HD Radio: Proving Performance with Modulation Error Ratio


        Radio on FacebookJoin us on Facebook

Low MER can actually decrease the coverage area of the IBOC transmissions, and especially for AM (according to the webinar) it can make the receivers in the field take longer to lock on the IBOC data, as Table 1 shows. Interference from MER and noise add linearly at the receiver. A standard Exgine signal has MER of 17-18dB using iBiquity PAR.

Data Carrier MERReduction in Service Contour
24dB0.05dB
22dB0.09dB
20dB0.14dB
18dB0.22dB
16dB0.31dB
14dB0.48dB
12dB0.74dB
10dB1.13dB
8dB1.79dB

Table 1. The effects of MER on FM reception.

An MER of 14dB or better is the standard for what is considered acceptable by iBiquity.

The MER of the inner partitions can be negatively affected (i.e., reduced) by components in the analog transmission as well. Stations using the MP3 mode (which you would use to broadcast HD3 for example) could inadvertently have their HD coverage compromised to some extent by the inclusion of high frequency SCAs. Figure 6 shows this.

Figure 6. Effects of increased modulation index. Click to enlarge.

Figure 6. Effects of increased modulation index. Click to enlarge.


Note that the MER for the inner partitions degrades as the baseband is loaded with more signals. A stereo subcarrier alone will affect IBOC quality. Traditional subcarriers primarily affect the MP3 partition, but can affect the MP1 as well.

Harris Broadcast will add MER measuring capability inside its new line of Flexiva exciters and transmitters after the introduction of the Generation 4 Exgine this coming December.

Broadcast Electronics provides an MER output via its IP interface for its VPe system; however, the company is still in the process of verifying how it compares to the NRSC standard (derived from the iBiquity paper). It is also in the process of developing software to verify MER per the NRSC standard, which is independent of the modulation equipment.

Aside from the more complex high-level measurements taken at the transmitter site, you will need devices at your studio location (or some other spot where reception is optimum) to keep track of the day-to-day aspects of your IBOC transmissions. Fortunately there are quite a few devices available.

- continued on page 4



Acceptable Use Policy
blog comments powered by Disqus

[an error occurred while processing this directive]

Today in Radio History

Milestones From Radio's Past

The history of radio broadcasting extends beyond the work of a few famous inventors.

Digital Edition

Each Issue as a Digital Edition

Read each issue online in our Digital Edition Format in your Web browser.

EAS Information More on EAS

NWS XML/Atom Feed for CAP Messages

The feed provides feeds for all US states and territories.

Wallpaper Calendar

Radio 2014 Calendar Wallpaper

Need a calendar for your computer desktop? Use one of ours.

The Wire

A virtual press conference

Information from manufacturers and associations about industry news, products, technology and business announcements.

Join Us Facebook Twitter YouTube LinkedIn
Radio magazine cover

Current Issue

“Free Beer” and “Hot Wings” in the Morning

Townsquare Media's WGRD builds a new studio for their syndicated morning show including video

Browse Back Issues

[an error occurred while processing this directive]