Pulse time filter - Page 2 - Electronic Circuits Projects Diagrams Free

3iMaJ · 20th March 2008, 07:57 PM

Quote:

Originally Posted by Bavananth

Thats what we suggested. (using extremely different bit streams for detection and no detection ). is that enough for a reliable system? Anyway it seems no other methods are available. So I concentrate on that.

Then, I bought a rf module for testing purpose (rrfq2-433MHz). But there is lot of noise(anonymous bits are received) at the receiver while I tried to send some data. Even when the transmitter is off there are some thing received(no 433MHz tx at lab environment). I can see only some sudden change at the received bit while I 'on' the transmitter but not the one I send. what do you think? Might be some problem with antenna matching? I just used monopole(lambda/2 wire) antenna. Any suggestions? ( program part is ok.)

Is there any kind of matching network or anything to the monopole? Whats the output impedence on the rf module? Monopoles at lambda/2 have a 72 + j42 input impedence, not 50 ohms.

Bavananth · 21st March 2008, 10:01 AM

Thank you. I'll learn those codings!

Output impedance is 50 ohms. So that might be a problem.Normally what method do you use to match monopole antennas? Stub? QWT? Please.

Bavananth · 21st March 2008, 05:34 PM

what method do you use to match monopole antennas? Show me some sites where I can learn them? I have only theoretical knowledge in matching! Please

3iMaJ · 21st March 2008, 06:20 PM

Well there are a couple things you can do. If you shorten the monopole to .46 wavelengths (or there about, you'll have to look it up to be sure) you can find the resonance length and that'll cure some of your matching problems. You'll still have a power loss because the real part of the impedence will not be 50 ohms, I would expect it to be 60 - 70 ohms, but that might be a close enough of a match for your purposes. Otherwise you might have to use some sort of matching network.

Bavananth · 21st March 2008, 07:07 PM

Thank you Maj. I'll try with that. I learned single stub matching, double stub matching(those horrible smith chart), QWT method etc etc. But don't no how to apply them in the real world . (I made a patch antenna for my module project and Just a BNC connector did every matching thing for that,thats all).

Anyway thankyou! Share if you have anything to tell me.

3iMaJ · 21st March 2008, 07:42 PM

Quote:

Originally Posted by Bavananth

Thank you Maj. I'll try with that. I learned single stub matching, double stub matching(those horrible smith chart), QWT method etc etc. But don't no how to apply them in the real world . (I made a patch antenna for my module project and Just a BNC connector did every matching thing for that,thats all).

Anyway thankyou! Share if you have anything to tell me.

A patch antenna is much easier to match to, in that case you can just use a simple microstrip matching network. But with a monopole I'm not quite sure how to match it since you also need a balan and all of that nonsense.

Antennas aren't really much of a science, we really undertstand two types of antennas exactly, that being the dipole/monopole and the loop, other than that antennas are generally guess and check.

Bavananth · 22nd March 2008, 10:21 AM

Thank you!Theses antenna are parts are really disgusting. I'll do that 0.46 lambda thing. I'm going to use a V antenna (not those inverted Vs) while I implement the system,. I lost those equations for V antenna design.(I Designed one for my TV, It works perfectly) Can some body help me sending them? In my other part of this project,I'm struggling with some SMD counters. Have requested for some counters in the "part/data sheet request" section. I'll try my best.

mvs sarma · 22nd March 2008, 10:27 AM

Quote:

Originally Posted by Bavananth

Thank you!..................... In my other part of this project,I'm struggling with some SMD counters. Have requested for some counters in the "part/data sheet request" section. I'll try my best.

you simply say that you have some samples, but not indicated their numbers.
already replies are awaiting you over there

v antenna calculator here
http://www.hamuniverse.com/dipivcal.html

Bavananth · 22nd March 2008, 10:46 AM

Thank you sarma! I've replied. But Is V antenna and Inverted V antenna similar?
I have studied that Inverted V antennas are normally used for VOR,DVOR radar communications. The one I built was not a UP side down V. It is kept parallel to the earth. I'll try to find the equations and send you. They very simple to build and very good in recieving.

Bavananth · 24th March 2008, 12:55 PM

Hi! I have to get a 4Vp-p Sinusoidal signal (more than 22KHz) from a DC power supply(5-6V). Can I use a wien bridge oscillators? I'm sure that Getting an accurate sinusoidal from such hand made ccts are really difficult! Anyone have a tested circuit diagram for wein bridge oscillators?

I went though
http://www.educypedia.be/electronics...osciltypes.htm

all shows different different ccts.????

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21st March 2008, 10:01 AM	(permalink)
Bavananth	Thank you. I'll learn those codings! Output impedance is 50 ohms. So that might be a problem.Normally what method do you use to match monopole antennas? Stub? QWT? Please.

21st March 2008, 05:34 PM	(permalink)
Bavananth	what method do you use to match monopole antennas? Show me some sites where I can learn them? I have only theoretical knowledge in matching! Please

21st March 2008, 06:20 PM	(permalink)
3iMaJ	Well there are a couple things you can do. If you shorten the monopole to .46 wavelengths (or there about, you'll have to look it up to be sure) you can find the resonance length and that'll cure some of your matching problems. You'll still have a power loss because the real part of the impedence will not be 50 ohms, I would expect it to be 60 - 70 ohms, but that might be a close enough of a match for your purposes. Otherwise you might have to use some sort of matching network.

21st March 2008, 07:07 PM	(permalink)
Bavananth	Thank you Maj. I'll try with that. I learned single stub matching, double stub matching(those horrible smith chart), QWT method etc etc. But don't no how to apply them in the real world . (I made a patch antenna for my module project and Just a BNC connector did every matching thing for that,thats all). Anyway thankyou! Share if you have anything to tell me.

22nd March 2008, 10:21 AM	(permalink)
Bavananth	Thank you!Theses antenna are parts are really disgusting. I'll do that 0.46 lambda thing. I'm going to use a V antenna (not those inverted Vs) while I implement the system,. I lost those equations for V antenna design.(I Designed one for my TV, It works perfectly) Can some body help me sending them? In my other part of this project,I'm struggling with some SMD counters. Have requested for some counters in the "part/data sheet request" section. I'll try my best.

22nd March 2008, 10:46 AM	(permalink)
Bavananth	Thank you sarma! I've replied. But Is V antenna and Inverted V antenna similar? I have studied that Inverted V antennas are normally used for VOR,DVOR radar communications. The one I built was not a UP side down V. It is kept parallel to the earth. I'll try to find the equations and send you. They very simple to build and very good in recieving.

24th March 2008, 12:55 PM	(permalink)
Bavananth	Hi! I have to get a 4Vp-p Sinusoidal signal (more than 22KHz) from a DC power supply(5-6V). Can I use a wien bridge oscillators? I'm sure that Getting an accurate sinusoidal from such hand made ccts are really difficult! Anyone have a tested circuit diagram for wein bridge oscillators? I went though http://www.educypedia.be/electronics...osciltypes.htm all shows different different ccts.????