IN MY OPINION

Interconnect Advances Fuel Technology Growth
By Orwill Hawkins, Vice President of Marketing, LadyBug Technologies

With increased frequencies, higher data rates, and lower noise levels, the microwave industry serves as a leader in technological capability. Demand for quality interconnects has increased right along with other higher-performance areas in the industry.
Read More...

MILITARY MICROWAVE DIGEST


MMD March 2014
New Military Microwave Digest

ON THE MARKET


E-Band Active X5 Multiplier
Model SFA-743843516-12SF-N1 is an E-band X5 active multiplier with center frequency at 79 GHz with minimum +/-5 GHz operational bandwidth. It converts 14.8 to 16.8 GHz/+5 dBm input signal to deliver 74 to 84 GHz frequency band with more than +16 dBm power.
Sage Millimeter

Hand-Flex™ Coaxial Cable
Covering DC to 12.5 GHz, this 8” coaxial cable, 141-8SMNB+, has a bulkhead Female Type-N connector at one end and SMA-Male at the other. Features include low loss, excellent return loss, hand formable, and an 8mm bend radius for tight installations.
Mini-Circuits

Phase Trimmer Series
This new phase trimmer series is designed for RF applications where phase match between two cables is needed for proper system performance. Phase trimmers, offered from DC to 50 GHz, will give an accurate phase adjustment over a specified frequency range.
RLC Electronics

Planar Monolithics Industries
Model PTRAN-100M18G-SFB-3UVPX-MAH is a transceiver covering the frequency range of 100 MHz to 18 GHz. The transceiver fits into a 3U Open VPX form factor utilizing the high speed VITA 67 RF connector.
Planar Monolithics Industries

SMT High-Power Attenuators
Now available with full design support capabilities are three new SMT high-power attenuators from Anaren. These 30 to 50W devices are high-performance, high-power chip attenuators covering DC to 3.0 GHz and feature high return loss and small footprints.
Richardson RFPD

See all products in this issue


July 2007

Wireless Short Range Devices and Narrowband Communications
By Conor O’Mahony, Applications Engineer, Analog Devices


Introduction
The term “Short Range Device” (SRD) covers radio transmitters which provide either unidirectional or bi-directional communication and which have a low capability of causing interference to other radio equipment. Due to the many different services provided by these devices, there is no exhaustive list covering the SRD application space, however, the following categories are amongst those covered:

• Telecontrol for Home/Building Automation Systems
• Automatic Meter Reading
• Wireless Sensor Applications
• Medical Telemetry
• Alarms
• Automotive, including Remote Keyless Entry & Remote Car Start Applications

When designing a SRD wireless system, careful consideration needs to be paid to the choice of frequency on which your radio will be communicating over and also the specified frequency plan required by the regulations in that particular region. Many of the worldwide regulations governing SRDs stipulate narrow communication channels, which significantly limits the transmit bandwidth (to 25kHz or less) and thus, the maximum data throughput.

Historically, for such applications, discrete transmitters and receivers would have been used to meet the difficult performance requirements needed in such narrowband applications. However, in recent years, fully integrated radio solutions like the ADF7021 are providing similar or better performance than discrete solutions at a fraction of the cost and size.

Narrowband Communications
Why Choose Narrowband?

In many cases, the radio regulations in a particular region will stipulate that communication channels have to be narrowband. A narrowband channel is generally defined as a channel bandwidth = 25 kHz. Such narrow channelizations are needed in many cases due to a lack of bandwidth and so, there is a need to fit as many channels into a given bandwidth as possible. For example, in Japan many of the ISM bands are less than 1MHz. Table 1 lists the four main worldwide regulations covering narrowband short range communications and describes the various RF operating frequencies and channel spacings.

Narrowband Performance Specifications
Due to the narrowband nature of the channels, there are various difficult specifications to meet for both transmit and receive. A description of some of these specifications is given below:

Transmitter Specifications
• Adjacent Channel Power (ACP): The amount of spectral energy leaking into adjacent channels
• Frequency Drift: The amount the transmitter will drift from its nominal operating frequency
  under extreme test conditions (voltage and temperature)
• Spurious Emissions: Emissions at frequencies other than those of the wanted carrier
  frequency and its sidebands

Receiver Specifications
• Adjacent Channel Rejection (ACR): The ability of the receiver to reject an interferer located
  in an adjacent channel
• Blocking: The ability of the receiver to reject out of band interferers (usually at 1- 10 MHz)

ADF7021:
The Narrowband Solution

The ADF7021 is the only available solution that covers all of the various sub 1 GHz worldwide narrowband operating frequencies. It is a low power, highly integrated BFSK/3FSK/4FSK transceiver designed for operation in the narrowband license-free ISM bands and licensed bands in the frequency ranges 80-650 MHz and 862–940 MHz. It has both Gaussian and Raised Cosine data filtering options to improve spectral efficiency for narrowband applications. It is suitable for circuit applications targeted at European ETSI-EN300-220, the Japanese ARIB-T67, the Chinese Short Range Device regulations and the North American FCC Part 15, Part 90 and Part 95 regulatory standards.

It provides excellent sensitivity, as low as -125 dBm at 1kbps, which adds several dB to the link margin and as a result, increases communication range. A low IF architecture is used in the receiver (100 kHz), minimizing power consumption and the external component count while avoiding interference problems at low frequencies. The IF filter has programmable bandwidths of 12.5 kHz, 18.75 kHz and 25 kHz. The ADF7021 supports a wide variety of programmable features, including Rx linearity, sensitivity, and IF bandwidth, allowing the user to trade off receiver sensitivity and selectivity against current consumption, depending on the application. A detailed block diagram of the ADF7021 is shown in Figure 1.

The ADF7021 has several features which aid in meeting various regulatory standards. To mitigate against spectral splatter when turning the Power Amplifier (PA) on and off, there is an automatic PA ramp feature, which has eight programmable settings. There is an automatic frequency control (AFC) feature, which allows real time tracking of a frequency error in the received signal for a maximum ±50 kHz error, thus allowing the use of low cost crystals. A summary of the ADF7021 specifications is given in Table 2.

To aid in meeting the difficult transmission masks and ACP specifications of narrowband regulations, the ADF7021 supports Gaussian and Raised Cosine data filtering and advanced modulation schemes like 3-Level FSK and 4-Level FSK. These features greatly increase the amount of data throughput that can be achieved in the narrow transmission bandwidths. Figure 2 highlights the use of Gaussian and Raised Cosine filtering in meeting a particular transmission mask in a narrow band application.

ANALOG DEVICES
www.analog.com
TXTLINX.COM101
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FROM WHERE WE SIT

Uncertain Times for DefenseIn Defense of DARPA; Lamenting Bell Labs
By Barry Manz

A federal agency like DARPA is a sitting duck for politicians and assorted other critics. It has come up with some truly bizarre programs over years that ultimately either delivered no tangible results, were canceled before they could cause any damage, or attempted to answer questions that nobody was asking or needed answers to. Read More...


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