UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

cmjones01 · 27th Mar 2012, 4:40 pm

Yes, I've heard that effect. It's because there are multiple transmitters for both 693kHz and 909kHz and they're all in different places at different distances from your radio. Their signals take different lengths of time to get to you (at the speed of light, according to my calculations, the radio signal will take about 0.5ms for 100 miles) so you hear this echo effect. Being AM, different signals from different transmitters on the same frequency will mix in your radio and you'll hear the 'echo' from both of them.

I don't know if the audio signals at each transmitter are perfectly synchronised with each other. They may well not be, which will make the effect more pronounced.

27th Mar 2012, 4:40 pm	#2
cmjones01 Nonode Join Date: Oct 2008 Location: Warsaw, Poland and Cambridge, UK Posts: 2,676	Re: Radio 5 Live Echo (Empty Hall) Effect ? Yes, I've heard that effect. It's because there are multiple transmitters for both 693kHz and 909kHz and they're all in different places at different distances from your radio. Their signals take different lengths of time to get to you (at the speed of light, according to my calculations, the radio signal will take about 0.5ms for 100 miles) so you hear this echo effect. Being AM, different signals from different transmitters on the same frequency will mix in your radio and you'll hear the 'echo' from both of them. I don't know if the audio signals at each transmitter are perfectly synchronised with each other. They may well not be, which will make the effect more pronounced.