Published: TV Technology

Issue: 9/25/97



Reduced ENG Band Creates Cost Concerns

by Joe Fedele



MIAMI--Part of the Balanced Budget Agreement of 1997 that was signed into law last month 

forced the FCC to reallocate a section of the Broadcast Auxiliary Service (BAS) band and make 

it available for auction to public safety and commercial licensees for their ever expanding voice 

and data communications requirements. 



The BAS band currently extends from 1,990 to 2,110 Mhz and is primarily used by broadcasters 

in the major markets for ENG applications, such as program back haul from the field for live 

news events.  It is also used by broadcasters in the more rural areas as a long haul medium for 

Studio-to-Transmitter (STL) links and Inter City Relays (ICR) for programming distribution.



As reported in the September 11th issue of TV Technology,  the BAS band could shrink from its 

current 120 Mhz size to as little as 70 Mhz.  This would leave broadcasters with only 10 Mhz of 

bandwidth for each of the seven channels used in the band. 



Consequently broadcasters may face the prospect of having to replace their existing analog ENG 

and other long haul microwave links in the 2 Ghz band with digitally compressed systems if they 

are to meet the challenges posed by the much narrower band. 

 

 Several microwave manufacturers are currently developing these products and are expected to 

meet the January 1, 2000 FCC deadline for the first change in the BAS band structure. But the 

cost of such conversions at today’s prices is staggering.



Dr. John Payne, president of Nucomm, a microwave systems manufacturer located in 

Hackettstown, N.J., notes that "an analog system that handles one video and two, four or six 

audio channels sells for about $25,000 per link.  But a comparable system that utilizes a digital 

codec (an encoder and decoder combination) and digital modulation scheme would cost about 

$93,000 per link." (see chart)



The price difference between the two is primarily due to such things as the redesign of 

modulation and amplification circuitry, the desired data rate output and the cost of proprietary 

MPEG-2 compression codecs.  But this near quadrupling in price for a single RF link is mainly 

attributed to the cost of the codecs themselves.



A single-channel codec that uses MPEG-2 compression with a bit rate of up to 15 Mbps and a 

4:2:0 sampling rate costs between $40,000 and $60,000.  Codecs with bit rates above 15 Mbps 

that sample at 4:2:2 cost considerably more.



Thomas Kavulic, accounts manager for RE America, a codec manufacturer based in 

Copenhagen, Denmark, says that codecs "are really high in price because the (terrrestrial) 

markets are not mature enough. But existing prices for a single-channel system are down from 

over $100,000 not too long ago."



So can we expect to see lower prices as broadcasters convert their systems from analog.  "Yes," 

say Kavulic, "but only when the market is there. Our focus is to manufacture compression 

engines and integrate them into new products with microwave manufacturers."



One of the problems that codec manufacturers face is that virtually all of the codecs on the 

market today have been manufactured for use by satellite distribution systems. 

 

"Terrestrial microwave paths experience selective frequency fading due to multi-path 

reflections," Paynes notes. "this type of fading is not present in satellite paths.  Multi-Path is 

usually severe because of low antenna height, small antenna size and the proximity to buildings 

and other objects." 



For ENG applications, users will be intentionally bounced off of a distant building or other 

structure due to the lack of a clear line-of-sight to the receive antenna.  Extreme fading often can 

also occur due to multi-path reflections from moving automobiles, airplanes or even helicopters.



But the high cost of making digital transmission systems is shared by microwave system 

designers as well.  Microwave equipment manufacturers will have to modify their systems to 

account for these transmission anomalies.  Forward Error Correction (FEC) and "adaptive 

equalization" circuitry must be added to or enhanced in their products if they are to be used in 

ENG applications.  This obviously adds to the cost of the product.



And unlike analog power amplifiers which run in saturated mode, digital systems must be 

operated in linear range and have a flat amplitude response over its bandwidth.  Such amplifiers 

are less efficient and can be more costly to manufacture.  



As such, broadcasters will have to insure that their antennas and feed horns are in good 

condition and not "out of round." Dishes with dings and bent feed horns will add reflections within 

the antenna feed system itself.   Payne warns that "this will have the same effect as multipath. 

I'd say overall a voltage standing wave ratio (VSWR) of less than 1.015:1 should be maintained."



But even cheaper codecs and less pricey transmission equipment may not ease the pain for 

many broadcaster who face the prospect of having to replace fully functional ENG, STL, and ICR 

links simply to meet the tighter restrictions imposed by the budget bill.