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Dec. 19, 2011 MU-D1-R 915 MHz
Circuit Design, Inc. Newsletter
In this issue

A new radio module with 300 m communication range in the US license-free band

A new radio modem has been released for the US market with the same commands as the modems which are already available in the Japanese and European markets. The modem, called MU-D1-R, operates in the US license free band and complies with FCC Part 15.

In order to achieve 300 m communication range in this band, the modem has a true diversity receiver function with two receiver circuits. It prevents signal dropout and provides reliable long communication. Although many true diversity receivers tend to be large, the MU-D1-R is compact at 36 x 26 x 8 mm and it even works with batteries.

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Technologies for reliable performance

1. DSSS (Direct Sequence Spread Spectrum)
The MU-D1-R uses noise-resistant direct sequence spread spectrum communication as it operates in the license-free 915 MHz ISM band, which is used by various kinds of equipment. Moreover, it provides 20 frequency channels and it enables several modules to operate at the same time.

2. True Diversity Receiver
The MU-D1-R contains two receiver circuits. Receiving signals using two receivers with two antennas which are over 1/2λ apart from each other prevents signal dropout due to multi-path fading, which is characteristic of radio.

The MU series corresponds to the worldwide sub-GHz band

The embedded modem MU series is able to input/output with simple commands and the main commands are common across the MU series. The MU series comprises the MU-D1-R, MU-1 and MU-2. The MU-1 and MU-2 are provided in 434 MHz and 429 MHz types for the European and Japanese markets. The European version of the 434 MHz type meets the requirements of European R&TTE and the Japanese version of the 429 MHz type complies with Japanese ARIB-T67, so you do not need to obtain extra certification any more.


Compared to the MU-1 and MU-2, the MU-D1-R has a much higher data rate. On the other hand, it has lower communication range. Besides telecontrol applications, the MU-D1-R is highly recommended for stable, medium speed data transmission with battery operation. If you intend to expand into the European and Japanese markets, the MU series is the ideal modem to achieve this.

Tea break

Already it's December. "Time and tide wait for no man." There's an old Japanese proverb "kouin yanogotoku". Translated directly into English, it's "Time flies like an arrow".

At this time of year, many people regret the time that they've spent idly. Have you spent your time wisely this year? For me, it was a year that made me think hard about life.

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