Skip to main content

RF Shorts for March 10, 2014

Czech Republic DVB-T2 Tests Continue

Chris Dziadul reports on Czech Republic to test 4k DVB-T2. The Czech national transmission company, Ceske Radiokomunikace (Cra), received permission from the Czech Telecom Office (CTO) to continue DVB-T2 testing and has started the next phase of testing which includes transmission of 4K content and looking into possible interference to DVB-T2 reception from new LTE networks.

Mohu Channels Set-Top Box/Antenna Reviewed

Mohu recently launched a Kickstarter campaign for Mohu Channels.

Mohu Channels combines an antenna, TV tuner and Android-based Internet TV set-top box into one package along with an integrated program guide.

Tom's Guide has a detailed review of Mohu's new product in the article Mohu's TV Tuner Plus Streaming Video Box Hands On by Sean Captain. Captain seemed pleased with the tuner performance, writing: "Mohu brought along one of its popular flat antennas (without an amplifier) for the demo, which allowed the Channels box to receive most of the major network affiliates in good quality. That's no mean feat in downtown Manhattan, without a clear line of sight to a broadcast antenna (even though we were just a dozen blocks from the Empire State Building, where the major broadcasters have antennas.)"

Captain did have some complaints about the software. For example, the program guide data comes from individual TV stations, so it’s necessary to tune to each channel to fill the guide. He said Mohu was looking for a way to speed grabbing guide data. Off-air guide data is free, so Mohu doesn't have to charge a monthly subscription fee for the data. This is a major plus compared to some other devices. Captain concluded: "For people who already have a streaming video box, such as a Roku, it might be hard to switch from what they are already comfortable with. (Roku's universal search feature in itself may be just too much to give up.) But as cable and satellite TV prices keep rising, cord-cutting could grow, and Mohu's ability to bring in live network TV could soften the blow for switchers."

It seems to me one thing the box is missing is the ability to add a USB storage drive to record over-the-air content for viewing later. Perhaps we'll see that in a later version if the Channels Kickstarter is successful!

Do-It-Yourself Time-Difference Direction-Finding Antenna

When tracking down interference to TV reception or wireless microphone receivers, a directional antenna helps. One difficulty, though, is that they can be large or difficult to use if the pattern is too broad. described a TDOA (Time Difference of Arrival) Directional Antenna built by Byonics that uses two dipoles and a 555 timer switching between them to provide an audible signal that disappears when the two dipoles are receiving the same signal at the same time (broadside). The approach isn't new--comments on the Hackday page provide links for similar direction finding antennas as well as other ways to implement it--but it appears to be relatively easy to construct and it might be fun to test.

See the Byonics TDOA website for more information on Byonic's solution.

Comments and RF related news items are welcome. Email me at