AMband.org

I have received a lot of questions about the contours shown on the Radio-Locator maps. For AM they are:

• Red – 3.0 mV/m – Generally the Sellable area of the station
• Purple – 0.5 mV/m – Rural protected service area, but nobody would buy ads.
• Blue – 0.1 mV/m – You might still get it on a car radio

For FM they are:

• Red – 60 db/uV or 1.0 mV/m – Protected service area for Class A and C stations
• Purple – 50 db/uv or 0.316 mV/m – A pretty weak Signal, nobody would buy ads.
• Blue – 40 db/uv or 0.1 mV/m – You won’t pick it up, except in rural areas

I determined this by comparing the plots of sample stations in Radiosoft’s Comstudy with their Radio-Locator maps. Hopefully this clears a few things up!

The National Radio Systems Committee has released a study on the effects of reducing the bandwidth of AM transmissions from the present standard of 10 kHz.  The study used representative receivers to present transmissions of speech, sports, music and commercials with bandwidths of  5 kHz, 7 kHz and 10 kHz.  The study assumes that both the desired and undesired stations operate using the same standard.

The results showed that mutually reducing transmission bandwidth down to 5 kHz  is a big plus for speech.  There was either a benefit, or no change from the 10 kHz results when reducing the transmitted bandwidth to 7 kHz irrespective of format or first adjacent channel interference level. (more…)

I just installed the brand new JVC KD-HDR1 car radio with HD Radio. This is by far the lowest cost HD radio on the market. ($279 after rebate from Crutchfield) It has a lot of features, including multichannel capability, and auxiliary inputs (with adapters) for CD changers, Ipods, XM and Delphi radio.
I give it a 7 out of 10, unfortunately it is the AM section that lowers the rating.

It has a builtin CD/CDR/MP3/WMA player with title text readout too. (more…)