RF category

Bluetooth Smart module is only 11x8x1.8mm

By Julien Happich @ eedesignnewseurope.com:

Amber wireless GmbH’s AMB2621 Bluetooth Smart module is a 2.4 GHz BLE wireless module based on the Bluetooth Smart 4.2 standard, measuring only 11x8x1.8mm and offered with or without integrated antenna.

Siglent SSA3032X Spectrum Analyzer Review & Experiments

Afroman reviews Siglent’s SSA3000X series spectrum analyzer and all the options. There is some RF information for beginners and usage experiments are also performed.

Siglent SSA3032X Spectrum Analyzer Review & Experiments [Link]

Send & Receive Radio With A Single Chip

Fitting transmit and receive capabilities of radio signals into one device may be impossible without using a significant filter, which is needed to isolate sent and received signals from each other.

The major obstacle to achieve that is the weakness of the received signal compared with the much stronger transmitted signal. However, researchers from Cornell University found their way to jump over this obstacle and created a two-way transceiver chip.

Alyosha Molnar, associate professor of electrical and computer engineering (ECE), and Alyssa Apsel, professor of ECE, had come up with a new solution to separate the signals. They made the transmitter consist of six sub-transmitters hooked into an artificial transmission line. Each one sends a weighted signal at regular intervals which combined with others such as a radio frequency signal in the forward direction, and at the same time they cancel each other in the opposite direction (towards to receiver).

The programmability of the individual outputs allows this simultaneous summation and cancellation to be tuned across a wide range of frequencies, and to adjust to signal strength at the antenna.

“You put the antenna at one end and the amplified signal goes out the antenna, and you put the receiver at the other end and that’s where the nulling happens,” Molnar said. “Your receiver sees the antenna through this wire, the transmission line, but it doesn’t see the transmit signal because it’s canceling itself out at that end.”

This research is based on a research reported six years ago by a group from Stanford University, which demonstrated a way for the transmitter to filter its own transmission, allowing the weaker incoming signal to be heard.

One of the sub-transmitter concept enhancements is that it will work over a range of frequencies, and instead of using a filter for every band, signal separation can be controlled digitally.

“You could have a single device that can be anything,” Apsel said. “You wouldn’t have to buy a new piece of equipment to have the newest version of it.”

You can find the full research at the IEEE Journal of Solid State Physics.

RFM69 output power

Bob @ electrobob.com tipped us with his latest article about RFM69 module.

As I was mentioning in my 1000.1000 Hardware selection, I have opted for the cool RFM69HW radio module. Weirdly enough, in quite a few sources (big distributor and ebay) the higher power HW module is cheaper. So there ie no reason not to get the higher power module, given quantity discounts. But I want it to operate at lower power most of times. The datasheet does not show any differences at lower power, so I had no reason not to go for the higher power module. It even says so on the features list on the front page, I can turn the power down to -18dBm.

RFM69 output power – [Link]

Teardown and analysis of microwave (26.5GHz) electro-mechanical step attenuators

Teardown and analysis of microwave (26.5GHz) electro-mechanical step attenuators from The Signal Path:

In this short episode Shahriar takes a close look at a pair of Hewlett Packard microwave electro-mechanical step attenuators operating up to 26.5GHz. Mechanical attenuators offer excellent repeatability, low insertion loss and nearly limitless linearity. The teardown reveals that the construction of both modules is very similar on the microwave path. In fact, the lower-frequency model still uses the same attenuator components. The newer model employs electronic control circuity while the older generation attenuator uses purely mechanically controlled DC path. Both models use a solenoid style actuators for step attenuation control.

Teardown and analysis of microwave (26.5GHz) electro-mechanical step attenuators – [Link]

NUT4NT, Open-Source 4-Channel GNSS Receiver Development Board

Although the industry of professional satellite navigation systems is limited to experts and large companies, Amungo Navigation is working towards bringing this industry to individual developers, small companies, and startups through its new open source platform NUT4NT.

NT1065 chip
NT1065 chip

NUT4NT is a development board which implements NT1065 chip with USB 3.0 interface. NT1065 is a Global Navigation Satellite System (GNSS) receiver designed by NTLab, a fabless microelectronic company. It is the first low-cost low-power RF front-end solution in the world. It also has 4 channels supporting all GNSS systems and bands.

GNSS receivers are electronic devices that receive and process signals from a GNSS satellite. These signals used to provide information about receiver’s position,velocity, and time.

NUT4NT has two different working modes. The first uses dual inputs and acts as a centimeter level precision positioning tool, without the need of high quality antenna. The other mode uses the four inputs and provides an array antenna processing system to simply reduce interference and noise.

Dual Inputs Mode (Left) - Four Inputs Mode (Right)
Dual Inputs Mode (Left)   –   Four Inputs Mode (Right)

Hardware and software specifications of NUT4NT:

  • Receiver chip: NT1065
  • USB 3.0 controller: CYUSB3014
  • Clock rate: 10 MHz
  • RF inputs: two or four, depending on board option
  • RF inputs referred Noise Floor: 1 dB
  • ADC resolution – two-bit
  • ADC frequency – up to 99 MHz
  • Samples transfer – continuous full stream, from 20 to 100 Mbytes/sec
  • Power: 5V @ 0.5 A from USB or external adapter
  • Size: 70x50x20 mm (early board) / 77x122x25 mm (single board)
  • All GNSS systems: GPS, GLONASS, Galileo, BeiDou, IRNSS and future
  • All GNSS band: L1/L2/L3/L5, G1/G2/G5, B1/B2, E1/E5 and future
  • Four-channel synchronous reception for antenna array processing
  • Signal dumper (grabber) software
  • Spectrum analyzer software
  • NT1065 configuration software
  • Supports libusb API
  • Supports native Cypress driver API
  • Software for Windows, Linux, and potentially all other OS’s with libusb

There are two options of NUT4NT boards, the Early Board and the Single Board.

Early Board is for $399 and there are only limited boards to order through the crowdfunding campaign page. It consists of two separated boards: the base board, which has the USB 3.0 controller, and NT1065 submodule board.

Single Board will be available later as a future plan, and it is said to have  only one board instead of two.

NUT4NT Early Board
NUT4NT Early Board

NUT4NT is an open source project. Software sources are available on github and the hardware’s documentation will be available soon.

More information and details about the product with many accessories are reachable on the product crowdfunding page.

VHF Frequency Counter with PC Interface


Scott has published a new build:

This is the general idea behind how this frequency counter works. It’s so simple! It’s entirely digital, and needs very few passive components. sn74lv8154 is configured in 32-bit mode (by chaining together its two 16-bit counters, see the datasheet for details) and acts as the front-end directly taking in the measured frequency.

VHF Frequency Counter with PC Interface – [Link]

Image courtesy of Google

Everything You Need To Know About Bluetooth beacons in A White Paper

Image courtesy of Google

Bluetooth 4.0 introduced the Bluetooth low energy (BLE), which is a version of Bluetooth protocol designed for devices with power constraints like battery powered sensors. Bluetooth low energy beacons are BLE (Bluetooth Low Energy) enabled devices, they repeatedly broadcast radio signals to nearby smartphones, containing a small amount of data.
Mobile apps can listen to the signals being broadcast and trigger an action after analyzing beacon’s information.

Beacons are used for proximity-aware applications like positioning and navigation indoors like anti-lost tracking tags, another application is for location based advertisements.

There is no official Bluetooth Special Interest Group (SIG) beacon standard, so beacons have pseudo-standards. For example, iBeacon standard is used by Apple and Eddystone is used for Google.

Apple iBeacon Advertising Packet
Apple iBeacon Advertising Packet

As you can see in the above image, there is one byte (power) value indicating the iBeacon’s calibrated output power in dBm measured at a distance of 1 meter.
So Beacons can be used to calculate the proximity distance between the beacon and the receiver of beacon’s information. This calculation relies on a comparison of a Received Signal Strength Indicator (RSSI) to a beacon’s transmit (Tx) power to approximate the distance to the beacon.
The calculated distance can’t be very accurate, since RF signals fade unpredictably according to real-world environmental factors like walls. Future versions of BLE will solve this by using Angle-of-Arrival (AoA) and Angle-of-Departure (AoD) which allow a multi-antenna Bluetooth device to accurately determine the spatial location of another Bluetooth device.

Beacons typically use non-connectable advertising, providing all of useful information in the advertising packet itself. So the radio can be shut off immediately after advertising hence this will save power.

A white paper from Silicon Labs covers a lot of informations about Beacons. The paper examines beacon applications, provides a short description of how BLE work, contains further description of iBeacon and Eddystone standards and highlights SoC solutions for BLE from Silicon Labs such as BLE112 and BLE113 which can have fully standalone applications through a simple scripting language called BGScript developed by Silicon Labs.

BGScript iBeacon example code for the BGM111 Bluetooth low energy module
BGScript iBeacon example code for the BGM111 Bluetooth low energy module


Developing Beacons with Bluetooth Low Energy (BLE) Technology

Beacons: Everything you need to know

Reading “Getting Started with Bluetooth Low Energy by Kevin Townsend, Carles Cufí, Akiba, and Robert Davidson (O’Reilly)” is advisable for anyone like to know more about who BLE works which is a corner stone to understand how beacons work.