rf distance measurement

No, just an artifact of what frequency range in the ultrasound is being considered. A transducer for soft tissues (baby imaging) or for brain scanning (blood flow doppler or imaging) use different frequencies, and for air... you want to go low frequency by comparison. The lower the frequency, the longer the range before the sound becomes thermalized (heat energy).

whit3rd wrote: ===========

FYI idiot , " ultrasonic sound " = f > 20kHz.

On a sunny day (Fri, 9 Sep 2022 21:08:22 -0000 (UTC)) it happened Hul Tytus snipped-for-privacy@panix.com wrote in <tfga06$ei9$ snipped-for-privacy@reader2.panix.com>:

All depends, you did not give the application info AFAIK.

There are so many ways to do 'long' distacne measurements in RF You can buy some thing that you can hang on your cat and your 'smart?'phone will tell you where it is same for your kids.. GPS. In X aplication there is no reason you could not combine ultrasound for short range and that for long range. And there is of course measuring from 2 angles,

Cheapest is a piece of rope with markings, tied to the source and you reading the length. There also exist binoculars with a range feature (bring the 2 images together or with laser range meter):

The possibilities for distance detection are endless.

I get a bit turned off by design becoming / being reduced to: 'do you know a chip for?'

I hope there are not going to outlaw discretes. Anyways after WW3 due to EMP and no more production you will have to learn how to use basics to survive. Hell even old diesel cars can still run and no new ones available due to 'sjip shorts' or whatever

So, to make it more fun: WTF are you trying to do?

There's a lot of frequency range between 21 kHz and 9 MHz, and lots of attenuation isn't always a killer. I worked on a machine that did doppler velocity measurement of blood flow, inside the brain. The skull gets in the way, but... the signal pickup gets all the benefits of phase-locked amplification, and gain is cheap.

Scale up the energy (we were using about 1/10 watt), and wait longer for the signal to show up (we were refreshing a video screen a few dozen times per second) and even 6000 dB loss isn't necessarily a killer. For raindrops, you'd want a wavelength in air of millimeters (for blood cells and doppler velocity measure, wavelength was about

whit3rd wrote: ==============

I hope someone cuts you ugly head off and sticks it on a broomstick in front of your house. AS a f****ng warning. You rabid schizo.

..... Phil

You'll want to think that over...

Jeroen Belleman

A TV signal at the receiver is a few microvolts, so in a 75 ohm system that's

Now recognize that the sender is NOT omnidirectional, nor is the receiver, but has focusing of maybe a couple of degrees, 0.04 radians; the effective signal/noise gets two factors of 4pi/((.04)^2), for another 80 dB So, we're at 420 dB.

OK, unless the '6000 dB' number has a fault, it doesn't seem workable.

You just can't help yourself from top posting, can you? If you insist in top posting, I won't be responding further.

You are thinking too much inside the box. An FPGA can process the equivalent of 500 MHz, by processing in parallel. Please don't try to tell me a counter can't be parallelized, because that just means you don't understand what it's doing. Feel free to ask questions.

BTW, just how old are you? They had stopped using mc when I was in college and that was... 50 years ago!

Please stop top posting.

TACAN is the military version. If you search on that you will get hits on the commercial version as well.

For 500 feet, he is likely outside. Ultrasonic can be impacted by the wind.

The troll raises he head and surveys the scene.

You got the point, that's good enough for me.

Jeroen Belleman

Bill - ECL does seem most likely but, since only 4 bits of a counter would be required, its not so combersome. AC versions of the CMOS family could handle the rest. Considering that a 12 bit counter conceptually would provide 2048 feet, the needs aren't great. Practically though 16 bits would probably be needed to handle various delays.

Hul

Anth> > Anth> > > > Anth> > > > > > Anyone know of any ICs designed for measureing distances with RF? I'm

ECL is not needed. You need to understand FPGAs if you want to use them.

For distance measurement, the ICAO standard system is called DME, Distance Measurement Equipment. It is usually paired with a VOR direction beacon.

I used to be able to hear 22 KHz and I could walk past a house and hear the 15K from TV sets. I'm down to about 8 KHz now, but there's not a lot going on above that.

Don't know all the details but the Apollo ranging system used 1960s RF technology to get foot scale accuracy across quarter million miles. Loads of info should be on the web.

piglet

Le 09/09/2022 à 00:39, Hul Tytus a écrit :

Look at the design of radio altimeters. Use of directional aerials on the source or/and the target can improve performances a lot.

Worth a look, thanks.

Hul

piglet snipped-for-privacy@hotmail.com wrote: