue with echos.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209
 
On a sunny day (Fri, 9 Sep 2022 00:08:39 -0700 (PDT)) it happened Ricky
<gnuarm.deletethisbit@gmail.com> wrote in
<ec0dd418-095c-4eba-a026-5bda091795c1n@googlegroups.com>:

On Thursday, September 8, 2022 at 10:40:16 PM UTC-4, jla...@highlandsniptechnology.com wrote:
On Thu, 8 Sep 2022 22:39:52 -0000 (UTC), Hul Tytus <h...@panix.com
wrote:
Anyone know of any ICs designed for measureing distances with RF? I\'m
thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one
foot. The basic method of one device emitting a signal and another echoeing it
back would be attractive.
Any recommendations?

Hul
Reflections will be a big error source.

Not if an active transponder retransmits the received signal with a fixed delay. That\'s how they measure distance in the TACAN
system on airplanes. They use different frequencies which prevents an issue with echos.
Click to expand...

Why use RF?
For 2 $ 50 centst you van get an ultrasonic distance measuring module on ebay
I have several.
 
On Fri, 09 Sep 2022 09:17:22 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:

On a sunny day (Fri, 9 Sep 2022 00:08:39 -0700 (PDT)) it happened Ricky
gnuarm.deletethisbit@gmail.com> wrote in
ec0dd418-095c-4eba-a026-5bda091795c1n@googlegroups.com>:

On Thursday, September 8, 2022 at 10:40:16 PM UTC-4, jla...@highlandsniptechnology.com wrote:
On Thu, 8 Sep 2022 22:39:52 -0000 (UTC), Hul Tytus <h...@panix.com
wrote:
Anyone know of any ICs designed for measureing distances with RF? I\'m
thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one
foot. The basic method of one device emitting a signal and another echoeing it
back would be attractive.
Any recommendations?

Hul
Reflections will be a big error source.

Not if an active transponder retransmits the received signal with a fixed delay. That\'s how they measure distance in the TACAN
system on airplanes. They use different frequencies which prevents an issue with echos.

Why use RF?
For 2 $ 50 centst you van get an ultrasonic distance measuring module on ebay
I have several.
Click to expand...

500 feet?
 
On a sunny day (Fri, 09 Sep 2022 07:38:18 -0700) it happened
jlarkin@highlandsniptechnology.com wrote in
<hujmhhtfsjmak6gg40jgreseas5ov4ar4f@4ax.com>:

On Fri, 09 Sep 2022 09:17:22 GMT, Jan Panteltje
pNaonStpealmtje@yahoo.com> wrote:

On a sunny day (Fri, 9 Sep 2022 00:08:39 -0700 (PDT)) it happened Ricky
gnuarm.deletethisbit@gmail.com> wrote in
ec0dd418-095c-4eba-a026-5bda091795c1n@googlegroups.com>:

On Thursday, September 8, 2022 at 10:40:16 PM UTC-4, jla...@highlandsniptechnology.com wrote:
On Thu, 8 Sep 2022 22:39:52 -0000 (UTC), Hul Tytus <h...@panix.com
wrote:
Anyone know of any ICs designed for measureing distances with RF? I\'m
thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one
foot. The basic method of one device emitting a signal and another echoeing it
back would be attractive.
Any recommendations?

Hul
Reflections will be a big error source.

Not if an active transponder retransmits the received signal with a fixed delay. That\'s how they measure distance in the
TACAN
system on airplanes. They use different frequencies which prevents an issue with echos.

Why use RF?
For 2 $ 50 centst you van get an ultrasonic distance measuring module on ebay
I have several.

500 feet?
Click to expand...

Its just about 150 meters...
Just add a big piezo speaker / transducer to the output, have some here too.
http://panteltje.com/pub/40_KHz_ultrasonic_transducers_IMG_5133.JPG

Then all you need is a decent audio power IC or wind your own transformer and use some MOSFETS.
http://panteltje.com/pub/ultra_sonic_anti_fouling_circuit_diagram_0.6_IMG_5163.JPG
http://panteltje.com/pub/ultrasonic_anti_fouling_test_transformer_IMG_5142.JPG
You can beam that say 44 kHz audio, wave length is a few cm
Done a lot of experimenting with ultra sound
This is fun too:
http://panteltje.com/pub/44kHz_radar_time_of_flight_test_in_wind_tunnel_IMG_4105.JPG

Top left and bottom right are the ebay distance meter modules, but I moved one of the transducers of each
to the opposite side:
http://panteltje.com/pub/wind_speed_by_differential_2_ebay_distance_meters_IMG_4891.JPG

But for long distance measurements I would use a laser, is also RF, just a bit more GHz,,
 
Ricky - the delay you mentioned is along the lines I\'ve been thinking. Any
suggestions on search terms? TACAN would be likely. What else?

Hul

Ricky <gnuarm.deletethisbit@gmail.com> wrote:
On Thursday, September 8, 2022 at 10:40:16 PM UTC-4, jla...@highlandsniptechnology.com wrote:
On Thu, 8 Sep 2022 22:39:52 -0000 (UTC), Hul Tytus <h...@panix.com
wrote:
Anyone know of any ICs designed for measureing distances with RF? I\'m
thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one
foot. The basic method of one device emitting a signal and another echoeing it
back would be attractive.
Any recommendations?

Hul
Reflections will be a big error source.

Not if an active transponder retransmits the received signal with a fixed delay. That\'s how they measure distance in the TACAN system on airplanes. They use different frequencies which prevents an issue with echos.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209
Click to expand...
 
Bill - the complex modulation & phase sensitive decoding along with multiple frequency direct
are areas that would require a bit of study on my part.
The 500mc clock required with the basic way with 2 transmiter/recievers is a problem too,
probably an fpga. If some IC maker has packaged some portion of this approach the task might
be simpler.

Hul

Anthony William Sloman <bill.sloman@ieee.org> wrote:
On Friday, September 9, 2022 at 8:40:00 AM UTC+10, Hul Tytus wrote:
Anyone know of any ICs designed for measureing distances with RF? I\'m
thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one
foot. The basic method of one device emitting a signal and another echoeing it
back would be attractive.
Any recommendations?

https://en.wikipedia.org/wiki/Tellurometer

Complex modulation and phase-sensitive decoding is popular.

The speed of light is about 1nsec per foot, so you are talking about round trip times of 20nsec, 200nsec and 1usec.

It\'s easy enough to create a 1nsec wide pulse, but detecting it after it has been reflected from something 500 feet away trickier.

--
Bill Sloman, Sydney
Click to expand...
 
Jan - did the requisite componets you mention answer your question \"why rf?\"?

Hul

Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:
On a sunny day (Fri, 09 Sep 2022 07:38:18 -0700) it happened
jlarkin@highlandsniptechnology.com wrote in
hujmhhtfsjmak6gg40jgreseas5ov4ar4f@4ax.com>:

On Fri, 09 Sep 2022 09:17:22 GMT, Jan Panteltje
pNaonStpealmtje@yahoo.com> wrote:

On a sunny day (Fri, 9 Sep 2022 00:08:39 -0700 (PDT)) it happened Ricky
gnuarm.deletethisbit@gmail.com> wrote in
ec0dd418-095c-4eba-a026-5bda091795c1n@googlegroups.com>:

On Thursday, September 8, 2022 at 10:40:16 PM UTC-4, jla...@highlandsniptechnology.com wrote:
On Thu, 8 Sep 2022 22:39:52 -0000 (UTC), Hul Tytus <h...@panix.com
wrote:
Anyone know of any ICs designed for measureing distances with RF? I\'m
thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one
foot. The basic method of one device emitting a signal and another echoeing it
back would be attractive.
Any recommendations?

Hul
Reflections will be a big error source.

Not if an active transponder retransmits the received signal with a fixed delay. That\'s how they measure distance in the
TACAN
system on airplanes. They use different frequencies which prevents an issue with echos.

Why use RF?
For 2 $ 50 centst you van get an ultrasonic distance measuring module on ebay
I have several.

500 feet?

Its just about 150 meters...
Just add a big piezo speaker / transducer to the output, have some here too.
http://panteltje.com/pub/40_KHz_ultrasonic_transducers_IMG_5133.JPG

Then all you need is a decent audio power IC or wind your own transformer and use some MOSFETS.
http://panteltje.com/pub/ultra_sonic_anti_fouling_circuit_diagram_0.6_IMG_5163.JPG
http://panteltje.com/pub/ultrasonic_anti_fouling_test_transformer_IMG_5142.JPG
You can beam that say 44 kHz audio, wave length is a few cm
Done a lot of experimenting with ultra sound
This is fun too:
http://panteltje.com/pub/44kHz_radar_time_of_flight_test_in_wind_tunnel_IMG_4105.JPG

Top left and bottom right are the ebay distance meter modules, but I moved one of the transducers of each
to the opposite side:
http://panteltje.com/pub/wind_speed_by_differential_2_ebay_distance_meters_IMG_4891.JPG

But for long distance measurements I would use a laser, is also RF, just a bit more GHz,,
Click to expand...
 
On Fri, 9 Sep 2022 20:51:56 -0000 (UTC), Hul Tytus <ht@panix.com>
wrote:

Ricky - the delay you mentioned is along the lines I\'ve been thinking. Any
suggestions on search terms? TACAN would be likely. What else?

Hul

Ricky <gnuarm.deletethisbit@gmail.com> wrote:
On Thursday, September 8, 2022 at 10:40:16 PM UTC-4, jla...@highlandsniptechnology.com wrote:
On Thu, 8 Sep 2022 22:39:52 -0000 (UTC), Hul Tytus <h...@panix.com
wrote:
Anyone know of any ICs designed for measureing distances with RF? I\'m
thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one
foot. The basic method of one device emitting a signal and another echoeing it
back would be attractive.
Any recommendations?

Hul
Reflections will be a big error source.

Not if an active transponder retransmits the received signal with a fixed delay. That\'s how they measure distance in the TACAN system on airplanes. They use different frequencies which prevents an issue with echos.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209
Click to expand...

Loran, shoran, raydist, decca, and gee were RF location systems
pre-GPS. And others. But they were long range nav systems.

Some like shoran were pulsed time-of-flight. The others were mostly
sine wave hyperbolic, or hybrids.

Navigating boats to oil wells and rigs in the Gulf of Mexico used to
be a big business. Those folks did some satellite nav systems pre-GPS;
I helped them a little.
 
On 10/9/22 00:38, jlarkin@highlandsniptechnology.com wrote:
On Fri, 09 Sep 2022 09:17:22 GMT, Jan Panteltje
pNaonStpealmtje@yahoo.com> wrote:

On a sunny day (Fri, 9 Sep 2022 00:08:39 -0700 (PDT)) it happened Ricky
gnuarm.deletethisbit@gmail.com> wrote in
ec0dd418-095c-4eba-a026-5bda091795c1n@googlegroups.com>:

On Thursday, September 8, 2022 at 10:40:16 PM UTC-4, jla...@highlandsniptechnology.com wrote:
On Thu, 8 Sep 2022 22:39:52 -0000 (UTC), Hul Tytus <h...@panix.com
wrote:
Anyone know of any ICs designed for measureing distances with RF? I\'m
thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one
foot. The basic method of one device emitting a signal and another echoeing it
back would be attractive.
Any recommendations?

Hul
Reflections will be a big error source.

Not if an active transponder retransmits the received signal with a fixed delay. That\'s how they measure distance in the TACAN
system on airplanes. They use different frequencies which prevents an issue with echos.

Why use RF?
For 2 $ 50 centst you van get an ultrasonic distance measuring module on ebay
I have several.

500 feet?
Click to expand...

A friend worked many years ago on an ultrasonic method for measuring the
velocity of raindrop to look for windshear, microbursts, etc, for
aviation. They used an ultrasonic transducer at the focus of a 2.5m dish
(ex sat-coms) and got good results out to 6 kilometers.

Why can\'t the OP use the guts of (or chips from) a laser tape measure?

Or put a PA on one of the Infineon 24GHz radar chips?

I don\'t think the Decawave modules would get the required range.

Clifford Heath.
 
Clifford Heath wrote:
================
A friend worked many years ago on an ultrasonic method for measuring the
velocity of raindrop to look for windshear, microbursts, etc, for
aviation. They used an ultrasonic transducer at the focus of a 2.5m dish
(ex sat-coms) and got good results out to 6 kilometers.
Click to expand...

** The range of ultrasonic sound in air in measured in meters.

Your story seems completely fake.


....... Phil
 
On Saturday, September 10, 2022 at 7:01:55 AM UTC+10, Hul Tytus wrote:
Anthony William Sloman <bill....@ieee.org> wrote:
On Friday, September 9, 2022 at 8:40:00 AM UTC+10, Hul Tytus wrote:
Anyone know of any ICs designed for measureing distances with RF? I\'m
thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one
foot. The basic method of one device emitting a signal and another echoeing it
back would be attractive.
Any recommendations?

https://en.wikipedia.org/wiki/Tellurometer

Complex modulation and phase-sensitive decoding is popular.

The speed of light is about 1nsec per foot, so you are talking about round trip times of 20nsec, 200nsec and 1usec.

It\'s easy enough to create a 1nsec wide pulse, but detecting it after it has been reflected from something 500 feet away trickier.

Bill - the complex modulation & phase sensitive decoding along with multiple frequency direct are areas that would require a bit of study on my part.
Click to expand...

Don\'t top post. It makes life difficult for your reader.

> The 500mc clock required with the basic way with 2 transmiter/receivers is a problem too,

It\'s 500MHz and back in 1995 I was planning to buy one off the shelf (for about $100) which was based on a thinned-crystal oscillator.

There are a lots of faster options around today.

The whole point about the Tellurometer approach is that you don\'t need that kind of clock speed, but you do have to measure small phase differences pretty accurately, which isn\'t all that difficult. Twenty bit Sigma Delta A/D converters can be useful here.

https://www.analog.com/media/en/technical-documentation/data-sheets/2420f.pdf

is dead slow, but once you have used a phase-sensitive detector to convert the phase difference into a DC voltage you can measure it as slowly as you like.
Ingenious people get the phase difference to reverse from time to time which lets you cancel out any DC offsets

Whatever you do is going to take a bit of study on your part. The more study you do, the more likely you are to come up with a n approach that can be made to work. Coming up with an approach that is likely to work well will take even more.

probably an fpga. If some IC maker has packaged some portion of this approach the task might
be simpler.
Click to expand...

A field programmable gate array is a fairly heavyweight device. Less ambitious programmable logic devices should contain enough gates to do the job.

I quite liked the Philips CMOS Coolrunner parts, which they eventually sold to Xilinx, They drew a lot less current than the competition (unless you clocked a lot of the gates really fast).

Nobody here has come up with an off-the-shelf part yet - I\'ve never heard of one, but that doesn\'t mean much.
--
Bill Sloman, Sydney
 
Bill - the coolrunner is an attractive device, especially for a fundamently simple circuit
as this. Unfortunantly it can\'t handle 500mc. If I remember correctly they are limited
to somewhere between 100 & 200mc.
The fpgas are, as you imply, a complex effert starting from scratch, but at least another
tool would be added to one\'s \"tool box\". Can you - or anyone else - suggest an fpga that
can handle 500mc and be in the $10, $20, $30 price range?
What\'s really needed is an 8 bit counter with a latch that can handle 500mc, ala the
20 pin ttl chips.

Hul

Anthony William Sloman <bill.sloman@ieee.org> wrote:
On Saturday, September 10, 2022 at 7:01:55 AM UTC+10, Hul Tytus wrote:
Anthony William Sloman <bill....@ieee.org> wrote:
On Friday, September 9, 2022 at 8:40:00 AM UTC+10, Hul Tytus wrote:
Anyone know of any ICs designed for measureing distances with RF? I\'m
thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one
foot. The basic method of one device emitting a signal and another echoeing it
back would be attractive.
Any recommendations?

https://en.wikipedia.org/wiki/Tellurometer

Complex modulation and phase-sensitive decoding is popular.

The speed of light is about 1nsec per foot, so you are talking about round trip times of 20nsec, 200nsec and 1usec.

It\'s easy enough to create a 1nsec wide pulse, but detecting it after it has been reflected from something 500 feet away trickier.

Bill - the complex modulation & phase sensitive decoding along with multiple frequency direct are areas that would require a bit of study on my part.

Don\'t top post. It makes life difficult for your reader.

The 500mc clock required with the basic way with 2 transmiter/receivers is a problem too,

It\'s 500MHz and back in 1995 I was planning to buy one off the shelf (for about $100) which was based on a thinned-crystal oscillator.

There are a lots of faster options around today.

The whole point about the Tellurometer approach is that you don\'t need that kind of clock speed, but you do have to measure small phase differences pretty accurately, which isn\'t all that difficult. Twenty bit Sigma Delta A/D converters can be useful here.

https://www.analog.com/media/en/technical-documentation/data-sheets/2420f.pdf

is dead slow, but once you have used a phase-sensitive detector to convert the phase difference into a DC voltage you can measure it as slowly as you like.
Ingenious people get the phase difference to reverse from time to time which lets you cancel out any DC offsets

Whatever you do is going to take a bit of study on your part. The more study you do, the more likely you are to come up with a n approach that can be made to work. Coming up with an approach that is likely to work well will take even more.

probably an fpga. If some IC maker has packaged some portion of this approach the task might
be simpler.

A field programmable gate array is a fairly heavyweight device. Less ambitious programmable logic devices should contain enough gates to do the job.

I quite liked the Philips CMOS Coolrunner parts, which they eventually sold to Xilinx, They drew a lot less current than the competition (unless you clocked a lot of the gates really fast).

Nobody here has come up with an off-the-shelf part yet - I\'ve never heard of one, but that doesn\'t mean much.
--
Bill Sloman, Sydney
Click to expand...
 
Clifford - looking at the laser tape measure sounds good. I\'ll
give it a try.

Hul

Clifford Heath <no_spam@please.net> wrote:
On 10/9/22 00:38, jlarkin@highlandsniptechnology.com wrote:
On Fri, 09 Sep 2022 09:17:22 GMT, Jan Panteltje
pNaonStpealmtje@yahoo.com> wrote:

On a sunny day (Fri, 9 Sep 2022 00:08:39 -0700 (PDT)) it happened Ricky
gnuarm.deletethisbit@gmail.com> wrote in
ec0dd418-095c-4eba-a026-5bda091795c1n@googlegroups.com>:

On Thursday, September 8, 2022 at 10:40:16 PM UTC-4, jla...@highlandsniptechnology.com wrote:
On Thu, 8 Sep 2022 22:39:52 -0000 (UTC), Hul Tytus <h...@panix.com
wrote:
Anyone know of any ICs designed for measureing distances with RF? I\'m
thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one
foot. The basic method of one device emitting a signal and another echoeing it
back would be attractive.
Any recommendations?

Hul
Reflections will be a big error source.

Not if an active transponder retransmits the received signal with a fixed delay. That\'s how they measure distance in the TACAN
system on airplanes. They use different frequencies which prevents an issue with echos.

Why use RF?
For 2 $ 50 centst you van get an ultrasonic distance measuring module on ebay
I have several.

500 feet?


A friend worked many years ago on an ultrasonic method for measuring the
velocity of raindrop to look for windshear, microbursts, etc, for
aviation. They used an ultrasonic transducer at the focus of a 2.5m dish
(ex sat-coms) and got good results out to 6 kilometers.

Why can\'t the OP use the guts of (or chips from) a laser tape measure?

Or put a PA on one of the Infineon 24GHz radar chips?

I don\'t think the Decawave modules would get the required range.

Clifford Heath.
Click to expand...
 
On Saturday, September 10, 2022 at 2:21:58 PM UTC+10, Hul Tytus wrote:
Anthony William Sloman <bill....@ieee.org> wrote:
On Saturday, September 10, 2022 at 7:01:55 AM UTC+10, Hul Tytus wrote:
Anthony William Sloman <bill....@ieee.org> wrote:
On Friday, September 9, 2022 at 8:40:00 AM UTC+10, Hul Tytus wrote:
Anyone know of any ICs designed for measureing distances with RF? I\'m
thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one
foot. The basic method of one device emitting a signal and another echoeing it
back would be attractive.
Any recommendations?

https://en.wikipedia.org/wiki/Tellurometer

Complex modulation and phase-sensitive decoding is popular.

The speed of light is about 1nsec per foot, so you are talking about round trip times of 20nsec, 200nsec and 1usec.

It\'s easy enough to create a 1nsec wide pulse, but detecting it after it has been reflected from something 500 feet away trickier.

Bill - the complex modulation & phase sensitive decoding along with multiple frequency direct are areas that would require a bit of study on my part.

Don\'t top post. It makes life difficult for your reader.

The 500mc clock required with the basic way with 2 transmiter/receivers is a problem too,

It\'s 500MHz and back in 1995 I was planning to buy one off the shelf (for about $100) which was based on a thinned-crystal oscillator.

There are a lots of faster options around today.

The whole point about the Tellurometer approach is that you don\'t need that kind of clock speed, but you do have to measure small phase differences pretty accurately, which isn\'t all that difficult. Twenty bit Sigma Delta A/D converters can be useful here.

https://www.analog.com/media/en/technical-documentation/data-sheets/2420f.pdf

is dead slow, but once you have used a phase-sensitive detector to convert the phase difference into a DC voltage you can measure it as slowly as you like.
Ingenious people get the phase difference to reverse from time to time which lets you cancel out any DC offsets

Whatever you do is going to take a bit of study on your part. The more study you do, the more likely you are to come up with a n approach that can be made to work. Coming up with an approach that is likely to work well will take even more.

probably an fpga. If some IC maker has packaged some portion of this approach the task might
be simpler.

A field programmable gate array is a fairly heavyweight device. Less ambitious programmable logic devices should contain enough gates to do the job.

I quite liked the Philips CMOS Coolrunner parts, which they eventually sold to Xilinx, They drew a lot less current than the competition (unless you clocked a lot of the gates really fast).

Nobody here has come up with an off-the-shelf part yet - I\'ve never heard of one, but that doesn\'t mean much.
Click to expand...

You are still top posting. Are you another one Jake Isks pseudonyms?

Bill - the Coolrunner is an attractive device, especially for a fundamentally simple circuit
as this. Unfortunately it can\'t handle 500MHz. If I remember correctly they are limited
to somewhere between 100 & 200MHz.
Click to expand...

The Tellurometer approach lets you get away with a slower clock.

The fpgas are, as you imply, a complex effort starting from scratch, but at least another
tool would be added to one\'s \"tool box\". Can you - or anyone else - suggest an fpga that
can handle 500MHz and be in the $10, $20, $30 price range?

What\'s really needed is an 8 bit counter with a latch that can handle 500mc, ala the 20 pin ttl chips.
Click to expand...

TTL works really badly at 500MHz.

ECLinPS offers counters that can be strung together more or less indefinitely to create a synchronous counter working at 500MHz.

I did a detailed design that depended on such a part back in 1995. The modern part is faster, but it\'s unlikely to make 1.3GHz if you string a bunch of them together.

https://www.onsemi.com/pdf/datasheet/mc100ep016a-d.pdf

You really do need to go to ECL if you want to ship fast clocks and signal around - you\'ve got to treat your interconnects as terminated transmission lines.

Using the Tellurometer approach and measuring phase shifts is much easier.

--
Bill Sloman, Sydney
 
On Saturday, 10 September 2022 at 01:49:57 UTC+1, palli...@gmail.com wrote:
Clifford Heath wrote:
================


A friend worked many years ago on an ultrasonic method for measuring the
velocity of raindrop to look for windshear, microbursts, etc, for
aviation. They used an ultrasonic transducer at the focus of a 2.5m dish
(ex sat-coms) and got good results out to 6 kilometers.

** The range of ultrasonic sound in air in measured in meters.

Your story seems completely fake.
Click to expand...

Yes. At 20kHz the attenuation of sound by the atmosphere will be around
0.5dB/m (depending on temperature and humidity), so at 6km with a total
path length of 12km the absorption will be around 6000dB.
At 60m the attenuation would be 60dB there and back plus the losses due
to imperfect focusing and most of the signal from each raindrop being scattered
in all directions.
Higher frequencies would give a tighter beam but even more attenuation.

John
 
John Walliker wrote:
===============
palli...@gmail.com wrote:
===================
A friend worked many years ago on an ultrasonic method for measuring the
velocity of raindrop to look for windshear, microbursts, etc, for
aviation. They used an ultrasonic transducer at the focus of a 2.5m dish
(ex sat-coms) and got good results out to 6 kilometers.

** The range of ultrasonic sound in air in measured in meters.

Your story seems completely fake.


Yes. At 20kHz the attenuation of sound by the atmosphere will be around
0.5dB/m (depending on temperature and humidity), so at 6km with a total
path length of 12km the absorption will be around 6000dB.
Click to expand...

** ROTFL !!


At 60m the attenuation would be 60dB there and back plus the losses due
to imperfect focusing and most of the signal from each raindrop being scattered
in all directions.
Higher frequencies would give a tighter beam but even more attenuation.
Click to expand...

** Yes, sound and RF radiations get attenuated by the inverse square law, so -6dB each time the distance doubles.

Attenuation by absorption is another ball game altogether, where 1dB per meter is common and massive.



...... Phil
 
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