Radio Design Project

xerka · 12-01-2004, 04:21 PM

My electrical engineering class is near the end of the semester and we've started working on a design project. The goal of the project is to create a very sensitive AM radio. During each round they will decrease the power of the AM signal and whoever can still here the variations in the signal stays in.

For mine I have a few ideas and was wondering if you guys had any suggestions.
First, I was thinking that we filter the signal with an active band pass filter that would amplify the signal as well. Or maybe just use a passive filter and then amplify the signal with a transistor. For the antenna I was thinking a wire loop antenna like http://www.geocities.com/SunsetStrip...8585/loop.html

Anybody else have some good experience with this that could give me some suggestions?

KnightElite · 12-01-2004, 04:34 PM

I know a lot of radio theory, but I have never actually built one, so I'm not sure what the best way to go would be. I would say you should get a very high gain OP-AMP that works at the frequency that you intend to be using (I take it this on one frequency only), or chain several high-gain op-amps together. That would be the way to get the highest possible, I would think.

A loop antenna is only good if you don't know whether their antenna will be horizontal or vertical. If theirs is horizontal, you should use a long horizontal antenna, if theirs is vertical, use a long vertical antenna.

Brians256 · 12-01-2004, 05:07 PM

I can say one thing from a theoretical standpoint: cool your amp stage. The noise level of an amplifying transistor is greatly improved by cooling it.

However, I don't know whether that will be a significant factor in your design. Other error sources may dominate (antenna design, circuit board routing, etc...).

bigben2k · 12-01-2004, 06:03 PM

FWIW

A passive filter can significantly attenuate a signal, so if you have a better option, use it.

I'll backup all advice above.

Do you have any information on the source of the signal? frequency? etc... What are some of the other contest's parameters?

PaulDriver · 12-01-2004, 06:17 PM

You should also compete aginst something like my Tube driven 1937 Delco Model R 1157 Radio

xerka · 12-01-2004, 08:13 PM

Quote:

Originally Posted by bigben2k

FWIW

Do you have any information on the source of the signal? frequency? etc... What are some of the other contest's parameters?

They haven't really told us the source of the signal, I'd assume some AM transmitter or they will just use the frequency generators in the lab. Today we agreed on one frequency 1 MHz. I guess they'll be changing the amplitude so we can hear two different tones and we have to record how many tone shifts there are. If you get it right you move on and they lower the strength of the signal. There's not really too many rules.

Here's a previous years competitor.
http://www.amradio.freeservers.com/

KnightElite · 12-02-2004, 11:06 AM

Okay, in that case you can just use a basic diode detector, just like the people in the link you sent did. Just put several high-gain op-amps prior to the detector, and you should do fairly well.

killernoodle · 12-02-2004, 01:20 PM

Quote:

Originally Posted by xerka

I guess they'll be changing the amplitude so we can hear two different tones and we have to record how many tone shifts there are.

That would make sense as it is an AM signal

Are there any size restraints for the unit? You could make a serious signal amplifier and antennae assembly with enough room...

Lothar5150 · 12-02-2004, 01:48 PM

Quote:

Originally Posted by xerka

My electrical engineering class is near the end of the semester and we've started working on a design project. The goal of the project is to create a very sensitive AM radio. During each round they will decrease the power of the AM signal and whoever can still here the variations in the signal stays in.

For mine I have a few ideas and was wondering if you guys had any suggestions.
First, I was thinking that we filter the signal with an active band pass filter that would amplify the signal as well. Or maybe just use a passive filter and then amplify the signal with a transistor. For the antenna I was thinking a wire loop antenna like http://www.geocities.com/SunsetStrip...8585/loop.html

Anybody else have some good experience with this that could give me some suggestions?

The antenna is key...trust me on this one

FM-23-10

FYI dead 'D' cell batteries make great resistors.

12-01-2004, 04:21 PM	#1
xerka Cooling Savant Join Date: Mar 2001 Location: Denver, CO Posts: 107	Radio Design Project My electrical engineering class is near the end of the semester and we've started working on a design project. The goal of the project is to create a very sensitive AM radio. During each round they will decrease the power of the AM signal and whoever can still here the variations in the signal stays in. For mine I have a few ideas and was wondering if you guys had any suggestions. First, I was thinking that we filter the signal with an active band pass filter that would amplify the signal as well. Or maybe just use a passive filter and then amplify the signal with a transistor. For the antenna I was thinking a wire loop antenna like http://www.geocities.com/SunsetStrip...8585/loop.html Anybody else have some good experience with this that could give me some suggestions? __________________ Folders: I've given up folding

12-01-2004, 04:34 PM	#2
KnightElite Cooling Savant Join Date: Sep 2002 Location: Saskatoon, Saskatchewan Posts: 294	I know a lot of radio theory, but I have never actually built one, so I'm not sure what the best way to go would be. I would say you should get a very high gain OP-AMP that works at the frequency that you intend to be using (I take it this on one frequency only), or chain several high-gain op-amps together. That would be the way to get the highest possible, I would think. A loop antenna is only good if you don't know whether their antenna will be horizontal or vertical. If theirs is horizontal, you should use a long horizontal antenna, if theirs is vertical, use a long vertical antenna. __________________ Can anyone else here say that they have a watercooled monster that's 45" tall?

12-01-2004, 06:03 PM	#4
bigben2k Responsible for 2% of all the posts here. Join Date: May 2002 Location: Texas, U.S.A. Posts: 8,302	FWIW A passive filter can significantly attenuate a signal, so if you have a better option, use it. I'll backup all advice above. Do you have any information on the source of the signal? frequency? etc... What are some of the other contest's parameters? __________________ WBTA (Water Block Testing Alliance) Nordic Hardware WC 101

12-02-2004, 11:06 AM	#7
KnightElite Cooling Savant Join Date: Sep 2002 Location: Saskatoon, Saskatchewan Posts: 294	Okay, in that case you can just use a basic diode detector, just like the people in the link you sent did. Just put several high-gain op-amps prior to the detector, and you should do fairly well. __________________ Can anyone else here say that they have a watercooled monster that's 45" tall?

12-01-2004, 05:07 PM	#3
Brians256 Pro/Staff Join Date: Oct 2001 Location: Klamath Falls, OR Posts: 1,439	I can say one thing from a theoretical standpoint: cool your amp stage. The noise level of an amplifying transistor is greatly improved by cooling it. However, I don't know whether that will be a significant factor in your design. Other error sources may dominate (antenna design, circuit board routing, etc...).

12-01-2004, 06:17 PM	#5
PaulDriver Cooling Neophyte Join Date: Oct 2004 Location: Sin City Posts: 37	You should also compete aginst something like my Tube driven 1937 Delco Model R 1157 Radio

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