What is the transmitter part? how does it relate the the rest?
Resistor R8 is wrong. The brightness of the display will change depending upon how many segments are lit.
Replace it with a short circuit and insert a 470 Ohm in series with each segment.
You also will need to insert 100 nF bypass capacitors. One between pins 5 & 10 of U1 and one between pins 1 & 4 of the 555.
Also, you are powering the 74LS ICs from the 4.5 Volt battery.
The manufacturers of 74LS series recommend that the supply voltge should be between 4.75 and 5.25 Volt. So your circuit will probably work when the battery is fresh, but it may become marginal as the battery ages. Why don't you supply it from the 5 Volt supply?