RF transmitter

[ProFPGA]

hi , i am looking for a circuit or ready made tx module that has a range of 1 mile or more .
i will be sending data over it via FM modulation .

Has anyone used such a module or made such a ckt ?

 

[Oznog]

The answer will change a lot depending on what the bandwidth of data is you wish to send.
"a mile or more" is a HUGE range to be asking for from a "basic" project.

Microchip's MRF modules can support a lot of bandwidth, and list up a 4000ft range on the MB version (in reality, nonideal conditions are common, which will reduce that range).

 

[ProFPGA]

i am open to any thing that works within ISM band , the rough range that comes to my mind is : 13Mhz - to - 900Mhz .

 

[Oznog]

No, how much DATA. 300 baud? 2 Mbaud???

 

[ProFPGA]

the data rate i am looking for is 9600 bps.
i did a little digging myself , i can use one of the microchip's RF transceiver.
the part is : MRF49XA.
but i am new to RF design , i dont how to calculate power output of a transmiiter and relate it to its range .
Say what will be the effective range of 0.4db tx or 1Watt tx???

 

[MikeMl]

the data rate i am looking for is 9600 bps.
i did a little digging myself , i can use one of the microchip's RF transceiver.
the part is : MRF49XA.
but i am new to RF design , i dont how to calculate power output of a transmiiter and relate it to its range .
Say what will be the effective range of 0.4db tx or 1Watt tx???

Here is a **broken link removed**. You need to know the TX power output (in dbm), the RX sensitivity (in dbm), antenna gains, and coax loss (if any). Figure crummy antennas, with gain of -10db (shortened whip instead of full dipole). Sending a signal in an urban environment is definitely more lossy than space, but it will give you a place to start.