could someone please suggest me a way to know whether a particular frequency is present or not ?so if i want to know a horn sound or an ambulance sound what filters or equipment should i be using?

and say if the source is 100m or 200m away from the receiver then how will this range effect that equipment ?

 

The Soundcard Oscilloscope here: https://www.zeitnitz.eu/scope_en
includes a spectrum analyser and works with a PC soundcard.

 

could someone pls suggest me a way to know whether a particular frequency is present or not ?so if i want to know a horn sound or an ambulance sound what filters or equipment should i be using?

and say if the source is 100m or 200m away form the reciever then how will this range effect that equipment ?

You would need a microphone, then an amplifier to detect the sound, and a filter chip (frequency detector chip - Google "LM567 DATASHEET" and you can then adjust the input resistors until you get an output for each device you want to detect. It will be easier to play the frequency from a recording while you adjust for each tone.

 

GopherT already told you the important part, you may also need a LM3914 to show you the voltage level of incoming signal.