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Copyright: 1996 - 2024
Webmaster:
    Kirt Blattenberger,

    BSEE - KB3UON

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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Long range (wireless)signal communication - RF Cafe Forums

RF Cafe Forums closed its virtual doors in 2012 mainly due to other social media platforms dominating public commenting venues. RF Cafe Forums began sometime around August of 2003 and was quite well-attended for many years. By 2010, Facebook and Twitter were overwhelmingly dominating online personal interaction, and RF Cafe Forums activity dropped off precipitously. If the folks at phpBB would release a version with integrated sign-in from the major social media platforms, I would resurrect the RF Cafe Forums, but until then it is probably not worth the effort. Regardless, there are still lots of great posts in the archive that ware worth looking at.

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vihangas
Post subject: vihangas
Post subject: Long range (wireless)signal communication Posted: Sun Dec 03, 2006 11:13 am

Lieutenant

Joined: Sun Dec 03, 2006 10:53 am
Posts: 2
Hi Guys,
I am new to this RF design and stuff..
Can anybody help out how to design a circuit for transfering a signal for a 1KM. I want to design product should be as small as it can be hold in palm like car secuity system. I dont want to transfer any kind of audio signal. It cud be some binary data. I have restrictions on cost of the product, It should not cross 15-20$.
Please guide me in designing this system.

vihang
vihangas@rediffmail.com

Top

fred47
Post subject: RF designPosted: Tue Dec 05, 2006 12:52 am

General


Joined: Wed Feb 22, 2006 3:51 pm
Posts: 104
Hi Vihangas,
In order to design something, you need a clear understanding of
1. what you're trying to do
2. what the restrictions are

In the first category, are you talking about 1 bit/second? 1k bits/second? 100k bits/second? 10M bits/second? What quantity of these (remote controls?) are you trying to build? - there's often a wide range in component prices, depending on quantity. Who is your market (consumer? law enforcement? military? terrorists?)

In the second category, what country are you in? (The laws of different countries vary dramatically, as far as power, frequencies, bandwidth, duty cycle, etc., are concerned).

"If you don't care where you're going, any solution is fine..."

Good Luck,
Fred


Top

vihangas
Post subject: requirmentsPosted: Tue Dec 05, 2006 2:47 pm

Lieutenant

Joined: Sun Dec 03, 2006 10:53 am
Posts: 2
Hey Fred,
Thanks for your reply. well I will not able to tell what could be bits/sec.
let me explain me in more details, see if you can only suggest me.
I stay in India. I am developing this wireless transceiver for the farmers (filed is agricultural). I want to operate a relay on receiver side which will on-off upon the signal send by transmitter. So that need not be the data. but the same time one transmitter should be unique for one receiver. Here I want both transmitter and receiver on battery. I expect receiver should send acknowledgement on receiving signal from transmitter and on successful action on it. What I can imagine about acknowledgment is there would be two frequencies one for positive response and one for negative response.
Why I am bit press for the cost is the cause where it going to use. Here farmer can not afford such product for more than 15-20$.
Now I request you only to give me the direction to move ahead.

Regards,
vihang


Top

fred47
Post subject: Remote controlPosted: Fri Dec 08, 2006 2:00 am

General


Joined: Wed Feb 22, 2006 3:51 pm
Posts: 104
Hi!

OK, so what we have is a transceiver with undefined (but low!) power, transmitting on an undefined (but high?) frequency, operating from an undefined (but inexpensive!) power source with an undefined life, of undefined reliability, of small physical size, communicating with a second transceiver of similarly undefined characteristics, which will control a relay to control an undefined load.

The first step in designing something is to be absolutely crystal clear on what you want - in other words, define what you mean by "success". You don't even have to be clear with anyone else - if it's you doing the design. But you do need a vision of the goal. Otherwise, who you need is Harry Potter, not an engineer.

Good Luck!

(I'm not being sarcastic - just a bit frustrated !)

Fred Posted: Sun Dec 03, 2006 11:13 am

Lieutenant

Joined: Sun Dec 03, 2006 10:53 am
Posts: 2
Hi Guys,
I am new to this RF design and stuff..
Can anybody help out how to design a circuit for transfering a signal for a 1KM. I want to design product should be as small as it can be hold in palm like car secuity system. I dont want to transfer any kind of audio signal. It cud be some binary data. I have restrictions on cost of the product, It should not cross 15-20$.
Please guide me in designing this system.

vihang
vihangas@rediffmail.com

Top

fred47
Post subject: RF designPosted: Tue Dec 05, 2006 12:52 am

General


Joined: Wed Feb 22, 2006 3:51 pm
Posts: 104
Hi Vihangas,
In order to design something, you need a clear understanding of
1. what you're trying to do
2. what the restrictions are

In the first category, are you talking about 1 bit/second? 1k bits/second? 100k bits/second? 10M bits/second? What quantity of these (remote controls?) are you trying to build? - there's often a wide range in component prices, depending on quantity. Who is your market (consumer? law enforcement? military? terrorists?)

In the second category, what country are you in? (The laws of different countries vary dramatically, as far as power, frequencies, bandwidth, duty cycle, etc., are concerned).

"If you don't care where you're going, any solution is fine..."

Good Luck,
Fred


Top

vihangas
Post subject: requirmentsPosted: Tue Dec 05, 2006 2:47 pm

Lieutenant

Joined: Sun Dec 03, 2006 10:53 am
Posts: 2
Hey Fred,
Thanks for your reply. well I will not able to tell what could be bits/sec.
let me explain me in more details, see if you can only suggest me.
I stay in India. I am developing this wireless transceiver for the farmers (filed is agricultural). I want to operate a relay on receiver side which will on-off upon the signal send by transmitter. So that need not be the data. but the same time one transmitter should be unique for one receiver. Here I want both transmitter and receiver on battery. I expect receiver should send acknowledgement on receiving signal from transmitter and on successful action on it. What I can imagine about acknowledgment is there would be two frequencies one for positive response and one for negative response.
Why I am bit press for the cost is the cause where it going to use. Here farmer can not afford such product for more than 15-20$.
Now I request you only to give me the direction to move ahead.

Regards,
vihang


Top

fred47
Post subject: Remote controlPosted: Fri Dec 08, 2006 2:00 am

General


Joined: Wed Feb 22, 2006 3:51 pm
Posts: 104
Hi!

OK, so what we have is a transceiver with undefined (but low!) power, transmitting on an undefined (but high?) frequency, operating from an undefined (but inexpensive!) power source with an undefined life, of undefined reliability, of small physical size, communicating with a second transceiver of similarly undefined characteristics, which will control a relay to control an undefined load.

The first step in designing something is to be absolutely crystal clear on what you want - in other words, define what you mean by "success". You don't even have to be clear with anyone else - if it's you doing the design. But you do need a vision of the goal. Otherwise, who you need is Harry Potter, not an engineer.

Good Luck!

(I'm not being sarcastic - just a bit frustrated !)

Fred



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