Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
BCM
Durkin Tactical Franklin Armory
User Panel

Posted: 10/27/2015 10:27:50 PM EDT
Ok, a little background: My senior design project consists of building a "spotter" scope (a ballistics computer) that takes range and wind reading puts them through some Arduinos and farts out a result. We have gone through three options: triangulation using the webcam and laser method, hard core engineering a rangefinder using the phase shifting method, and buying a rangefinder (the option we went with). We are still trying to build a back up just in case the bought rangefinder goes out. We have the schematic and have talked to a professor about the feasibility of building one. So we can do it but we want to find a way to do this without using an XOR logic gate because it reduces our range to 250 yards and we need a minimum of 300 yards. Any help will be greatly appreciated.
Link Posted: 11/1/2015 3:22:23 PM EDT
[#1]
Quoted:
Ok, a little background: My senior design project consists of building a "spotter" scope (a ballistics computer) that takes range and wind reading puts them through some Arduinos and farts out a result. We have gone through three options: triangulation using the webcam and laser method, hard core engineering a rangefinder using the phase shifting method, and buying a rangefinder (the option we went with). We are still trying to build a back up just in case the bought rangefinder goes out. We have the schematic and have talked to a professor about the feasibility of building one. So we can do it but we want to find a way to do this without using an XOR logic gate because it reduces our range to 250 yards and we need a minimum of 300 yards. Any help will be greatly appreciated.
View Quote


A mixer will operate in the frequency domain to produce a signal proportional to phase difference.

Any saturated amplifier that behaves in a non-linear mode will also do the same thing.
A simple 'badly' designed one transistor amplifier that produces a lot of distortion in the large signal (as opposed to small signal) environment.

We usually use a lot of feedback around amplifiers to AVOID creating phase related harmonics.

You WANT a crappy design.
Link Posted: 11/3/2015 2:42:50 PM EDT
[#2]
We were originally planning to use a heterodyne mixer but we don't have time to build one. I'm intrigued with your amp design though. Please forgive me if I seem noobish.
Link Posted: 11/3/2015 3:39:47 PM EDT
[#3]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
We were originally planning to use a heterodyne mixer but we don't have time to build one. I'm intrigued with your amp design though. Please forgive me if I seem noobish.
View Quote


Any device you can drive into non-linear operation will do the job.

Make the signal big enough to drive a Schottky diode on and off and you will have the harmonics you want.
A 2N2222 amp in large signal mode (even on-off) will do the job.
Link Posted: 11/5/2015 3:07:29 PM EDT
[#4]
Ok! Is it just a 2N2222? Or can I use any BJT (i.e 2N3904)? By Schottky diode you mean like a 1N914? Sorry but my EE professors have never gone over Schottky diodes in their classes.
Link Posted: 11/5/2015 4:20:26 PM EDT
[#5]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Ok! Is it just a 2N2222? Or can I use any BJT (i.e 2N3904)? By Schottky diode you mean like a 1N914? Sorry but my EE professors have never gone over Schottky diodes in their classes.
View Quote


You can use just about any device that has gain and can be driven hard enough to be non-linear.

Just watch out how much power is getting dissipated by both the DC bias and the large AC signal.

A 1N914 is NOT a Schottky diode.
It is a 'conventional' semiconductor diode.
They still need 0.7 V to turn on.

Schottky diodes only need about 0.3  They are metal junction diodes instead of conventional P-N junction diodes.

Sounds like you need to read ahead in your textbook or choose a better book.
Close Join Our Mail List to Stay Up To Date! Win a FREE Membership!

Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!

You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.


By signing up you agree to our User Agreement. *Must have a registered ARFCOM account to win.
Top Top