I am trying to use 4 Arduino RF 315/433 MHz Transmitter-receiver Modules to generate a signal to send to a drum module. I am concerned about cross talk. If I use 4 separate modules (transmitter and receiver) will this create 4 separate channels thus avoiding "cross talk"? Data is generated by striking a piezzo pickup wired to the Arduino transmitter. Is this the best unit to use for data transmission of this kind
The commonly available 315/433 MHz modules are single channel. To have two channels, use an RX/TX pair at 315 MHz and another at 433 MHz. For a bit more money you could use higher frequency modules (in the 2.4 GHz band), and get around 256 channels. One possibility is the Pololu Wixel.
What you want is the nRF24L01 module. It is a transceiver and has 6 "pipes" that can be used to talk to 6 different nRF24L01 modules without crosstalk. There are several libraries specifically for using this module, including one to implement an almost unlimited "star" network, where every module can talk with 5 others, and can route messages to any device on the network. I know, sounds like overkill, but they are dirt cheap for what they do.
If you have 1 controller to send and 4 Arduinos to receive, you will need 5 nRF24L01 modules. I get mine from China, via eBay. Just search for "nRF24L01" (quotes not needed). You can get them from the USA as well, though they tend to be about 2-3 times the cost, but with (most likely) faster delivery. The Chinese ones will go for about 2 to 3 dollars each, or as low as $10-15 for ten pieces.