I'd seriously consider radio such as this one: -
It's good for 5km so 1km line of sight should be OK but there will be more powerful devices that fit the bill. It came from here. Here is more detail: -
The TX3H-869.5-15 from Radiometrix, is an FM transmitter module
achieving a power output of 450mW at 869.5MHz. It is fully
pin-compatible with the company's established range of SIL TX modules
and is a drop-in UHF replacement for the TX1H VHF product, having near
identical dimensions of only 45x17x6mm.
TX3H is an excellent choice for the designer of a licence exempt
wireless data application where the size of antenna is restricted yet
a range in kilometres is also specified. The module can support data
rates of up to 15kbits/s and has a potential range of 5km or more when
paired with Radiometrix receivers such as the new RX3G, depending on
the type of antenna used and the environment.
It'll save you a few pennies on cable install costs.