Los Frijoles
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I have been looking around online for the past several months on this sort of stuff and I have not found much on transmitting data over longer distances. I know there are modules that can transmit far (XBee pro), but I would like to design something myself since that is infinitely more fun.
Since I do most of my stuff using PICs (currently a PIC24FJ256GB108 or PIC18F4550), I have been looking at BPSK for a modulation since it seems to be the easiest to do for binary-based systems such as a microcontroller. I understand the basic concept of BPSK: A one is a positive sine of the RF wave and a 0 is the negative sign of the wave, switched at the zero point. My basic idea is to connect the UART of a PIC running at a low baud (1200 maybe) and be able to send small snippets of data long distances (a mile or more) assuming the device is in the open air (e.g. in a R/C plane). So far the simplest schematic of a BPSK modulator I have seen is this one:
**broken link removed**
The whole thing basically functions as a really big XOR gate (3 of the gates are ganged together to get more output apparently). However, since it uses a logic gate and an RF signal is analog, I do not see how this would work.
Another schematic I have seen this one (too big, so its a link):
**broken link removed**
It is a complete schematic for a BPSK transmitter. I would like to understand how it works. Since I have no background really in radios and stuff aside from the things I have already done with WirelessUSB, could someone explain how this works?
How is demodulating accomplished?
Has anyone else done anything like this before?
Sorry for all these questions, but I finally got enough information that I could post something.
Since I do most of my stuff using PICs (currently a PIC24FJ256GB108 or PIC18F4550), I have been looking at BPSK for a modulation since it seems to be the easiest to do for binary-based systems such as a microcontroller. I understand the basic concept of BPSK: A one is a positive sine of the RF wave and a 0 is the negative sign of the wave, switched at the zero point. My basic idea is to connect the UART of a PIC running at a low baud (1200 maybe) and be able to send small snippets of data long distances (a mile or more) assuming the device is in the open air (e.g. in a R/C plane). So far the simplest schematic of a BPSK modulator I have seen is this one:
**broken link removed**
The whole thing basically functions as a really big XOR gate (3 of the gates are ganged together to get more output apparently). However, since it uses a logic gate and an RF signal is analog, I do not see how this would work.
Another schematic I have seen this one (too big, so its a link):
**broken link removed**
It is a complete schematic for a BPSK transmitter. I would like to understand how it works. Since I have no background really in radios and stuff aside from the things I have already done with WirelessUSB, could someone explain how this works?
How is demodulating accomplished?
Has anyone else done anything like this before?
Sorry for all these questions, but I finally got enough information that I could post something.