Field Report: Inovonics INOmini 632

April 1, 2012

One surprisingly challenging issue with operating HD Radio technology, especially using FM HD Radio multicast channels, is cost-effective and professional monitoring. There are elaborate devices, modulation monitors and test equipment that poll, sample and test HD Radio signals but there's been a great need for inexpensive, straightforward monitoring of the station's digital signals.

Inovonics INOmini 632

The need for this sort of monitoring made for one of the most anticipated products from the Radio magazine Pick Hits of the 2011 NAB Show: The Inovonics INOmini 632 FM and FM/HD Radio monitor/receiver. Although the unit was shown in the spring, Ibiquity certification took a little longer than expected. The reason is apparently related to some of the most useful and important features of the receiver.

The INOmini form factor is 1RU by 1/3 rack space width. The 632 is specifically designed to monitor FM HD Radio in professional radio station environments. The unit can demodulate analog and decode HD Radio (including multicast) channels. The front-panel display is a selectable readout showing frequency, channel, signal strength, left and right audio meters, RDS (PI, PS, PTY, RT and even RT+!) or HD Radio PAD (name, type, lname, artist, title). The audio output uses XLR males for analog and AES/EBU, and a 3-pin Phoenix connector with open-collector alarm outputs that indicate carrier loss, digital loss and audio loss.

The 632 is powered using an external supply. Using the parallel power jacks and a supplied dc jumper, up to three units can be daisy chained to help manage wall-wart congestion in equipment racks.

Performance at a glance
◊ Displays essential RDS and HD Radio PAD
◊ Analog and AES3 outputs
◊ Front-panel alarms and rear-panel tallies
◊ Receives FM analog and HD Radio broadcasts
◊ LCD screen and jog-wheel navigation

When I received the unit I did what just about any engineer would do: I opened the box, plugged it in and connected an antenna and a set of headphones. In fact even the manual anticipated that reaction: "If, like most of us, you've allowed youthful enthusiasm to override methodical procedure, you've either already figured out the 632 receiver menu for yourself, or you are ready to throw this unit under the wheels of a passing locomotive."

Open the box

- continued on page 2

This unit isn't coming close to a CSX line any time soon. As thoroughly articulated in the user's manual, the 632 is extremely simple to understand and operate. There's a single knob for navigation and control. Turn the knob to move a flashing cursor, press the knob to select, turn the knob to adjust, and then press again to set/exit. Receiver mode can be manually selected and "forced": analog stereo (blend or no blend), analog mono, HD-1, HD-2, or HD-3 all the way (theoretically) to HD-8. Considering that a very common implementation of FM HD Radio with multicast uses three digital channels, (HD-1 to HD-3), the INOmini size makes it so all an FM station's digital on-air channels can be monitored in a single rack space (and with a single power plug, but more on that later). For a small monitor, the 632 display can show an impressive amount of information. The normal, idle display shows the frequency, mode (FM:M/S, HD-1 ... HD-8), RBDS PI Code (raw and decoded per NRSC-4 specifications) when in analog mode and or name field on HD Radio mode. The small signal strength meter changes to a DQ (digital quality) meter in HD Radio mode.

When an alarm condition occurs such as the station losing the HD Radio signal, audio failure or carrier failure, the front panel flashes Low Signal, Audio Loss or HD Loss, and also triggers the appropriate alarm outputs on the rear panel. Even if the alarm outputs are not used, the flashing front panel should attract the attention of a passing engineer. Pressing the front panel knob mutes the display but the rear panel alarm remains triggered and will do so until the alarm condition is cleared (digital carrier, audio or analog carrier restored).

Beyond HD Radio

Although the device isn't specifically an RBDS or HD Radio PAD data analysis tool, the most common and visible RBDS Data and HD Radio PAD fields can be manually selected and displayed. If, for example you are tweaking RBDS transmission percentages, field padding, repetition rates, individual fields can be cleared and redisplayed. In FM analog mode, the PI code display even seems to clear and redisplay each time the receiver decodes the transmission. Even Radiotext + fields are displayed and there are similar pages for the similar HD Radio PAD fields (name, type, artist, title). These features are a big improvement over waiting for consumer RDS or HD Radio display time-outs and display refreshes. As stations get more sophisticated in how their HD Radio PAD and RBDS data is used, this can become a very useful feature for spot checks.

The carrier loss alarm trigger level is set immediately below the signal strength meter on the same display page. The audio loss (silence sense) alarm can be disabled or a delay can be set from 1-120 seconds. There's no adjustment for HD loss but the alarm will trigger if HD Radio mode is selected and after a delay of a few seconds after loss of digital signal.

Many of us have anticipated the release of the 632 ever since it was awarded a Radio magazine Pick Hit, but sale of the unit was pending certification by iBiquity. What made certification difficult was that certain features critical to HD Radio's success on a consumer level are actually limitations for professional equipment. Fortunately the 632 was licensed by iBiquity in January 2012 under a "limited certification" because of the following variances, specified in the unit's documentation:

? The Inovonics 632 displays only four characters of call sign (not all six characters as defined in the requirements.)
? The Inovonics 632 displays only 39 characters of artist (not 64 characters as defined in the certification requirements supporting the ID3v2.3 standard.)
? The Inovonics 632 displays only 39 characters of title (not 64 characters as defined in the certification requirements supporting the ID3v2.3 standard.)

◊ 800-733-0552

In addition the 632 is inhibited from blending to analog. This means the 632 is actually a real, honest-to-goodness air monitor for the digital channels. The receiver can be set to avoid the typical consumer analog stereo blend. I've excerpted the user's manual a couple of times. The excellent technical writing is worth recognition. For such a simple, easy-to-use device, the user's manual is exceptionally complete and accurate. For all this I thank Inovonics. There are two items I would like to see added. The selection between FM and HD modes is done from the idle display, however the FM stereo/mono/blend/no-blend selection is done a few pages away in the menus. It would be useful for the initial mode selection to be in one place: FM auto, mono, stereo, HD-1, etc., even if the blend setting were in a different menu location.

I would also like to see IP integration. Either an internal network connection or an optional, add-on device that would echo the alarm functions using SNMP, maybe even an email or SMS client to send alarms. It's likely that either of my desired features may not be possible within the reasonable price point offered for the monitor. The features above in no way detract from an otherwise excellent monitoring product for analog but especially for FM HD Radio channels.

For the use of cost-effective, dedicated HD Radio monitoring, the INOmini 632 is a problem-solver that I expect will become a fixture at stations nationwide very soon.

Thomas is vice president of engineering, Lincoln Financial Media, Atlanta.

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