long range transmitting question - Electronic Circuits Projects Diagrams Free

bootstrap's_bootstraps · 1st October 2004, 04:55 AM

Hey,
this is probably a stupid question. I don't care. I'm asking it anyways. Is there a way somehow do get like a normal low-power FM transmitter that could send it's signal thru some nearby telephone or cellphone tower and use the transmission of the tower? Or would you have to go thru all sorts of descrambling and decoding crap?

zachtheterrible · 1st October 2004, 06:26 AM

well it would be a much better bet in analog than digital (it would be next to impossible in digital). I know nothing of how cell phones work, but i would imagine that the cell phone sends out a signal to identify itself in order for the phone to be able to use the network. If you have a high frequency oscilliscope and a phone that is compatible with this cell phone tower, you could see the signal that the phone sends out and copy it. How to receive it with another radio . . . duno. you could probably receive it with a landline. You would have to somehow input the number though.

By doing this, you're basically just making an illegal cell phone :lol:

**Nigel Goodwin** · 1st October 2004, 07:13 AM

Quote:

Originally Posted by bootstrap's_bootstraps

Hey,
this is probably a stupid question. I don't care. I'm asking it anyways. Is there a way somehow do get like a normal low-power FM transmitter that could send it's signal thru some nearby telephone or cellphone tower and use the transmission of the tower? Or would you have to go thru all sorts of descrambling and decoding crap?

I'm presuming you're talking about band 2 FM transmittters?, about 100MHz? - cellphones don't work anywhere near that frequency anyway!.

stevez · 1st October 2004, 12:17 PM

It sounds like you are asking if the telephone lines or the towers that support the equipment can be used as a very large antenna. The simple answer is yes. You'd have to couple the antenna to whatever so that all of the power is transferred to the 'antenna.' Aside from the obvious safety and interference problems I'd wonder if the antenna would radiate at all or just use up the power in leakage, resistance, etc. Note that the lines themselves and switching, control, etc equipment are unlikely to be efficient at VHF frequencies - or just won't pass them.

For what it's worth, my cable TV (and internet service) is RF transmitted thru the cable at frequencies from 50 mHz to 500 mHz and is directly coupled to my modem. The main cable is expensive and designed for low loss (efficient handling) at those frequencies - and even at that the distribution system contains amplifiers or repeaters that boost the level of energy to account for the losses.

bootstrap's_bootstraps · 1st October 2004, 11:32 PM

Quote:

Originally Posted by stevez

It sounds like you are asking if the telephone lines or the towers that support the equipment can be used as a very large antenna. The simple answer is yes. You'd have to couple the antenna to whatever so that all of the power is transferred to the 'antenna.' Aside from the obvious safety and interference problems I'd wonder if the antenna would radiate at all or just use up the power in leakage, resistance, etc. Note that the lines themselves and switching, control, etc equipment are unlikely to be efficient at VHF frequencies - or just won't pass them.

For what it's worth, my cable TV (and internet service) is RF transmitted thru the cable at frequencies from 50 mHz to 500 mHz and is directly coupled to my modem. The main cable is expensive and designed for low loss (efficient handling) at those frequencies - and even at that the distribution system contains amplifiers or repeaters that boost the level of energy to account for the losses.

Well.... Is it illegal? I'm just sort of wanting to "share" the tower's range, not interfere with anything. What does "couple" or "coupling" mean? (I'm 13 years old, and I'm new in eletronics, and so I don't always understand some of this jargon. :roll: ) Would building a circuit plan for this be difficult? It shouldn't be...right? I'm wanting to get a little FM transmitter I built and multiply it's poor range (like 10 feet) by combining it with the range of a tower...all with a plan to conquer the world!!! :twisted: mwahahaha!!!! anyways, any help would be appreciated and please steer clear from big words. :D

zachtheterrible · 2nd October 2004, 01:00 AM

If you want better range on your transmitter, one thing to do would to get a better receiver. I made a little fm transmitter and for the longest time (just ask everyone here) i was asking questions about boosting my power . . . come to find out, my clock radio was the problem :lol: . i'm just aboout to build a receiver that will significantly increase the range on my transmitter

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1st October 2004, 04:55 AM	(permalink)
bootstrap's_bootstraps	long range transmitting question Hey, this is probably a stupid question. I don't care. I'm asking it anyways. Is there a way somehow do get like a normal low-power FM transmitter that could send it's signal thru some nearby telephone or cellphone tower and use the transmission of the tower? Or would you have to go thru all sorts of descrambling and decoding crap? __________________ Thanks

1st October 2004, 06:26 AM	(permalink)
zachtheterrible	well it would be a much better bet in analog than digital (it would be next to impossible in digital). I know nothing of how cell phones work, but i would imagine that the cell phone sends out a signal to identify itself in order for the phone to be able to use the network. If you have a high frequency oscilliscope and a phone that is compatible with this cell phone tower, you could see the signal that the phone sends out and copy it. How to receive it with another radio . . . duno. you could probably receive it with a landline. You would have to somehow input the number though. By doing this, you're basically just making an illegal cell phone :lol: __________________ I'm no electronics god, i just talk too much.

1st October 2004, 12:17 PM	(permalink)
stevez	It sounds like you are asking if the telephone lines or the towers that support the equipment can be used as a very large antenna. The simple answer is yes. You'd have to couple the antenna to whatever so that all of the power is transferred to the 'antenna.' Aside from the obvious safety and interference problems I'd wonder if the antenna would radiate at all or just use up the power in leakage, resistance, etc. Note that the lines themselves and switching, control, etc equipment are unlikely to be efficient at VHF frequencies - or just won't pass them. For what it's worth, my cable TV (and internet service) is RF transmitted thru the cable at frequencies from 50 mHz to 500 mHz and is directly coupled to my modem. The main cable is expensive and designed for low loss (efficient handling) at those frequencies - and even at that the distribution system contains amplifiers or repeaters that boost the level of energy to account for the losses. __________________ stevez

2nd October 2004, 01:00 AM	(permalink)
zachtheterrible	If you want better range on your transmitter, one thing to do would to get a better receiver. I made a little fm transmitter and for the longest time (just ask everyone here) i was asking questions about boosting my power . . . come to find out, my clock radio was the problem :lol: . i'm just aboout to build a receiver that will significantly increase the range on my transmitter __________________ I'm no electronics god, i just talk too much.