Last summer I was in Phoenix, AZ, commissioning an HD Radio installation when I received a call to assist another engineer repairing a transmitter. During the repair he showed me an early version of the Microgen FM analyzer. I was impressed and decided to research the product when I returned to Tulsa, OK. The result of my research: I added the TS9080 to my collection of test equipment.
Unlike most contract engineers, I carry a large assortment of RF test equipment, i.e. E4402B spectrum analyzer, IFR COM 120C service monitor and more. The 4402 will accurately measure absolute peak deviation and all the harmonics, the COM 120 will monitor deviation, transmitter frequency and more. But I was still unable to see key information to fine-tune FM transmitters. The Microgen TS9080 allows an engineer to peer deep inside the integrated parts of the FM Stereo carrier.
Put to use
The TS9080 continuously decodes RBDS with more information that you knew was there, a division histogram, and displays modulation power over a time period. It has an audio baseband spectrum analyzer from 0-100kHz, a peak deviation monitor, stereo monitor with an oscilloscope view of left and right channels and a XY scatter display showing stereo quality similar to a vector scope.
|Performance at a glance|
Digital phase FM demodulator
User programmable input gain control
BNC IF 10.7MHz input and output
Ilog remote control software
The TS9080 displays a multipath XY plot for signal integrity. It displays pilot in percentage or kilohertz, RBDS in percentage or kilohertz, and signal strength in multiple settings. Personally I would prefer decibels. The unit also has a balanced left and right audio output, which is perfect for the Tektronix Vector scope, and a stereo headphone output. It will also provide computer stereo output via the USB control cable. All of these readings can be taken through the receiver.
It has a total of four inputs: an FM receiver, multiplex input, analyzer input (ability to look at composite signal before applying it to an exciter) and 10.7MHz input. The Microgen software works great with my laptop and desktop computer. The unit can be used to monitor multiple sites and provide an external alarm if there is a failure. Scans of the market will display call letters or slogans if they are sending RBDS. These ‘scans’ can also be saved as setups for future measurements.
The software side
Each section of the computer display has a copy button. This takes the image of that section and places it on the Windows clipboard. From here it can be pasted into a document to provide a permanent record or report for a client. Since screen resolutions of computers vary, with lower resolutions some of the detail screens are not displayed. These are available through on screen buttons and will pop up over the main screen. So while your particular computer may not display everything at once, it is all there.
The software also lets you save short recordings on your computer. When played back, they display the data as if live.
In my shop, I have run the TS9080 through multiple tests and found it to be more than acceptable. Testing the unit with the E4402B and COM 120C I have found the unit to be very accurate.
The analyzer's data is clearly displayed with the included Ilog software.
While it works well right out of the box, I have learned its deviation should be field calibrated to be extremely accurate. This is a simple procedure. The calibration resides in the computer not the unit itself. It must be calibrated for each PC. I use the second Bessel null of 13,587kHz method to complete my calibration.
Once calibrated it is ready to use; keep in mind that the most accurate readings are taken from the transmitter sample port. Don't forget to check the sample port's power output or this could be a short trip. Always start with 40 to 60dB of attenuation between the port and the Mircogen unit; it works best at about -20dB. When using an antenna, extremely low multipath of less than 1 percent gives the best readings (the lower the better).
The unit can also be used from the studio to monitor your station as well as others in the market. While most FM antennas work and provide adequate results, I would recommend using a high-gain in-band beam antenna to reduce multipath. If you are going to monitor other stations, you would also need a rotor to turn the antenna toward the transmitter sites. Multipath can and is most often the cause of inaccurate remote readings and the Microgen will provide that information.
In the FM world it is important for a multitude of reasons to accurately set the pilot, RBDS and audio levels. Station product quality is a must in today's markets.
The TS9080 is manufactured in England by Microgen Electronics. The unit is powered by the USB port on the computer. It measures 5.8"×1.4"×11.6" and weighs only 2.43 pounds. It is small and light enough to carry in a laptop bag. The software is supplied on CD-ROM with free updates from the Microgen website.
I give the Microgen TS9080 100 percent thumbs up. It is an outstanding test tool and a must for serious engineers.
Diehl is the president/owner of RF Solutions, LLC, Tulsa, OK. Microgen products are distributed in the US by Sierra Multimedia.
Note: Since the release of the TS9080, Microgen has added features and also offers the TS9085.
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