I picked up on of these some time ago from ebay store of Virtual Village 1 Channel RF Radio Wireless Data Transmitter Receiver
Product SKU : 003605-001
http://www.virtualvillage.com/1-channel-rf-radio-wireless-data-transmitter-receiver-003605-001.html
They don't appear to have ANY documentation or sample circuit/code
As a newbie I'd welcome any pointers, sample code etc
tks
Noel
Basically, what you input on the TX pin of the transmitter, appears on the RX pin of the receiver. If you hook up one arduino digital pin to the TX on the transmitter, and on another arduino, hook up a digital pin to the RX on the receiver, then you toggle the TX pin, you should see the toggling on the other arduino RX pin (using digitalRead() and digitalWrite() functions, of course).
Provided you hook up the other pins correctly (power VCC, ground GND, and the antenna pin - a length of wire here, adjusted in length for the frequency of 315 MHz, which should be around 9.5 inches for 1/4 wave, at least according to some googling), you should be set.
They say 10 KHz max data frequency; not sure what that would translate to baud-rate, but you're probably looking at 4800 bps - you might be able to bump it up further, but probably not much. Plus there are distance issues that affect speed...
They are essentially a wireless "wire"; there isn't much to know other than this. Note that if you want to both transmit and receive, you will need two sets, and if you want full-duplex operation, you will need two different frequencies as well.
Hope this helps!
thanks for your reply - just noticed they have mfg part numbers also
TDL 9912 TUODIRF superregenerate receiving modules；TDL-9921;TDL9921,RF transmitting modules；RF
TDL 9921 tuodielectronics，RF wireless transmitting modules，PT2262，PT2260，PT2272，TDL-9912
Chinese Data Sheet's (for what they're worth)
http://www.tuodi.com/product/product4/TDL9921.pdf
http://www.tuodi.com/product/product4/TDL9912.pdf
Not a lot to go on here - will need to do some more digging, thought I'd post this here in case they are use to anybody else
tks
Noel
These are very similar to the ones I bought from Reynolds Electronics http://www.rentron.com/PicBasic/RemoteControl.htm. The transmitter and receiver from Reynolds are great, but you can not just use them as a wireless serial link. You need to be able to send a wake up signal to the receiver before you start transmitting your data.
I use them in electronics projects like my wireless firing system, but they really aren't designed to be a communications link. You need an encoder/decoder setup or you need to have a micro-controller on each end to be able to use them properly and weed out the interference.
Personally, I use the CIP-8E and the CIP-8D encoder and decoder with them for my projects. They give you an 8 channel link and a 7 bit security code that lets you use 1 transmitter with many, many receivers. Great for multi-cue firing systems for fireworks. 
I am having the same issue with the TDL-9921. Trying to figure out how to read from the data pin.