THE GORT   

 

 

 

 

 

 

 

 

The excellent Harris AMS-G1 C-Quam AM Stereo exciter is seen in this video being put through its paces. This is a technical review and includes a long look 'under the hood' of the equipment.

 

This is not the older VPCM AM Stereo system that Harris developed themselves, but  the better known C-Quam system, which is still in use on around 300 radio stations in France, Australia and the USA.

 

 

Sadly, the US regulator, the FCC, left the market to decide which system won, and the money guys able to roll their system out won with the C-QUAM system, whose main developer was Motorola. It finally became dominant by the early 1990s with Kahn, Harris and Magnavox all pulling out quite early.

 

The FCC finally made its decision in 1993, but by then the AM band had become ravaged and damaged by the AM Stereo wars.

 

Mototola have since made many changes to their system and have largely conquered its problems, such as Platform Motion.

Texas station KSET 1300 changed its call sign to KLLS (a tribute to Chicago radio station WLS as Double-L-S ) in  2016. It then broadcast a classic hits / Top40 music format with AM Stereo  branding itself as "Musicradio Double-L-S".

 

Jeff Davis, a DJ on WLS in the 80s and still on 94.7, WLS-FM, was the voice of 1300, whic is centred in Lumberton, just east of Houston, Texas.  The station broadcast to the 'Golden Triangle' and was owned by South East Texas Telecom LLC.

 

On February 12, 2017 KLLS went off-air due to antenna array damage and effects of Hurricane Harvey. The FCC granted a silent STA to effect antenna repairs but its owner sold it to a Spanish talk outlet.

 

In the USA there are currently 126 high power (50kW) AM stations broadcasting in the AM Stereo mode.

 

 

For a full listing of high power AM stations in the USA, click http://www.amstereo.org

 

Many other countries have had AM stereo stations too, especially Brazil, Spain and Australia -

We've been champions of AM STEREO transmissions since first hearing it in the early 1980s. Subsequent work on two systems (Kahn-Hazeltine and Motorola C-QUAM) with broadcasters convincing us that this is the way for AM to move, but historically the quest to cram in more and more small low power transmitters has worked against AM, leaving the band full of  low quality equipment.

Without doubt, AM transmissions can sound as good as FM, but receivers are often built to poor levels and make the sound 'muddy', plus the AM interference doesn't help. To combat interference effects, many radio manufacturers have reduced the IF bandwidth of AM receivers, reducing AM's ability to sound clear and bright.Ttransmitters need extra band space to make the audio sound right, there's plenty of kit on the FM band (VHF) but its cramped on the Medium Wave (AM). 

 

AM Stereo provides clear full-dimensional Stereo sound that envelops the listener with fidelity usually thought of as something only found on the FM band. AM Stereo has been used all around the world for over two decades and is employed by hundreds of stations on every continent. Since its introduction, millions of AM Stereo receivers have been sold for home, car, and portable listening enjoyment.

 

AM Stereo is an analogue system that has been optimized for high quality (meaning good audio fidelity) reception even with weak, distant signals. The greater long-distance range of AM signals, especially at night, gives stations a much larger coverage area, extending hundred and often to thousands of miles.  FM by contrast is limited to little more than 'line of sight', a maximum of perhaps 70 miles if the highest locations or tall masts are chosen for antennas.

 

The big advantage of AM Stereo is that it not only reaches huge distances, but it is reverse compatible with existing mono receivers. They receive the same programme and  with quite an improvement in audio quality too.

We've been champions of AM STEREO transmissions since first hearing it in the early 1980s. Subsequent work on two systems (Kahn-Hazeltine and Motorola C-QUAM) with broadcasters convincing us that this is the way for AM to move, but historically the quest to cram in more and more small low power transmitters has worked against AM, leaving the band full of  low quality equipment.