Doug Lung /
04.20.2012 02:30 PM
RF Test Equipment at the 2012 NAB Show

While I didn't have time to do an extensive search of RF test equipment at the 2012 NAB Show, I found a few items I think will be of interest to broadcasters.

The Rohde & Schwarz ETL TV analyzer has become the standard for TV transmitter performance measurement and fine tweaking of exciter correction. The wide dynamic range of its spectrum analyzer allows it to be used for FCC Proof of Performance measurements. The price, however puts it out of reach of many smaller stations, especially when ordered with all of the measurement options such as MPEG signal analysis and network analyzer. At the 2012 NAB Show, Rohde & Schwarz introduced the ETC Compact TV analyzer. It looks like a compact ETL, with spectrum and signal analysis, but without all of the options available for the ETL. I don't think Rohde & Schwarz has set a U.S. price for it, as the estimates I heard ranged from one that would make it very attractive compared to the ETL, to a price which would make it more expensive than an ETL with the same or even more features. I would expect the lower price is the correct one, since the product sheet says "Economical TV transmitter testing."

If even a bare-bones R&S ETL is out of the question, I found an analyzer from Unique Broadband Systems, located in the same booth as Axcera, which allows remote monitoring of a DTV signal over a network at a fraction of the cost of an ETL or ETC. Among other things, it provides a true MER/SNR measurement as well as shoulder level measurement to an accuracy of 1.5 dB. While I wouldn't trust it for exciter adjustment, it provides a good way to verify adaptive correction circuitry is working properly and, if automatic correction is turned off, it will catch increasing MER/SNR in transmitters before it affects reception. Once an ATSC version is available, I'll cover its performance and capability in a future RF Technology column. To view information on the transmission analyzer, you will need to download the full UBS catalog [PDF].

I hadn't looked at power meters and antenna analyzers for a while and I was impressed with the devices I saw at Anritsu and Bird Electronics. While neither is specifically targeted at broadcasters, they provide enough capability to check antennas, tune IOTs and possibly tune filters at far lower cost.

Bird showed their SignalHawk series of analyzers at NAB. I liked the 4.5 pound compact SH-36S-PC, which is compact enough to throw in your carry-on bag. It provides all the functions I use most often in my 10 year old Anritsu analyzer that requires a 70 pound travel case at a fraction of the cost.

You have to move up to Bird's Site Analyzers to get antenna measurement capability. The Anritsu Site Master offers some additional measurement options as well as spectrum analyzer capability. Features vary between the two manufacturers' products, as well as price. Review the specifications to see which would work best for you.

These units won't replace a network analyzer, which can cost several times what the most expensive antenna analyzer from Anritsu or Bird costs, but they will allow you to see how your antenna is performing, make measurements to track any changes, and include a frequency domain reflectometer (FDR) to provide a way to identify bad components in a transmission line or antenna input. Newer antenna analyzers have interference rejection, which allows antenna measurement even when there is a signal on the same channel.

Anritsu and Bird aren't the only companies offering spectrum analyzers with antenna measurement capability. You will find similar products from Agilent and Rohde and Schwarz, to name two.



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1.
Posted by: Anonymous
Fri, 50-20-2012 07:50 PM Report Comment
Doug - The ETC does look like a viable candidate for 8-VSB if it had the needed firmware but presently it does not support that signal standard. In talking to Vandy ENG R&S Asia Product Manager at the R&S booth, she said that presently the ETC goes for around $18K but is presently suitable for DVB-T, DVB-T2, ISDB-T and other European and Asian standards but not presently the US standard. She said that it is an FPGA based unit as is the ETL. The big difference that I could find is that the ETC OS is running a Linux based solution were as the ETL is running Microsoft XP Embedded based solution. You are correct in that the ETL is a lot more expensive (~$38k or more depending on options) and has a lot of capabilities which not all would be used in the USA. Something of interest is if the ETL had other firmware made for it that it most likely could be used in the AM and Shortwave broadcast venues beside the FM and TV venues that it is presently running. The ETL is really a great unit and really works very well for what it does. The EFA is even better for DTV transmitter work since it has better specifications than the ETL, but both are definitely out of the question for stations in the smaller markets or for most all independent contractors and service persons. The ETC would be the better solution for the smaller markets as well as the independent contractor folks if R&S decides to support the US market standard and is able to keep the expected ~$18k price. It's specs are a little less than the ETL but are more than adequate for DTV transmitter maintenance. The ETL or even the ETC would be an upgrade for folks with the obsolete Tektronix RFA-300A or even the very old HP-89441V. Pat N7QE




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