> >
> > David, what is required for at least a 20dB signal to
> noise
> > ratio outdoors in most of the L.A. market?
> >
>
> To simply overcome noise based on a variety of receivers, 10
> mv/m is about the minimum. At KTNQ we found that 90% of
> diary returns came from inside the 15 mv/m contour, in fact.
>
whoa, that is a HECK OF A TON of field strength!! AUGH!! OWW!! Quit RF-BURNING me!! :-D
If it's that bad outdoors on a good car radio or excellent portable for a 20dB signal to noise ratio, what's it like in a metal and concrete building for a cheap radio? What's the minimum field there for at least 20dB snr?
Here near El Cajon / La Mesa, CA, I can hear KNX and KFI fairly well (with a little noise but it's EASILY listenable, and with a Select-A-Tenna the noise disappears completely). KMXE is a bit weaker but is still quite audible, KLAC and KABC are weaker still (moderately noisy) but I can still hear everything on them. It isn't until I get to KTNQ or KFWB that the signal is barely detectable (If I'm wearing headphones, it's quiet around me, and I crank the volume up, I might be able to detect something.) (all the above (except where specifically noted) is using my portable walkman (Panasonic, not Sony) without the Select-A-Tenna.
What field strengths might KNX or KTNQ or KMXE be putting into El Cajon in the daytime? I'm going to guess somewhere in the range of 0.25mV/m to 1mV/m, but you can correct me if I'm wrong.
I'd guess KLSD (1360) is about 10mV/m at night where I am, and it's a rock-solid blowtorch.
Are you saying Los Angeles is several dozen db noisier than San Diego, or do our ideas of a
, <a href=http://70.181.196.176:1180/stephen/amradio/AM_signal_2.mp3>decent signal,
, <a href=http://70.181.196.176:1180/stephen/amradio/AM_signal_4.mp3>usable signal, or <a href=http://70.181.196.176:1180/stephen/amradio/AM_signal_5.mp3>barely detectable (but I still sometimes listen to stations that are this weak)</a> differ?
<a href=http://70.181.196.176:1180/stephen/amradio/partial_am_scan_10-10-2004/1070.mp3>Here's a brief one of KNX on a SRF-42 with the Select-A-Tenna before they started running IBOC.</a> (Normally KNX would be about like one in the "decent signal" link.)<P ID="edit"><FONT class="small">
Edited by tfcwings on 06/22/05 10:40 AM.</FONT></P>