Day Sequerra has updated its M2.0 HD modulation monitor, adding some nice and very useful features. I first reviewed the original M2.0 in Radio magazine in May 2006, and the new M2.2R model is an attractive piece of test equipment that will likely go in your facility where it can be seen by you and others.
Two rows of blue LEDs that correspond to demodulated audio make it very interesting to look at. The front panel is very clean and all local control is accomplished via a set of 10 push buttons located thereon. “Tuner band” selects the AM or FM band; “Presets” of course allows one to go to one of 20 presets for each band. Tuning is done by two buttons (one labeled up and one down). After one selects the band, and tunes to the station needed, the receiver will indicate whether or not there is an HD Radio signal present with three blue LEDs also on the front panel. These three LEDs are HD locked, multicast and delay set, which corresponds to the time alignment between the main (analog FM) audio and the MPS.
If the receiver is locked on a station with an HD Radio signal, then using the Mode-service button on the front panel will allow the user to go back and forth between MPS and SPS-1 (known to some as HD1 and HD2). Holding down the Mode-Service button for five seconds will force the radio to stay on the analog signal; in this mode, the two rows of blue LEDs indicate demodulated L and R audio, while the lower LED bar graph indicates main carrier modulation (up to 125 percent so that AM positive peaks can be read).
When the receiver is locked to the MPS (or HD1), pressing the Forcing button will make the receiver display the analog audio in the top blue LED row and the digital audio in the lower row. The left channel audio out will correspond to the analog, and the right channel the digital — including the front panel headphone out. This facilitates the adjustment of the time delay between the analog FM signal and the MPS.
Performance at a glance
Analog and digital demodulator and modulation monitor
High-level and antenna inputs for both bands
LED bar graph level indicators
2RU steel chassis
Balanced analog XLR and AES3 outputs
Six alarm relays
Multiple measurement capability
When the receiver is forced into analog, pressing the data-display button will make the receiver display RBDS data on the vacuum fluorescent display; in MPS mode, the VFD will display the MPS PAD; in SPS mode, the VFD will read SPS PAD.
One feature that is now standard in the M2.2R is the ability to read pilot injection, RBDS injection, and 67 or 92kHz injection levels, giving it nice functionality as a piece of test equipment. It also has the ability to read synchronous AM noise. I found the front panel controls to be simple and very easy to learn.
Another standard feature of the M2.2R is the Performance Loss Monitor. A set of six relays allow the unit to signal the outside world when it detects loss of carrier, loss of audio, loss of OFDM lock (i.e., loss of digital signal), loss of RBDS data, loss of PAD and a choice between loss of multicast (MC) or delay bit. All of these alarms are configured by the same front panel buttons, and are accessible via a high-density DB15 located on the rear panel.
Remote Dashboard is Day Sequerra's proprietary software used to remotely control the M2.2R. This of course means that you need to install this application on a computer, and connect to the M2.2R by a LAN or, if the unit lives at a transmitter site, a LAN extension or WAN connection. The Dashboard provides the ability to remotely change channels on the receiver, and if HD Radio is available, the ability to re-assign the audio outputs from either analog or digital in the case of AM, or analog, MPS or SPS in the case of FM. The dashboard has 50 presets for AM and for FM as well; it also allows you to set up alarms that correspond to RF levels, analog, MPS or SPS audio. These alarms are separate from those mentioned earlier; the user is alerted to their presence by the GUI, or via e-mail. I should also note that these alarms correspond to the service the radio is tuned to at the time of the alarm: either analog, or MPS or SPS-1.
When a remote control session is in place, the VFD will read remote connection and each of the front-panel controls is locked out. This obviously prevents a local user from disturbing a remote user session. The unit's front panel LED displays still indicate the demodulated audio levels while the unit is remotely controlled.
Dashboard also allows the user to remotely look at either the decoded MPS or SPS-1 PAD data, which can also be logged (on the client computer) should the user want to do so. There is no indication of modulation or audio levels on the Remote Dashboard GUI, and therefore the majority of users will likely locate this modulation monitor in an area frequented by engineering personnel.
One of the best features of the M2.2R is the quality of the audio — especially noticeable with the demodulated HD audio. The lack of a good modulation monitor and HD Radio test equipment in general was a bit of a handicap when I first started putting HD Radio stations on the air; we had to cobble together car radios attached to outboard silence sensors. The Day Sequerra M2.2R not only addresses those early issues but also gives the broadcast engineer a powerful tool in the quest to make the best use of this new technology.
Irwin is the chief engineer of WKTU-FM, New York City.
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